Tri-band high-efficiency circular polarization convertor based on double-split-ring resonator structures

Cheng Y., Wang J.

In this paper, a tunable terahertz circular-polarization (CP) convertor based on graphene metamaterial is proposed and investigated numerically and theoretically. The unit-cell of the CP convertor is composed of a sub-wavelength metal grating sandwiched with bi-layered complementary-oval-shaped (COS) graphene array sheet separated by a dielectric spacer. The electric property of the COS graphene can be adjusted dynamically by varying the Fermi energy level ( E f ) through the external gate voltage. The simulation results indicate that the proposed CP convertor can transform the incident right-circularly polarized (RCP) wave to left-circularly polarized (LCP) waves when E f = 0.8 eV, and the polarization conversion ratio (PCR) is up to 99.9% at 1.1 THz. The numerical simulation results are consistent well with the theoretical calculation by wave-transfer matrix method. The physical origins behind the enhanced CP conversion are supported by field distributions and Fabry-Pérot interference theory. Furthermore, the conversion properties of the CP convertor can be adjusted continuously by changing the Fermi energy level. Thus, our design can be found potential applications in many areas, such as remote sensors, reflector antennas, and radiometers in terahertz region. • A tunable terahertz circular-polarization (CP) convertor based on anisotropic graphene metamaterial was proposed. • The polarization conversion ratio (PCR) of the proposed CP convertor is up to 99.9% at 1.1 THz when E f = 0.8eV. • The enhanced CP conversion is mainly attributed to the combination of anisotropic structure and interference effect. • The conversion properties of the proposed CP convertor can be adjusted dynamically by changing the Fermi energy level, and the frequency tuning bandwidth is up to 20.2%.

Cheng Y., Zhu X., Li J., Chen F., Luo H., Wu L.

In this work, a broadband tunable reflective polarization convertor using a single layer complementary-cross-shaped (CCS) graphene metasurface was proposed and investigated numerically in terahertz (THz) region. The electric property of CCS graphene could be flexibly tuned through the Fermi energy level ( E f ). When E f = 0.9 eV, the proposed graphene metasurface can realize a relative high polarization conversion ratio (PCR) of over 80% from 2.15 THz to 4 THz with a relative bandwidth of 60.16%. Furthermore, the PCR peak can reach up to as high as 99%, 99.5% and 91.5% at 2.4 THz, 3.4 THz and 3.96 THz, respectively. The physical origins of this polarization conversion properties are turned out to be supported by field distributions and Fabry-Perot interference theory. Furthermore, the broadband polarization conversion properties will be regulated by varying the Fermi energy level. • A switchable broadband reflective cross-polarization convertor based on a graphene metasurface was proposed. • The proposed convertor can achieve a relatively high polarization conversion ratio (PCR) of over 80% and a relative bandwidth of 60.16% from 2.15 THz to 4 THz when E f was 0.9 eV. • Physics origin of MMA is studied by electric field distributions and Fabry-Perot interference theory. • The broadband PCR can be regulated continuously with the variations of Fermi energy.

Han B., Li S., Li Z., Huang G., Tian J., Cao X.

We propose a chiral metasurface (CMS) that exhibits asymmetric transmission (AT) of double circularly and linearly polarized waves at the same frequency band. In order to realize the manipulation of electromagnetic (EM) waves in the whole space, the unit cell of CMS consists of three layers of dielectric substrate and four layers of metal patches. The Z-shaped chiral micro-structure and a grating-like micro-structure are proposed and designed to achieve AT. The simulated results show that the x-polarized wave that is incident along one direction can be transmitted into the right-hand circularly polarized (RHCP) wave and the left-hand circularly polarized (LHCP) wave that is incident along the opposite direction can be reflected as the LHCP wave in the frequency band of 4.69GHz-5.84 GHz. The maximum chirality response can be reflected by AT and circular dichroism (CD) and they can reach up to 0.38 and 0.75, respectively. In addition, we also produced the sample of CMS, and the experimental results are in good agreement with the simulated results.

Zhou E., Cheng Y., Chen F., Luo H.

