摘要：
In this article, a water-based metasurface for antenna radar cross section (RCS) reduction is proposed for the first time. The metasurface has a two-layer structure of metal patch and structural water and achieves more than 9 dB RCS reduction in the super high-frequency (SHF) band from 10.6 to 26 GHz based on the mechanism of phase cancellation and wave absorption. Low scattering characteristics are achieved in the X-, Ku-, and K-bands. By using the metasurface as a radiator and introducing a feed structure, a low-scattering antenna in the C-band can be obtained. The impedance bandwidth of the antenna is from 5.7 to 6.07 GHz. The proposed antenna has an extremely small size and low profile, high aperture efficiency, and directional high gain radiation characteristics. Additionally, it exhibits low scattering across a broad frequency band. This work verifies the feasibility of water-based metasurfaces for antenna RCS reduction.
摘要：
In this study, we designed and observed an ultrabroadband absorber and bi-functional sensor based on a water-based metamaterial (MM). The cavity material of the unit cell was photosensitive resin, the internal water layer was formed by connecting two opposite cross-types and rectangles, and the bottom layer was a copper backplate. Simulation results exhibited that the absorption rate for the water-based MM was above 90% in the frequency ranges of 3.01-3.12 and 13.31-57.75 GHz. Experimental results were in good agreement with the simulation results. We observed and analyzed the distribution of electric and magnetic fields at the absorption peaks and determined that the physical mechanism was the strong magnetic resonance between the water layer and the surrounding photosensitive resin. Owing to the irregular shape of the water layer, the absorption properties of the proposed MM were sensitive to incidence and polarization angles. At a higher polarization angle of 45 degrees, the corresponding absorption band changed to 3.28-4.34 and 13.31-57.75 GHz, covering the operating bands for 5G communication. The proposed water-based MMs were also sensitive to the refractive index and have two detection frequencies. The amplitude and frequency variations with different cover materials can be sensed. The sensitivities corresponding to the two resonance points were 25.58 dB/RIU and 5.04 GHz/RIU and 27.85 dB/RIU and 4.09 GHz/RIU, respectively, exhibiting good sensing performance. Thus, the designed water-based MMs have potential applications in 5G signal shielding and biological detection.
摘要：
In electromagnetic (EM) simulations, conventional triangular patches are implemented to discretize the surfaces of conducting objects. The EM scattering of the conducting objects is presented based on the Rao-Wilton-Glisson basis function and continuity of the surface current across the boundary with different mesh sizes. The radar cross section (RCS) is acquired for conducting objects using physical optics (PO). The numerical results are compared with those from a commercial software (FEKO), which indicated the accuracy and effectiveness of the method in this study.
摘要：
<jats:title>Abstract</jats:title>
<jats:p>A low-profile coding metasurface based on beam diffusion and absorption is proposed, which can be applied for broadband Radar Cross section (RCS) reduction. Through inserting resistors into the polarization conversion element, the proposed unit cell can convert a portion of the electromagnetic wave to ohmic loss as well as retain polarization conversion. Subsequently, the power loss and surface current were used to explain the mechanism of absorption and polarization conversion, and the arrangement of the elements was optimized using a simulated annealing algorithm. Furthermore, both the simulated and measured results have shown that the RCS reduction is greater than 10 dB at 6.7–19.3 GHz (the relative bandwidth is 96.9%), and the metasurface still maintains great characteristics at 45° incidence. Thanks to the proposed metasurface offer advantages such as fewer resistors, a wider bandwidth for RCS reduction, an ultra-thin profile (0.066 <jats:inline-formula>
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<?CDATA ${\lambda }_{{\rm{L}}},$?>
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</jats:inline-formula> where <jats:inline-formula>
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</jats:inline-formula> represents the longest wavelength), a stable incident angle, and a more uniform scattering of energy, it can be used in electromagnetic stealth for large targets.</jats:p>
作者机构：
[Cheng, Houyuan; Zhou, Xiangli; Yang, Helin; Jin, Jing; Fu, Yang; Zhou, Xiaofeng] Cent China Normal Univ, Coll Phys Sci & Technol, Wuhan 430000, Peoples R China.;[Ding, Fan] Hanjiang Natl Lab, Wuhan 430070, Peoples R China.;[Ding, Fan] China Ship Dev & Design Ctr, Wuhan 430064, Peoples R China.
