Transmission and reception properties of non-reciprocal antennas

Most antenna theories treat an antenna is reciprocal, though non-reciprocal passive antennas are possible with gyrators and circulators. We describe basic properties of transmitting and receiving antennas which can be non-reciprocal, then related them considering thermodynamic equilibrium. An extension of the fundamental equation is derived, which is valid for any passive antennas. Based on the extended fundamental equation, we propose to define a new property of receiving antenna, reception efficiency. The reception efficiency is equal to the radiation efficiency for reciprocal antennas. The properties of a non-reciprocal passive antenna can be organized with the receiving efficiency, making transmission and reception pairs. Further, we introduce reciprocity conjugate and construct a non-reciprocal antenna model with two reciprocal antennas.