Single-Feed Circularly Polarized Super Realized Gain Antenna

This paper presents a super realized gain, circularly polarized strip-crossed dipole antenna operating at 3.5 GHz. Superdirective behavior is achieved by leveraging strong interelement mutual coupling through careful adjustment of the strip dimensions. The antenna features a single driven element, with the other element passively loaded with a reactive impedance. The structure is optimized to maximize left-hand circularly polarized(LHCP) realized gain, ensuring high polarization purity and good impedance matching. The optimized design exhibits a 50 Ωimpedance bandwidth of 3.29–4.17 GHz (23.75%) and an axial ratio bandwidth of 3.43–3.57 GHz (4%). At 3.5 GHz, the antenna achieves a peak realized gain of 6.1 dB (ka ≈ 1.65), with anaxial ratio of 1.4 dB. These results demonstrate that circular polarization and superdirectivity can be simultaneously realized in a geometrically simple, low-profile (0.15λ) antenna, rendering it suitable for integration into compact sub-6 GHz wireless and sensing platforms.