Finite Scattering Matrix for an Infinite Antenna Array

A finite scattering matrix, S, for a plane‐wave excited infinite array is developed for the purpose of relating a number of array and active‐element properties. The size of S depends on the polarization in space, the grating lobe locations, and the propagating modes in the feed. Array properties such as scattering on receive, transmission amplitude and phase, surface‐wave propagation, phase and amplitude of the active‐element pattern, etc., are described by this matrix. For the lossless array, the unitary conditions on S further relate the array properties. Some of the results are illustrated by the exact S matrix for an infinite TEM parallel‐plate array. The active element charactenst1cs, and the occurrence of surface‐wave‐type mutual admittances, are discussed in terms of S.