Cavity-Backed Circularly Polarized Self-Phased Four-Loop Antenna for Gain Enhancement

Abstract

A cavity-backed loop antenna is presented for radiating circular polarization (CP) waves and gain enhancement. The antenna is double-side printed on a substrate. It consists of two pairs of orthogonal dual square loops fed in parallel. It satisfied self-phase shift to radiate CP waves, as the smaller loop has a 90° phase ahead of the larger loop. With two more loops than dual-loop antenna, the gain can be increased to 13.5 dBic, while the size changes little. A coplanar balun is incorporated for impedance matching and simple feeding. The experimental and simulated results are in good agreement.