A Wideband Circularly Polarized Array Antenna With High Phase Center Stability

A wideband circularly polarized(CP) array antenna with high phase center stability is presented in this paper. The effective bandwidth of the antenna can cover the whole typical frequencies of the global navigation satellite system in the L-band. Meanwhile the metal structure of the antenna can be used in the satellite-borne radio occultation experiment. The antenna element is mainly composed of a single-feed crossed dipole antenna and a parasitic magneto-electric dipole, thereby, the wideband $C P$ performance with simple feeding structure is realized. To attain wide azimuth beamwidth, nine antenna elements are arranged in a deformed H-shaped array, whose amplitude and phase are optimized using differential evolution algorithm. In this way, the number of azimuth elements is reduced, which leads to lower cost and lighter weight. A prototype was fabricated and measured to verify the design. The measured results show that the prototype reaches $\mathbf{- 1 2} \text{dB}$ impedance bandwidth of $44.9 \%$ and 3 dB AR bandwidth of $\mathbf{4 1 . 1 \%}$. Moreover, phase center stability is below 1.27 mm of more than 90° and a 10 dBic beamwidth of more than 90° are achieved. This design can be a good candidate in satellite occultation detection fields.