Wideband circularly polarized sequentially rotated microstrip antenna array with sequential-phase feeding network

Abstract

A wideband 2 × 2 sequential-phase fed circularly polarized (CP) microstrip antenna array (MAA) with sequentially rotated elements is proposed. Firstly, the antenna element loaded with shorting pins is studied as compared to the traditional counterpart. Then, a feeding network is designed to be connected together in a sequential rotation manner, resulting in forming a four-port network to allow symmetrical positioning of CP microstrip patch elements. After that, straight strips are added to the feeding network in order to increase the distance and reduce coupling between array elements. They also play a role in improving the impedance matching of the array. Finally, the proposed antenna array is designed and simulated. The results are presented that its impedance bandwidth is about 36.3% at 24.1~34.8 GHz for |S 11 | < −10 dB and axial-ratio (AR) bandwidth is about 20.4% at 24.2~29.7 GHz for AR < 3 dB. Besides, a peak gain of 11.1 dBic is simulated over the operating frequency range, which is significantly improved compared to the classic and existing works.