Design of a Circularly-Polarized Tightly-Coupled Microstrip Patch Array

A circularly polarized (CP) tightly coupled microstrip patch array (TCMPA) operating in K/Ka-band is presented. The unit-cell element of the proposed array is a microstrip patch with chamfered corners and cross-slot printed on a single Rogers 4350B substrate. The use of cross-slot contributes to both, wider 3 dB axial ratio (AR), and impedance bandwidths. In a tightly coupled array environment, the designed simple element enables phased array bandwidths characterized with broadside AR < 3dB and VSWR < 2:1 of ~15% and ~65%, respectively. Moreover, radiation and aperture efficiencies are >97% and ~100%. A wider-angle scanning with slightly degraded AR is seen in an elevation cone of ±60° in all cardinal and inter-cardinal planes.