A Novel Compact Monopulse Parallel-Plate Slot Array Antenna

In this letter, the design of a novel radial planar monopulse antenna with two differences and one sum far-field patterns are presented. The antenna consists of the parallel radial line, slot array on the upper plate and feeding network on the underside of the plate. The slots are included of split-ring slots (SRS) that have been designed for circular polarization to work in the X-band. The feeding network is designed by microstrip line to provide the phase excitation for each beam. At 10.58 GHz, the sum pattern gain is 18.1 dB and differences gains are 12 and 11.9 dB for elevation and azimuth beams, respectively. The axial ratio in the main beam of sum pattern is better than 1.2 dB.