Dual-Circularly Polarized Phased Array With Modified Cavity and Notched Patch

A novel design of a K-band dual-circularly polarized (DCP) wide-scanning phased array antenna with enhanced isolation is proposed in this letter. To obtain the DCP operation, two stacked square patches are chamfered and coupled fed by two orthogonally arranged slots. A rectangular cavity is adopted in the array element, which benefits the impedance matching and axial ratio during beam scanning. The middle part of the cavity rims is deliberately cut, and an inner square hole is etched on the lower chamfered patch to achieve higher isolation between orthogonal ports. Calculated results show the proposed DCP element achieves an active VSWR below 3 in 18.8–20 GHz during ±60° beam scanning in both of the principal planes. The axial ratio is below 5 dB, and the orthogonal port isolation is higher than 15 dB during wide-angle scanning. The validity of this design is experimentally verified by the array antenna prototypes with 8 × 8 elements.