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In radio communication, a ground dipole,^[1] also referred to as an earth dipole antenna, transmission line antenna,^[1] and in technical literature as a horizontal electric dipole (HED),^[1]^[2]^[3] is a huge, specialized type of radio antenna that radiates extremely low frequency (ELF) electromagnetic waves.^[4]^[5] It is the only type of transmitting antenna that can radiate practical amounts of power in the ELF frequency range of 3 Hz to 3 kHz.^[5] A ground dipole consists of two ground electrodes buried in the earth, separated by tens to hundreds of kilometers, linked by overhead transmission lines to a power plant transmitter located between them.^[1]^[5] Alternating current electricity flows in a giant loop between the electrodes through the ground, radiating ELF waves, so the ground is part of the antenna. To be most effective, ground dipoles must be located over certain types of underground rock formations.^[5] The idea was proposed by U.S. Dept. of Defense physicist Nicholas Christofilos in 1959.^[5]

Although small ground dipoles have been used for years as sensors in geological and geophysical research, their only use as antennas has been in a few military ELF transmitter facilities to communicate with submerged submarines. Besides small research and experimental antennas,^[5]^[6] three full-scale ground dipole installations are known to have been constructed; two by the U.S. Navy at Republic, Michigan and Clam Lake, Wisconsin,^[2]^[7]^[8] and one by the Russian Navy on the Kola peninsula near Murmansk, Russia.^[8]^[9]^[10] The U.S. facilities were used between 1985 and 2004 but are now decommissioned.^[8]

Antennas at ELF frequencies

ELF frequencies (according to one of several definitions) range from 3 Hz to 3 kHz, with corresponding wavelengths from 100,000 km to 100 km.^[1] The frequency used in the U.S. and Russian transmitters, about 80 Hz,^[1]^[11] generates waves 3750 km (2300 miles) long,^[12]^[13] roughly one quarter of the Earth's diameter. ELF waves have been used in very few manmade communications systems because of the difficulty of building efficient antennas for such long waves. Ordinary types of antenna (half-wave dipoles and quarter-wave monopoles) cannot be built for such extremely long waves because of their size. A half wave dipole for 80 Hz would be 1162 miles long. So even the largest practical antennas for ELF frequencies are very electrically short, very much smaller than the wavelength of the waves they radiate.^[1] The disadvantage of this is that the efficiency of an antenna drops as its size is reduced below a wavelength.^[1] An antenna's radiation resistance, and the amount of power it radiates, is proportional to (L/λ)² where L is its length and λ is the wavelength. So even physically large ELF antennas have very small radiation resistance, and so radiate only a tiny fraction of the input power as ELF waves; most of the power applied to them is dissipated as heat in various ohmic resistances in the antenna.^[5] ELF antennas must be tens to hundreds of kilometers long, and must be driven by powerful transmitters in the megawatt range, to produce even a few watts of ELF radiation. Fortunately, the attenuation of ELF waves with distance is so low (1 - 2 dB per 1000 km)^[5] that a few watts of radiated power is enough to communicate worldwide.^[2]

A second problem stems from the required polarization of the waves. ELF waves only propagate long distances in vertical polarization, with the direction of the magnetic field lines horizontal and the electric field lines vertical.^[1] Vertically oriented antennas are required to generate vertically polarized waves. Even if sufficiently large conventional antennas could be built on the surface of the Earth, these would generate horizontally polarized, not vertically polarized waves.

History

In 1958, the realization that ELF waves could penetrate seawater led U.S. physicist Nicholas Christofilos to suggest that the U.S. Navy use them to communicate with submarines.^[7]^[13] The U.S. military researched many different types of antenna for use at ELF frequencies. Cristofilos proposed applying currents to the Earth to create a vertical loop antenna, and it became clear that this was the most practical design.^[1]^[13] The feasibility of the ground dipole idea was tested in 1962 with a 42 km leased power line in Wyoming, and in 1963 with a 176 km prototype wire antenna extending from West Virginia to North Carolina.^[5]^[13]

How a ground dipole works

A ground dipole functions as an enormous vertically oriented loop antenna^[5]^[14] (see drawing, right). It consists of two widely separated electrodes (G) buried in the ground, connected by overhead transmission cables to a transmitter (P) located between them. The alternating current from the transmitter (I) travels in a loop through one transmission line, kilometers deep into bedrock from one ground electrode to the other, and back through the other transmission line. This creates an alternating magnetic field (H) through the loop, which radiates ELF waves. The axis of the magnetic field produced is horizontal, so it generates vertically polarized waves. The radiation pattern of the antenna is directional, with two lobes (maxima) in the plane of the loop, off the ends of the transmission lines.^[3]^[5] In the U.S. installations two ground dipoles are used, oriented perpendicular to each other, to allow transmission in all directions.

