A Compact and Fast $1 \times 4$ Continuously Steerable Endfire Phased-Array Antenna Based on Liquid Crystal

Abstract

This letter presents a planar endfire Yagi-Uda antenna phased array fed by a corporate network. The phase of each radiating element is controlled by a loaded line phase shifter based on liquid crystal technology. The phase shifters are meandered to minimize the dimension of the array and are measured to provide maximum differential phase shift of 400 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${^\circ }$</tex-math></inline-formula> with a figure-of-merit of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${54}{{^\circ }\rm {dB}^{-1}}$</tex-math></inline-formula> at 28.4 GHz. Each phase shifter is tuned individually by applying bias voltage through high impedance chromium line together with dc blocks. The array is designed for full-range scanning in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> -plane with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$&gt;\!{360}{^\circ }$</tex-math></inline-formula> phase shifters. Measurements show that it can be steered from −40 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${^\circ }$</tex-math></inline-formula> to 40 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${^\circ }$</tex-math></inline-formula> by applying dc bias in the range of 0–5 V and from −50 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${^\circ }$</tex-math></inline-formula> to 60 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${^\circ }$</tex-math></inline-formula> with degraded patterns. The maximum gain of the phased array antennas is measured to be 4.5 dBi. The array beam is able to be fast steered within approximately 1 s.