In this paper, a high-gain and wideband circular polarization (CP) patch antenna using reflective focusing metasurface was proposed and demonstrated. The initial design of patch antenna is made of a slot planar patch radiation part fed by coplanar waveguide (CPW). The simulated return loss below −10 dB of the initial design is from 6.2 to 13.8 GHz with the relative bandwidth of 76%, and the average gain is only about 4.5 dBi. In addition, the simulated 3-dB axial ratio bandwidth (ARBW) of the initial design is 78.7% from 6 to 13.8 GHz. The antenna structure was modified to enhance the gain and radiation performance by adding the reflective focusing geometric metasurface. The metasurface with wideband high efficiency cross-polarization reflection, is arranged to construct the phase gradient paraboloid for energy gathering. Simulation results indicated that the antenna combined with reflective focusing metasurface achieves an effective wideband impedance bandwidth (return loss

Fan J., Cheng Y., He B.

Abstract It has been demonstrated that metasurfaces have the ability to manipulate the wavefront. However, most multifunctional metasurfaces reported to date only operate in either reflection or transmission mode. In this paper, a bilayer metasurface based on geometric phase is proposed to independently tailor the wavefronts of transmitted and reflected circularly polarized (CP) waves at two different terahertz frequencies. More specifically, the metasurface can transform the incident CP wave to its cross-polarization component with a high conversion coefficient of about 0.87 (0.92) after refraction (reflection) at 0.6 (1.67) THz. The full 2π phase shift can be obtained independently by varying the geometrical parameters of the unit-cell structure at two different operation modes. As proofs of concept, anomalous refraction and reflection, dual-band full-space cylindrical focusing metalens and vortex beam generation with different modes are numerically demonstrated. Our work provides an effective method to integrate two or more different functionalities into a simple metasurface-based device, and the independent phase modulation characteristic of our proposed metasurface also shows infinite potential in wavefront control of full space.

Khan M.I., Chen Y., Hu B., Ullah N., Bukhari S.H., Iqbal S.

In this work, a multiband polarization converting metasurface is presented which achieves cross-polarization conversion in five frequency bands while linear-to-circular and circular-to-linear polarization transformation in eight frequency bands. The polarization transforming functionality of the structure is spread over an ultra-wide frequency range (5–37 GHz) covering most of X, C, Ku, K and Ka bands. Such an extraordinary ultra-wideband operation originates from multiple plasmonic resonances occurring in the structure based on two coupled rectangular split-ring resonators. Moreover, the polarization transforming capability is stable within the frequency range 5–19 GHz for wide oblique incidence angles, which is up to 60°, both for transverse-electric and transverse-magnetic polarizations. Furthermore, the proposed structure acts as a meta-mirror which preserves handedness of the circular polarization upon reflection. Measurements performed on the fabricated metasurface are found to be consistent with numerical simulation results. The ability to perform three functionalities through a single compact structure with extraordinary wideband, qualifies the proposed design to be a promising candidate for integration with important microwave applications such as satellite, radar, and 5G communication.

Fei P., Vandenbosch G.A., Guo W., Wen X., Xiong D., Hu W., Zheng Q., Chen X.

Yu Y., Xiao F., Rukhlenko I.D., Zhu W.

We present the design, simulation, and characterization of an ultrathin polarization converter based on planar anisotropic transmissive metasurface. The metasurface consists of two identical metallic structures printed on both sides of a dielectric substrate and possesses a nearly uniform transmittance with a π phase difference over the whole bandwidth for waves of orthogonal linear polarizations. It is demonstrated numerically and experimentally that the designed metasurface can high-efficiently change the polarization plane of a linearly polarized plane wave or convert the circularly polarized plane wave into the wave of opposite handedness in a wide frequency bandwidth. The polarization conversion ratios in both cases could reach almost 100% from 15.8 GHz to 16.7 GHz. The proposed metasurface converter may find uses in various applications combining highly efficient control of polarization with a low insertion loss.

Cheng Y., Fan J., Luo H., Chen F.

