Design of Moire-Inspired Metasurface Lens for Focusing Electromagnetic Power in Fresnel Near-Field Region

Abstract

This paper proposes a Moire-inspired metasurface lens system to focus electromagnetic power in the Fresnel near-field region. The proposed metasurface lens (MSL) system is composed of two MSLs and a square patch antenna source. The MSLs are modeled based on the transmit phase distributions of Moire lens theory, and each unit cell structure (patch shape and Jerusalem cross slot shape) is determined to fit the calculated transmit phase distributions at each location. When changing the unit cell structure, phase and transmittance variations are achieved over 330 degrees and -3 dB. The square patch antenna source is then designed to excite the field to the MSLs. The measured reflection coefficients are below -10 dB at 5.8 GHz while rotating the second MSL. The focal length can be adjusted from a minimum of 38 cm to a maximum of 110 cm according to the rotation angle of the second MSL. The proposed MSL system can be employed for wireless power transmission applications to focus electromagnetic power at various locations in the near-field region.