Antenna Matching Theorems

The maximum power transfer theorem in antenna theory is a corollary of the property of antenna self‐reciprocity that makes possible to represent a receiving antenna system as a Kirchhoff‐type equivalent network. This chapter introduces a global‐type matching condition for a class of reciprocal antennas. The transmitting and receiving situations of an
N
‐port antenna system are mutually interrelated using the reciprocity theorem of the time‐correlation type. The total radiated electromagnetic (EM) wave field is causal and hence admits the far‐field expansion. The
N
‐port antenna system is in its receiving state irradiated by the uniform EM plane wave. The chapter also introduces the scattered EM wave field that accounts for the presence of the receiving antenna system as the difference between the total EM field and the incident wave field.