Dual-linearly polarized travelling-wave array antenna based on triple plus slots fed by square waveguide

Abstract

A dual-linearly polarized travelling-wave array antenna design at Ku-band composed by a novel single element named as triple plus slot is presented. It is formed by a plus slot with an additional pair of short auxiliary slots. The generation of the dual polarization is based on the two degenerated modes TE10 and TE01 supported by a square waveguide following a series feeding topology. Following the operation principle of the conventional plus slot, the transversal slot is only excited by the TE10 mode to generate vertical polarization while the longitudinal slot is only excited by the TE01 mode to generate horizontal polarization. The auxiliary slots provide new degrees of freedom to the antenna design process that allow to accomplish some strict requirements and overcome some design issues. Thus, the proposed triple plus slot has been experimentally validated in a dual-linearly polarized travelling-wave array configuration. The antenna has been fabricated and measured, providing some features such as high efficiency (>80%), high gain (>13 dB) with a 1 dB-gain bandwidth higher than 10%, grating lobe mitigation, high isolation between orthogonal polarizations (>25 dB) as well as a fractional impedance bandwidth (S11 < −14 dB) higher than 11.7% (from 16 to 18 GHz).