chapter  11
25 Pages

Arrays

WithBoris Levin

The electrical characteristics of radiators system at given frequency are conditioned by its phasing mode, that is, by choice of the phase shift between the currents in radiators. Antenna array can have two modes of phasing: the maximal radiation forward and the minimal radiation backward. Self-complementary and log-periodic antennas belong to the class of frequency-independent antennas. The log-periodic antenna is an antenna array. The self-complementary antenna of several dipoles of the same shape and dimensions is also an antenna array. Phased antenna array found a wide use in antenna technology. These are a system of radiators, which allow the dramatically increase the directivity of the structure in a given direction. Attenuators or amplifiers and phase shifters are used to adjust the amplitude and to form the desired phase shifts respectively. Both the phase shifters and attenuators or amplifiers operate in an analog mode, providing the correct linear coupling of the main parameters and the real phases and amplitudes.