Electric-controlled metasurface antenna array with ultra-wideband frequency reconfigurable reflection suppression

The electric-controlled metasurface antenna array(ECMSAA)with ultra-wideband frequency reconfigurable reflection suppression is proposed and realized.Firstly,an electriccontrolled metasurface with ultra-wideband frequency reconfigurable in-phase reflection characteristics is designed.The element of the ECMSAA is constructed by loading the single electric-controlled metasurface unit on the conventional patch antenna element.The radiation properties of the conventional patch antenna and the reflection performance of electric-controlled metasurface are maintained when the antenna and the metasurface are integrated.Thus,the ECMSAA elements have excellent radiation properties and ultra-wideband frequency reconfigurable in-phase reflection characteristics simultaneously.To take a further step,a 6×10 ECMSAA is realized based on the designed metasurface antenna element.Simulated and measured results prove that the reflection of the ECMSAA is dynamically suppressed in the P and L bands.Meanwhile,high-gain and multi-polarization radiation properties of the ECMSAA are achieved.This design method not only realizes the frequency reconfigurable reflection suppression of the antenna array in the ultra-wide frequency band but also provides a way to develop an intelligent low-scattering antenna.

Physical-Layer Key Generation Based on Multipath Channel Diversity Using Dynamic Metasurface Antennas

Physical layer key generation(PKG)technology leverages the reciprocal channel randomness to generate the shared secret keys.The low secret key capacity of the existing PKG schemes is due to the reduction in degree-of-freedom from multipath fading channels to multipath combined channels.To improve the wireless key generation rate,we propose a multipath channel diversity-based PKG scheme.Assisted by dynamic metasurface antennas(DMA),a two-stage multipath channel parameter estimation algorithm is proposed to efficiently realize super-resolution multipath parameter estimation.The proposed algorithm first estimates the angle of arrival(AOA)based on the reconfigurable radiation pattern of DMA,and then utilizes the results to design the training beamforming and receive beamforming to improve the estimation accuracy of the path gain.After multipath separation and parameter estimation,multi-dimensional independent path gains are utilized for generating secret keys.Finally,we analyze the security and complexity of the proposed scheme and give an upper bound on the secret key capacity in the high signal-to-noise ratio(SNR)region.The simulation results demonstrate that the proposed scheme can greatly improve the secret key capacity compared with the existing schemes.

Characteristic mode analysis of wideband high-gain and low-profile metasurface antenna

A wideband high-gain and low-profile metasurface antenna is proposed by analyzing characteristic quantities and parameters in the characteristic modes(CMs). The detailed modal current and modal weighting coefficient are analyzed to explain the broadband operation and high gain. A dominant characteristic mode is well excited, leading to a broadband operation. The mode behaviors of the excitation are changed to suppress the unwanted higher-order modes and improve the radiation performance by changing the widths of two patches. The measured impedance bandwidth for-10 dB is 39.8%(5.3 GHz–7.94 GHz) with a gain of 7.8 dBi–10.04 dBi over the operating bandwidth.

Design of multi-band metasurface antenna array with low RCS performance

In this paper, a multi-band metasurface（MS） antenna array with low radar cross section（RCS） performance is proposed and measured. Firstly, a 44 antenna array is composed of four 22 Jerusalem cross structure antenna arrays working at different frequency bands, which is aimed at enhancing the bandwidth effectively. Then, each antenna can be seen as a unit of MS in spite of adding the feeding structure. Based on phase cancellation principle, the MS is arranged into a chessboard configuration in order to realize wideband RCS reduction. Thus, excellent radiation and scattering characteristics are obtained simultaneously. Simulated and measured results indicate that this work provides a novel method to achieve bandwidth expansion as well as wideband RCS reduction of the antenna array.

Joint radio frequency front-end and digital back-end antijamming scheme based on a metasurface antenna array

An array’s degree of freedom(DoF)determines the number of jamming incidents that can be managed and the antijamming performance.Conventional arrays can improve the DoF only by increasing the number of antennas.On the other hand,when the received signal is digitized,high-power jamming will reduce the number of bits used to represent the desired signal,further increasing the difficulty of back-end antijamming based on digital signal processing.In this paper,we propose a joint radio frequency(RF)front-end and digital back-end antijamming scheme based on a metasurface antenna array.The metasurface antennas can rapidly switch patterns when receiving signals,so that a single channel can be equivalent to multiple channels and increase the DoF.We use independent component analysis to estimate the channel and then optimize the array parameters under the minimum signal-to-jamming ratio constraint of each antenna.The proposed scheme works well under high-power jamming conditions by suppressing jamming at the RF front end and using a low-precision analog-to-digital converter.Simulation results show that the proposed scheme reduces the bit error rate of the received signals by one order of magnitude compared with the conventional array.

Broadband millimeter-wave metasurface antenna array withprinted ridge gap waveguide for high front-to-back ratio

A novel broadband metasurface (MTS) antenna array with high front-to-back ratio (FBR) is proposed for 28 GHz millimeter-wave applications. With slot pairs loaded on patch cells, an aperturecoupled slotted-mushroom MTS antenna is designed to obtain broadband radiation characteristicswith a compact size. To suppress the backward radiation of this antenna, the printed ridge gapwaveguide (PRGW) technology with a perfect magnetic conductor (PMC) shielding made ofmushroom unit-cells underneath the microstrip feeding line is applied. On this basis, a 4×4 MTSantenna array with the PRGW feed network is developed. Simulated results show that the FBR canbe highly improved by over 16 dB within the entire bandwidth. To validate the design, a prototypeof the proposed antenna is fabricated. Measured results show that an FBR greater than 28 dB canbe obtained over a 24% impedance bandwidth (from 24.9 GHz to 31.7 GHz) with the reflectioncoefficient less than 10 dB. The measured antenna gain ranges from 17 dBi to 19.2 dBi and thecorresponding measured aperture efficiencies are 35% and 45.6%. The measured results alsosuggest that the proposed MTS antenna possesses -35 dB cross-polarization level and stable radiation patterns. In addition, the proposed antenna remains a very low profile of 1.7 mm (0.17λ_(0) at28 GHz). All the achieved features indicate that the proposed MTS antenna is an importantcandidate for B5G and 6G wireless communication.

Ultra-thin single-layer transparent geometrical phase gradient metasurface and its application to high-gain circularly-polarized lens antenna

A new method to design an ultra-thin high-gain circularly-polarized antenna system with high efficiency is proposed based on the geometrical phase gradient metasurface（GPGM）.With an accuracy control of the transmission phase and also the high transmission amplitude,the GPGM is capable of manipulating an electromagnetic wave arbitrarily.A focusing transmission lens working at Ku band is well optimized with the F /D of 0.32.A good focusing effect is demonstrated clearly by theoretical calculation and electromagnetic simulation.For further application,an ultra-thin single-layer transmissive lens antenna based on the proposed focusing metasurface operating at 13 GHz is implemented and launched by an original patch antenna from the perspective of high integration,simple structure,and low cost.Numerical and experimental results coincide well,indicating the advantages of the antenna system,such as a high gain of 17.6 d B,the axis ratio better than 2 d B,a high aperture efficiency of 41%,and also a simple fabrication process based on the convenient print circuit board technology.The good performance of the proposed antenna indicates promising applications in portable communication systems.