Compact Wideband Circularly Polarized Patch Antenna Array Using Self-Sequential Rotation Technology

In this letter, a compact wideband circularly polarized patch antenna array is proposed to cover the 57–71 GHz band. The antenna array is constructed by 45
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inclined slits loaded circular radiating patches with rectangular back cavities, two-layer sequential rotation feed networks, and a waveguide transition. Novel self-sequential rotation technology is introduced using a dual-high-order-mode cavity to improve the axial ratio (AR) and impedance bandwidths of the subarray. Compared with conventional sequential rotation feed networks, the proposed feeding scheme provides higher aperture efficiency. A 4 × 4 patch antenna array is fabricated using standard printed circuit board technology. Measured results show that the
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10 dB impedance and 3 dB AR overlapped bandwidth is 23.8%(57–72.3 GHz). The measured peak gain is 20.5 dBic with an aperture efficiency of 87.7% at 66 GHz.