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For a reciprocal antenna, these two patterns are identical. A multitude of antenna pattern measurement techniques have been developed. The first technique developed was the far-field range, where the antenna under test (AUT) is placed in the far-field of a range antenna.
Instead, the radiation pattern of the antenna is determined by a single simulation, and the receiving pattern inferred by reciprocity. When determining the pattern of an antenna by measurement, the antenna may be either receiving or transmitting, whichever is more convenient.
When actual measurements of an antenna's gain are made by a laboratory, the field strength of the test antenna is measured when supplied with, say, 1 watt of transmitter power, at a certain distance. That field strength is compared to the field strength found using a so-called reference antenna at the same distance receiving the same power in ...
A second unit used to measure gain is the ratio of the power radiated by ... According to reciprocity, the efficiency of an antenna used as a receiving antenna is ...
For such an antenna, the near field is the region within a radius r ≪ λ, while the far-field is the region for which r ≫ 2 λ. The transition zone is the region between r = λ and r = 2 λ . The length of the antenna, D, is not important, and the approximation is the same for all shorter antennas (sometimes idealized as so-called point ...
In electromagnetics, the antenna factor (AF, units: m −1, reciprocal meter) is defined as the ratio of the electric field E (units: V/m or μV/m) to the voltage V (units: V or μV) induced across the terminals of an antenna:
A reference antenna is an antenna with known performance. It is normally used to calibrate other systems. It is normally used to calibrate other systems. During a relative calibration, an antenna's phase center offset (PCO) and phase center variations (PCV) are computed with respect to the reference antenna which is normally assigned zero PCV ...
Directivity is an important measure because many antennas and optical systems are designed to radiate electromagnetic waves in a single direction or over a narrow-angle. By the principle of reciprocity, the directivity of an antenna when receiving is equal to its directivity when transmitting.