The amount of power radiated by a loop antenna is proportional to (IA)², where I is the AC current in the loop and A is the area enclosed,^[5] To radiate practical power at ELF frequencies, the loop has to carry a current of hundreds of amperes and enclose an area of at least several square miles.^[5] Christofilos found that the lower the electrical conductivity of the underlying rock, the deeper the current will go, and the larger the effective loop area.^[2]^[5] Radio frequency current will penetrate into the ground to a depth equal to the skin depth of the ground at that frequency, which is inversely proportional to the square root of ground conductivity σ. The ground dipole forms a loop with effective area of A = Lδ / √2, where L is the total length of the transmission lines and δ is the skin depth.^[5]^[11] So ground dipoles are sited over low conductivity underground rock formations (this contrasts with ordinary radio antennas, which require good earth conductivity for a low resistance ground connection for their transmitters). The two U.S. Navy antennas were located in the Upper Peninsula of Michigan, on the Canadian Shield (Laurentian Shield) formation,^[2]^[15] which has unusually low conductivity of 2×10⁻⁴ siemens/meter.^[5] resulting in an increase in antenna efficiency of 20 dB.^[3] The earth conductivity at the site of the Russian transmitter is even lower.^[11]

Because of their lack of civilian applications, little information about ground dipoles is available in antenna technical literature.

U.S. Navy Project ELF antennas

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Map showing location of the US Navy ELF transmitters. The red lines show the paths of the ground dipole antennas. The Clam Lake facility *(left)* had two crossed 14 mi. ground dipoles. The Republic facility had two 14 mi. dipoles oriented east-west, and one 28 mi. dipole oriented north-south.

After initially considering several larger systems (Project Sanguine), the U.S. Navy constructed two ELF transmitter facilities, one at Clam Lake, Wisconsin and the other at Republic, Michigan, 145 miles apart.^[2]^[4] They could operate independently, or phase synchronized as one antenna for greater output power.^[4] The Clam Lake site, the initial test facility, transmitted its first signal in 1982^[4] and began operation in 1985, while the Republic site became operational in 1989.

The Clam Lake antenna consisted of two perpendicular 14 mile (24 km) ground dipole transmission lines in the shape of a cross, with the transmitter station at their intersection.^[4]^[15] The Republic antenna consisted of three ground dipoles, two 14 mile and one 28 mile transmission line,^[4] in the shape of the letter "F" (the shape is not significant and was dictated by land availability).^[15] The lines, made of 1.5 cm aluminum cable supported on insulators on 40 ft. wooden poles, resembled ordinary power transmission lines.^[5] The ends of the transmission lines were grounded by 1 to 3 miles of buried copper cable and ground rods,^[5] later replaced by arrays of electrodes in deep 300 ft. boreholes,^[4] to reduce surface ground currents to address environmental concerns.

The transmitters operated at a frequency of 76 Hz, with an alternate frequency capability of 45 Hz.^[5] Each Clam Lake ground dipole was normally driven with a current of 300 amperes, from a 1.2 MW peak power transmitter powered from a 4160 V utility line with diesel backup.^[5] Each loop had a resistance of 5 ohms and an inductance of 50 millihenries, which could be tuned out by capacitor banks.^[5] The transmitter synthesized the sinusoidal output waveform with banks of high power SCRs.^[14] The relative amplitude and phase of the drive current in each of the perpendicular loops could be controlled to radiate in a specific direction, or equally in all directions.^[5]

As with all ELF radiators, the antennas were extremely inefficient, with almost all of the input power dissipated as heat in ground resistance. At an input power of 450 kW, each of the Clam Lake dipoles radiated less than 1 watt of ELF waves, giving an efficiency of 2×10⁻⁶.^[5] The total output power of both sites working together was 8 watts.^[2] However due of the low attenuation of ELF waves this tiny radiated power was able to communicate with submarines over about half the Earth's surface.^[16]

Throughout their operating life both antennas were controversial, and the focus of legal challenges and protests attempting to shut them down, by antiwar groups and environmental groups concerned about the effects of electromagnetic radiation exposure.^[7]^[17]^[18]^[19] On five occasions transmission line poles were cut down by protesters, temporarily interrupting operation.^[4]^[18]

Both transmitters were shut down in 2004.^[8]^[18] The official Navy explanation was that advances in VLF communication systems had made them unnecessary.^[8]

Russian Navy ZEVS antennas

Mining Engineer (Excluding Oil ) Truman from Alma, loves to spend time knotting, largest property developers in singapore developers in singapore and stamp collecting. Recently had a family visit to Urnes Stave Church. The Russian Navy operates an ELF transmitter facility, named ZEVS ("Zeus"), to communicate with its submarines, located northwest of Murmansk on the Kola peninsula in northern Russia.^[9]^[10] Signals from it were detected in the 1990s at Stanford University and elsewhere.^[10]^[11] It normally operates at 82 Hz, using MSK (minimum shift keying) modulation.^[10] although it reportedly can cover the frequency range from 20 to 250 Hz.^[9]^[11] It reportedly consists of two parallel ground dipole antennas 60 km long, driven at currents of 200 to 300 amperes.^[10]^[11] Calculations from intercepted signals indicate it is 10 dB more powerful than the U.S. transmitters.^[11] Unlike them it is used for geophysical research in addition to military communications.^[9]^[10]

Radiated power

The total power radiated by a ground dipole is^[5]

P = \frac{π^{2} f^{2} I^{2} L^{2}}{2 c^{2} h σ}

where

f is the frequency

I is the RMS current in the loop

L is the length of the transmission line

c is the speed of light

h is the height above ground of the ionosphere D layer

σ is the ground conductivity

The radiated power of an electrically small loop antenna normally scales with the fourth power of the frequency, but at ELF frequencies the effects of the ionosphere result in a less severe reduction in power proportional to the square of frequency.

