A Wideband Gap Waveguide-Fed 16-Element Circularly Polarized Patch Antenna Array

This paper presents a design of a 4 x 4 circularly polarized (CP) patch antenna array based on gap waveguide (GW) sequential feeding network. The proposed antenna single element consists of an aperture coupled circular patch antenna. A two-level sequential feeding network, that is used to enhance the polarization bandwidth, is designed, and investigated. The GW technology is employed to decrease the feeding network loss; and consequently, to achieve a low-loss antenna array. The antenna input port is a standard waveguide (WR-28), and it is coupled to the GW-based feed network using an appropriate transition. The proposed array is printed on RT5880 substrate, (with a relative permittivity of 2.2). The measured and simulated results show that both input vertical bar S-11 vertical bar and axial ratio bandwidths are greater than 30% over the frequency range of 25.8-35 GHz. The maximum gain is 18 dBic. The proposed work is considered a great choice for millimeter-wave applications.