SIW-Based -Band Leaky-Wave Antenna With Improved Beam Steering Performance

Abstract

A high-scanning rate leaky-wave antenna (LWA) working at <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ka</i> -band with continuous backward-to-forward beam-scanning capability, good open stopband (OSB) suppression and wide scanning angle is exhibited. The proposed LWA is made by etching an array of cascaded high-Q resonators and open discontinuities on the substrate integrated waveguide (SIW). The resonator is designed by combining two symmetrically unbalance split ring resonators (USRRs) on the top surface of the SIW. The LWA's working mechanics were thoroughly investigated through band structure theory. An in-depth interpretation of the LWA's characteristics is provided by studying the surface current distribution and the equivalent circuit model of the resonator structure. The LWA's OSB is effectively alleviated by properly selecting the length of the radiation slot. Yet, the antenna scanning rate is directly improved by the oscillation quality of the resonators (i.e., USRRs), which is realized by tuning the split gap of the USRR. In the experiments, a prototype of the proposed LWA was fabricated and measured. The simulated and measured data show good agreement in terms of the antenna's scanning range and radiation gain. The measured results indicates that a continuous beam scanning from −56° to +48° is rendered over the frequency band from 32 to 36 GHz, which implies a spectral scanning rate of 8.84° per percentage. Finally, it is shown that the average gain can reach up to 9.1 dBi.