Receiving antennas

Ground dipoles are not needed for reception of ELF signals. The requirements for receiving antennas at ELF frequencies are less stringent than transmitting antennas, because the signal to noise ratio in ELF receivers is dominated by the large atmospheric noise in the band. The level of signal strength at the antenna is far above the noise in the receiver circuit, so small inefficient receiving antennas can be used. Various types of coil and ferrite loop antennas have been used for reception.

References

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In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

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A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang, p.1692, on VLF Group website, Stanford Univ.
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↑ ^5.00 ^5.01 ^5.02 ^5.03 ^5.04 ^5.05 ^5.06 ^5.07 ^5.08 ^5.09 ^5.10 ^5.11 ^5.12 ^5.13 ^5.14 ^5.15 ^5.16 ^5.17 ^5.18 ^5.19 ^5.20 ^5.21 ^5.22 ^5.23 One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang
↑ One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang
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In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang
↑ ^10.0 ^10.1 ^10.2 ^10.3 ^10.4 ^10.5 Template:Cite web
↑ ^11.0 ^11.1 ^11.2 ^11.3 ^11.4 ^11.5 ^11.6 One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang
↑ λ = c/f = 3×10⁸ m/s / 80 Hz = 3750 km
↑ ^13.0 ^13.1 ^13.2 ^13.3 Template:Cite news
↑ ^14.0 ^14.1 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

My blog: http://www.primaboinca.com/view_profile.php?userid=5889534
↑ ^15.0 ^15.1 ^15.2 One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang
↑ 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

My blog: http://www.primaboinca.com/view_profile.php?userid=5889534
↑ 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

My blog: http://www.primaboinca.com/view_profile.php?userid=5889534
↑ ^18.0 ^18.1 ^18.2 Template:Cite web
↑ 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

My blog: http://www.primaboinca.com/view_profile.php?userid=5889534

[Barr-1] 1.00 ^1.01 ^1.02 ^1.03 ^1.04 ^1.05 ^1.06 ^1.07 ^1.08 ^1.09 One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang, p.1692, on VLF Group website, Stanford Univ.

[NavyFactSheet-2] 2.0 ^2.1 ^2.2 ^2.3 ^2.4 ^2.5 ^2.6 Template:Cite web on Federation of American Scientists website

[Wolkoff-3] 3.0 ^3.1 ^3.2 55 years old Systems Administrator Antony from Clarence Creek, really loves learning, PC Software and aerobics. Likes to travel and was inspired after making a journey to Historic Ensemble of the Potala Palace.

You can view that web-site... ccleaner free download Cite error: Invalid <ref> tag; name "Wolkoff" defined multiple times with different content

[Altgelt-4] 4.0 ^4.1 ^4.2 ^4.3 ^4.4 ^4.5 ^4.6 ^4.7 Template:Cite web

[Jones-5] 5.00 ^5.01 ^5.02 ^5.03 ^5.04 ^5.05 ^5.06 ^5.07 ^5.08 ^5.09 ^5.10 ^5.11 ^5.12 ^5.13 ^5.14 ^5.15 ^5.16 ^5.17 ^5.18 ^5.19 ^5.20 ^5.21 ^5.22 ^5.23 One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang

[Ginzberg-6] One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang

[Coe-7] 7.0 ^7.1 ^7.2 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

My blog: http://www.primaboinca.com/view_profile.php?userid=5889534 Cite error: Invalid <ref> tag; name "Coe" defined multiple times with different content

[Sterling-8] 8.0 ^8.1 ^8.2 ^8.3 ^8.4 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

My blog: http://www.primaboinca.com/view_profile.php?userid=5889534

[Bashkuev-9] 9.0 ^9.1 ^9.2 ^9.3 One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang

[Trond-10] 10.0 ^10.1 ^10.2 ^10.3 ^10.4 ^10.5 Template:Cite web

[Fraser-Smith-11] 11.0 ^11.1 ^11.2 ^11.3 ^11.4 ^11.5 ^11.6 One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

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G-index: Difference between revisions

