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In this paper, a frequency-selective rasorber (FSR) with a high efficiency transmission window is proposed for stealth and security applications. By utilizing a new equivalent circuit model to generate the transmission window, there is no lumped and distributed inductor/capacitor (LC) element is used in this structure. Moreover, communication security and stealth performance are promised on the account...
As an effective approach for manipulating propagation of waves, transformation optics has inspired many novel applications during past decades. In this paper, our recent efforts in metamaterial devices for manipulation of waves in microwave region are reviewed with emphasis on (1) multifunctional device with three different kinds of electromagnetic properties, (2) homogeneous illusion device exhibiting...
In this paper, a planar metasurface operating in microwave region to generate Bessel beam carrying orbital angular momentum (OAM) is proposed. The beam generator is realized by utilizing the abrupt phase changes at the interface of the metasurface, instead of the gradual phase differences in the optical lenses. The proposed planar metasurfaces are designed and simulated respectively, and the results...
In this work, a metamaterial resonator based on complementary split ring resonator (CSRR) loaded with square open-loop resonator (OLR) is presented theoretically and experimentally. It is shown through equivalent circuit model that the addition of OLR to the conventional CSRR-loaded cell generates transmission zero in the upper stop band and improves the upper band rejection level without increasing...
In this paper, an electrical array antenna based on liquid crystal (LC) miniaturized phase shifter is designed and simulated, with the capability of beam steering from backfire to endfire. Special chamfered design of meander line is proposed to obtain compact phase shifter based on LC. The antenna integrates phase shifters, power dividers and patch antennas on a substrate to achieve reduced occupied...
A dual band CRLH leaky wave antenna with electrically steerable beam based on liquid crystals is designed and investigated. Lots of full-wave simulations are conducted with CST MW Studio software package to optimize and analyze the performance of the antenna. It shown that the proposed LWA achieves the beam scanning from −16° to + 21° at 7.2 GHz and from −10° to + 19° at 9 GHz simultaneously, through...
In this paper, a single-layer transmission-type metasurface is proposed to generate vortex beams and converge the beam in microwave region. Utilizing the abrupt phase changes introduced by the unit cells, the required phase differences accumulated along the propagation path in conventional optical lens can be easily achieved, resulting in a planar structure of the proposed microwave lens. The results...
In this paper, a liquid crystal tunable frequency selective surface (FSS) in S-band is proposed. The relative permittivity of liquid crystal can be changed from 2.5 to 3.3, with the change of bias voltage applied to it. In that way, the FSS proposed in the paper has a tunable feature. The full-wave simulation of the tunable FSS is carried out in the paper and the equivalent circuit model (ECM) is...
In this letter, we propose an ultra-thin transformation optics metalens to achieve N-beam emissions. Theoretical design is firstly verified by full-wave simulation. Then a four-beam TO metalens antenna is proposed, fabricated and measured to further verify theoretical approach. Compared with the single dipole source, the realized gain of the proposed four-beam antenna is increased by 6 dB, while operational...
This paper presents the results of our research in the field of frequency selective surface in recent years. Aiming at the traditional passive frequency selective surface (FSS) in this paper, we mainly do two aspects of research work, which is the research of the small frequency selective surface and the research of the ultra wide band frequency selective surface. The center frequency value of the...
Metamaterials has inspired many novel physical mechanism and applications for the past decades. In these cases, the thickness of metamaterial is a must to achieve the unique electromagnetic response, which will definitely result in bulky structures and the accompanying loss, especially in microwave region. In this paper, our efforts in planar metasurface are reviewed with emphasis on manipulation...
In this paper, a design method of electrically controlled leaky wave antenna based on liquid crystal is proposed and investigated. The leaky wave antenna is composed of a rectangular waveguide and an inverted PCB micro-strip structure with eight short slots. By loading bias voltage to the liquid crystal, the leaky wave antenna implements wide beam scanning on fixed frequencies. Simulation results...
A novel band-pass Frequency Selective Surface (FSS) working on L-band is presented in this paper. By means of the coupling effect of the metallic patches on three different layers, the distributed capacitance of the periodic structure is formed and therefore decreases the resonant frequency. Investigations on the structure variables are presented and a novel unit cell, whose size is only λ0/20, is...
The complexity and high insert loss of radio frequency (RF) front ends are main constrains in application of Multiple-Input Multiple-Output (MIMO) system, especially in large scale scenarios. As an attractive solution, the concept of switched parasitic array (SPA) was proposed to realize the same performance of MIMO system with single RF chain. To assess its feasibility and efficiency, in this paper,...
In this paper, a high-efficient metasurface to realize the refraction controlling of electromagnetic wave is designed in the microwave region. Based on the Pancharatnam-Berry (P-B) Phase Principle and Generalized Laws of Refraction, a novel artificial electromagnetic unit cell has been raised to complete the function of efficiently transmission of wave refraction, which forms the desired metasurface...
In this work, a compact transition which can efficiently convert guided waves to spoof surface plasmon polaritons (SSPPs) is proposed. By using the S-parameter retrieval technique, the bloch impedance of the SSPP unit cell is extracted and tuned around 50 ohm in a wide frequency band to achieve good impedance matching. Then, the momentum can be matched with fewer gradient matching grooves leading...
In this paper, anomalous reflection for circularly polarized (CP) waves is proposed to achieve, where the reflected waves possess orbital angular momentum (OAM) along their direction of propagation based on the Pancharatnam-Berry (geometrical) phase. Based on the phase gradient metasurface (PGM), we firstly presented a polarization-converting metasurface reflector for circularly polarized waves. On...
This paper presents an average complexity model of a military vehicle (Humvee) carrying a radio transmission antenna for the Electromagnetic Compatibility (EMC) simulation by using the Finite Difference Time Domain method (FDTD). Electromagnetic (EM) fields inside and nearby of the vehicle are computed. The high strength EM fields locations called hot-spot inside the cabin are investigated. Surface...
Vivaldi antenna is widely used for ultra wide band systems because of its wide band, low cost and high directivity. In this paper, a novel Vivaldi antenna is proposed for measurement system. The design and optimization method is introduced. By applying a tapered-slot structure to the conventional Vivaldi antenna, the radiation characteristics of the antenna are obviously improved. The band width of...
Two kinds of EIT structures are proposed, and their validities are demonstrated by using numerical simulation and experimental measurement. The type I structure consists of an “I” shaped of cut-wire pair (CWP) and a split ring resonator (SRR). In this study, we found EIT effect in metamaterial originates from magnetic interactions between resonators. Specially, by controlling the separation distance...
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