A 3.5/28 GHz Beam-Steerable Shared-Aperture Antenna Based on Shorting-Vias-Loaded Patch

This paper presents a low-profile shared-aperture antenna for 3.5/28 GHz applications. The antenna utilizes a 3.5 GHz patch with a double-layer structure to integrate a 28 GHz 4⨯2 substrate integrated waveguide (SIW) slot array antenna. The array consists of four 2-element subarrays and is excited by four ports below the patch to realize beam steering. For feeding the subarray, this paper introduces a SIW vertical interconnection structure which loads the patch with shorting vias. By adjusting the loading position and the patch dimension, the influence brought by those vias can be minimized. Therefore both antennas can share the same aperture with low mutual interference. The antenna prototype is fabricated and achieves a gain of 6.3 and 11.6 dBi at 3.5 and 28 GHz, respectively. Besides, the radiation beam at 28 GHz of the prototype is steerable within +/-30° on the E-plane.