Simple Backward-to-Forward Scanning Tri-Polarization Leaky-Wave Antenna

A simple tri-polarization periodic leaky-wave antenna with continuous backward-to-forward scanning capability is proposed. The mechanism for tri-polarization implementation, realized through the elliptical patch and spoof surface plasmon polaritons transmission line, is analyzed for the first time using characteristic mode analysis and the method of pattern synthesis. To achieve unidirectional radiation for the linearly polarized beams, a half-mode substrate integrated waveguide structure is placed adjacent to the transmission line. By using equivalent circuit analysis, a groove is etched onto the antenna unit cell to suppress the open-stopband. A prototype is designed, and fabricated. The measured results show that an overlapping beam scanning range for the dual circularly polarized and linearly polarized beams is 71°.