In this paper, a dual-band and high-efficiency circular polarization (CP) convertor based on anisotropic metamaterial (AMM) was proposed and investigated in microwave region. The proposed AMM based CP convertor is composed of a sub-wavelength metal grating sandwiched with bi-layered disk-split-ring (DSR) structure array, which can convert the normal incident CP wave to its orthogonal one around two adjacent frequency ranges. Based on the intrinsic anisotropic and Fabry-Perot-like cavity-enhanced effect, a high CP conversion efficiency can be achieved by applying the proposed AMM. Numerical simulation results indicate that the cross-polarization transmission coefficients can achieve maximum values of 0.84 at 4.5 GHz, and 0.92 at 7.9 GHz, respectively, which is in well agreement with experiment. In addition, the measured CP conversion efficiency is beyond 99% at resonance frequencies. The mechanism of the CP conversion properties can be explained by the electromagnetic (EM) interference model and the simulated electrical field distribution. Due to its excellent polarization conversion properties, the proposed CP convertor based on AMM structure shows potential application in such as radar, remote sensing, and satellite communication.

Cheng Z., Cheng Y.

In this paper, a multi-functional polarization convertor for terahertz (THz) light composed of a bilayer wire-split-ring (WSR) structure chiral metamaterial (CMM) was proposed and investigated numerically. Simulation results indicate that when normal incident light is propagating along the – z axis direction through the proposed CMM structure, the y-polarization is converted to the left- and right-circular polarization (LCP and RCP) at 1.14 THz and 1.34 THz, respectively. Meanwhile, the x-polarization is converted to y-polarization in the frequency range of 2.19 – 2.47 THz. The further calculation results show that the proposed CMM structure can transmit a nearly pure circular polarization light with a polarization extinction ratio (PER) of over 30 dB and an orthogonal linear polarization light with a polarization conversion ratio (PCR) of over 90%. The mechanism of the polarization conversion properties is illustrated by the simulated electrical field and surface current distribution. Due to its excellent multi-functional polarization conversion properties, the proposed CMM is useful for the development of the integrated THz polarization manipulation devices.

Mun S., Hong J., Yun J., Lee B.

Controlling the polarization state of light has been a significant issue for various integrated optical devices such as optical imaging, sensors, and communications. Recent advances in metamaterials enable the optical elements for controlling light to be miniaturized and to have various multi-functions in subwavelength scale. However, a conventional approach of a circular polarizer has an inherent limitation to eliminate the unwanted circular polarization, which means that the efficiency varies significantly depending on the polarization state of incident light. Here, we propose a novel concept of a circular polarizer by combining two functions of transmission and conversion for orthogonal circular polarizations with a total thickness of 440 nm. The proposed three-layer metasurface composed of rotating silver nanorods transmits the left-handed circularly polarized (LCP) light with maintaining its own polarization state, whereas the right-handed circularly polarized (RCP) light is converted into LCP light. Regardless of the polarization state of incoming light, the polarization of light in the last medium is LCP state in the broadband operating wavelength range from 800 nm to 1100 nm. The converted RCP and the transmitted LCP have efficiencies of up to 48.5% and 42.3%, respectively. Thus the proposed metasurface serves as a stable circular polarizer for a randomly polarized light. In addition, high-efficiency asymmetric transmission of about 0.47 is achieved at the same time due to the conversion characteristic of RCP component. The proposed metasurface has the significance as an ultra-thin optical element applicable to optical switching, sensors, and communications in unidirectional channel as well as a broadband circular polarizer for randomly polarized light.

Wu Z., Ra’di Y., Grbic A.

An electronically tunable metasurface can rotate the polarization angle of an incident polarized electromagnetic wave, showing promise for a new paradigm of real-time wave manipulation.

Cheng Y., Fan J., Luo H., Chen F., Feng N., Mao X., Gong R.

In this paper, we present an anisotropic metamaterial (AMM) composed of a sub-wavelength metal grating sandwiched with bi-layered double-arrow-shaped (DAS) structure array, which can achieve high-efficiency circular polarization (CP) conversion via giant asymmetric transmission (AT) in terahertz (THz) region. Numerical simulation results indicate that near complete CP conversion with cross-polarization transmission coefficients can reach 0.91 and 0.93, which can be observed at 0.31 and 0.55 THz, respectively. Based on the combination of polarization conversion effects and Fabry-Perot-like cavity-enhanced effect of AMMs, the AT parameter for CP wave can reach a maximum of 0.83 at 0.30 THz, and 0.87 at 0.56 THz, respectively. With appropriate geometric parameters design of each unit-cell, embedded in the proposed AMM, the cross-polarization transmission coefficient and AT parameter for CP waves can be increased to the maximal values of 0.98 and 0.9, respectively. The proposed AMM shows great potential applications in high performance dual-band CP convertor and isolator in THz region.

