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  • Wideband Low-Profile Circul...
    Qiu, Lei-Lei; Zhu, Lei; Xu, Yanhui

    IEEE transactions on antennas and propagation, 07/2020, Letnik: 68, Številka: 7
    Journal Article

    This communication proposes a wideband low-profile circularly polarized patch antenna based on a broadband 90° modified Schiffman phase shifter and a meandering L-shaped microstrip feed. The whole antenna consists of a broadband hybrid feeding network and a circular patch radiator. The hybrid network has two branches that operate in the first and second Schiffman periods, and thus can achieve 113% 10 dB return loss bandwidth and 75% phase shift bandwidth within 90°± 4.6° under a relaxed coupling strength of 1.58. To reduce the profile, the planar microstrip L-shaped feeding probe is properly meandered, which provides not only broadband impedance matching, but also an extra degree of freedom in the reduction of cross polarization, thus achieving a wide axial ratio (AR) bandwidth. Simulated and measured results show that the antenna has indeed achieved a low profile (<inline-formula> <tex-math notation="LaTeX">0.05~\lambda _{0} </tex-math></inline-formula>) with 50.5% impedance bandwidth, 47.8%AR bandwidth, and 34% gain bandwidth (>3 dBi).