A X-/Ka-Band Circularly Polarized Shared-Aperture Phased Array Antenna

A circularly polarized (CP) X-/Ka-band shared- aperture phased array is proposed in this paper. Its unit cell consists of one X-band element and 3 × 3 Ka-band elements. The Ka-band element is a rectangular dielectric resonator antenna (DRA) with a metasurface etched on the top side. The X-band element is a dual-feed magneto-electric dipole antenna with dual CP capabilities. By hollowing out the center and the sides of the dipole antenna, 3 × 3 Ka-band elements can effectively share the same aperture with the X-band element. A shared-aperture array prototype was fabricated and measured for performance verification. The results show that the proposed array can achieve an impedance bandwidth from 7 GHz to 8.5 GHz for the X-band and from 26 GHz to 28 GHz for the Ka-band. It can realize ± 45° beam scanning with an axial ratio (AR) variation less than 5 dB for both bands.