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This study introduces a cost-effective and eco-efficient method for fabricating an advanced microwave absorber using a layer-by-layer rGO and SiO 2 structure. The rGO/SiO 2 composite, synthesized via modified Hummer's and Stöber methods, demonstrates remarkable microwave absorption properties. The resultant porous structure, characterized by an S BET of 294.89 m2/g, enables multiple reflections and scatterings of electromagnetic waves. At a sample thickness of 3.8 mm, the material achieves a reflection loss (RL) of −47.43 dB at 12.56 GHz and an effective absorption bandwidth (EAB) of 11.04 GHz. For a 6 mm thick sample, an exceptionally high EAB of 12.72 GHz is observed, maintaining a high RL of −42.32 dB. These results demonstrate that the rGO/SiO 2 material is a promising candidate for applications in electromagnetic wave absorption, offering a simple, scalable solution for mitigating electromagnetic pollution and enhancing military stealth technologies. [ABSTRACT FROM AUTHOR]

Three-dimensional network structures of flower-like 1T/2H Molybdenum disulfide nanosheets anchored to carbon fibers were prepared, which exhibited satisfactory electromagnetic wave absorption properties, providing a path for the preparation of electromagnetic wave absorbing materials with wide effective absorption bandwidth. [Display omitted] • 3D 1T/2H MoS 2 /CNFs interconnected network structures were prepared; • Heterogeneous interfaces between CNFs and MoS 2 , 1T and 2H MoS 2 phase was built; • Excellent EM wave absorption with RL min of −42.26 dB and EAB of 6.48 GHz was obtained; • The EM wave absorption performance was proved by radar reflectance cross section simulation. With the wide application of electromagnetic waves in national defense, communication, navigation and home appliances, the electromagnetic pollution problem is becoming more and more prominent. Therefore, high-performance, and low-density composite wave-absorbing materials have attracted much attention. In this paper, three-dimensional (3D) network structures of flower-like 1T/2H Molybdenum disulfide nanosheets anchored to carbon fibers (1T/2H MoS 2 /CNFs) were prepared by electrostatic spinning technique and calcination process. The morphology and electromagnetic wave absorption properties were tuned by changing the content of flower-like MoS 2. The optimized 1T/2H MoS 2 /CNFs composite exhibits superior electromagnetic wave absorption with minimum reflection (RL min) of −42.26 dB and effective absorption bandwidth (EAB) of 6.48 GHz at 2.5 mm. Multi-facts contribute to the super performance. First, the uniquely designed nanosheet and 3D interconnected networks leads to multiple reflection and scattering of electromagnetic waves, which promotes the attenuation of electromagnetic waves. Second, the propriate content of CNFs and MoS 2 with different phase regulates its impedance matching characteristic. Third, Numerous heterogeneous interfaces existed between CNFs and MoS 2 , 1T and 2H MoS 2 phase results in interface polarization. Besides, the 1T/2H MoS 2 rich in defects induces defect polarization, improving the dielectric loss. Furthermore, the electromagnetic wave absorption performance was proved via radar reflectance cross section simulation. This work illustrates 1T/2H MoS 2 /CNFs is a promising material for electromagnetic absorption with wide bandwidth, strong absorption, low density, and high thermal stability. [ABSTRACT FROM AUTHOR]

The utilization of sheet structure composites as a viable conductive filler has been implemented in polymer-based electromagnetic shielding materials. However, the development of an innovative sheet structure to enhance electromagnetic shielding performance remains a significant challenge. Herein, we propose a novel design incorporating silver-modified nanosheet self-assembled hollow spheres to optimize their performance. The unique microporous structure of the hollow composite, combined with the self-assembled surface nanosheets, facilitates multiple reflections of electromagnetic waves, thereby enhancing the dissipation of electromagnetic energy. The contribution of absorbing and reflecting electromagnetic waves in hollow nanostructures could be attributed to both the inner and outer surfaces. When multiple reflection attenuation is implemented, the self-assembled stack structure of nanosheets outside the composite material significantly enhances the occurrence of multiple reflections, thereby effectively improving its shielding performance. The structure also facilitates multiple reflections of incoming electromagnetic waves at the internal and external interfaces of the material, thereby enhancing the shielding efficiency. Simultaneously, the incorporation of silver particles can enhance conductivity and further augment the shielding properties. Finally, the optimized Ag/NiSi-Ni nanocomposites can demonstrate superior initial permeability (2.1 × 10−6 H m−1), saturation magnetization (13.2 emu g−1), and conductivity (1.2 × 10−3 Ω•m). This work could offer insights for structural design of conductive fillers with improved electromagnetic shielding performance. [ABSTRACT FROM AUTHOR]