通讯机构：
[Yang, HL ] C;Cent China Normal Univ, Coll Phys Sci & Technol, Wuhan 430000, Peoples R China.
关键词：
Broadband switchable;Multifunctional;Water-based metasurface;Toner coated honeycomb;Wide angle of incidence stability
摘要：
A water-based switchable absorber/reflector (WSAR) based on toner-coated honeycomb is proposed. The structure consists of a metasurface absorbing layer, a toner honeycomb layer, a water layer and a metal plate. The combination of metasurface and coated toner honeycomb can realize the function of broadband absorption, and the water layer is used as a control purpose to obtain a good reflection effect by filling the container with water. When the water container is in the state of without water, it behaves as an electromagnetic wave absorber with good absorption performance in the frequency band of 4.72-17.50 GHz. When the water container is in the state of full water,it behaves as a reflector with good reflection performance (reflection coefficient close to -1 dB in the 4.5-10 GHz band) in the operating frequency band. The characteristics and mechanism of the WSAR are analyzed by using the energy loss and equivalent impedance matching, and the correctness of the design is verified by experiments. The proposed structure has certain application value in radar target stealth, electromagnetic compatibility, adaptive camouflage.
期刊：
Microwave and Optical Technology Letters,2024年66(2):e34083- ISSN：0895-2477
通讯作者：
Yang, HL
作者机构：
[Yang, Helin; Fu, Yang; Yang, Haohui] Cent China Normal Univ, Coll Phys Sci & Technol, Wuhan 430000, Peoples R China.;[Ding, Fan] China Ship Dev & Design Ctr, Wuhan, Peoples R China.;[Chen, Shiju] Sci & Technol Complex Syst Control & Intelligent A, Beijing, Peoples R China.
通讯机构：
[Yang, HL ] C;Cent China Normal Univ, Coll Phys Sci & Technol, Wuhan 430000, Peoples R China.
关键词：
chaff cloud;dipole cluster;electromagnetic scattering;radar cross section (RCS);the linear method of moment (LMM)
摘要：
This paper equates chaff clouds to dipole clusters and studies the electromagnetic scattering problem of dipole clusters based on the linear method of moment (LMM) that solve the electric field Integral equation with the pulse basis function. Firstly, the radar cross section (RCS) of three dipole elements is calculated. The dipole element is divided into 11 segment line units using pulse basis functions. The actual chaff clouds are modeled as two nearest dipole cluster models, which are cubic dipole cluster with uniform distribution formed and spherical dipole cluster with Gaussian distribution formed. The total RCS and total E-Field magnitude of two dipole cluster models were calculated. Finally, two physical models are constructed based on the simulation models and an experiment is designed. The electromagnetic scattering characteristics of the two models are measured, which verifies the accuracy of the simulation results and the operability of the experiment.
作者机构：
[Yang, Helin; Zhao, Ruonan; Jin, Jing; Fu, Yang; Zhou, Xiaofeng; Liang, Junyu] Cent China Normal Univ, Coll Phys Sci & Technol, Wuhan 430079, Peoples R China.
通讯机构：
[Yang, HL ] C;Cent China Normal Univ, Coll Phys Sci & Technol, Wuhan 430079, Peoples R China.
关键词：
Frequency -selective surface (FSS);Complex permittivity;Effective permittivity;high Q factor sensor
摘要：
In this paper, a metamaterial sensor is proposed based on a band stop frequency-selective surface (FSS) with high Q factor of 421.9 at 8.032 GHz. The sensor consists of a square loop FSS and a F4B dielectric substrate. This is the first sensor based on a band stop FSS sensing the effective permittivity of 3D printed hollow structures. The equivalent circuit method is used to analyze the characteristics of the sensor, and the results agree well. Two materials under test and four different hole radii of 3D printed hollow structures are used to verify the sensing function. At the same time, the effective permittivity of the 3D printed hollow structure is analyzed, and the correctness of the effectiveness is verified by simulation inversion and Maxwell-Garnett formula. The sensor has the advantages of high Q factor, wide incidence angle and polarization angle insensitivity, which can provide some guidance in metamaterials sensing.
