Wideband Dual-Polarized Gap Waveguide Antenna Array Based on Novel 3-D-Printed Feeding-Network Topologies

A wideband dual-polarized array based on gap waveguide technology using new feeding-network topologies is proposed in this article for millimeter-wave (mm-Wave) applications. Compared with the traditional dual-polarized gap waveguide antenna array, this feeding-network of the proposed subarray exhibits only two layers (polarization separation layer and power divider layer). Two orthogonal polarizations are excited by two orthogonal modes of a cylindrical cavity. A high-order mode cavity acts as a 1 to 4 power divider. The proposed
$2\times $
2 subarray has an overall bandwidth of 24% (
$\vert S_{11}\vert < -10$
dB,
$\vert S_{21}\vert < -10$
dB and gain fluctuations within 3 dB) with a peak gain of 15.2 dBi. Although the overall bandwidth of the subarray is wide, the port isolation is low (about 15 dB) and the cross-polarization level is relatively high due to the polarization separation being realized on a one-layer structure. In the array design, a dual-polarized feeding network with high isolation above 40 dB is realized by using ridge gap waveguide and groove gap waveguide transmission lines. Since the feed network is designed symmetrically, the cross-polarization is also canceled out. The simulated cross-polarization ratio of the array is higher than 50 dB. Based on the new feeding network topologies, measured results demonstrate that the
$4\times $
4 array achieves an overall bandwidth of 22.8% (
$\vert S_{11}\vert < -10$
dB,
$\vert S_{21}\vert < -40$
dB and gain fluctuations within 3 dB) with a peak gain of 19.8 dBi. The proposed antenna features a wide overall bandwidth with dual polarization, low cost, and good radiation performance, which is well suited for 5G mm-Wave applications.