An all-metal heatsink microstrip antenna for wireless power transmission

An all-metal microstrip antenna with high gain, high efficiency, and heat-sinking capability is proposed for wireless power transmission (WPT). The antenna structure consists of a radiating patch and a cylindrical metal ring that shorts the patch to the ground. The metal ring also supports the patch so that the microstrip structure can be substrate-free, which improves the antenna’s radiation efficiency. The geometric parameters of the supportive metal ring are optimized with simulation results showing that a gain of 10.0 dBi and a radiation efficiency higher than 99.3% can be achieved. A prototype of the antenna is fabricated, assembled, and tested. The measurement results agree with the simulation very well. Moreover, simulation results show that the proposed dielectric-free structure serves as a heat sink when a power amplifier is integrated on the backside of the antenna ground. The heat from the amplifier can be effectively conducted to the radiating patch via the metal ring, which considerably reduces the temperature of the amplifier. The heat-sinking capability of the antenna is measured with a surface-mount ceramic chip as the heat source. The chip’s temperature with a thermal dissipation rate of 1 W is reduced from 80.1 °C to 66.7 °C without additional cooling devices. With the proposed antenna integrated with a class-F power amplifier, an active gain of 21.2 dBi is measured in the wireless power transmission experiment.