Diverse electromagnetic (EM) responses of a programmable metasurface with a relatively large scale have been investigated, where multiple functionalities are obtained on the same surface. The unit cell in the metasurface is integrated with one PIN diode, and thus a binary coded phase is realized for a single polarization. Exploiting this anisotropic characteristic, reconfigurable polarization conversion is presented first. Then the dynamic scattering performance for two kinds of sources, i.e. a plane wave and a point source, is carefully elaborated. To tailor the scattering properties, genetic algorithm, normally based on binary coding, is coupled with the scattering pattern analysis to optimize the coding matrix. Besides, inverse fast Fourier transform (IFFT) technique is also introduced to expedite the optimization process of a large metasurface. Since the coding control of each unit cell allows a local and direct modulation of EM wave, various EM phenomena including anomalous reflection, diffusion, beam steering and beam forming are successfully demonstrated by both simulations and experiments. It is worthwhile to point out that a real-time switch among these functionalities is also achieved by using a field-programmable gate array (FPGA). All the results suggest that the proposed programmable metasurface has great potentials for future applications.
The simultaneous improvement of radiating and scattering performance of an antenna is normally considered as a contradiction. In this study, wideband radar cross‐section (RCS) reduction and gain enhancement are both achieved for a conventional patch antenna by loading metamaterial in an improved way. First, two artificial magnetic conductor units are selected to construct a chessboard‐like metamaterial surface (CLMS) which has wideband low RCS property. Then the CLMS is applied to a conventional patch antenna for the purpose of RCS reduction. Through a detailed investigation of three loading manners, a metamaterial‐based patch antenna with both improved RCS and gain is proposed and experimentally validated. Both simulated and measured results show that, compared with the original antenna, the gain of the proposed antenna is enhanced almost over the whole operation band, and the wideband (in‐band and out‐of‐band) RCS reduction is achieved concurrently.
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