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[[Image:L-over2-rad-pat-per.jpg|thumb|The [[radiation pattern]] of a simple omnidirectional antenna, a vertical half-wave [[dipole antenna]]. In this graph the antenna is at the center of the "donut," or [[torus]]. Radial distance from the center represents the power radiated in that direction. The power radiated is maximum in horizontal directions, dropping to zero directly above and below the antenna.]] | |||
In [[radio communication]], an '''omnidirectional antenna''' is a class of [[antenna (electronics)|antenna]] which radiates [[radio wave]] power uniformly in all directions in one plane, with the radiated power decreasing with elevation angle above or below the plane, dropping to zero on the antenna's axis. This [[radiation pattern]] is often described as "doughnut shaped". Note that this is different from an [[isotropic radiator|isotropic antenna]], which radiates equal power in ''all'' directions and has a "spherical" radiation pattern. Omnidirectional antennas oriented vertically are widely used for nondirectional antennas on the surface of the Earth because they radiate equally in all horizontal directions, while the power radiated drops off with elevation angle so little radio energy is aimed into the sky or down toward the earth and wasted. Omnidirectional antennas are widely used for [[radio broadcasting]] antennas, and in mobile devices that use radio such as [[cell phone]]s, [[FM radio]]s, [[walkie-talkie]]s, [[Wireless network|wireless computer networks]], [[cordless phone]]s, [[GPS]] as well as for base stations that communicate with mobile radios, such as police and taxi dispatchers and aircraft communications. | |||
== | ==Types== | ||
[[Image:Vpol dual band blade antenna blade L1 3D.jpg|thumb|Radiation pattern of a 3λ/2 [[monopole antenna]]. Although the radiation of an omnidirectional antenna is symmetrical in azmuthal directions, it may vary in a complicated way with elevation angle, having ''lobes'' and ''nulls'' at different angles. ]] | |||
Common types of low-gain omnidirectional antennas are the [[whip antenna]], [[Rubber Ducky antenna|"Rubber Duck" or "Rubber Ducky"]], [[Monopole antenna|ground plane antenna]], vertically oriented [[dipole antenna]], [[discone antenna]], [[mast radiator]], horizontal [[loop antenna]] (sometimes known colloquially as a 'circular aerial' because of the shape), and the [[halo antenna]]. | |||
== | Higher-gain omnidirectional antennas can also be built. "Higher gain" in this case means that the antenna radiates less energy at higher and lower elevation angles and more in the horizontal directions. High-gain omnidirectional antennas are generally realized using collinear dipole arrays. These arrays consist of half-wavelength dipoles with a phase shifting method between each element that ensures the current in each dipole is in phase.<ref>{{cite book |editor=Johnson, R, Jasik, H |title=Antenna Engineering Handbook |publisher=McGraw Hill |location= |year=1984 |isbn= |pages=27–14 }}</ref> The [[Coaxial Colinear]] or COCO antenna uses transposed coaxial sections to produce in-phase half-wavelength radiators. A [[Franklin Array]] uses short U-shaped half-wavelength sections whose radiation cancels in the far-field to bring each half-wavelength dipole section into equal phase. | ||
Types of higher gain omnidirectional antennas are the coaxial collinear (COCO) antenna<ref>{{cite journal |doi=10.1109/8.18724 |author=Judasz, T., Balsley, B. |title=Improved Theoretical and Experimental Models for the Coaxial Colinear Antenna |journal=IEEE Transactions on Antennas and Propagation |volume=37 |issue=3 |pages=289–296 |date=March 1989 }}</ref> and Omnidirectional [[Microstrip antenna|Microstrip Antenna]] (OMA).<ref>{{cite journal |doi=10.1002/mop.21187 |author=Bancroft R |title=Design Parameters of an Omnidirectional Planar Microstrip Antenna |journal=Microwave and Optical Technology Letters |volume=47 |issue=5 |pages=414–8 |date=December 5, 2005 }}</ref> | |||
Some planar antennas (constructed from printed circuit board) are omnidirectional antennas.<ref>{{cite web |author=Yanaga; Kurashima; Arita; Kobayashi |title=A Planar UWB Monopole Antenna Formed on a Printed Circuit Board |year=2003? |work= |publisher= |url=http://www.fujitsu.com/downloads/MICRO/fcai/input/uwb_monopole_antenna.pdf |format=PDF}}</ref> | |||
==Analysis== | |||