Zou H., Xiao Z., Li W., Li C.

A number of polarization convertors based on metamaterials(MMs) have been investigated recently, but no one has proposed a high-efficiency linear polarization transformer both in transmission and reflection modes. Here, a bilayered MM embedded with vanadium dioxide (VO2) composed of a pair of sloping gold patches, bottom hybrid layer and a dielectric spacer is proposed as a double-use linear polarization convertor. It has been demonstrated numerically that this device has advantages of switching between transmission polarization conversion and reflection polarization conversion based on the phase transition of the VO2 film in the terahertz (THz) regime and the polarization conversion ratios (PCR) in both cases are higher than 90% in wide bands. The simulated linear polarization transmission/reflection coefficients and the surface current distributions give insight into the mechanism of the linear polarization conversions. Moreover, the physical mechanism of polarization sensitivity of the designed structure is investigated by the distributions of electric field. The proposed double-use linear polarization convertor shows great prospects in polarization imaging, and polarized light communications.

Lin B., Guo J., Chu P., Huo W., Xing Z., Huang B., Wu L.

Metasurfaces offer a convenient means to control the polarization state of light. Converting linear polarization (LP) and maintaining circular polarization (CP) in reflection mode have been widely realized, but these two types of polarization control have not been achieved using a single metasurface. This article reports an anisotropic metasurface that allows both multiband LP conversion and CP-maintaining reflection, due to the anisotropy of the metamaterial's unit cell. This system facilitates ultrawide-band polarization converters for $e.g.$ antennas, wireless communication, and radar technology.

Wu Y., Liao S., Zhang H.

Xu D., Lv Y., Zhang Y.Q., Jin X.R.

We propose a structure utilizing a double-layer aluminum ring resonator embedded in a dielectric layer of metamaterial to demonstrate the appearances of unidirectional reflectionlessness, asymmetric reflection, and asymmetric transmission for the incident linear and circular polarizations. A significant feature of this structure is that it allows multiple functions to be implemented in the same structure without changing any structure parameters. For the vertical incident x- and y-polarizations, not only significant unidirectional reflectionlessness and asymmetric reflection effects are verified but also the strong linear to circular polarization conversions are illustrated in both transmission and reflection modes. For the vertical incidences of right-handed and left-handed circular polarizations, unidirectional reflectionlessness and asymmetric reflection are also demonstrated in detail. In addition, when linearly or circularly polarized waves are incident obliquely, the structure exhibits a stable asymmetric transmission phenomenon within a wide incident angle range. Furthermore, it also supports the occurrences of unidirectional reflectionlessness and asymmetric reflection stably within wide ranges of incident angle, resonator spacing, and rotation angle of the upper aluminum ring.

Khan Y., Salma, Kamal B., Ullah S., Ali U., Khan B., Shah M.A.

Norman S., Seddon J., Lu Y., Hale L., Zaman A.M., Addamane S., Brener I., Degl'Innocenti R., Mitrofanov O.

Terahertz (THz) near-field imaging and spectroscopy provide valuable insights into the fundamental physical processes occurring in THz resonators and metasurfaces on the subwavelength scale. However, so far, the mapping of THz surface currents has remained outside the scope of THz near-field techniques. In this study, we demonstrate that aperture-type scanning near-field microscopy enables non-contact imaging of THz surface currents in subwavelength resonators. Through extensive near-field mapping of an asymmetric D-split-ring THz resonator and full electromagnetic simulations of the resonator and the probe, we demonstrate the correlation between the measured near-field images and the THz surface currents. The observed current dynamics in the interval of several picoseconds reveal the interplay between several excited modes, including dark modes, whereas broadband THz near-field spectroscopy analysis enables the characterization of electromagnetic resonances defined by the resonator geometry.

