Dual-Band Circularly Polarized Asymmetric Linear Tapered Horn Antenna for Feeder of Synthetic Aperture Radar Onboard Microsatellite

A novel dual-band waveguide-fed circularly polarized (CP) horn antenna is proposed for the feeder of synthetic aperture radar (SAR) onboard microsatellites. The proposed horn antenna consists of an asymmetric linearly tapered slot and a waveguide feed. The left-hand circular polarization (LHCP) design was simulated, and the 3-D-printed prototype was fabricated to validate the simulation and measured in an anechoic chamber. The measured circularly polarized (CP) antenna can achieve dual-band operations at C-/X-band with a 3 dB axial ratio bandwidth of 40% (5-6.5 GHz; 8.5-10 GHz), VSWR less than 1.4 in the operating band, and a peak gain of 13.6 dBic (5.3 GHz) and 18.5 dBic (9.4 GHz). The measured half-power beamwidth (HPBW) at C-band and X-band frequencies in the xz-plane and yz-plane are achieved at 26°/37° and 18°/23°, respectively. The proposed antenna features a simpler configuration and lower manufacturing cost, making it competitive for SAR applications.