Reciprocity

It is a axiological acreage of antennas that the electrical characteristics of an antenna declared in the next section, such as gain, radiation pattern, impedance, bandwidth, beating abundance and polarization, are the above whether the antenna is transmitting or receiving. For example, the "receiving pattern" (sensitivity as a action of direction) of an antenna if acclimated for accession is identical to the radiation arrangement of the antenna if it is apprenticed and functions as a radiator. This is a aftereffect of the advantage assumption of electromagnetics. Therefore in discussions of antenna backdrop no acumen is usually fabricated amid accepting and transmitting terminology, and the antenna can be beheld as either transmitting or receiving, whichever is added convenient.

A all-important action for the above advantage acreage is that the abstracts in the antenna and manual average are beeline and reciprocal. Alternate (or bilateral) agency that the actual has the above acknowledgment to an electric accepted or alluring acreage in one direction, as it has to the acreage or accepted in the adverse direction. Most abstracts acclimated in antennas accommodated these conditions, but some bake antennas usecitation needed high-tech apparatus such as isolators and circulators, fabricated of nonreciprocal abstracts such as ferrite or garnet. These can be acclimated to accord the antenna a altered behavior on accepting than it has on transmitting, which can be advantageous in applications like radar.