Latest revision as of 14:03, 19 November 2013

Contents

Antennas at ELF frequencies

History

How a ground dipole works

U.S. Navy Project ELF antennas

Russian Navy ZEVS antennas

Radiated power

Receiving antennas

See also

References

Navigation menu

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+{{duplication|dupe=Project Sanguine|date=December 2013}}
+[[Image:Clam Lake ELF.jpg|thumb|225px|The U.S. Navy Clam Lake, Wisconsin [[Extremely low frequency|ELF]] transmitter in 1982.  Sections of the [[right of way (transportation)|rights of way]] for the power lines that make up the two crossed ground dipole antennas can be seen passing through the forest at lower left.  ]]
+In [[radio communication]], a '''ground dipole''',<ref name="Barr">{{cite journal
+  | last = Barr
+  | first = R.
+  | authorlink =
+  | coauthors = D. Llanwyn Jones, C.J. Rodger
+  | title = ELF and VLF radio waves
+  | journal = Journal of Atmospheric and Solar-Terrestrial Physics
+  | volume = 62
+  | issue =
+  | pages = 1689–1718
+  | publisher = Pergamon
+  | location =
+  | date = June 14, 2000
+  | url = http://nova.stanford.edu/~vlf/IHY_Test/Tutorials/SubionosphericVLFPropagation/Papers/Barr_2000.pdf
+  | issn =
+  | doi =
+  | id =
+  | accessdate = 2012-02-23}}, p.1692,  on  [http://nova.stanford.edu/~vlf/  VLF Group website, Stanford Univ.]</ref> also referred to as an '''earth dipole antenna''', '''transmission line antenna''',<ref name="Barr" /> and in technical literature as a  '''horizontal electric dipole''' (HED),<ref name="Barr" /><ref name="NavyFactSheet" >{{cite web
+  | last =
+  | first =
+  | authorlink =
+  | coauthors =
+  | title = Extremely Low Frequency Transmitter Site, Clam Lake, Wisconsin
+  | work = Navy Fact File
+  | publisher = United States Navy
+  | date = June 28, 2001
+  | url = http://www.fas.org/nuke/guide/usa/c3i/fs_clam_lake_elf2003.pdf
+  | format =
+  | doi =
+  | accessdate = February 17, 2012}} on [http://www.fas.org/  Federation of American Scientists website]</ref><ref name="Wolkoff">{{cite conference
+  | first = E. A.
+  | last = Wolkoff
+  | authorlink =
+  | coauthors = W. A. Kraimer
+  | title = Pattern Measurements of U.S. Navy ELF Antennas
+  | booktitle = ELF/VLF/LF Radio Propagation and Systems Aspects
+  | pages = 26.1–26.10
+  | publisher = AGARD Conference proceedings Sept. 28 - Oct. 2, 1992, NATO
+  | date = May 1993
+  | location = Belgium
+  | url = http://www.dtic.mil/dtic/tr/fulltext/u2/a267991.pdf
+  | doi =
+  | id =
+  | accessdate = February 17, 2012}}</ref>  is a huge, specialized type of radio [[antenna (radio)|antenna]] that radiates [[extremely low frequency]] (ELF)  [[electromagnetic wave]]s.<ref name="Altgelt" >{{cite web
+  | last = Altgelt
+  | first = Carlos
+  | authorlink =
+  | coauthors =
+  | title = The World's Largest "Radio" Station
+  | work = The Broadcaster's Desktop Resource
+  | publisher = [http://www.oldradio.com/   Barry Mishkind, OldRadio.com website]
+  | date =
+  | url = http://www.oldradio.com/archives/jurassic/ELF.doc
+  | format =
+  | doi =
+  | accessdate = February 17, 2012}}</ref><ref name="Jones" >{{cite journal
+  | last = Jones
+  | first = David Llanwyn
+  | authorlink =
+  | coauthors =
+  | title = Sending signals to submarines
+  | journal = New Scientist
+  | volume = 26
+  | issue = 1463
+  | pages = 37–41
+  | publisher = Holborn Publishing Group
+  | location = London
+  | date = July 4, 1985
+  | url = http://books.google.com/books?id=NOPpwVvNu44C&pg=PA39&dq=ELF+transmitter&hl=en&sa=X&ei=dhI4T8KrIbLZiQKCg8yqCg&ved=0CFYQ6AEwBA#v=onepage&q=sanguine&f=false
+  | issn =
+  | doi =
+  | id =
+  | accessdate = February 17, 2012}}</ref>  It is the only type of transmitting antenna that can radiate practical amounts of power in the ELF [[frequency]] range of 3&nbsp;Hz to 3&nbsp;kHz.<ref name="Jones" />  A ground dipole consists of two [[ground (electricity)|ground]] electrodes buried in the earth, separated by tens to hundreds of kilometers, linked by overhead transmission lines to a power plant [[transmitter]] located between them.<ref name="Barr" /><ref name="Jones" />   [[Alternating current]] electricity flows in a giant loop between the electrodes through the ground, radiating ELF waves, so the ground is part of the antenna.  To be most effective, ground dipoles must be located over certain types of underground rock formations.<ref name="Jones" />  The idea was proposed by U.S. Dept. of Defense physicist [[Nicholas Christofilos]] in 1959.<ref name="Jones" />
+Although small ground dipoles have been used for years as sensors in geological and geophysical research,  their only use as antennas has been in a few military ELF transmitter facilities to communicate with submerged [[submarine]]s.   Besides small research and experimental antennas,<ref name="Jones" /><ref name="Ginzberg">{{cite journal
+  | last = Ginzberg
+  | first = Lawrence H.
+  | authorlink =
+  | coauthors =
+  | title = Extremely low frequency (ELF) propagation measurements along a 4900 km path
+  | journal = IEEE Transactions on Communications
+  | volume = COM-22
+  | issue = 4
+  | pages = 452–457
+  | publisher = IEEE