Traditional electromagnetic interference–shielding materials are predominantly electrically conductive, posing short-circuit risks when applied in highly integrated electronics. To overcome this dilemma, we propose a micro capacitor-structure model comprising conductive fillers as polar plates and intermediate polymer as a dielectric layer to develop insulating electromagnetic interference–shielding polymer composites. The electron oscillation in plates and dipole polarization dielectric layers contribute to the reflection and absorption of electromagnetic waves. Guided by this, the synergistic nonpercolation densification and dielectric enhancement enable our composite to combine high resistivity, shielding performance, and thermal conductivity. Its insulating feature allows for direct potting into the crevices among assembled components to address electromagnetic compatibility and heat-accumulation issues. [ABSTRACT FROM AUTHOR]

The combination of dielectric and magnetic materials can significantly improve microwave absorption properties. In this work, we introduce a novel Zr–Sm doped barium ferrite BaFe 11.6 (ZrSm) 0.2 O 19 , which is compounded with rGO aerogel and presents superior microwave absorption properties. The results show that the BaFe 11.6 (ZrSm) 0.2 O 19 /rGO composite aerogel exhibits a unique three-dimensional porous network structure which enhances the reflection and scattering of electromagnetic waves. Meanwhile, the addition of BaFe 11.6 (ZrSm) 0.2 O 19 abounds the folds and defects on the surface of rGO sheet layer, generating a large amount of polarisation and relaxation. In addition, with the increase of BaFe 11.6 (ZrSm) 0.2 O 19 content, the permeability gradually increases, while the dielectric constant gradually decreases. At a certain content, both of them can be well balanced to obtain high attenuation constants and great impedance matching, which regulates the wave-absorbing properties of the material. The minimum reflection loss (RL min) of BaFe 11.6 (ZrSm) 0.2 O 19 /rGO composite aerogel can reach −53.17 dB at a matching thickness of 2.9 mm, and the absorption bandwidth reaches 7.04 GHz, which has been improved by 40% than pure BaFe 11.6 (ZrSm) 0.2 O 19. Therefore, it is expected to be a candidate for lightweight, thin, high loss, large bandwidth microwave absorbing materials. [ABSTRACT FROM AUTHOR]

Abstract The authors present spatio‐temporally resolved wideband measurements of Sub‐Terahertz (Sub‐THz) reflection coefficients in the frequency range of 92–110 GHz. A stochastic model for single reflection fixed links that is capable of modelling random scattering from small‐scale discontinuities such as those encountered in complex structures in walls and partitions of buildings is presented. The model auto‐regressively produces filter coefficients that are fed into an Infinite‐Impulse‐Response (IIR) filter which convolves them with the spatio‐temporal series in order to generate the next output sample based on previous observations. The IIR filter allows for flexible stochastic generation of samples, and its parameters can be adjusted as needed to suit different channel conditions. A total of 20 suitable start‐up filter coefficients are generated from 21.7 % of the sample size for each complex delay tap distribution, which corresponds to 50 complex instances of the channel. These coefficients are then utilised to validate the remaining measured sample set. The model is in quantitative agreement with measurement statistics and can be used to construct relatively simple modified reflection coefficients that can be used in micro‐cellular ray‐optical network planning tools.

Abstract A novel numerical method is introduced for minimising the presence of scattering echoes in the frontal area of a dielectric ellipsoid through the application of the method of auxiliary sources (MAS) method. This approach utilises a Gaussian radio pulse that spans the frequency spectrum from 0 to 6 GHz. The approach involves determining the properties of an ellipsoid, such as its dimensions and a dielectric permittivity, using a specially developed MATLAB software package to make this ellipsoid invisible. This provides a valuable military and defence technology tool, particularly for stealth and invisibility technology applications. It is beneficial for avoiding detection by radar systems utilised for enemy surveillance and identifying concealed objects. This aims to eliminate the need for metamaterials for invisibility cloaking. The suggested methodology has been confirmed through a validation process, which involved a comparison of the outcomes derived from numerical experiments conducted during pulse echo observations using the FDTD method and an analytical solution. MAS offers a notable advantage over other methods and commercial software by significantly reducing computational time for simulating and analysing 3D dielectric objects. This allows for quicker consideration of various parameter scenarios and optimisation for desired outcomes.

Based on the far field function of electric field, a new glass carbon fiber gradient-stitched structure is proposed and designed in the paper. In the frequency range of 8–28 GHz, the electric field distribution of transverse electric and magnetic field (TEM) waves incident obliquely on the surface of the structure by optimizing the glass fiber fabric units. It is confirmed that the surface has the function of suppressing electromagnetic wave reflection. The electrical performance simulation and testing results of the structure show that the radar cross section (RCS) is reduced by 90% in the frequency range of 12.3–26.5 GHz. In addition, a multi-scale analysis model is established to quickly predict the tensile modulus and strength of the composite material. The strength and modulus reached 26.9 GPa and 403 MPa, respectively. The simulating and testing results of mechanical properties are in good agreement. [ABSTRACT FROM AUTHOR]

