Sijia Li

Wideband, thin, and polarization-insensitive perfect absorber based the double octagonal rings metamaterials and lumped resistances

By loading the lumped resistances into the double octagonal rings metamaterials, a wideband, thin, and polarization-insensitive perfect absorber is investigated theoretically and experimentally. The perfect absorber is constructed of double octagonal rings loading the eight lumped resistances and the substrate with height of 3u2009mm. The effects of the double octagonal rings and eight lumped resistances are explored by absorption and the electric field distributions. The simulated results indicate that the structure obtains 9.25u2009GHz-wide absorption from 7.93 to 17.18u2009GHz with absorptivity larger than 90% at the incident angles from 0° to 20° and achieves above 12.2u2009GHz-wide absorption from 5.8 to 18u2009GHz with a full width at half maximum at wide incident angles from 0° to 70°. The fabricated metamaterial absorber device was measured and analyzed. A good agreement is observed between the simulation and the measurement.

Multiband and broadband polarization -insensitive perfect absorber devices based on a tunable and thin double split-ring metamaterial

We demonstrate a polarization-insensitive perfect absorber with multiband and broadband absorption based on a tunable and thin metamaterial, which consists of a double split-ring microstructure (DSRM) on double-layer and a coating substrate. The multiband absorption at different frequencies and broadband absorption with the relative bandwidth of 90.63% from 5.69GHz to 15.12GHz, of which the absorptivity is larger than 90%, can be achieved by changing the rotary angle of the proposed DSRM perfect metamaterial absorber (DSRM-PMA). The advantages of polarized-insensitivity, wide bandwidth and multiband absorption are illuminated by the angular absorptions and the surface current distributions. The DSRM-PMA device with similar geometry in simulation is fabricated and tested to clearly validate the functionality of our design. The simulated and experimental results indicate that the DSRM-PMA performs multiband and broadband absorptions with the rotary angle of 0° and 90° respectively.

A programmable metasurface with dynamic polarization, scattering and focusing control.

Diverse electromagnetic (EM) responses of a programmable metasurface with a relatively large scale have been investigated, where multiple functionalities are obtained on the same surface. The unit cell in the metasurface is integrated with one PIN diode, and thus a binary coded phase is realized for a single polarization. Exploiting this anisotropic characteristic, reconfigurable polarization conversion is presented first. Then the dynamic scattering performance for two kinds of sources, i.e. a plane wave and a point source, is carefully elaborated. To tailor the scattering properties, genetic algorithm, normally based on binary coding, is coupled with the scattering pattern analysis to optimize the coding matrix. Besides, inverse fast Fourier transform (IFFT) technique is also introduced to expedite the optimization process of a large metasurface. Since the coding control of each unit cell allows a local and direct modulation of EM wave, various EM phenomena including anomalous reflection, diffusion, beam steering and beam forming are successfully demonstrated by both simulations and experiments. It is worthwhile to point out that a real-time switch among these functionalities is also achieved by using a field-programmable gate array (FPGA). All the results suggest that the proposed programmable metasurface has great potentials for future applications.

Loaded metamaterial perfect absorber using substrate integrated cavity

By embedding the metal cavity into the substrate, a kind of ultrathin substrate integrated cavity metamaterial perfect absorber (SIC-MPA) is proposed in theory and experiment. The SIC-MPA is constructed of a single-square loop metal patch with four splits, a square metal patch in the center and several SICs loaded into the metamaterial perfect absorber. The electric fields of the resonant structures for the SIC-MPA are separated, and the electromagnetic wave leakage is decreased by the SICs. The simulated results show that the SIC-MPA has the advantage of high quality factors (Q-factors) of the absorptivity and the monostatic radar cross section (RCS) reduction. Experiments are carried out to verify the simulation results, and the measurement results show that the Q-factor of the measured absorptivity is increased by 23% and the Q-factors of the measured RCS reduction with 1.5u2009dB and 3u2009dB are increased by 21.5% and 18.7% compared with the conventional MPA.

Analysis and Design of Three-Layer Perfect Metamaterial-Inspired Absorber Based on Double Split-Serration-Rings Structure

We systematically analyzed, designed, fabricated, and measured a three-layer perfect metamaterial-inspired absorber based on the double split-serration-rings (DSSRs) structure in this communication. The equivalent circuit model was presented to demonstrate the absorbing mechanism. The characters of polarized-insensitivity, wideband, and multiband absorption for the absorber were illuminated by the angular absorptions and surface current distributions. Transformation from wideband absorption with a relative bandwidth of 93.5% from 5.34 to 14.72 GHz, of which the absorptivity was larger than 90%, to multiband absorption was obtained by rotating DSSR-II of 90°. Two absorber prototypes with a thickness of 3.6 mm had been easily implemented using the common printed circuit board fabrication techniques and measured in a microwave anechoic chamber. Simulated and experimental results indicated that the perfect metamaterial-inspired absorber performed wideband and multiband absorption when DSSRs were perpendicular and parallel to each other, respectively.

