Compact Omnidirectional Circularly Polarized Antenna Realized by a Parallel ME-dipole Pair

A compact omnidirectional circularly polarized antenna (OCP) realized by a parallel ME-dipole pair is proposed in this paper. This antenna consists of two symmetrical meandering clues and a small ground plane, which helps to obtain a compact design. The arrangement of two clues and ground plane help to construct equivalent M-dipole and E-dipole, respectively, which are the key operation to realize OCP radiation. For the final antenna design, simulated
$\vert S_{11}\vert$
below -10dB is from 1.723 GHz to 1.728 GHz. At
$f_{0}=1.726$
GHz, satisfactory OCP pattern is achieved, and the simulated 3-dB axial-ratio beamwidth in the cutting plane of
$\varphi=45^{\circ}$
and 135° are as wide as 360° and 167°, respectively.