Ultra-Wideband $E$-Plane Monopulse Antenna Using Vivaldi Antenna

An ultra-wideband (UWB) E-plane monopulse antenna working in the frequency range from 3.1 to 10.6 GHz is proposed. The UWB E-plane two-element array is constructed using Vivaldi antennas. By shortening the adjacent tapered lines of the two Vivaldi antennas and using corrugated edges, sum and difference characteristics of the array are improved. The UWB monopulse comparator is a multilayer planar magic T consisting of an UWB 90° directional coupler and two UWB 45° phase shifters in series. By integrating the array and the comparator, the UWB E-plane monopulse antenna is designed and fabricated with the low-cost PCB process. In the frequency range from 3.1 to 10.6 GHz, the sum gain is measured as more than 10.1 dBi, the sidelobe level less than -13.1 dB, and the null depth greater than 22.5 dB. The good sum and difference characteristics obtained make the proposed UWB E-plane monopulse antenna desirable for target detecting and tracking.