A Fabry–Perot Conical Beam Antenna With Multi-Polarization Reconfigurable Capability

In this communication, a Fabry–Perot (FP) conical beam antenna with multipolarization reconfigurable capability is proposed. A single-layer partially reflective surface (PRS) with circular slots is designed for the prescribed flare angle determined by the height of the FP antenna and resonant frequency. A group of Vivaldi patches with a set of shorting vias around a common central axis on a printed circuit board (PCB) are used as the primary source, which is fed by nested coaxial waveguide. Vivaldi patches coupled with parallel baluns, which are connected to the internal coaxial waveguide, are used to produce a horizontally polarized conical beam. A vertically polarized conical beam can be obtained when the external coaxial waveguide is used to feed the Vivaldi patches. When circularly polarized conical beams are required, the internal and external coaxial waveguides need to be excited at the same time with the same amplitude and the proper phase difference. A prototype of the proposed FP conical beam antenna with multipolarization reconfigurable capability at 12 GHz is designed, fabricated, and measured to verify the concept. The measured results are in good agreement with the simulated ones. A maximum gain of
$\ge 12.8$
dBic is achieved with the proposed FP conical beam antenna for the two circular polarization states, with an axial ratio (AR) and impedance bandwidth (IBW) of
$\ge 16.7$
% and 8%, respectively. The maximum gain and IBW for the horizontal polarization (HP) and vertical polarization (VP) are
$>13.2$
dBi and 9.2%, respectively.