Aiming at the focusing of near-field electromagnetic (EM) energy, a design approach of multi-type focusing (MTF) based on 1-bit metasurface is proposed in this paper. The surface electric field required for multi-focus is actually obtained by the superposition of the surface electric field of each single focus. This method can flexibly design the number, position, and energy distribution ratio of the focus according to the phase arrangement of the metasurface. Dipole structure is used as ``0'' and ``1'' unit of 1-bit metasurface. The phase difference of reflection is 180°, and the reflection coefficient is over 90% in 7.4-21.9 GHz. Using this 1-bit unit, the linear focus metasurface, multi-focus metasurface and metasurface generating two foci with different energy distribution are realized respectively. The energy distribution metasurface was manufactured and measured, and the measured results are consistent with the simulations. The design method used in this paper is simple and effective to realize multi-focus metasurface design and has potential application value in microwave imaging, radio frequency identification (RFID), and wireless power transmission.
"Design of Electromagnetic Wave Multi-Type Focusing Based on 1-Bit Metasurface," Progress In Electromagnetics Research M,
Vol. 105, 79-88, 2021. doi:10.2528/PIERM21080505
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