V-Band Wideband Circularly Polarized Endfire Multibeam Antenna With Wide Beam Coverage

A V-band wideband circularly polarized (CP) endfire multibeam antenna array with the wide beam coverage is presented in this letter. First, a wideband compact endfire CP element with the wide axial ratio (AR) beamwidth is proposed. The design procedure and working principle of the element are discussed in detail. Besides, connected holes are used to reduce the mutual coupling and improve the AR performance. After that, a wideband substrate integrated waveguide Butler matrix is designed to feed the antenna array. Finally, the multibeam antenna is fabricated, measured and investigated. The measured results demonstrated that the proposed multibeam antenna provides a wide -10 dB impedance bandwidth of 28.5% (55.5 to 74 GHz) and a wide 3 dB AR bandwidth of 24.6% (57 to 73 GHz). Additionally, a wide beam coverage ranging from 45°-66° is achieved. Good agreement achieves between measured results and simulated ones.