A Dynamically Phase Tunable Metasurface for a Broad Bandwidth Ultra-Low Radar Cross Section

Abstract

An electrically tunable metasurface is designed for radar cross-section (RCS) reduction application in this paper. It consists of 24 × 24 cells individually loaded with variable capacitors so that their phase profiles can be independently controlled by the bias voltage. Therefore, based on the diffusive scattering principle and reflect-array theory, we arrange the adaptive phase differences between adjacent basic elements and reconfigure the appropriate phase distribution determined by a genetic algorithm (GA) corresponding to the operation frequency. Thus, stable monostatic and bistatic RCS reduction with normal incidence can be realized over a wide band by independently tuning the capacitance of each loaded varactor. Simulation results verify that the bistatic RCS reduction can reach at least 10 dBSm within both 4.2-7.3 GHz and 9.3-11.3 GHz. Simultaneously, the monostatic RCS reduction reaches at least 17.5 dBSm and 14 dBSm within the above two bands, respectively. INDEX TERMS Metasurface, radar cross section, varactor tuning.

Phase Random Metasurface With Diffuse Scattering Based on Subwavelength Unit’s Design of Shunt Resonance Circuit

“…Then, a unit cell configuration exhibiting stable reflection phase over 6. [8][9][10][11][12][13][14][15][16].4GHz is presented. According to Fraunhofer criterion on diffuse scattering, six optimized unit cells with different physical sizes and equal phase gradient are determined to construct the metasurface with random phase distribution.…”

“…From then on, more researchers focus on anomalous electromagnetic phenomena brought by metasurface and it is applied promptly in various fields, including but not limited to wave-front control technology [7] [8], polarization convertor, propagating waves(PW) to surface waves(SW) convertor [9] [10], ultrathin flat lenses [11], holographic technology, vortex-beam generators. It is also used to reduce monostatic radar cross section (RCS) [12] [13] [14][15] [16]. For example, it is demonstrated that metasurfaces can be used to realize specific electromagnetic characters such as reflection in specific direction without altering its physical shape, by utilizing achromatic phase shift stemming from spin-orbit interaction in ultrathin space-variant and spectrally engineered metasurfaces [17].…”

Tunable liquid crystal metasurface with polarization selection characteristic

“…In recent years, tunable and reconfigurable metasurfaces are more desirable for rapid developments in multifunctional and multistandard communication systems. Tunable and reconfigurable metasurfaces were achieved by various methods, such as micro-electromechanical systems (MEMS), varactor diode, liquid crystal (LC), etc [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. Ferrite is an approach to realize tunability [14].…”

“…Although MEMS-based metasurfaces exist the advantage of high tuning, they suffer from expensive costs and complicated fabrication processes. Varactor diodes and p-i-n diodes have the characteristics of high tuning or switching speed and large tuning range, which is very suitable for the design of tunable metasurfaces [18][19][20][21][22][23]. For example, four varactor diodes are used in the metasurface unit cell, whose reflection band can be tuned from 1.23 to 2.24 GHz [19].…”

Reprogrammable Digital Holograms and Multibit Spatial Energy Modulation Using a Reflective Metasurface

“…By integrating tunable components into the meta-atom, the response of the metasurface to incident light can be dynamically modified. Reconfigurability in metasurfaces is typically achieved by optical, − thermal, − and electrical mechanisms, − mechanical stretching, − chemical reactions, , and so on. Taking advantage of the digital description possibilities offered by a real-time addressable ultra-thin metasurface, reprogrammable image holography can be achieved with high imaging precision.…”