摘要：
<jats:title>Abstract</jats:title>
<jats:p>A compact 4-port coplanar waveguide (CPW) fed ultra-wideband (UWB) multiple-input-multiple-output (MIMO) antenna with enhanced isolation is proposed to operate from 3.66 GHz to 16.61 GHz with 127.78% impedance bandwidth. The proposed antenna system consists of 4 orthogonal arrays of monopole antennas improved by four iterations. The UWB characteristic of the antenna is obtained from an improved monopole antenna fed by CPW. The final MIMO antenna is machined on a Rogers 4003C substrate with dimensions of <jats:inline-formula>
<jats:tex-math>
<?CDATA $60\times 60\times 0.3$?>
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</jats:inline-formula> mm<jats:sup>3</jats:sup>. The orthogonal arrangement of antennas brings about the polarization diversity and certain isolation of MIMO antennas. Four rows of orthogonal metasurface elements with via holes and the ring of the backplane further improve the isolation between antenna elements in the MIMO system. The MIMO antenna has an impedance bandwidth of 12.95 GHz with <jats:inline-formula>
<jats:tex-math>
<?CDATA ${{\rm{S}}}_{11}\lt -10$?>
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</jats:inline-formula> dB and good isolation ( <jats:inline-formula>
<jats:tex-math>
<?CDATA ${{\rm{S}}}_{21}{={\rm{S}}}_{41}\lt -30$?>
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<mml:mn>30</mml:mn>
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</jats:inline-formula> dB and <jats:inline-formula>
<jats:tex-math>
<?CDATA ${{\rm{S}}}_{31}\lt -20$?>
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</jats:inline-formula> dB). In particular, S<jats:sub>31</jats:sub> is always less than −25 dB at frequencies greater than 6 GHz. The measured results of MIMO antenna agree with the simulated results. The optimized MIMO antenna has excellent performance in many aspects, such as UWB, compact size, omnidirectional radiation, enhanced isolation and high efficiency, which means that it has application potential in UWB wireless communication systems.</jats:p>
作者机构：
[Huang, Xiaojun; Ma, Yutao] Xian Univ Sci & Technol, Coll Commun & Informat Engn, Xian 710054, Peoples R China.;[Li, Xiaoyan] Northwestern Polytech Univ, Coll Phys Sci & Technol, Xian 710129, Peoples R China.;[Guo, Linyan] China Univ Geosci, Coll Geophys & Informat Technol, Beijing 430074, Peoples R China.;[Yang, Helin] Cent China Normal Univ, Coll Phys Sci & Technol, Wuhan 430079, Peoples R China.
通讯机构：
[Xiaojun Huang] C;College of Communication and Information Engineering, Xi’an University of Science and Technology, Xi’an 710054, China<&wdkj&>Author to whom correspondence should be addressed.
关键词：
frequency selective rasorber;dual-polarization;low-profile;in-band;band-patterned octagonal ring
摘要：
In this paper, the out-of-band monostatic radar cross section (RCS) reduction of a traditional Vivaldi antenna is achieved by loading a water-based metasurface (WBM) consisting of a water column onto the surface of the antenna. The proposed antenna achieves average RCS reduction of -6 dB and -10 dB in (6–12 GHz) and (6–18 GHz) when the copolarized plane wave incident along the -z and -y axes, respectively. The working band of the proposed antenna is 2–6 GHz, in which the performance of the antenna is not affected by the WBM.
