Circularly Polarized Loop-Type Ground Radiation Antenna for IoT Applications

Abstract

A circularly polarized loop-type ground radiation antenna using a ground mode tuning (GMT) structure is proposed for Internet of Things (IoT) devices. The antenna is designed to excite two orthogonal modes of equal magnitude on the ground plane. The GMT structure consists of an inductor and a metallic strip that has been installed at the edge of the ground plane to obtain a 90° phase shift between the two modes. The proposed antenna generates left-hand circularly polarized waves in the +z-direction and right-hand circularly polarized waves in the -z-direction. The antenna was fabricated to validate the simulation results. The measured -6 dB bandwidth of the antenna was 150 MHz and the axial ratio bandwidth with reference to 3 dB was 130 MHz, completely covering the 2.4-2.48 GHz band.