A Dual-frame microstrip antenna with four-bridge feeding control for CNSS applications

This letter presents a dual-band and circular polarization microstrip antenna, with a dual-frame patch and slots loaded on its external sides. Based on the multimode resonant theory, a dual-band operation at 1.616 GHz and 2.492 GHz for CNSS applications is realized by the capacity coupling between the frames inside and outside through four-arm conductive bridges. The perturbation is introduced in different directions of the proposed dual-frame structure to achieve dual-hand circular polarization. In addition, the radiation efficiency and gain of the designed antenna are improved and balanced by the suppression of high-order harmonics, due to an EBG defect loaded in the ground plane. The simulation and measurement of the dual-frame microstrip antenna agree well, and the results show good performances.