摘要：
<jats:p>A specially designed dumbbell type polarization conversion metasurface (PCM) is proposed. The designed PCM achieves line-to-line polarization conversion in ultra-wideband (UWB) from 7.63 GHz to 18.80 GHz. A low-profile metasurface antenna composed of PCM and slot feed is proposed based on characteristic mode analysis (CMA), which realizes the integrated design of radiation and scattering. Because of the checkerboard scattering properties, low-radar cross section (RCS) low-profile multiple-input-multiple-output (MIMO) antenna and array antenna are designed with PCM. The low-RCS high-isolation low-profile MIMO antenna with size of 1.27×1.27×0.07<jats:italic>λ</jats:italic><jats:sub>0</jats:sub><jats:sup>3</jats:sup> (λ0: the free-space wavelength corresponding to the center frequency point) operating at 5.8 GHz consists of four orthogonal arranged metasurface antennas. The isolation is greater than 26 dB with impedance bandwidth from 5.51 GHz to 6.06 GHz. In addition, the low-RCS high-gain low-profile array antenna with size of 2.55×2.55×0.07<jats:italic>λ</jats:italic><jats:sub>0</jats:sub><jats:sup>3</jats:sup> is also designed. The operating band covers from 5.63 GHz to 6.12 GHz with the gain of 12-15.6 dBi. The RCS reduction of the two antennas for normal incidence is between 6 dB and 23 dB in both X- and Ku-bands. The measured results of the antennas agree with the simulated results, which shows that they have potential application value in 5.8 GHz WLAN wireless communication.</jats:p>
作者机构：
[Huang, Xiaojun; Gao, Huanhuan; Ma, Xiongwei] Xian Univ Sci & Technol, Coll Commun & Informat Engn, Xian 710054, Peoples R China.;[Li, Xiaoyan] Northwestern Polytech Univ, Coll Phys Sci & Technol, Xian 710129, Peoples R China.;[Guo, Linyan] China Univ Geosci, Sch Geophys & Informat Technol, Beijing 100083, Peoples R China.;[Yang, Helin] Cent China Normal Univ, Coll Phys Sci & Technol, Wuhan 430079, Peoples R China.
通讯机构：
[Xiaojun Huang; Helin Yang] C;College of Communication and Information Engineering, Xi’an University of Science and Technology, Xi’an, China<&wdkj&>College of Physical Science and Technology, Central China Normal University, Wuhan, China
摘要：
A novel metamaterial sensor with ultrahigh Q-factor of 665.85 and 1883.3 at 5.46 GHz and 11.3 GHz is pre-sented in this paper, which consists of a metal pattern with cross structure and ring (CSR), a dielectric slab FR4 and a metal backplate. Based on the principle of the absorber, the Q-factor of the two resonance frequency points is improved by optimizing the ring and cross structure to strengthen the resonance. It is because of its wide angle incidence, insensitive polarization, and narrow-band absorptivity greater than 90 %, which is very conducive to the design of material refractive index sensor. Equivalent circuit method is used to analyze the characteristic of the metamaterial structure and the experimental results are in good agreement with the simulations. By loading three giving materials, the sensing function is analyzed and verified in experiments. The design has the ad-vantages of ultrahigh Q-factor, angle and polarization insensitivity, and has potential application prospects in metamaterial sensing.
作者机构：
[Cheng, Houyuan; Li, Yujun; Li, Shangru; Yang, Helin; Wu, Jiong; Yang, Yuejie] Cent China Normal Univ, Coll Phys Sci & Technol, Wuhan 430079, Peoples R China.
通讯机构：
[Helin Yang] C;College of Physical Science and Technology, Central China Normal University, Wuhan, 430079, People's Republic of China
关键词：
water antenna;dielectric antenna;hemispherical helix;directional high-gain radiation;reconfigurable pattern
摘要：
<jats:title>Abstract</jats:title>
<jats:p>This letter proposed a water antenna with a novel shape of a hemispherical helix made of pure water. A plastic water pipe is bent into a hemispherical helix and filled with water to form the helical arm of the antenna. The water arm acts as a director, which enables the antenna to obtain wide-angle radiation characteristic in the axial direction with a beam width of 95.5°. The impedance bandwidth of the antenna (S<jats:sub>11</jats:sub> < −10 dB) is 1.30–1.89 GHz. Based on this antenna, a four-element antenna array is also designed. A quasi-Butler matrix is used to feed this antenna array to achieve a reconfigurable pattern. The antenna array can achieve directional high-gain radiation in five directions, covering a total range of 66°. The maximum gain of the array in the effective frequency band can reach 13.8 dBi.</jats:p>
摘要：
A dumbbell shaped novel wideband polarization conversion metasurface (PCM) is proposed for use on patch antenna to reduce radar cross section (RCS). The metasurface (MS) composed of rectangle and two pairs of irregular hexagons realizes line-to-line polarization conversion from 7.7 GHz to 18.8 GHz with polarization conversion rate (PCR) higher than 90%. When the PCM and its orthogonal elements are coplanar arranged orderly around the radiating patch, the RCS of the antenna is significantly reduced by at least 6 dB in the entire X-band and Ku-band. The proposed antenna has a stable operation at 5.2 GHz, a low profile of 0.05 and the peak realized gain of 7.72 dBi. This antenna can be used for wireless communication in military environments.