Accommodating multiple tasks within a tiny metasurface unit cell without them interfering with each other is a significant challenge. In this paper, an electromagnetic (EM) wave modulation metasurface capable of reflection, transmission, and absorption is proposed. This multitasking capability is achieved through a cleverly designed multi-layer structure comprising an EM Wave Shield Layer (ESL), a Polarization Modulation Layer (PML), and a Bottom Plate Layer (BPL). The functionality can be arbitrarily switched by embedding control materials within the structure. Depending on external excitation conditions, the proposed metasurface can realize reflection-type co-planar polarization to cross-polarization conversion, transmission-type electromagnetically induced transparency-like (EIT-like) modes, and broadband absorption. Notably, all tasks operate approximately within the same operating frequency band, and their performance can be regulated by the intensity of external excitation. Additionally, the operating principle of the metasurface is analyzed through impedance matching, an oscillator coupling model, and surface current distribution. This metasurface design offers a strategy for integrated devices with multiple functionalities. [ABSTRACT FROM AUTHOR]

In this paper, the electromagnetic wave (EMW) absorption properties of SiCN ceramics with a shellular structure prepared by 3D printing technology (DLP) at different pyrolysis temperatures were investigated. The research shows that polarization loss and multiple reflections are the principal reasons for the improvement in sample absorption performance. The shellular structure is favorable for the multiple reflections and scattering of electromagnetic wave inside the material. The turbostratic carbon, graphitic carbon and SiC generated by pyrolysis are conducive to improving the dielectric loss of the sample, adjusting its impedance matching performance and improving its absorption performance. The RL min of SiCN-1200 reaches − 21.12 dB (3.22 mm), and the effective band width is 4.20 GHz, covering the whole X-band. The excellent EMW absorption performance of DLP-SiCN ceramics, together with additive manufacturing, enable the integration of material, structure and function within a single component. [ABSTRACT FROM AUTHOR]

A novel numerical method is introduced for minimising the presence of scattering echoes in the frontal area of a dielectric ellipsoid through the application of the method of auxiliary sources (MAS) method. This approach utilises a Gaussian radio pulse that spans the frequency spectrum from 0 to 6 GHz. The approach involves determining the properties of an ellipsoid, such as its dimensions and a dielectric permittivity, using a specially developed MATLAB software package to make this ellipsoid invisible. This provides a valuable military and defence technology tool, particularly for stealth and invisibility technology applications. It is beneficial for avoiding detection by radar systems utilised for enemy surveillance and identifying concealed objects. This aims to eliminate the need for metamaterials for invisibility cloaking. The suggested methodology has been confirmed through a validation process, which involved a comparison of the outcomes derived from numerical experiments conducted during pulse echo observations using the FDTD method and an analytical solution. MAS offers a notable advantage over other methods and commercial software by significantly reducing computational time for simulating and analysing 3D dielectric objects. This allows for quicker consideration of various parameter scenarios and optimisation for desired outcomes. [ABSTRACT FROM AUTHOR]

The authors present spatio‐temporally resolved wideband measurements of Sub‐Terahertz (Sub‐THz) reflection coefficients in the frequency range of 92–110 GHz. A stochastic model for single reflection fixed links that is capable of modelling random scattering from small‐scale discontinuities such as those encountered in complex structures in walls and partitions of buildings is presented. The model auto‐regressively produces filter coefficients that are fed into an Infinite‐Impulse‐Response (IIR) filter which convolves them with the spatio‐temporal series in order to generate the next output sample based on previous observations. The IIR filter allows for flexible stochastic generation of samples, and its parameters can be adjusted as needed to suit different channel conditions. A total of 20 suitable start‐up filter coefficients are generated from 21.7 % of the sample size for each complex delay tap distribution, which corresponds to 50 complex instances of the channel. These coefficients are then utilised to validate the remaining measured sample set. The model is in quantitative agreement with measurement statistics and can be used to construct relatively simple modified reflection coefficients that can be used in micro‐cellular ray‐optical network planning tools. [ABSTRACT FROM AUTHOR]

Recently, great attention has been given to the idea of a smart environment. It often involves the use of reconfigurable intelligent surfaces (RIS) for the management of electromagnetic wave reflections as the world awaits the emergence of 6G. Changeable intelligent surfaces may enhance the creation of wireless communication. The design and analysis of several unit cell reflections are presented in this work. The first design relies on the Switching Technique which involves switching on and off to acquire the phase as well as the coefficient of reflection to accommodate 6G standards. The unit cells design is configured to operate in the millimeter band and X band. In the second design, the radius of the circular patch was changed to adjustment of the phase and reflection coefficient. The use of Floquet technique is employed in investigating the scattering characteristics of a unit cell's constituent elements based on the assumption that every element consists of an extremely iterating periodic structure. To determine the optimal force reflection and the transformation phase, the return loss alongside reflection phase graphs of each resonant component were examined. The simulation results indicate that the first design exhibits a reflection phase shift range of -180 to 90 and a reflection magnitude over 0.93 at a frequency of 11GHz. In contrast, the second design demonstrates a reflection phase shift range of -135 to 135 and a reflection magnitude surpassing 0.9 at a frequency of 28GHz. The analysis and simulation of the design models were carried out using the CST model. [ABSTRACT FROM AUTHOR]