Broadband Metamaterial Surface for Antenna RCS Reduction and Gain Enhancement

This paper presents a broadband metamaterial surface with low radar cross section (RCS) and introduces its application on antenna. The metamaterial surface is composed of polarization-dependent artificial magnetic conductors (PDAMCs), which are orthogonal arranged in chessboard-like configuration for backscatter cancellation. By optimizing the PDAMC cell, effective phase difference is obtained in wideband and the surface achieves 10dB RCS reduction over the bandwidth of 32%. As a potential application, the metamaterial surface is employed to replace the metallic ground of a slot antenna. Illustrated by detecting wave, the novel antenna shows low RCS at boresight. While the antenna operates, the gain gets enhanced as a result of parasitic radiation of the surface. Full wave simulations and measurements validate that the novel antenna achieves both broadband low RCS and high gain compared with the slot antenna installed on a same-size metallic plate.

Hybrid metamaterial device with wideband absorption and multiband transmission based on spoof surface plasmon polaritons and perfect absorber

We reported on the design, realization, and numerical characterization of a hybrid metamaterial (HM) with the absorption and transmission at different frequencies based on the spoof surface plasmon polaritons and perfect absorber. A unit cell is composed of a three-layer metamaterial with double orthogonal split ring resonators and a ground plate loaded with two-sided metallic grooves. It is shown that the hybrid metamaterial primarily exhibits a broadband polarization-sensitive absorption from 6.57 to 28.16u2009GHz with a full-width at half-maximum in one direction and a multiband transmission in the opposite one. When the incidence is parallel to HM, the ground plate loaded with two-sided metallic grooves can support a structural vibration of spoof surface plasmon polaritons. To demonstrate design, a HM device easily implemented using common printed circuit board fabrication method is fabricated and measured and the experimental results agree well with the simulated results.

Broadband and High-Isolation Dual-Polarized Microstrip Antenna With Low Radar Cross Section

A Ku-band dual-linear polarized broadband aperture-coupled antenna with high-isolation and low radar cross section (RCS) in special direction is presented, fabricated, and measured based on substrate integrated waveguide technology. The substrate-integrated rows of metallized via holes (SIRMHs) are inserted into the conventional aperture-coupled antenna to enhance the isolation and improve the impedance matching. Monostatic RCS is reduced because the surface current of the metallized ground plane is guided by the SIRMHs. The theoretical and experimental results are in good agreement. Experimental results indicated that the isolation is more than 40 dB, the bandwidth obtains 21% of return loss less than -20 dB, and the RCS is reduced to as much as 23 dB from 12.2 to 16 GHz compared to a traditional antenna when incident angle is 30 °.

Broadband Low-RCS Metasurface and Its Application on Antenna

This paper presents a metasurface (MS) with broadband low radar cross section (RCS) and investigates its application on antenna. The MS is composed of polarization-dependent artificial magnetic conductors (PDAMCs) for backscattering cancellation. By orthogonally arranging the PDAMCs in a fencelike configuration, the scattering beam is deviated from specular direction, so that the MS achieves RCS reduction over a broad frequency band. As a potential application, the MS is employed to simultaneously promote the radiating and scattering performances of a slot antenna. Full wave simulations and measurements confirm that the novel antenna achieves broadband RCS reduction and significant gain enhancement compared with a reference antenna with metallic ground.

Jigsaw puzzle metasurface for multiple functions: polarization conversion, anomalous reflection and diffusion.

We demonstrate a simple reconfigurable metasurface with multiple functions. Anisotropic tiles are investigated and manufactured as fundamental elements. Then, the tiles are combined in a certain sequence to construct a metasurface. Each of the tiles can be adjusted independently which is like a jigsaw puzzle and the whole metasurface can achieve diverse functions by different layouts. For demonstration purposes, we realize polarization conversion, anomalous reflection and diffusion by a jigsaw puzzle metasurface with 6 × 6 pieces of anisotropic tile. Simulated and measured results prove that our method offers a simple and effective strategy for metasurface design.