Dual Polarized Shared Aperture Cavity Backed Antenna for K/Ka band operation

In this paper, a dual band dual linear polarized printed antenna with ring shaped aperture as the radiating element is proposed. The radiating ring aperture is backed by a cavity that is fed by an aperture coupled microstrip line. H-shaped slots are used for coupling the microstrip line to the cavity due to their small size compared to a simple rectangular slot. Tapered gradient has been used in the H- shaped slots to increase the bandwidth and reduce the cross polar level. The proposed antenna uses a single radiating surface for dual band operation which makes the antenna low profile. A dual port slot coupled arrangement for both the bands poses several challenges thus a tightly packed arrangement of vias around the central aperture is used to improve the coupling between the two bands. The bandwidth achieved at K and Ka band are, 18.06% and 13.9% respectively, minimum element gain across the bands is 6.73 dBi and 5.15 dBi, minimum cross polarization levels are 26.9 dB and 32 dB with a small element of size $9\times 9$ mm. The proposed antenna can be used as an element of an array for satcom application.