High-Order Mode Resonant Planar Dual-Sense Bidirectional Circularly Polarized Antenna With Arbitrary Orthogonal Polarization Flared Angles

Abstract

A design approach to a planar dual-sense bidirectional circularly polarized (CP) antenna is advanced. The resultant antenna can exhibit orthogonal CP radiations in arbitrary directions between 90° and 180°, i.e., the flared angle formed by pure left-handed CP (LHCP) and right-handed CP (RHCP) directions could be set in a wide range from 90° to 180°. The operational principle is revealed by an equivalent source model at first. Then, prototype antennas are advanced by incorporating a high-order mode resonant, V-shape dipole to a planar magnetic dipole, and a parasitic electric dipole. As numerically simulated and experimentally validated, the flared angle formed by LHCP and RHCP directions can be adjusted as 90° and 135°. In the 90° case, the presented bidirectional CP antennas can exhibit impedance bandwidth of 6.6%, 3 dB axial ratio (AR) bandwidth of 13.0% in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$+ x$ </tex-math></inline-formula> -axis, and 8.9% in the +z-axis. The advanced low-profile (height < 0.05 wavelength) antenna can simultaneously provide spatial and polarization diversity abilities in one principal-cut elevation plane. Therefore, it would be a promising colocated, spatial/polarization diversity antenna in future wireless systems.