A tunable ⵣ‐shaped microstrip leaky wave antenna based on liquid crystal

Abstract

This article presents an electrically tunable dual-beam ⵣ-shaped microstrip leaky wave antenna (MLWA) based on liquid crystal (LC). A new ⵣ-shaped microstrip component (Berber's alphabet: pronounced jzj) is proposed as a single unit-cell to achieve a dual-beam radiation pattern with adjustable dualbeam angles controlled by the ⵣ-shaped length-to-width ratio. The dual-beam radiation pattern of ⵣ-shaped microstrip is theoretically derived. The tunable dual-beam scanning is achieved using a nematic liquid crystal (N-LC). An AC voltage controls the permittivity of N-LC applied on the inverted radiating metal. The orientation angle of the N-LC molecules is also determined theoretically. Besides, the MLWA is rearranged due to the meandering configuration of its microstrip transmission lines, which reduces the antenna's size. As a result, this antenna has a symmetrical dual-beam at a pointing angle of ±37 in the YZ-plane. Furthermore, the proposed MLWA is tuned up to 25 at a fixed frequency in XZ-plane directions by applied AC voltage from 0 to 20 V, which changes the permittivity of the N-LC from 2.47 to 3.25, respectively. Meanwhile, the MLWA has a realized gain of up to 7.5 dB and a beam scanning range of 40 in the XZ-plane for all operating frequencies. Finally, the proposed antenna can be suitable for satellite and radar communication systems.