Wideband Circularly Polarized Millimeter-Wave DRA Array for Internet of Things

This work proposes a novel millimeter-wave (mm-wave) wideband circularly polarized (CP) antenna array for Internet of Things (IoT) applications. The proposed design addresses the issues of having IoT sensors deployed in remote locations or over large geographical regions. Elliptically shaped dielectric resonator antennas (DRAs) are used as array elements to improve radiation characteristics and achieve circular polarization over a wide impedance bandwidth around 28 GHz. Two different sequential-phase corporate feed networks are studied and compared to obtain wider impedance, 3-dB gain, and axial ratio (AR) bandwidths. Furthermore, a ridge gap waveguide technique based on the low-cost PCB technology is adopted to reduce the transmission losses in the considered sequential-phase feed networks. The proposed mm-wave antenna exhibits an impedance bandwidth of 35% (28.1-40 GHz) and 3-dB gain bandwidth of 19.3% (27.6-33.5 GHz). The achieved 3-dB AR bandwidth is 22.6% (27.5-34.5 GHz). The proposed antenna was fabricated and measured, and good agreement between measured and simulated results was obtained. The reported results show that the suggested wideband CP mm-wave antenna has a lot of promise in preventing polarization mismatch losses between IoT devices and satellites caused by their varying orientations.