Li N., Zhao J., Tang P., Cheng Y.

In this paper, a novel composite chiral metasurface (CCMS) was proposed and investigated, which is composed of a rectangle-patch-ring resonator (RPRR) structure sandwiched between two twisted sub-wavelength metal gratings separated by a dielectric substrate. Both simulation and experimental results demonstrate that the proposed CCMS achieves a significant asymmetric transmission (AT) effect and efficient cross-polarization conversion for the incident linear polarization wave in a triple-broadband range. Simulation results are in good agreement with the experiments. Specifically, the CCMS converts normal impinging y-/x-polarization wave along the forward/backward (-z/+z) direction into transmitted x-/y-polarization wave with the cross-polarization transmission coefficient over 0.7 at 4.15–5.5 GHz, 7.29–10.77 GHz and 12.49–16.59 GHz, respectively. In addition, the AT coefficient (Δlin) and the total transmittance (Tx) of the x-polarization wave propagation along the –z axis direction are both over 0.5 in the triple-broadband frequency range. The simulated polarization azimuth rotation and ellipticity angles, induced surface current, and electric field vector distributions further confirm the characteristics of the triple-broadband high-efficiency AT effect and cross-polarization conversion of the designed CCMS. The proposed CCMS design serves as an important reference for practical applications of microwave devices.

Lv Q., Chen Y., Yu S., Zhou X., Wei Y., Li L., Wang J., Li B.

In this paper, we present a straightforward design of a quad-band bidirectional metasurface microwave absorber (MMA) utilizing circular-patch resonators (CPRs). The MMA is comprised of tri-layer metal CPR structures separated by a dielectric substrate, which achieves perfect absorption due to the fundamental dipolar mode resonance in the CPRs structure. The absorption properties of the MMA can be adjusted by varying the radius of the CPRs structure. Moreover, we have demonstrated that strong absorption of the quad-band bidirectional MMA can be achieved by combining four CPRs with varying radii as a super unit-cell. Our simulation results reveal that the designed quad-band bidirectional MMA exhibits absorbance of 96.4%, 98.2%, 97.6% and 97.1% at 9.08 GHz, 10.07 GHz, 11.39 GHz and 12.95 GHz, respectively, which has been validated through experiments. Furthermore, the quad-band MMA maintains absorption stability under normal forward (+z) incident waves with different polarization angles for both transverse electric (TE) and transverse magnetic (TM) modes. Given its performance characteristics, the quad-band MMA may be an attractive option for potential applications in sensing, detecting, and communication.

Van D.P., Van H.P., Phuong A.P., Thi T.N., Xuan K.B., Dinh L.V., Tran M.C.

Abstract Simple and ultra-thin structure with high efficiency in absorbing electromagnetic waves in adjacent frequency bands are of great interest nowadays. Metamaterial or metasurface is one of the leading candidates for such studies. In this paper, by employ the open square frame structure combined with the central polygonal disk of the base cell, we built an absorber material with high symmetry and possessing four separate absorption peaks at adjacent frequencies in the C, X, Ku-band (4 GHz to 16 GHz). Notably, the four peaks have high absorption and are quite equally distant. The polarization-dependent analysis also shows that the structure possesses wave polarization independence and still ensures high absorption at incident angles as wide as 60 degrees. In addition, due to the ultra-thin nature of the structure, it also shows a flexible wave absorption response at different bending angles with special requirements. Moreover, a coding defect surface is applied to study the real-life application possibility of the full-size structures and shows that the absorption is stable with a concrete number of defects. This structure has high applicability in electromagnetic stealth technology, communication technology as well as related directional electromagnetic wave control requirements.

Chen X., Gao W., Lei D.