+  | location =
+  | date = April 1974
+  | url = https://www.cna.org/sites/default/files/research/5500011300.pdf
+  | issn =
+  | doi =
+  | id =
+  | accessdate = May 14, 2012}}</ref>  three full-scale ground dipole installations are known to have been constructed; two by the U.S. Navy at [[Republic, Michigan]] and [[Clam Lake, Wisconsin]],<ref name="NavyFactSheet" /><ref name="Coe">{{cite book
+  | last = Coe
+  | first = Lewis
+  | authorlink =
+  | coauthors =
+  | title = Wireless Radio: A brief history
+  | publisher = McFarland
+  | year = 2006
+  | location = USA
+  | pages = 143–144
+  | url = http://books.google.com/books?id=W1JAeg1PiWIC&pg=PA143&dq=%22extremely+low+frequency%22+ELF+propagation+waveguide&hl=en&sa=X&ei=rsw3T8y9D6egiQKWw5WqCg&ved=0CEUQ6AEwAjgK#v=onepage&q=%22extremely%20low%20frequency%22%20ELF%20propagation%20waveguide&f=false
+  | doi =
+  | id =
+  | isbn = 0786426624}}</ref><ref name="Sterling">{{cite book
+  | last = Sterling
+  | first = Christopher H.
+  | authorlink =
+  | coauthors =
+  | title = Military communications: from ancient times to the 21st century
+  | publisher = ABC-CLIO
+  | year = 2008
+  | location =
+  | pages = 431–432
+  | url = http://books.google.com/books?id=RBC2nY1rp5MC&printsec=frontcover&source=gbs_atb#v=snippet&q=zevs&f=false
+  | doi =
+  | id =
+  | isbn = 1851097325}}</ref> and one by the Russian Navy on the [[Kola peninsula]] near [[Murmansk]], Russia.<ref name="Sterling"/><ref name="Bashkuev">{{cite journal
+  | last = Bashkuev
+  | first = Yu. B.
+  | authorlink =
+  | coauthors = V. B. Khaptanov and A. V. Khankharaev
+  | title = Analysis of Propagation Conditions of ELF Radio Waves on the "Zeus"–Transbaikalia Path
+  | journal = Radiophysics and Quantum Electronics
+  | volume = 46
+  | issue = 12
+  | pages = 909–917
+  | publisher = Plenum
+  | location =
+  | date = December 2003
+  | url = http://www.springerlink.com/content/vg073205217452u1/
+  | issn =
+  | doi = 10.1023/B:RAQE.0000029585.02723.11
+  | id =
+  | accessdate = February 17, 2012}}</ref><ref name="Trond">{{cite web
+  | last = Jacobsen
+  | first = Trond
+  | authorlink =
+  | coauthors =
+  | title = ZEVS, The Russian 82 Hz ELF Transmitter
+  | work = [http://www.vlf.it/index.htm  Radio Waves Below 22 kHz]
+  | publisher = Renato Romero webpage
+  | year = 2001
+  | url = http://www.vlf.it/zevs/zevs.htm
+  | doi =
+  | accessdate = February 17, 2012}}</ref>  The U.S. facilities were used between 1985 and 2004 but are now decommissioned.<ref name="Sterling"/>
+==Antennas at ELF frequencies==
+ELF frequencies (according to one of several definitions) range from 3&nbsp;Hz to 3&nbsp;kHz, with corresponding [[wavelength]]s from 100,000&nbsp;km to 100&nbsp;km.<ref name="Barr" />  The frequency used in the U.S. and Russian transmitters, about 80&nbsp;Hz,<ref name="Barr" /><ref name="Fraser-Smith">{{cite journal
+  | last = Fraser-Smith
+  | first = Anthony C.
+  | authorlink =
+  | coauthors = Peter R. Bannister
+  | title = Reception of ELF signals at antipodal distances
+  | journal = Radio Science
+  | volume = 33
+  | issue = 1
+  | pages = 83–88
+  | publisher = American Geophysical Union
+  | location = USA
+  | year = 1998
+  | url = http://ee.stanford.edu/~acfs/82Hz.pdf
+  | issn =
+  | doi = 10.1029/97RS01948
+  | id =
+  | accessdate = 2012-05-14}}</ref> generates waves 3750&nbsp;km (2300 miles) long,<ref>λ = c/f = 3×10<sup>8</sup> m/s  / 80 Hz = 3750 km</ref><ref name="Sullivan">{{Cite news
+  | last = Sullivan
+  | first =  Walter
+  | coauthors =
+  | title = How huge antenna can broadcast into the silence of the sea
+  | newspaper = The New York Times
+  | location = USA
+  | pages =
+  | publisher = The New York Times Co.
+  | date = October 13, 1981
+  | url = http://www.nytimes.com/1981/10/13/science/how-huge-antenna-can-broadcast-into-the-silence-of-the-sea.html?pagewanted=all
+  | accessdate = May 22, 2012}}</ref> roughly one quarter of the Earth's diameter.  ELF waves have been used in very few manmade communications systems because of the difficulty of building efficient antennas for such long waves.  Ordinary types of antenna ([[half-wave antenna|half-wave dipoles]] and [[monopole antenna|quarter-wave monopoles]]) cannot be built for such extremely long waves because of their size.  A [[half wave dipole]] for 80&nbsp;Hz would be 1162 miles long.  So even the largest practical antennas for ELF frequencies are very [[Electrical length|electrically short]], very much smaller than the wavelength of the waves they radiate.<ref name="Barr" />  The disadvantage of this is that the efficiency of an antenna drops as its size is reduced below a wavelength.<ref name="Barr" />  An antenna's  [[radiation resistance]], and the amount of power it radiates, is proportional to ('''''L'''''/'''''λ''''')<sup>2</sup> where '''''L''''' is its length and '''''λ''''' is the wavelength.  So even physically large ELF antennas have very small radiation resistance, and so radiate only a tiny fraction of the input power as ELF waves; most of the power applied to them is dissipated as heat in various ohmic [[Electrical resistance|resistances]] in the antenna.<ref name="Jones" />  ELF antennas must be tens to hundreds of kilometers long, and must be driven by powerful [[transmitter]]s in the [[megawatt]] range, to produce even a few watts of ELF radiation.  Fortunately, the attenuation of ELF waves with distance is so low (1 - 2 [[Decibel|dB]] per 1000&nbsp;km)<ref name="Jones" /> that a few watts of radiated power is enough to communicate worldwide.<ref name="NavyFactSheet" />
