A Polarization and Beam Steering Reconfigurable Cavity-Backed Magneto-Electric Dipole Antenna Array Using Reflection-Type Phase Shifter

Abstract

This article introduces a reconfigurable cavity-backed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\,\,\times4$ </tex-math></inline-formula> magneto-electric (ME) dipole antenna array with agile polarization and steerable beam features for both linear and circular polarizations (CPs). The proposed ME dipole element backed by a cavity can reduce the mutual coupling and enhance the scanning performance of the antenna array. To achieve continuous beam-scanning ability, reflection-type phase shifters are designed with varactor diodes and integrated with the feeding network. The polarization agility is determined by embedding two switchable cross strips into the ME dipole element. By manipulating the states of the two switchable cross strips through dc bias controls, three different polarization states including linear polarization (LP), left-hand CP (LHCP), and right-hand CP (RHCP) can be realized. For verification, a prototype of the antenna array was fabricated and measured. A good agreement between the simulation and the measurement is obtained, thus validating the multiple reconfigurable capability of the antenna array in polarization and radiation pattern. The measured results demonstrate that the beam can be scanned continuously in a range between ±40° for the three polarization states. Meanwhile, the measured overlapped bandwidth for the reflection coefficient ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert \text{S}_{11}\vert \le -10$ </tex-math></inline-formula> dB) and the 3 dB axial ratio (AR) is from 2.0 to 2.4 GHz for all states.