No abstract

This article presents a new design of a common‐mode suppressed differentially fed circularly polarized (CP) antenna using a quasi‐self‐complementary (QSC) structure. The antenna radiating element consists of a semicircular‐ring radiating patch and its complementary radiating slot counterpart. The design idea for producing CP radiation is based on field orthogonality of the QSC structure. For better impedance matching, a fan‐shaped notch (stub) around the feeding position was cut from (implemented in) the semicircular radiating patch (slot). In addition, to improve the axial ratio, a QSC semielliptical structure is embedded in the central area of the antenna. For the designed differentially fed CP antenna, measurement shows that the differential‐mode (DM) operating band with return loss >10 dB covers 4.76‐6.38 GHz. The measured DM 3‐dB axial‐ratio band is 4.95‐5.43 GHz. Also, very good common‐mode (CM) suppression is observed with the measured CM reflection coefficient >−1.21 dB in 4.50‐6.5 GHz.