A novel nano-laminated GdB2C2 material was successfully synthesized using GdH2, B4C, and C via an in situ solid-state reaction approach for the first time. The formation process of GdB2C2 was revealed based on the microstructure and phase evolution investigation. Purity of 96.4 wt.% GdB2C2 was obtained at a low temperature of 1500 °C, while a nearly fully pure GdB2C2 could be obtained at a temperature over 1700 °C. The as-obtained GdB2C2 presented excellent thermal stability at a high temperature of 2100 °C in Ar atmosphere due to the stable framework formed by the high-covalence four-member and eight-member B-C rings in GdB2C2. The GdB2C2 material synthesized at 1500 °C demonstrated a remarkably low minimum reflection loss (RLmin) of −47.01 dB (3.44 mm) and a broad effective absorption bandwidth (EAB) of 1.76 GHz. The possible electromagnetic wave absorption (EMWA) mechanism could be ascribed to the nano-laminated structure and appropriate electrical conductivity, which facilitated good impedance matching, remarkable conduction loss, and interfacial polarization, along with the reflection and scattering of electromagnetic waves at multiple interfaces. The GdB2C2, with excellent EMWA performance as well as remarkable ultra-high-temperature thermal stability, could be a promising candidate for the application of EMWA materials in extreme ultra-high temperatures. [ABSTRACT FROM AUTHOR]

The incidence of electromagnetic H-wave on the thin metal layer at the angle of theta is considered, taking into account the dependence of the specularity coefficients on the surfaces of the thin layer q1 and q2 on the angle of incidence of electrons. The behavior of reflection, transmission and absorption coefficients depending on the thickness of the thin layer is analyzed. The obtained results are compared with experimental data. [ABSTRACT FROM AUTHOR]

The rapid development of electronic devices in various fields has stimulated an increased demand for electromagnetic interference (EMI) shielding materials working in ultra‐wideband frequencies of gigahertz. However, the aggregation problem and single attenuation mechanism severely limit the broadband shielding applications of nanomaterials. To address these challenges, a novel composite of parallel expanded graphite (EG) embedded in the densified Fe3O4 matrix is designed and successfully synthesized through the in situ chemical coprecipitation followed by pressure sintering. This unique structure creates heterogeneous interfaces by combining the conductive EG and magnetic Fe3O4. The significant dielectric and magnetic loss then arise from conduction and polarization loss, as well as the eddy current and resonance effects. The multiple reflections of electromagnetic waves between the oriented EG sheets further cause the "absorb–reflect–reabsorb" effect that prolongs the propagation paths and enhances the dissipation of electromagnetic waves. Based on these multiple mechanisms over an ultrawide range of frequencies (8.2–40 GHz), the EG/Fe3O4 composites exhibit exceptional EMI shielding performance, with an average shielding effectiveness of 29.3 dB, indicating the potential for multifunctional EMI shielding applications. [ABSTRACT FROM AUTHOR]

The authors design and experimentally analyse an anisotropic metasurface for the simultaneous conversions of linear cross and circular polarisations in the C and partial X bands. The proposed compact structure utilises a dual‐cut square‐ring resonator and a square patch on an FR4 substrate above a ground plane. The full‐wave simulations exhibit over 92% efficiency in cross‐conversion over a fractional bandwidth (BW) of 52.3%. The proposed metasurface efficiently converts linear to circular polarisation in two different bands, achieving left‐hand circularly polarised and right‐hand circularly polarised efficiencies exceeding 93% and 89%, respectively. The compact unit‐cell with dimension 0.22λ × 0.22λ attains stable polarisation transformation efficiency rates exceeding 80% up to 40° incident angles. The design is adaptable for efficient wide BW across both lower and higher (millimetre‐wave) frequencies through scaling. A prototype of the proposed polarisation converter (PC) was realised and validated effectively in measurements, aligning well with simulations. This PC features a novel and simple structure with multifunctional wideband operation, stable incident angle output, polarisation insensitivity, and scalability, making it an efficient front‐end for various radio frequency applications, including polarisation control and polarisation transformers. [ABSTRACT FROM AUTHOR]

