Millimeter-wave wideband circularly polarized monopulse antenna using the sequential rotation feeding technique

Abstract

This article presents the design and implementation of a single-layer wideband millimeter-wave circularly polarized (CP) monopulse cavity-backed antenna based on substrate integrated waveguide (SIW) technology. The antenna consists of a 2×8 array of CP cavity-backed antenna elements, a 90° 3-dB coupler, power dividers, and phase shifters. In order to enhance the operating bandwidths, the sequential rotation feeding technology is adopted in the design of the monopulse antenna. To validate the proposed concept, a prototype operating at 42 GHz was fabricated and measured. The measured 3-dB axial ratio (AR) bandwidth for the sum beam can cover a frequency range from 37 to 46 GHz. The measured gain for the sum beam at the center frequency of 42 GHz is 17.5 dBiC, while the null-depth of the difference beam is measured to be −36.8 dB. The proposed monopulse antenna has advantages of low-cost, easy-fabrication, and easy integration with planar circuits.