A compact low-profile dual-band circularly polarized antenna for BDS-3

A compact low-profile dual-band Circularly Polarized (CP) microstrip antenna is proposed for the BeiDou Navigation Satellite System (BDS). To achieve dual-band functionality, a single-layer multimode design is employed, incorporating F-, L-, and T-shaped slots at the corners for CP performance. Additionally, a Defected Ground Structure (DGS) is implemented to further enhance the antenna’s efficiency. A detailed parameter analysis is conducted to optimize the antenna’s size and performance balance. After optimization, the final dimensions of the antenna are minimized while still meeting the design requirements. The prototype of the optimized antenna is fabricated and tested, demonstrating coverage of frequency bands from 1.182 GHz to 1.217 GHz and 1.547 GHz to 1.569 GHz. The antenna effectively supports dual-band CP for B1I and B2b frequency bands. A performance metric, the Ratio of relative Bandwidth to Volume (RBV), is introduced to evaluate the antenna’s efficiency. Compared to similar designs, the proposed antenna offers a smaller size without sacrificing performance, making it well-suited for BDS airborne applications.