Design of a Low-Profile Dual-Band Shared-Aperture Circularly Polarized Phased Array

A dual-band circularly polarized phased array is proposed for satellite communications. The low-band and high-band radiators are realized by a circular slot etched on a substrate-integrated waveguide (SIW) and a magnetoelectric (ME) dipole positioned at the center and the corners of the SIW, respectively. The low-band design combines two modes with broadside radiation patterns and a wide axial ratio (AR) bandwidth. The measurement of the array with four low-band and seven high-band elements demonstrates that both the −10 dB impedance bandwidth and the 3 dB AR bandwidths of broadside beams can cover 12.5–14.2 GHz and 16.8–18.5 GHz for the low and high band, respectively. For broadside beams, the 3 dB AR beamwidths in the phi = 0° plane are 76° and 32° at 13 and 18 GHz, respectively. For maximum scanning beams, the ARs within the 3 dB beamwidth are below 3 and 4.6 dB at 13 and 18 GHz, respectively.