+A second problem stems from the required [[polarization (waves)|polarization]] of the waves.  ELF waves only propagate long distances in [[vertical polarization]], with the direction of the [[magnetic field]] lines horizontal and the [[electric field]] lines vertical.<ref name="Barr" />  Vertically oriented antennas are required to generate vertically polarized waves.  Even if sufficiently large conventional antennas could be built on the surface of the Earth, these would generate horizontally polarized, not vertically polarized waves.
+==History==
+[[Image:Ground dipole ELF antenna.svg|thumb|upright=1.8|Ground dipole antenna, similar to the U.S. Clam Lake antennas, showing how it works.  The [[alternating current]] ''I''&nbsp;  is shown flowing in one direction only through the loop for clarity.]]
+In 1958, the realization that ELF waves could penetrate seawater led U.S. physicist [[Nicholas Christofilos]] to suggest that the U.S. Navy use them to communicate with submarines.<ref name="Coe">{{cite book
+  | last = Coe
+  | first = Lewis
+  | authorlink =
+  | coauthors =
+  | title = Wireless Radio: A Brief History
+  | publisher = McFarland
+  | year = 2006
+  | location =
+  | pages = 143–144
+  | url = http://books.google.com/books?id=W1JAeg1PiWIC&pg=PA143&dq=#v=onepage&q&f=false
+  | doi =
+  | id =
+  | isbn = 0786426624}}</ref><ref name="Sullivan" />  The U.S. military researched many different types of antenna for use at ELF frequencies.   Cristofilos proposed applying currents to the Earth to create a vertical loop antenna, and it became clear that this was the most practical design.<ref name="Barr" /><ref name="Sullivan" />  The feasibility of the ground dipole idea was tested in 1962 with a 42&nbsp;km leased power line in [[Wyoming]], and in 1963 with a 176&nbsp;km prototype wire antenna extending from [[West Virginia]] to [[North Carolina]].<ref name="Jones" /><ref name="Sullivan" />
+==How a ground dipole works==
+A ground dipole functions as an enormous vertically oriented [[loop antenna]]<ref name="Jones" /><ref name="Sueker">{{cite book
+  | last = Sueker
+  | first = Keith H.
+  | authorlink =
+  | coauthors =
+  | title = Power Electronics Design: A Practitioner's Guide
+  | publisher = Elsevier
+  | year = 2005
+  | location =
+  | pages = 221–222
+  | url = http://books.google.com/books?id=KuFt9Bcc9zYC&pg=PA222&dq=ELF+transmitter&hl=en&sa=X&ei=2X04T6bOCOqoiAKg05nQCg&ved=0CHYQ6AEwCDge#v=onepage&q=ELF%20transmitter&f=false
+  | doi =
+  | id =
+  | isbn = 0750679271}}</ref> ''(see drawing, right)''.  It consists of two widely separated electrodes ''(G)'' buried in the ground, connected by overhead transmission cables to a transmitter ''(P)'' located between them.    The [[alternating current]] from the transmitter ''(I)'' travels in a loop through one transmission line, kilometers deep into bedrock from one ground electrode to the other, and back through the other transmission line.  This creates an alternating magnetic field ''(H)'' through the loop, which radiates ELF waves.  The axis of the magnetic field produced is horizontal, so it generates vertically polarized waves.  The [[radiation pattern]] of the antenna is directional, with two lobes (maxima) in the plane of the loop, off the ends of the transmission lines.<ref name="Wolkoff" /><ref name="Jones" />  In the U.S. installations two ground dipoles are used, oriented perpendicular to each other, to allow transmission in all directions.
+The amount of power radiated by a loop antenna is proportional to ('''''IA''''')<sup>2</sup>, where '''''I''''' is the AC current in the loop and '''''A''''' is the area enclosed,<ref name="Jones" />  To radiate practical power at ELF frequencies, the loop has to carry a current of hundreds of amperes and enclose an area of at least several square miles.<ref name="Jones" />   Christofilos found that the lower the [[electrical conductivity]] of the underlying rock, the deeper the current will go, and the larger the effective loop area.<ref name="NavyFactSheet" /><ref name="Jones" />  Radio frequency current will penetrate into the ground to a depth equal to the ''[[skin depth]]'' of the ground at that frequency, which is inversely proportional to the square root of ground conductivity '''''σ'''''.  The ground dipole forms a loop with effective area of '''''A''''' = '''''Lδ''''' / &radic;2, where '''''L''''' is the total length of the transmission lines and '''''δ''''' is the [[skin depth]].<ref name="Jones" /><ref name="Fraser-Smith" />    So ground dipoles are sited over low conductivity underground rock formations (this contrasts with ordinary radio antennas, which require ''good'' earth conductivity for a low resistance [[ground (electricity)|ground]] connection for their transmitters).  The two U.S. Navy antennas were located in the Upper Peninsula of Michigan, on the [[Canadian Shield]] (Laurentian Shield) formation,<ref name="NavyFactSheet" /><ref name="Heppenheimer" >{{cite journal
