Dual-Circularly Polarized Single-Element Patch Antenna With Compact Multiport Feeding

A circularly polarized (CP) S-band patch antenna that makes use of a multiport setup to improve its radiation efficiency and compactness is presented. The design highlights a single-element patch with eight-port feeding, by using compact slot meandering. To the best of the authors' knowledge, no earlier literature discloses a similar single-element patch with eight feeding points made compact by slot meandering while demonstrating comparable performances, bandwidth, agility, and polarization purity. In addition, our design utilizes eight 50-
$\Omega$
microstrip ports to set and excite the orthogonal polarization states. The miniaturized feeding arrangement, directly under the patch, enables the antenna to produce both left-handed and right-handed CP (as well as other polarization states), making the design suitable for full-duplex and diversity scenarios.