A Reciprocity Relation of the Time-Correlation Type and Its Application to Antenna Matching

An antenna reciprocity relation that relates the far-field transmitted and scattered wave amplitudes with the relevant Kirchhoff-network quantities is derived via the reciprocity theorem of the time-correlation type. The obtained relation can be envisaged as the complement of the well-known time-convolution antenna relation from which the antenna equivalent circuits can be rigorously constructed. A corollary of the result is the equivalent ("far-field") matching condition whose validity is verified on electric and magnetic dipole antennas.