Purpose: Stainless-steel electromagnetic shielding (EMS) fabrics are widely applied as protective materials against electromagnetic interference (EMI). However, these fabrics primarily shield electromagnetic waves through reflection, which can lead to the formation of resonance effects that severely compromise their protective capabilities and potentially cause secondary electromagnetic pollution in the external environment. Design/methodology/approach: In this paper, carbon nanotube fibers are added via spacing method to replace some stainless-steel fibers to impart absorbing properties to stainless-steel EMS fabric. The shielding effectiveness (SE) of the EMS fabrics across various polarization directions is analyzed. Additionally, a spacing arrangement for the carbon nanotube fibers is designed. The EMS fabric with carbon nanotube fibers is manufactured using a semi-automatic sample loom, and its SE is tested using a small window method test box in both vertical and horizontal polarization directions. Findings: According to the experimental data and electromagnetic theory analysis, it is determined that when the spacing between the carbon nanotube fibers is less than a specific distance, the SE of the stainless-steel EMS fabric significantly improves. The fabric exhibits stable absorbing properties within the tested frequency range, effectively addressing the issue of secondary damage that arises from relying solely on reflective shielding. Conversely, as the spacing between the carbon nanotube fibers exceeds this distance, the SE diminishes. Notably, the SE in the vertical polarization direction is substantially higher than that in the horizontal polarization direction at the same frequency. Originality/value: This study provides a new path for the development of high-performance EMS fabrics with good wave-absorption characteristics and SE. [ABSTRACT FROM AUTHOR]

Dielectric properties are crucial in understanding the behavior of water within soil, particularly the soil water content (SWC), as they measure a material's ability to store an electric charge and are influenced by water and other minerals in the soil. However, a comprehensive review paper is needed that synthesizes the latest developments in this field, identifies the key challenges and limitations, and outlines future research directions. In addition, various factors, such as soil salinity, temperature, texture, probing space, installation gap, density, clay content, sampling volume, and environmental factors, influence the measurement of the dielectric permittivity of the soil. Therefore, this review aims to address the research gap by critically analyzing the current state-of-the-art dielectric properties-based methods for SWC measurements. The motivation for this review is the increasing importance of precise SWC data for various applications such as agriculture, environmental monitoring, and hydrological studies. We examine time domain reflectometry (TDR), frequency domain reflectometry (FDR), ground-penetrating radar (GPR), remote sensing (RS), and capacitance, which are accurate and cost-effective, enabling real-time water resource management and soil health understanding through measuring the travel time of electromagnetic waves in soil and the reflection coefficient of these waves. SWC can be estimated using various approaches, such as TDR, FDR, GPR, and microwave-based techniques. These methods are made possible by increasing the dielectric permittivity and loss factor with SWC. The available dielectric properties are further synthesized on the basis of mathematical models relating apparent permittivity to water content, providing an updated understanding of their development, applications, and monitoring. It also analyzes recent mathematical calibration models, applications, algorithms, challenges, and trends in dielectric permittivity methods for estimating SWC. By consolidating recent advances and highlighting the remaining challenges, this review article aims to guide researchers and practitioners toward more effective strategies for SWC measurements. [ABSTRACT FROM AUTHOR]

We consider the problem of the effect of small plasma density variations on the propagation and reflection of ELF (extremely-low-frequency) electromagnetic wave incident on the morning ionosphere from above. Modifications of the electromagnetic wave field near the Earth surface and coefficient of wave energy reflection from ionosphere caused by infrasonic wave are studied. The greatest modifications of the field on the Earth surface and reflection coefficient are related to the density perturbations at altitudes of strong electromagnetic wave attenuation (80–110 km). Reflection of electromagnetic waves is especially sensitive to the plasma density perturbations if the value of horizontal refractive index is close to a unit. In this case, modulation percentage of reflection coefficient can exceed the modulation percentage of density in the infrasonic wave by an order of magnitude. The parametric influence of plasma density perturbations in an infrasonic wave on the ELF electromagnetic field is analyzed. If the values of the horizontal wave numbers of the electromagnetic and infrasonic waves are close to each other, the field of the electromagnetic wave near the Earth surface can increase several times. The obtained results are important for understanding the interconnection of ionospheric wave processes of different nature. The study of the modulation of coefficient of ELF reflection from the ionosphere is relevant for explaining the operation modes of a plasma magnetospheric maser. [ABSTRACT FROM AUTHOR]

Protective properties of composite electromagnetic screens on the base of conventional commercial paints were studied. The shielding fillers included metal-containing products from industrial wastewater treatment. Such compositions with a thickness of 100 to 150µm, were found to allow reaching high-frequency electromagnetic radiation shielding coefficients up to 3.0-3.5. Reflection coefficients of electromagnetic waves reach up to 0.3, which meets contemporary technical requirements. [ABSTRACT FROM AUTHOR]

A calculation method for designing facing building materials with the functions of shielding electromagnetic waves has been developed. The method makes it possible to design materials with the required shielding efficiencies and adjustable coefficients of absorption and reflection of electromagnetic waves. The dependence of the shielding efficiency on the mode of pressing the material has been studied. Verification of the calculation apparatus showed satisfactory convergence of theoretical and experimental data. [ABSTRACT FROM AUTHOR]

