A Circularly Polarized Antenna Based on Narrowed Crossed Dipole for Smartphone Satellite Communication

A circularly polarized (CP) antenna for satellite communication on smartphone is proposed in this article. The antenna is designed based on proposed narrowed crossed dipole, which has a significantly smaller size compared to the conventional one. Only one of the dipoles is excited directly, the other works as a parasitic element. By adjusting the lengths of the dipoles, CP radiation is realized. Finally, a matching circuit based on coupled microstrip line and balun chip for balanced feeding is introduced. A prototype of the proposed antenna was fabricated and tested to validate the concept. The measured bandwidth with S11 < -10 dB for the antenna is 2.47 – 2.51 GHz (covering the S band of the BeiDou Navigation Satellite System (BDS) of 2483.5 ∼ 2500 MHz). Besides, the measured 3 dB axial ratio (AR) bandwidth is about 1.4%. The maximum gain is 1.9 dBic and the efficiency is higher than 78% over the operating band. The proposed antenna shows great potential in the satellite communication application for smartphone.