Pattern Reconfigurable Yagi Antenna Based on Active Corrugated Stripline

Abstract

We present a method of designing pattern reconfigurable Yagi antenna based on the active corrugated strip line (ACSL) technology. A conventional dipole is used as a driven element, and a pair of ACSLs in different states is set on both sides of the dipole symmetrically. The ACSLs in different states have different average phase constants ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta _{\mathrm {ave}}$ </tex-math></inline-formula> ), where the ACSL with a lower <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta _{\mathrm {ave}}$ </tex-math></inline-formula> serves as a director, while the other serves as a reflector. By changing the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta _{\mathrm {ave}}$ </tex-math></inline-formula> of the ACSLs, a front-to-back pattern reconfigurable Yagi antenna is realized. A prototype of the proposed antenna working at the center frequency of 2.4 GHz was fabricated and measured to validate the predicted performance. The fabricated antenna has a compact size ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.42\lambda _{0}\times 0.42\lambda _{0}$ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> is the wavelength in space) and low profile ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.004\lambda _{0}$ </tex-math></inline-formula> ). The measured −10 dB impedance bandwidth and the gain of the antenna are 8.3% and 6.2 dBi (at 2.4 GHz), respectively.