Inspired by the design philosophy of information metasurfaces based on the digital coding concept,a planar 4-bit reconfigurable antenna array with low profile of 0.15λ0(whereλ0is the free-space wavelength)is presented.The array is based on a digital coding radiation element consisting of a 1-bit magnetoelectric(ME)dipole and a miniaturized reflection-type phase shifter(RTPS).The proposed 1-bit ME dipole can provide two digital states of"0"and"1"(with 0°and 180°phase responses)over a wide frequency band by individually exciting its two symmetrical feeding ports.The designed RTPS is able to realize a relative phase shift of 173°.By digitally quantizing its phase in the range of 157.5°,additional eight digital states at intervals of 22.5°are obtained.To achieve low sidelobe levels,a 1:16 power divider based on the Taylor line source method is employed to feed the array,A prototype of the proposed 4-bit antenna array has been fabricated and tested,and the experimental results are in good agreement with the simulations.Scanning beams within a±45°range were measured with a maximum realized gain of 13.4 dBi at12 GHz.The sidelobe and cross-polarization levels are below-14.3 and-23.0 dB,respectively.Furthermore,the beam pointing error is within 0.8°,and the 3 dB gain bandwidth of the broadside beam is 25%.Due to its outstanding performance,the array holds potential for significant applications in radar and wireless communication systems.
Zheng Xing WangHanqing YangRuiwen ShaoJun Wei WuGuobiao LiuFeng ZhaiQiang ChengTie Jun Cui
Complete control of spatially propagating waves(PWs)and surface waves(SWs)is an ultimate goal that scientists and engineers seek for,in which negative reflection of PW and negative surface wave are two exotic phenomena.Here,we experimentally demonstrate an anisotropic digital coding metasurface capable of controlling both PWs and SWs with a single coding pattern.On the basis of the digital description of coding metasurfaces,a simple coding method is proposed to allow dual functionalities(either PW or SW manipulations)under two orthogonal polarizations at arbitrarily oblique incidences,thus improving the adaptability of digital coding metasurfaces in more practical circumstances.With elaborately designed ellipse-shaped coding particles,we experimentally demonstrate various functions under oblique incidences,including the negative reflection of PW,negative SW,anomalous reflection and their arbitrary combinations,all having good agreements with theoretical and numerical predictions.We believe that the proposed method may enable the digital coding metasurfaces to have broad applications in radar detections,wireless communications and imaging.
Shuo LiuTie Jun CuiAhsan NoorZui TaoHao Chi ZhangGuo Dong BaiYan YangXiao Yang Zhou
In this review article, a brief introduction on the theory, experiments and applications of metamaterials is presented. The main focuses are concentrated on the composing meta-atoms, the method of transformation optics, the experimental demonstration of negative refraction, and the realizations of invisibility cloaks and electromagnetic black hole. At the end of this review, some typical applications of metamaterials, including high-performance antennas made of zero-refractive-index materials, inhomogeneous metamaterial lenses, and planar metasurfaces, are introduced in details.
