A Mortarboard-Shaped Receiver Antenna for Drone Wireless Charging to Achieve an Outspread Misalignment Tolerance Towards Imperfect Landing

In drone wireless charging, the performance is highly affected by imperfect landing of drones on the charging pad. To enhance the lateral misalignment tolerance, a novel mortarboard-shaped receiver (Rx) antenna for the drone is proposed. The antenna comprises of five coils and employs a hybrid combining topology integrated with the rectifying circuits to amalgamate the harvested voltages from the individual Rx coils. The design is analytically optimized to efficiently exploit the three orthogonal H-field components generated by the transmitter coil antenna to maximize the Rx misalignment region within which a uniform voltage is received. A low-cost PCB technology is employed to realize the proposed Rx antenna. The analytically optimized design of the proposed antenna is experimentally validated and demonstrates a 90.25% uniformity achieved in the load voltage, which is 276% higher than the conventional Rx coil of the literature. This means that the drone can land anywhere on the $\sim 90\%$ (measured 94%) region of the Tx antenna area without degrading the power transfer performance. The wide tolerance range proves that the proposed Rx can potentially eliminate the lateral misalignment problem to a greater extent for realizing a misalignment tolerant wireless charging system for drones.