Holographic Design of Beam-Switchable Leaky-Wave Antenna

Abstract

A holographic design of beam-switchable leaky-wave antenna (LWA) is presented. The proposed design consists of a holographic impedance modulated surface (HIMS) and control circuit. In this design, the HIMS, which carries impedance characteristics of four beams, is obtained by using a modified modulation method in the same aperture. Thus, the proposed HIMS can generate four switchable beams at a fixed frequency when itis excited by different reference waves. By controlling p-i-n diodes inserted along the feedline, four working states can be obtained. The proposed LWA is fabricated and measured. Four switchable beams with pitch angles of θ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> = θ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> = -30°, θ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> = θ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> = 30° and azimuth angles of φ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> = 0°, φ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> = 90°, φ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> = 180°, and φ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> = 270° are obtained at 18 GHz. The measured peak gain of each beam is better than 17.2 dBi.