+  | last = Heppenheimer
+  | first = T. A.
+  | authorlink =
+  | coauthors =
+  | title = Signaling Subs
+  | journal = Popular Science
+  | volume = 230
+  | issue = 4
+  | pages = 44–48
+  | publisher = Times Mirror Magazines
+  | location = New York
+  | date = April 1987
+  | url = http://books.google.com/books?id=IAEAAAAAMBAJ&pg=PA44#v=onepage&q&f=false
+  | issn =
+  | doi =
+  | id =
+  | accessdate = February 17, 2012}}</ref>  which has unusually low conductivity of 2×10<sup>−4</sup> siemens/meter.<ref name="Jones" /> resulting in an increase in antenna efficiency of 20 dB.<ref name="Wolkoff">{{cite conference
+  | first = E. A.
+  | last = Wolkoff
+  | authorlink =
+  | coauthors = W. A. Kraimer
+  | title = Pattern measurements of U.S. Navy ELF antennas
+  | booktitle = AGARD conference proceedings 529: ELF/VLF/LF Radio Propagation and Systems Aspects
+  | pages = 26.1–26.10
+  | publisher = Advisory Group for Aerospace Research and Development, NATO
+  | date = May 1993
+  | location = Neuilly Sur Seine, France
+  | url = http://www.dtic.mil/dtic/tr/fulltext/u2/a267991.pdf
+  | doi =
+  | id =
+  | accessdate = May 15, 2012}}</ref>  The earth conductivity at the site of the Russian transmitter is even lower.<ref name="Fraser-Smith" />
+Because of their lack of civilian applications, little information about ground dipoles is available in antenna technical literature.
+==U.S. Navy Project ELF antennas==
+{{main|Project Sanguine}}
+[[Image:US Navy ELF transmitter map.png|thumb|upright=2.0|Map showing location of the US Navy ELF transmitters.  The <span style="color:red;">red lines</span> show the paths of the ground dipole antennas.  The Clam Lake facility ''(left)'' had two crossed 14 mi. ground dipoles.  The Republic facility had two 14 mi. dipoles oriented east-west, and one 28 mi. dipole oriented north-south.]]
+After initially considering several larger systems ([[Project Sanguine]]), the U.S. Navy constructed two ELF transmitter facilities, one at [[Clam Lake, Wisconsin]] and the other at [[Republic, Michigan]], 145 miles apart.<ref name="NavyFactSheet" /><ref name="Altgelt" /> They could operate independently, or phase synchronized as one antenna for greater output power.<ref name="Altgelt" />   The Clam Lake site, the initial test facility,  transmitted its first signal in 1982<ref name="Altgelt" /> and began operation in 1985, while the Republic site became operational in 1989.
+The Clam Lake antenna consisted of two perpendicular 14 mile (24&nbsp;km) ground dipole transmission lines in the shape of a cross, with the transmitter station at their intersection.<ref name="Altgelt" /><ref name="Heppenheimer" />  The Republic antenna consisted of three ground dipoles, two 14 mile and one 28 mile transmission line,<ref name="Altgelt" /> in the shape of the letter "F" (the shape is not significant and was dictated by land availability).<ref name="Heppenheimer" />  The lines, made of 1.5&nbsp;cm aluminum cable supported on insulators on 40&nbsp;ft. wooden poles, resembled ordinary power transmission lines.<ref name="Jones" />  The ends of the transmission lines were grounded by 1 to 3 miles of buried copper cable and ground rods,<ref name="Jones" />  later replaced by arrays of electrodes in deep 300&nbsp;ft. boreholes,<ref name="Altgelt" /> to reduce surface ground currents to address environmental concerns.
+The transmitters operated at a frequency of 76&nbsp;Hz, with an alternate frequency capability of 45&nbsp;Hz.<ref name="Jones" />  Each Clam Lake ground dipole was normally driven with a current of 300 amperes, from a 1.2 MW peak power transmitter powered from a 4160 V utility line with diesel backup.<ref name="Jones" />  Each loop had a resistance of 5 ohms and an inductance of 50 millihenries, which could be tuned out by capacitor banks.<ref name="Jones" />  The transmitter synthesized the sinusoidal output waveform with banks of high power [[silicon controlled rectifier|SCR]]s.<ref name="Sueker" />  The relative amplitude and [[phase (waves)|phase]] of the drive current in each of the perpendicular loops could be controlled to radiate in a specific direction, or equally in all directions.<ref name="Jones" />
+As with all ELF radiators, the antennas were extremely inefficient, with almost all of the input power dissipated as heat in ground resistance.   At an input power of 450&nbsp;kW, each of the Clam Lake dipoles radiated less than 1 watt of ELF waves, giving an efficiency of 2×10<sup>−6</sup>.<ref name="Jones" />  The total output power of both sites working together was 8 watts.<ref name="NavyFactSheet" />  However due of the low attenuation of ELF waves this tiny radiated power was able to communicate with submarines over about half the Earth's surface.<ref name="Blair" >{{cite book
+  | last = Blair
+  | first = Bruce G.
+  | authorlink =
+  | coauthors =
+  | title = Strategic Command and Control: Redefining the Nuclear Threat