Multidimensional spin-selective manipulation of optical waves is crucial for various intriguing applications in modern nanophotonics, such as quantum-information processing and chiral sensing and imaging. In this work, we observed giant broadband asymmetric transmission of circularly polarized waves and spin-preserving reflection, together with near-unity transmission circular dichroism, in a planar chiral metasurface composed of high-index transition-metal-dichalcogenide nanoantennas with large material anisotropy. The perpendicular and parallel electric and magnetic dipole moments excited in the nanoantennas under circularly polarized waves are explored to account for the asymmetric transmission and optical chirality. Combined with the Pancharatnam–Berry phase, we achieved the wavefront manipulation for transmitted circularly polarized waves with an efficiency approaching 91.5% and spin-selective focusing of an incident light via a metasurface metalens. Our work will pave the way for studying the multidimensional manipulation of optical spins through engineering transition-metal-dichalcogenide-based metasurfaces.

Xu S., Zhang H., Cong L., Xue Z., Lu D., Wang Y., Hu X., Liang L., Ji Y., Fan F., Chang S.

AbstractManipulating terahertz (THz) polarization in an efficient and broadband manner is of great significance to facilitating THz applications, including communications, imaging, defense, and homeland security. In this work, a dispersion compensation scheme is proposed for high‐efficiency and ultra‐broadband THz polarization manipulation using an anisotropic dielectric‐metal hybrid metadevice. The operating bandwidth is broadened by dispersion compensation, where the dielectric grating provides an artificial birefringence with a phase dispersion of positive slope and the metallic grating provides a phase dispersion of negative slope. Experimental results show that the device achieves two ultra‐broadband dispersion compensation, corresponding to the achromatic quarter‐wave plate in the lower frequency band (QWP: 0.5–2.0 THz, PCR >0.95) and the achromatic half‐wave plate in the higher frequency band (HWP: 1.0–2.1 THz, PCR >0.9), respectively. Theoretically, the bandwidth of QWP can be further improved to 2.6 THz by optimizing the grating dispersion, which brings huge application space to cover most of the THz radiation. This hybrid metadevice configuration offers a versatile platform for engineering electromagnetic waves, and the strategy of phase compensation can be generalized to extend the bandwidth of the metadevice in imaging and communications.

Fan J., Chen Y., Huang J., Zhong H., Zhang M., Su H., Li L., Liang H.

Terahertz (THz) waves hold immense potential for advancements in areas such as in 6G wireless communications, non-destructive testing, and biomedicine. However, the underdeveloped control level of THz devices has been a severe obstacle. Here, a THz meta-polarizer, comprising rectangular metallic holes, is proposed to achieve the simultaneous control of the amplitude, phase, and polarization. Each unit of this meta-polarizer can function as a miniature linear polarizer. The component polarized along the short side can pass through the unit, while the component polarized orthogonally is unable to do so. Leveraging the principles of the Malus' law, we can adjust the desired amplitude distribution of the transmitted x-polarized wave by modifying its polarization distribution. This adjustment is made possible by tuning the azimuth angle of each hole. The phase delay of the transmitted wave can be further manipulated by adjusting the hole dimensions perpendicular to the polarization direction. For given near-field amplitude distributions, the required phase distributions for generating far-field target holograms can be calculated using the Gerchberg–Saxton algorithm based on Fresnel diffraction theory. The meta-polarizer then realizes calculated phase distributions, enabling the creation of the required holograms. As a proof of concept, we designed THz meta-polarizers that can achieve two- and four-level amplitude holograms in the near field, respectively. Moreover, we also manipulated the phase distributions, allowing us to decouple the near- and far-field holograms. The experimental results agree well with the simulations. Owing to its ability to simultaneously control the phase, amplitude and polarization, the proposed THz meta-polarizer holds great application potential in 6G wireless communications, radar detection systems, and holography.

Xing X., Zou D., Ding X., Yao J., Wu L.

AbstractPolarization, a fundamental behavior of electromagnetic waves, holds immense potential across diverse domains such as environmental monitoring, biomedicine, and ocean exploration. However, achieving efficient modulation of terahertz waves with wide operational bandwidth poses significant challenges. Here, we introduce an all-silicon polarization converter designed specifically to operate in the terahertz range of the electromagnetic spectrum. Simulation results demonstrate that the average conversion efficiency of cross-linear waves exceeds 80% across a wide frequency range spanning from 1.00 to 2.32 THz, with the highest conversion efficiency peaking at an impressive 99.97%. Additionally, our proposed structure facilitates linear-to-circular polarization conversion with an ellipticity of 1 at 0.85 THz. Furthermore, by rotating the cross-shaped microstructure, active control over arbitrary polarization states can be achieved. To summarize, the proposed structure offers remarkable flexibility and ease of integration, providing a reliable and practical solution for achieving broadband and efficient polarization conversion of terahertz waves. Graphical abstract

Zhao R., Ding F., Zhou X., Chen S., Fu Y., Yang H.

