A cavity based high gain MEMS antenna for microwave and millimetre wave applications

A cavity based high gain microstrip patch antenna with wide bandwidth is reported. The slot coupled antenna device was produced on a microwave PCB substrate with a suspended patch supported by a polymer ring structure. After the fabrication of the microstrip feed line and the coupling slot on the substrate and the patch on a polyimide film, two polymer rings of identical design were deposited on the microwave and the polyimide substrates respectively using a SU8 epoxy resin and the photolithography technique. The two polymer rings were then aligned and bonded together to obtain a cavity based patch antenna for high gain operation. The resultant height of the SU8 ring and hence the gap between the polymer and the microwave substrates was 1.5 mm. Reflection and radiation measurements were carried out to evaluate the performance of the antenna device. The results show that the device has a gain of 8.3 dBi at ~12 GHz and a -10dB bandwidth of ~2.5 GHz or 19%. The simulated results are demonstrated to be in good agreement with measurement. The predicted efficiency of the device is about 98%. (4 pages).