+  | publisher = Brookings Institution Press
+  | year = 1985
+  | location =
+  | pages = 269–270
+  | url = http://books.google.com/books?id=0xP9_05cbQgC&pg=PA270&dq=transmitter+#v=onepage&q=elf&f=false
+  | doi =
+  | id =
+  | isbn = 0815709811}}</ref>
+Throughout their operating life both antennas were controversial, and the focus of legal challenges and protests attempting to shut them down, by [[Antiwar movement|antiwar groups]] and [[environmental movement|environmental groups]] concerned about the effects of electromagnetic radiation exposure.<ref name="Coe" /><ref name="Spinardi" >{{cite book
+  | last = Spinardi
+  | first =  Graham
+  | authorlink =
+  | coauthors =
+  | title = From Polaris to Trident: the development of US Fleet ballistic missile technology
+  | publisher = Cambridge Univ. Press
+  | year = 1994
+  | location = London
+  | pages = 81–82
+  | url = http://books.google.com/books?id=8mH-EbdNl0UC&pg=PA81&dq=ELF+transmitter&hl=en&sa=X&ei=3Xg4T4CMGumqiQKjp9HFCw&ved=0CFIQ6AEwAzgU#v=onepage&q=ELF%20transmitter&f=false
+  | doi =
+  | id =
+  | isbn = 0-521-41357-5}}</ref><ref name="TheNuclearResistor" >{{cite web
+  | last = Cohen-Joppa
+  | first = Felice
+  | authorlink =
+  | coauthors =
+  | title = Project ELF Closes
+  | work = [http://nuclearresister.org/   The Nuclear Resistor], Issue 135
+  | publisher = Felice and Jack Cohen-Joppa
+  | date = October 15, 2004
+  | url = http://nuclearresister.org/135elfcloses.html
+  | doi =
+  | accessdate = February 17, 2012}}</ref><ref name="Brodeur" >{{cite book
+  | last =  Brodeur
+  | first = Paul
+  | authorlink =
+  | coauthors =
+  | title = Currents of Death
+  | publisher = Simon and Schuster
+  | year = 2000
+  | location = New York
+  | pages =
+  | url = http://books.google.com/books?id=mke1FlCkIm4C&pg=PA62&dq=ELF+transmitter&hl=en&sa=X&ei=3Xg4T4CMGumqiQKjp9HFCw&ved=0CEgQ6AEwATgU#v=onepage&q=ELF%20transmitter&f=false
+  | doi =
+  | id =
+  | isbn = 0-7432-1308-4}}</ref>  On five occasions transmission line poles were cut down by protesters, temporarily interrupting operation.<ref name="Altgelt" /><ref name="TheNuclearResistor" />
+Both transmitters were shut down in 2004.<ref name="Sterling" /><ref name="TheNuclearResistor" />  The official Navy explanation was that advances in [[Very low frequency|VLF]] communication systems had made them unnecessary.<ref name="Sterling" />
+==Russian Navy ZEVS antennas==
+{{Main|ZEVS (transmitter)}}
+The Russian Navy operates an ELF transmitter facility, named ZEVS ("Zeus"), to communicate with its submarines, located northwest of [[Murmansk]] on the [[Kola peninsula]] in northern Russia.<ref name="Bashkuev" /><ref name="Trond" />  Signals from it were detected in the 1990s at Stanford University and elsewhere.<ref name="Trond" /><ref name="Fraser-Smith" />  It normally operates at 82&nbsp;Hz, using MSK (minimum shift keying) modulation.<ref name="Trond" /> although it reportedly can cover the frequency range from 20 to 250&nbsp;Hz.<ref name="Bashkuev" /><ref name="Fraser-Smith" />   It reportedly consists of two parallel ground dipole antennas 60&nbsp;km long, driven at currents of 200 to 300 amperes.<ref name="Trond" /><ref name="Fraser-Smith" />  Calculations from intercepted signals indicate it is 10 dB more powerful than the U.S. transmitters.<ref name="Fraser-Smith" />  Unlike them it is used for geophysical research in addition to military communications.<ref name="Bashkuev" /><ref name="Trond" />
+==Radiated power==
+The total power radiated by a ground dipole is<ref name="Jones" />
+:<math>P = \frac {\pi^2 f^2 I^2 L^2}{2 c^2 h \sigma} \,</math>
+where
+:'''''f''''' is the frequency
+:'''''I''''' is the RMS current in the loop
+:'''''L''''' is the length of the transmission line
+:'''''c''''' is the [[speed of light]]
+:'''''h''''' is the height above ground of the [[ionosphere]] D layer
+:'''''σ''''' is the ground [[electrical conductivity|conductivity]]
+The radiated power of an electrically small loop antenna normally scales with the fourth power of the frequency, but at ELF frequencies the effects of the ionosphere result in a less severe reduction in power proportional to the square of frequency.
+==Receiving antennas==
+Ground dipoles are not needed for reception of ELF signals.   The requirements for receiving antennas at ELF frequencies are less stringent than transmitting antennas, because the [[signal to noise ratio]] in ELF [[Radio receiver|receivers]] is dominated by the large atmospheric noise in the band.  The level of signal strength at the antenna is far above the noise in the receiver circuit, so small inefficient receiving antennas can be used.  Various types of coil and ferrite loop antennas have been used for reception.
+==See also==
+*[[Communication with submarines]]
+==References==
+{{reflist|33em}}
+[[Category:Radio frequency antenna types]]

G-index: Difference between revisions

Latest revision as of 14:03, 19 November 2013

Antennas at ELF frequencies

History

How a ground dipole works

U.S. Navy Project ELF antennas

Russian Navy ZEVS antennas

Radiated power

Receiving antennas

See also

References

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