Receiving antennas

Abstract

Consider a source-free closed surface and two solutions of Maxwell’s equations (E ₁, H ₁) and (E ₂, H ₂), generated by sources outside the surface S. The reciprocity theorem (see equation (1.18)) is expressed as follows:

$$ \iint_S {(E_1 \times H_2 - E_2 \times H_1 ).ndS = 0} $$

(4.1)

The fields (E ₁, H ₁) and (E ₂,H ₂) are respectively those associated with an antenna when it is transmitting and when it is receiving, and S is a closed surface as depicted in Fig. 4.1. The vector n is the inward normal to the surface.