Stochastic optimization of sparse antenna arrays

Indoor Radar Cross Section (RCS) measurement is an important issue when the dimensions oí the anechoic chamber are not very large compared with the wavelength. Basically, the efficiency oí the chamber absorbing materials, that cover the inner surface, strongly decreases for low frequencies. In the V/UHF band, the measurement antennas usually consist of big horns. The trouble is that their directivity is weak, leading to significant coupling between the target under test and the surrounding walls [1]. Antenna arrays, with limited number of elements, are an attractive way to get a more directive illumination (see Fig. 1).