A Highly Efficient 1-bit Reflectarray Antenna Using Electromagnet-Controlled Elements
Ao Hu, Keisuke Konno, Qiang Chen, Toru Takahashi
Abstract
A novel mechanically reconfigurable reflectarray element actuated by an electromagnet working in C-band is proposed. The 1-bit phase shift of reflecting wave is achieved by bending a half-wavelength dipole with magnetostatic force. Due to the isolation between element and RF phase shifter, the proposed reflectarray element is free from insertion loss. This is the first article demonstrating the performance of a reconfigurable reflectarray with the element totally isolated from the RF phase shifter. Due to the contactless reconfigurable system, the mechanical connection between the electromagnet and the reflectarray element is physically unnecessary. Prototypes of the proposed reconfigurable reflectarray elements are fabricated and their mechanical tunability is theoretically and experimentally clarified. The detailed working principle of electromagnet control and implementation method are discussed. Next, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$25 \times 8\,\,1$ </tex-math></inline-formula> -bit reconfigurable reflectarray using the proposed elements is fabricated and its scattering performance is demonstrated via field measurement. The measured gain and aperture efficiency of the fabricated 1-bit reconfigurable reflectarray are 22.7 dBi and 34.0% at specular direction, respectively. According to a comparison with previous works, it is clarified that the aperture efficiency of the proposed 1-bit reconfigurable reflectarray outperforms previously developed ones.