Reconfigurable Liquid Crystal Dielectric Image Line Leaky Wave Antenna at W-Band

Abstract

This paper presents a reconfigurable dielectric image line leaky wave antenna at W-band. Reconfigurability is achieved by applying bias to anisotropic liquid crystal (LC) filled into the antenna. Instead of separating RF components and DC-bias network by complex or space consuming methods, the bias electrodes are simultaneously used as radiation elements. In order to evaluate this concept, a non-reconfigurable antenna with isolated unit cells is compared to a reconfigurable antenna, which has its unit cells connected by a metallic line. The non-reconfigurable demonstrator shows gain of up to $\mathrm{18}$ dBi and can scan through broadside from −30$\mathrm{^{\circ }}$ to +10$\mathrm{^{\circ }}$ in the investigated frequency range from $75 \,\mathrm{G}\mathrm{Hz}\,\mathrm{to}\, 102 \,\mathrm{G}\mathrm{Hz}$. This frequency scanning sector can be shifted by $10\mathrm{^{\circ }}$ when utilizing the reconfigurable LC antenna, while gain of up to $15$ dBi is maintained. Since the bias electrodes are directly mounted on the image line, less than $50 \,\mathrm{V}$ is necessary to control the LC. The antenna is comparably easy to fabricate, and only one bias voltage is directly related to a steering angle, which can be advantageous compared to complex phased arrays with multiple LC phase shifters.

Keywords

• Beam steering
• dielectric image line
• leaky wave antennas
• liquid crystal
• W-band