en>Khazar2: clean up, typos fixed: ablility → ability, et. al. → et al. (5) using AWB

2013-08-15T13:42:18Z

clean up, typos fixed: ablility → ability, et. al. → et al. (5) using AWB

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A '''dielectric resonator antenna''' is a radio [[antenna (radio)|antenna]] mostly used at [[microwave]] frequencies and higher, that consists of a block of [[ceramic]] material of various shapes, the [[dielectric resonator]], mounted on a metal surface, a [[ground plane]]. Radio waves are introduced into the inside of the resonator material from the [[transmitter]] circuit and bounce back and forth between the resonator walls, forming [[standing waves]]. The walls of the resonator are partially transparent to radio waves, allowing the radio power to radiate into space.<ref name="Huang">{{cite book
| last = Huang
| first = Kao-Cheng
| authorlink =
| coauthors = David J. Edwards
| title = Millimetre wave antennas for gigabit wireless communications: a practical guide to design and analysis in a system context
| publisher = John Wiley & Sons
| year = 2008
| location = USA
| pages = 115–121
| url = http://books.google.com/books?id=G4CggacS5qUC&pg=PA115&dq=%22dielectric+resonator+antenna%22&hl=en&sa=X&ei=FeRAT6e-IMXhiAL-sMUm&ved=0CEwQ6AEwAg#v=onepage&q=%22dielectric%20resonator%20antenna%22&f=false
| doi =
| id =
| isbn = 0-470-51598-8}}</ref> An advantage of dielectric resonator antennas is they lack metal parts, which become lossy at high frequencies, dissipating energy. So these antennas can have lower losses and be more efficient than metal antennas at high microwave and [[millimeter wave]] frequencies.<ref name="Huang" /> Dielectric waveguide antennas are used in some compact portable wireless devices, and military millimeter-wave radar equipment. The antenna was first proposed by Long, et al., in 1973.

Dielectric resonator antennas (DRA) offer the following attractive features:
* The dimension of a DRA is of the order of <math>\frac{\lambda_0} {\sqrt{\epsilon_r}}</math>, where <math>\lambda_0</math>; is the free-space wavelength and <math>\epsilon_r</math> is the [[Relative static permittivity|dielectric constant]] of the resonator material. Thus, by choosing a high value of <math>\epsilon_r</math> (<math>\epsilon_r\approx10-100</math>), the size of the DRA can be significantly reduced.
* There is no inherent conductor loss in dielectric resonators. This leads to high radiation efficiency of the antenna. This feature is especially attractive for millimeter (mm)-wave antennas, where the loss in metal fabricated antennas can be high.
* DRAs offer simple coupling schemes to nearly all transmission lines used at microwave and mm-wave frequencies. This makes them suitable for integration into different planar technologies. The coupling between a DRA and the planar transmission line can be easily controlled by varying the position of the DRA with respect to the line. The performance of DRA can therefore be easily optimized experimentally.
* The operating bandwidth of a DRA can be varied over a wide range by suitably choosing resonator parameters. For example, the bandwidth of the lower order modes of a DRA can be easily varied from a fraction of a percent to about 10% or more by the suitable choice of the dielectric constant of the resonator material.
* Each mode of a DRA has a unique internal and associated external field distribution. Therefore, different radiation characteristics can be obtained by exciting different modes of a DRA.

==See also==
*[[Dielectric waveguide]]
*[[Dielectric wireless receiver]]

==References==
# R. K. Mongia, and P. Bhartia, “Dielectric Resonator Antennas – A Review and General Design Relations for Resonant Frequency and Bandwidth”, ''International Journal of Microwave and Millimeter-Wave Computer-Aided Engineering'', 1994, 4, (3), pp 230-247.[http://www3.interscience.wiley.com/cgi-bin/abstract/114177828/ABSTRACT?CRETRY=1&SRETRY=0]
# Antenova [http://www.antenova.com Antenova info]

==External links==
*[http://www.youtube.com/watch?v=EXvdruxTDKk Animation of Radiation from a Circularly Tapered Dielectric Waveguide Antenna (on YouTube) ]

==Notes==
{{reflist}}

{{Antenna_Types}}

[[Category:Radio electronics]]
[[Category:Radio frequency antenna types]]

Prolate spheroidal wave function - Revision history

en>Khazar2: clean up, typos fixed: ablility → ability, et. al. → et al. (5) using AWB