[[Image:Schwarzbeck RE 1790.jpg|right|thumb|240px|Vertical polarized VHF- UHF [[biconical antenna]] 170 – 1100 MHz with omni directional H-plane pattern]] | |||
Omnidirectional radiation patterns are produced by the simplest practical antennas, [[monopole antenna|monopole]] and [[dipole antenna]]s, consisting of one or two straight rod conductors on a common axis. Antenna gain (G) is defined as antenna efficiency (e) multiplied by antenna [[directivity]] (D) which is expressed mathematically as: <math>G = eD</math>. A useful relationship between omnidirectional radiation pattern [[directivity]] (D) in [[decibels]] and half-power [[beamwidth]] (HPBW) based on the assumption | |||
of a <math>\sin{b\theta} / {b\theta}</math> pattern shape is:<ref>{{cite journal |author=McDonald, Noel |title=Omnidirectional Pattern Directivity in the Presence of Minor Lobes: Revisited |journal=IEEE Transactions on Antennas and Propagation |volume=41 |issue=2 |pages=63–8 |date=April 1999 |doi= |url=}}</ref> | |||
<math> D = 10\log_{10} {\left ({101.5\over {HPBW - 0.00272(HPBW)^2}}\right )} \;\; dB.</math> | |||
==See also== | |||
* [[Choke ring antenna]] | |||
* [[Directional antenna]] | |||
==References== | |||
{{Reflist}} | |||
[[Category:Radio frequency antenna types]] | |||
Revision as of 23:03, 23 December 2013
In radio communication, an omnidirectional antenna is a class of antenna which radiates radio wave power uniformly in all directions in one plane, with the radiated power decreasing with elevation angle above or below the plane, dropping to zero on the antenna's axis. This radiation pattern is often described as "doughnut shaped". Note that this is different from an isotropic antenna, which radiates equal power in all directions and has a "spherical" radiation pattern. Omnidirectional antennas oriented vertically are widely used for nondirectional antennas on the surface of the Earth because they radiate equally in all horizontal directions, while the power radiated drops off with elevation angle so little radio energy is aimed into the sky or down toward the earth and wasted. Omnidirectional antennas are widely used for radio broadcasting antennas, and in mobile devices that use radio such as cell phones, FM radios, walkie-talkies, wireless computer networks, cordless phones, GPS as well as for base stations that communicate with mobile radios, such as police and taxi dispatchers and aircraft communications.
Types
Common types of low-gain omnidirectional antennas are the whip antenna, "Rubber Duck" or "Rubber Ducky", ground plane antenna, vertically oriented dipole antenna, discone antenna, mast radiator, horizontal loop antenna (sometimes known colloquially as a 'circular aerial' because of the shape), and the halo antenna.
Higher-gain omnidirectional antennas can also be built. "Higher gain" in this case means that the antenna radiates less energy at higher and lower elevation angles and more in the horizontal directions. High-gain omnidirectional antennas are generally realized using collinear dipole arrays. These arrays consist of half-wavelength dipoles with a phase shifting method between each element that ensures the current in each dipole is in phase.[1] The Coaxial Colinear or COCO antenna uses transposed coaxial sections to produce in-phase half-wavelength radiators. A Franklin Array uses short U-shaped half-wavelength sections whose radiation cancels in the far-field to bring each half-wavelength dipole section into equal phase.
Types of higher gain omnidirectional antennas are the coaxial collinear (COCO) antenna[2] and Omnidirectional Microstrip Antenna (OMA).[3]
Some planar antennas (constructed from printed circuit board) are omnidirectional antennas.[4]
Analysis
Omnidirectional radiation patterns are produced by the simplest practical antennas, monopole and dipole antennas, consisting of one or two straight rod conductors on a common axis. Antenna gain (G) is defined as antenna efficiency (e) multiplied by antenna directivity (D) which is expressed mathematically as: . A useful relationship between omnidirectional radiation pattern directivity (D) in decibels and half-power beamwidth (HPBW) based on the assumption of a pattern shape is:[5]
See also
References
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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
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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 - ↑ Template:Cite web
- ↑ 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