Advances in mobile electronics and telecommunication systems along with 5G technologies have been escalating the electromagnetic interference (EMI) problem in recent years. Graphene-based material systems such as pristine graphene, graphene-polymer composites and other graphene-containing candidates have been shown to provide adequate EMI shielding performance. Besides achieving the needed shielding effectiveness (SE), the method of applying the candidate shielding material onto the object in need of protection is of enormous importance due to considerations of ease of application, reduced logistics and infrastructure, rapid prototyping and throughput, versatility to handle both rigid and flexible substrates and cost. Printing readily meets all these criteria and here we demonstrate plasma jet printing of thin films of graphene and its composite with copper to meet the EMI shielding needs. SE over 30 dB is achieved, which represents blocking over 99.9% of the incoming radiation. Graphene and its composite with copper yield higher green index compared to pure copper shields, implying reduced reflection of incoming electromagnetic waves to help reduce secondary pollution. [ABSTRACT FROM AUTHOR]

People spend two-thirds of their time in buildings. Building materials are, therefore, natural shielding for us. Many studies describe the shielding effect of non-building materials. This study evaluates the shielding effectiveness (SE) of electromagnetic fields for various building materials over a frequency range of 1 GHz to 9 GHz. Measurements of SE, reflection (R), and calculated absorption (A) were conducted to determine the shielding properties of mineral wool (MW), hardened polystyrene (PT), extruded polystyrene (PE), polyurethane board (PUR), brick wall (BW), brick wall filled with mineral wool (BW-MW), and concrete wall. The results demonstrate that MW, PT, PE, and PUR exhibit low SE and R, indicating minimal shielding capabilities, with absorption values that do not significantly deviate from the level of measurement uncertainty. Conversely, BW, BW-MW, and concrete wall materials exhibit high SE, with notably increased absorption at higher frequencies, highlighting their potential for effective EMI shielding. Particularly, the concrete wall presents the highest absorption values, making it a superior choice for shielding applications. Reflection trends revealed a plateau for BW in the 6 GHz to 9 GHz range, indicating a frequency-dependent behavior of shielding mechanisms. This study underscores the importance of balancing reflective and absorptive properties in shielding materials and suggests that composite materials may offer enhanced performance. The findings of this research provide guidance for the selection and design of shielding materials in environments with a frequency spectrum of electromagnetic frequencies from 1 GHz to 9 GHz. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs), which have a diameter on the nanometer scale, are tube-like materials composed of carbon and graphite sheets. Carbon nanotubes play an important role in many fields such as nanotechnology, electronics, optics and material science due to their superior properties such as high elasticity, high thermal conductivity, low density and being more chemically inert. In this study, the use of carbon nanotubes in radar absorbing materials (RAM) to reduce the reflection of electromagnetic waves was investigated. In this sense, by using a polymeric composite structure reinforced with carbon nanotubes, a material with unique properties such as solid absorption, low weight/thickness and costeffectiveness has been produced, minimizing the reflection of electromagnetic waves. For this purpose, carbon nanotubes with different particle sizes of 8 nm, 30-50 nm and 48-78 nm were blended with polyester at the ratio of 1%. The resulting composites were characterized using a Network analyzer in the frequency range of 8-12 GHz. According to the results obtained, it was observed that radar absorption increased with increasing particle size. It has been determined that by changing the particle sizes of carbon nanotubes in composites, the absorption bands can be adjusted to suit different applications in different frequency bands. [ABSTRACT FROM AUTHOR]

[Display omitted] Dimensional design and heterogeneous interface engineering are promising approaches for the fabrication of superior absorbers with high loss performance and a wide effective bandwidth. Therein, ZnO nanorods were successfully synthesized and combined with CoNi nanosheets by hydrothermal method, and PDA was then encapsulated on the surface of the material to form a unique one dimensional (1D) core-sheath structure. The extensive defects and residual functional groups are present in the calcined material, as well as the multiple heterogeneous interfaces enhance the dielectric loss induced by polarization. Simultaneously, the 1D structure wrapped with PDA offers an efficient pathway for electron transfer, hence facilitating the enhancement of conductive loss. In addition, the CoNi-LDHs sheet layer stacked on the surface not only causes multiple scattering and reflections of electromagnetic waves, but also provides magnetic losses to optimize the impedance matching. Finally, radar cross section (RCS) simulations further reveal that the composite can dissipate electromagnetic energy in practical applications. Consequently, the 1D multilayer ZnO@CoNi/C composite exhibits an optimal reflection loss of −55 dB with a thickness of 2.3 mm and an effective absorption bandwidth (EAB) value of 6.8 GHz when the filling ratio is only 20 wt%. In summary, this paper provides a new direction for the fabrication of 1D multilayer nonhomogeneous interfacial absorbers with excellent performance. [ABSTRACT FROM AUTHOR]

