C‐/Ka‐band circularly polarized shared‐aperture antenna array

Abstract

A C-/Ka-band circularly polarized (CP) shared-aperture scanning antenna array has been proposed in this paper. Here, the antenna array working in the C-band (6.48–6.52 GHz) is composed of 4 × 4 cross-dipole antenna elements, and each cross-dipole antenna element is fed by a 1-to-2 power divider with 90° phase difference, so that it can induce left/right-hand CP wave. As for the antenna array working in the Ka-band (27.5–28.5 GHz), it is made up of 16 × 16 CP antenna elements, in which each CP antenna element is an aperture-coupled chamfered patch fed by substrate integrated waveguide (SIW) structure. To realize the proposed scanning array, the C-band antenna array is set within the gap between adjacent antenna elements of the Ka-band antenna array, and the radiation apertures of all the antenna elements are printed on the same plane. Notably, such a layout can yield good isolation performance between the C-band antenna and the Ka-band antenna element. From the measured results, in the C-band, the proposed scanning array can achieve a beam scanning range of 0°–38° with axial ratio (AR) < 3 dB, a port isolation of greater than 45 dB, and a maximum gain of 18.2 dBic. On the other hand, in the Ka-band, the proposed scanning array can yield a beam scanning range of 0°–45° with AR <3 dB, a port isolation of greater than 37 dB, and a maximum gain of 26.2 dB.