Antenna excitation for maximum gain

The problem of obtaining the excitation of an antenna array for maximum power gain is considered in terms of network parameters defined at the input terminals. The reciprocal problem of loading an antenna for maximum absorption area is also considered. The network parameters may be either calculated by solving appropriate boundary value problems, or measured on arrays already constructed. Some procedures for experimentally determining the excitation for maximum gain are presented. If the array elements are closely spaced, supergain antennas are obtained. Formulas for estimating the frequency sensitivity, or , of such supergain arrays are given, and the gain-bandwidth product is discussed.