In this paper we have presented a novel Intelligent Reflecting Surface (IRS) for future 6G communications. IRS is suitable for compensating the power loss of wireless communications, such as Satellite based communications, through redirecting the reflected signals. We have analyzed a novel saw-tooth shape unit-cell within C-band and X-band. A full 360° phase variation of an IRS is required in some applications such as beam steering. We have investigated the IRS using three different methods: 1) full wave simulations of the IRS, 2) analysis of the equivalent circuit model (ECM) of the unit-cell, and 3) measurements of the reflection coefficients of ‘shorted’ and ‘open’ unit-cells. Two sets of ‘shorted’ and ‘open’ unit-cells were tested using waveguide based method. Tested results show that the unit-cell can achieve up to 340° phase variation at a particular frequency. It is possible to redirect the reflected signal towards a desired direction through different combination of ‘shorted’ and ‘open’ unit-cells. Phase differences of the tested results at different frequencies (e.g. 8.2-8.4 GHz, 9.1 GHz, and 9.56 GHz) suggest that the designed unit-cells can be utilized in beam redirection purposes. We have presented one such scenario of beam redirection of the IRS at 10 GHz.

Abstract A great interest has been directed towards high frequency surface wave radar (HFSWR), because it is applied as long‐range early warning and real‐time measurements of sea surface condition tools in maritime surveillance. However, the unwanted reflection from the ionosphere (ionosphere clutter) damages the consistent detection performance of HFSWR. Target detection and environmental information extraction from radar echoes are primarily determined by the extent to which the medium contaminates the transmitted signals. Although the ionospheric signal corruption mechanisms are complex and various, a number of eliminating contamination approaches have been developed in the last 50 years. The purpose of this paper is providing an overview of the past and current clutter theoretical models and clutter suppression techniques for HFSWR system. The experimental results involved in the complex long‐term ionosphere observation and ionosphere echo analysis are first discussed. Special attention is paid to the correlation between the signal degradation sources and eliminating clutter techniques. Furthermore, the clutter suppression methods are classified based on the design idea. The specific clutter suppression methods as well as its operation principle are briefly introduced. Finally, several research trends and open issues are presented, with emphasis on the need for proactively controlling the radar design cost and generally agreed‐upon standards.

Measurements of complex magnetic permeability, μ(f,H) = μ′(f,H) − iμ″(f,H) and dielectric permittivity ε(f,H) = ε′(f,H) − iε″(f,H), in the frequency range, f of (0.4–7) GHz, and polarizing field, H of (0–135) kA/m, were performed, for a kerosene-based ferrofluid with magnetite nanoparticles. Based on these measurements, the phenomenon of ferromagnetic resonance was highlighted and some microwave propagation parameters of the ferrofluid were determined: the attenuation constant, α(f,H), and the reflection coefficient, R(f,H), at the air-material interface, at the normal incidence. Knowing these parameters we proposed a theoretical model establishing for the first time an equation that allows the calculation of the overall reflection coefficient, Rw(f,H), at the normal incidence of the wave, for a ferrofluid of thickness d, deposited on a totally reflective support, following multiple internal reflections of the electromagnetic wave in the material. The results show that by increasing both, H, and d, the parameter, Rw(f,H) presents a minimum that decreases from 0.90 (for d = 2 mm) to 0.64 (for d = 10 mm), at frequency f = 5 GHz, which indicates an increase in the absorption of the electromagnetic wave by the ferrofluid. The obtained results are useful in the study of some materials that could be used as electromagnetic absorbers in the microwave range, by the determination of the overall reflection coefficient, Rw(f,H), controlled both by the thickness, d, of the absorber and by the external applied field, H. [ABSTRACT FROM AUTHOR]

The microwave absorption performance of high-entropy alloys (HEAs) can be improved by reducing the reflection coefficient of electromagnetic waves and broadening the absorption frequency band. The present work prepared flaky irregular-shaped Al1.5Co4Fe2Cr and Al1.5Co4Fe2Cr@rGO alloy powders by mechanical alloying (MA) at different rotational speeds. It was found that the addition of trace amounts of reduced graphene oxide (rGO) had a favorable effect on the impedance matching, reflection loss (RL), and effective absorbing bandwidth (EAB) of the Al1.5Co4Fe2Cr@rGO HEA composite powders. The EAB of the alloy powders prepared at 300 rpm increased from 2.58 GHz to 4.62 GHz with the additive, and the RL increased by 2.56 dB. The results showed that the presence of rGO modified the complex dielectric constant of HEA powders, thereby enhancing their dielectric loss capability. Additionally, the presence of lamellar rGO intensified the interfacial reflections within the absorber, facilitating the dissipation of electromagnetic waves. The effect of the ball milling speed on the defect concentration of the alloy powders also affected its wave absorption performance. The samples prepared at 350 rpm had the best wave absorption performance, with an RL of −16.23 and −17.28 dB for a thickness of 1.6 mm and EAB of 5.77 GHz and 5.43 GHz, respectively. [ABSTRACT FROM AUTHOR]

