A Compact Crossed Inverted-V Antenna with a Common Reflector for Polarization Diversity in the IoT

Abstract

This article presented a compact and high gain antenna with reconfigurable polarization based on two inverted-V dipoles fabricated in a crossed configuration, and with a common planar reflector. The proposed antenna could generate four different types of polarizations, such as vertical polarization (VP), horizontal polarization (HP), right-hand circular polarization (RHCP), and left-hand circular polarization (LHCP). A pair of inverted-V dipoles drove the polarization diversity, where each dipole had an integrated matching circuit and a microstrip balun. Using a crossed inverted-V configuration with a ground plane as the common reflector, we could achieve compactness in size, high directivity, and a wider beamwidth than a normal dipole antenna. To verify the performance of the proposed antenna, we fabricated a sub-6GHz antenna with a Taconic TLX-9 substrate, which had a relative permittivity of 2.5. The proposed antenna showed a measured 10-dB impedance bandwidth of 752 MHz (5.376 GHz to 6.128 GHz). The peak gains for the VP, HP, RHCP and LHCP operations at 5.8 GHz were about 5.2 dBi, 4.61 dBi, 5.25 dBic, and 5.51 dBic, respectively. In addition, the half-power beamwidth (HPBW) for all the polarizations were greater than 78° in the operation band.