A Compact K/Ka-Band Dual-CP Shared-Aperture Phased Array With Wide-Angle Scanning Capability

This letter presents a compact shared-aperture phased array operating in the K/Ka bands with wide-angle beam steering capability. The K- and Ka-band antenna elements are staggered, featuring a compact size. Specifically, the Ka-band antenna has the left-handed circular polarization (LHCP) and the K-band antenna has the right-handed circular polarization (RHCP). Both antennas are fed by stripline-based Wilkinson power dividers to improve the CP radiations. To improve the beamwidths and therefore the beam-scanning performance, a back-cavity structure is employed in the design. In addition, a quarter-wavelength opened stubs are integrated into the feeds of the elements, which is functioned as band-stop filters to suppress out-of-band radiation, and hence, the cross-band isolation can be improved. The phased array is prototyped and characterized experimentally, demonstrating the phased array antenna has a beam-scanning range of ±65° in both the K and Ka bands, respectively, with an average scanning loss of less than 4 dB.