Circularly polarized beam-scanning leaky wave antenna based on a slow-wave substrate integrated waveguide

Abstract

A circularly polarized (CP) beam-scanning leaky wave antenna (LWA) based on a slow-wave substrate integrated waveguide (SW-SIW) is presented in this paper. The SW effect is realized by introducing a spoof surface plasmon polariton (SSPP), excited by periodic etched 45° tilted slots on the top metallic layer of an SIW. With extra delta modulation, the electromagnetic waves radiate through the etched slots and scan continuously from a backward to forward direction as the frequency changes. Taking advantage of the tilted slots and relative displacement between the upper and lower slots, the direction of the electric field of the radiated waves and phase difference between them are adjustable, making a CP characteristic available. Both the simulated and measured results show the proposed LWA exhibits good performance. The total scanning angle reaches 70°, and the average gain is 8.9 dBi from 9.5 GHz to 11.7 GHz. The CP characteristic is verified through the axial ratio of less than 3 during the operating frequency range. A simple structure, compact size, and good performance make the proposed design promising for a compact wireless communication system.