Parameter optimization for the three-frequency feed for the mirror antenna of the non-linear radar

Analyzed below is a radiating structure represented by a flat self-complementary three-sector structure fed by three segments of the microstrip line and located above the stepped metal screen, and to be used as an exciter for the non-linear radar antenna. When proper matching with the feeding coaxial cable is achieved, results of the numerical simulation proved that the antenna can provide near-circular polarization of radiation at the probing signal frequency, and linear polarization at the second and third harmonics of this signal.