A High-Gain, Wideband, Circularly Polarized Antenna With Multibeam Radiation for Millimeter-Wave Applications

This article proposes a wideband differential fed circularly polarized (CP) antenna [48% overlapped bandwidth, which is the minimum value of axial ratio (AR) bandwidth, gain bandwidth, and impedance matching bandwidth] with multiple beams radiation across V- and W-band enabled by a parabolic reflector, a long-slot radiator, and a wideband 3-D printed polarizer. The long-slot structure is an array consists with substrate integrated waveguide (SIW)-based open-slot elements (the vias besides a conventional SIW slot are moved to form an open slot), which yields wideband characteristics when compared with traditional slot array. Cooperating with wideband parabolic reflector and modified 3-D printed polarizer, it finally achieves 48% CP bandwidth. Finally, by setting multiple ports on the feeding network, multibeam radiation can be achieved. For validation, a multibeam CP antenna operating from 58 to 94.5 GHz with 20.5-dBic peak gain level and three radiation beams is fabricated and measured. Based on the authors' extensive research, the proposed antenna yields a superior bandwidth when compared with recently reported millimeter-wave (mm-wave) long-slot structures and high-gain CP antennas.