Miniaturized and circularly polarized antenna with high front-to-back-ratio in the L1 band for global navigation satellite systems

A miniaturized, multi-band and circularly polarized (CP) antenna with high Front-to-Back-Ratio (FTBR) in the L1 band for global navigation satellite systems (GNSS) is developed in this paper. The proposed CP antenna consists of four dielectric substrates, each of which forms a folded monopole antenna and a parasitic inverted-L antenna for four frequency bands (L1/L2/L5/L6). To improve a FTBR, a microstrip resonator is situated in the multi-layer substrate beneath the antenna elements. The FTBR is improved by 4.2 dB in the L1 band when compared to the FTBR of the antenna without the microstrip resonator. The measured boresight gain is more than 1.5 dBic over the four bands.