Circularly Polarized Switched-Beam Antenna Arrays With Reduced Sidelobe Level

A novel method of sidelobe level reduction in switched-beam antenna arrays fed by Butler matrices has been proposed. The presented method takes advantage of circularly polarized two-port antenna elements, hence the sidelobe level reduction is achieved with conceptually lossless feeding networks without increasing the number of radiating elements. The presented approach allows for realization of amplitude taper by combining an N ×N Butler matrix with N two-way power dividers. Theoretical analysis as well as simulation and measurement results of the manufactured prototype operating in 2.4-GHz frequency range have been presented.