In this paper, we report a reconfigurable multifunctional polarization converter (RMPC) based on positive-intrinsic-negative (PIN) diodes, enabling to achieve different functions in different bands and states. The simulations and experiments show that when the PIN diode is off, it acts as a broadband linear polarization (LP) converter at 9.12–15.93 GHz. Simultaneously, when the PIN diode is on, the LP incident wave is converted into a left-handed circular polarization wave at 8.69–11.41 GHz and a cross-polarization wave at 13.40–14.97 GHz, whereas full reflection is obtained at 12.05–12.54 GHz. The RMPC consists of two dielectric plates and three layers of metal copper plates. Finally, a sample was fabricated and measured, the simulated and experimental results were in good agreement. Compared with other works, the RMPC has more working states and wider operating frequency bands, which has an application potential in the field of radar stealth and satellite communication.

Ishrat Jahan M., Rashed Iqbal Faruque M., Bellal Hossain M.

This paper proposes a flower-shape resonator-based triple band with a high-performance metamaterial wave absorber to find the dispersion relation utilizing one dimensional (1-D) periodic waveguide. The proposed absorber comprises flower-shaped square split ring resonator-based resonators separated by a Rogers RT5870 (lossy) dielectric layer with a thickness of 1.575 mm and back annealed copper with 0.035 mm thickness, and the size of the unit cell is 8 mm × 8 mm. The outcomes of simulations conducted using the Computer Simulator Technology (CST) Microwave Studio simulator reveal the presence of three absorption peaks at frequencies of 5.032, 7.96, and 13.94 GHz with an absorption of 99.709%, 99.966%, and 99.973%, respectively. As a result, this work presents a substitute concept in terms of phase velocity of mode in limited with periodic arrangements, showing it determines the type with terms of modalities a one-dimensional periodic concave parallel plates wavelength. The suggested phase velocity has been analysed using simulations using the CST Microwave Studio simulator and the CST eigenmode solver. A comparable circuit analysis demonstrates the superior performance of the metamaterial wave absorber, indicating its potential for excellent functionality within the advanced design system (ADS) software. Additionally, the proposed structures, modelled with the High-Frequency Structure Simulator (HFSS), exhibit a close correspondence with the maximum absorbance observed at each resonance peak in CST simulation results. The proposed research demonstrates excellent features such as unity absorption, angle insensitivity, and more, making it highly suitable for dispersion relation as well as C, X, and Ku band applications.

Luo W., Bai Y., Lv S., Meng F., Wang R.

Li W., Zhang B., Yao B., Chang R., Wang J., Duan J., Qu Z., Zhang B.

Abstract This paper proposes a metasurface that can simultaneously realize the dual functions of ultra-broadband electromagnetic induced transparency (EIT) and perfect transmission linear polarization conversion (LPC). The metasurface can be regarded as two identical layers separated by air, and each layer is composed of two N-type copper resonators rotated 45° counterclockwise immediately on both sides of the F4B dielectric layer. The simulation results show that the rotating N-type resonator causes the destructive interference of the electric resonance unit’s near-field coupling magnetic resonance unit, resulting in an ultra-wideband EIT effect with a maximum transmission coefficient of 0.93 and a relative bandwidth of 40.03%. It was also found that a near-perfect transmission LPC with a polarization conversion ratio of 99.97% was obtained near the 9.06 GHz frequency. The physical mechanisms of the EIT phenomenon and LPC are analyzed using the surface current distribution and magnetic field, and the frequency dependence of some structural parameters is also analyzed to illustrate the spectral properties of the depression. The metasurface was fabricated and measured to verify its bifunctional performance. This simultaneous implementation of EIT and LPC on the metasurface provides a new approach for applications in communications, multifunctional device design, and antennas.