Parasitic Beam-Switching Antenna Array for mmWave Energy Harvesting in IoMT Application

Millimeter-wave (mmwave) 5G band is very promising for Radio Frequency (RF) energy harvesting application to power fast growing billions of IoT devices due to its un-precedented high Effective Radiated Power. Typically, medium to high gain antenna arrays are used in mmwave 5G applications, however, due to their large feeding networks such as beamforming networks, power loss can become critical. Ideally, antennas for RF energy harvesting applications must be simple to avoid unwanted power losses, small in size to be compatible for seamless integration, and have wide angular coverage and circular polarization for diverse reception. In this study, we present a parasitic antenna array with a simple beam- switching technique that eliminates the need for complex feeding networks. We also augment and validate the investigation by developing equivalent circuit models of the array and demonstrate the effectiveness of the proposed design. The antenna is designed and optimized at 28 GHz, fabricated and characterized. The antenna system radiates three independent beams with ±S2° beam-switching range, gain of 7.2 dB and 140° of total angular coverage.