Trial model of adaptive antenna equipped with switched loads on parasitic elements

An adaptive antenna that forms an adaptive beam by adjusting current induced in the parasitic elements has been experimentally produced. The antenna consists of a radiating element placed at the center and six parasitic elements placed on the circumference of a circle with a radius of 0.5 λ. These elements are monopoles on the reflector. A three-state switched load is connected with each parasitic element. The combination for which the correlation between the received signal and the reference signal maximizes is selected from all load setting combinations. The advantages of using three alternative loads instead of a variable reactance, that is, fast convergence and avoidance of falling into local cost function minimum are demonstrated by numerical experiments. The adaptive beam pattern and bit error rate (BER) of the binary phase shift keying (BPSK) signal were measured in an anechoic chamber, and the capability of the adaptive antenna to form adaptive beams was confirmed.