Multibeam Bidirectional Wideband/Wide-Scanning-Angle Holographic Leaky-Wave Antenna

Abstract

This letter shows experimentally the realization of a high-gain multibeam bidirectional radiation in a wide frequency range via a planar holographic leaky-wave structure where the beams can scan from backward to forward direction as the frequency varies from 12 to 18 GHz. To realize these two key features, i.e., wideband characteristic and bidirectional multiple-beam pattern, we exploit the characteristic of a wideband surface wave launcher and inherent nature of a metasurface supporting TE mode at the same time. In more detail, this antenna benefits from a TE-mode antipodal Vivaldi as a distinguished feed, which has a broadband behavior, on a surface without metallic ground plane and realizes a high-gain bidirectional multibeam pattern. A four-beam linearly polarized antenna, including two backward and broadside beams in front side and two backward and broadside beams in the back side of the antenna is designed, fabricated, and tested at 12 GHz. The measured gain, sidelobe level, cross polarization, efficiency, and 3 dB bandwidth of the gain, are 17.8 dBi, −17 dB, −30 dB, 26.5%, and 43.3%, respectively, which are great achievements. Moreover, the maximum scan angle of $\text{44}^\circ $ , i.e., from $({\boldsymbol{\theta },\boldsymbol{\varphi }}) = ({\text{30}^\circ,180}) $ to $({\boldsymbol{\theta },\boldsymbol{\varphi }}) = ({\text{14}^\circ,\text{0}^\circ})$ , is achieved for the backward beams when the frequency varies from f = 12 GHz to f = 18 GHz.