Isotropic Radiator

(redirected from Isotropic antennas)

isotropic radiator

[¦ī·sə¦trä·pik ′rād·ē‚ād·ər]
(physics)
An energy source that radiates uniformly in all directions.

Isotropic Radiator

 

an imaginary antenna emitting electromagnetic energy of equal intensity in all directions. It has a circular directivity pattern in any plane. The isotropic radiator is used in antenna technology as a standard for the comparative evaluation of the directional characteristics of various antennas, particularly in determining the front-to-rear factor. A great deal of attention is being devoted to the design of antennas whose directional properties are close to those of an isotropic radiator. In particular, such antennas are required for use on artificial earth satellites that are unstabilized in space. Antennas of that type make possible the maintenance of communications with the satellite when it changes its position in space.

isotropic

The properties of a material that are the same in all directions. For example, an isotropic antenna radiates the same power in all directions. In practice, antennas cannot be 100% isotropic. However, a perfect isotropic antenna, called an "isotropic radiator," can be calculated, and it is used as a basis for measuring the signal strength of real antennas. Contrast with anisotropic. See dBi.
References in periodicals archive ?
Theoretically, non-directional radiation pattern is known as isotropic radiation pattern; but, isotropic antennas are practically not available.
The SU-Tx is equipped with an ESPAR antenna, and transmits symbols to the SU-Rx, which is equipped with an isotropic antenna, while jointly keeping interference to N PU-Rxs (equipped with isotropic antennas) under a certain limit.
Anritsu Company said it has expanded its electromagnetic field (EMF) measurement system with the introduction of isotropic antennas that provide frequency coverage from nine kHz to six GHz.
Consider a linear uniform adaptive array with M isotropic antennas separated by a distance d between neighbors, k + 1 independent transmitted signals impinge the array from directions [[theta].sub.0], [[theta].sub.1], [[theta].sub.2], ..., [[theta].sub.k], with the broadside direction.
where [[parallel] x [parallel].sub.F] is the Frobenius norm, [n.sub.R] the number of receiving antennas, and [H.sub.ref] the channel matrix with the two isotropic antennas at the BS and the '2-ISO' at the MS, respectively.
[L.sub.s] = the spreading loss in dB between isotropic antennas
[13] employed a modified PSO algorithm for thinning large multiple concentric circular ring arrays of uniformly excited isotropic antennas to generate a pencil beam in the vertical plane with minimum relative side lobe level.
The proposed method has been applied to generate two different beam pairs from a single concentric ring array of isotropic antennas. Two different cases comprising a pencil/pencil beam pair and a pencil/flat-top beam pair have been considered.
However, by assuming isotropic antennas, we get range and frequency terms in the RF equation.
The above definition characterizes the communication link performance of two antennas as compared to two ideal multi-element isotropic antennas that pick up all the available multi-pole channel power, i.e., the total available link power.
Where: G is the ratio of the signal leaving the target to the signal arriving at the target (both referenced to isotropic antennas) (in dB)
One other point about spreading loss: The loss value derived from the nomograph and from the above formula is for the spreading loss between two isotropic antennas (that is, antennas with "unity" or 0-dB gain).