In physical engineering, a rock surface, whether naturally or artificially formed, is rough. When irradiating rocks, microwaves produce reflections and diffractions on the surface of rough rocks, which significantly affect the absorption of microwave energy by rocks, thus influencing the result of microwave irradiation. In order to explore the influence of rough rock surfaces on the effect of microwave-assisted rock breaking, microwave irradiation tests were carried out on basalt samples with different values of roughness to test the temperature and P-wave velocity of the samples before and after microwave irradiation. Numerical test methods were used to systematically study the influence of rough rock surfaces on microwave irradiation. The results show that, under the same microwave irradiation conditions, the effect of microwave irradiation on rough surface basalt is more significant than that of flat surface basalt. The surface temperature distribution range of flat surface specimens is narrow, the surface temperature range of rough surface specimens is wider and more inhomogeneous, and the maximum surface temperatures of rough surface specimens are much higher than those of flat surface specimens. After irradiation, new macroscopic cracks were generated on the surface of the samples, and the crack propagation of the rough surface samples was more obvious. The decrease in P-wave velocity before and after the irradiation of flat surface samples is small, and that of rough surface samples is larger. The main factors affecting the effect of microwave irradiation on the rough surface are the refraction and reflection of electromagnetic waves, heat conduction, and stress concentration on the surface. [ABSTRACT FROM AUTHOR]

Expressions are derived for the reflection coefficients of electromagnetic waves with p and s type polarizations from a semi-infinite dielectric medium having an inhomogeneous layer. The influence of the layer was taken into account by the method of perturbation theory in a quadratic approximation of the layer thickness. A method is proposed for converting expressions derived using perturbation theory into other expressions that give more accurate values of the reflection coefficient. The angular dependences of the reflection coefficient obtained by the developed method are compared with those obtained by the numerical solution of electrodynamic equations. Requirements for the layer characteristics are formulated to minimize the error of the analytical solution. [ABSTRACT FROM AUTHOR]

A great interest has been directed towards high frequency surface wave radar (HFSWR), because it is applied as long‐range early warning and real‐time measurements of sea surface condition tools in maritime surveillance. However, the unwanted reflection from the ionosphere (ionosphere clutter) damages the consistent detection performance of HFSWR. Target detection and environmental information extraction from radar echoes are primarily determined by the extent to which the medium contaminates the transmitted signals. Although the ionospheric signal corruption mechanisms are complex and various, a number of eliminating contamination approaches have been developed in the last 50 years. The purpose of this paper is providing an overview of the past and current clutter theoretical models and clutter suppression techniques for HFSWR system. The experimental results involved in the complex long‐term ionosphere observation and ionosphere echo analysis are first discussed. Special attention is paid to the correlation between the signal degradation sources and eliminating clutter techniques. Furthermore, the clutter suppression methods are classified based on the design idea. The specific clutter suppression methods as well as its operation principle are briefly introduced. Finally, several research trends and open issues are presented, with emphasis on the need for proactively controlling the radar design cost and generally agreed‐upon standards. [ABSTRACT FROM AUTHOR]

Abstract With the spread of airborne corner reflector (ACR) in the field of shipborne equipment, radar guided anti‐ship missile is facing new challenges. In order to achieve the mastery of the jamming principle of this apparatus, the paper studied its motion properties and sequential Radar Cross Section (RCS) properties. Firstly, the motion model of the ACR was obtained under certain constraints, by deriving the centroid dynamics equation and rotation dynamics equation according to the theoretical mechanics. Then, the dynamic sequential RCS model of ACR array was established by combining the motion model with the modified geometric optics method and coherent synthesis method. Through the simulation and analysis of the motion model, it was found that the flight process of the ACR can be divided into two stages: fast falling and steady falling. In the fast falling stage, the variables of the ACR system change rapidly, while the ACR rotates slowly and falls smoothly in the steady falling stage. From simulation of dynamic sequential RCS model, the results showed that the obvious depolarisation effect is occur in the fast falling stage. Further statistical analysis showed that, the omnidirectivity of single ACR is well from the dynamic perspective, meanwhile array placement can effectively enhance RCS amplitude and improve the probability density distribution.

[Display omitted] Expanded graphite (EG) is a modified conductive lamellar carbon that has been widely studied in the field of electromagnetic wave absorption due to its low density, good electrical conductivity, and unique structure. However, its application is limited because the interlayer gap cannot match microwave wavelength, and its single composition has less microwave loss. In this study, sea urchin-like NiFe 2 O 4 /EG composites are prepared in situ between expanded graphite layers by microwave treatment. The sea urchin-like NiFe 2 O 4 grows between the expanded graphite to form a three-dimensional conductive network structure, which enhances conductive loss of composites and further increases the interlayer distance of EG. The extended interlayer distance promotes multiple reflections and scattering of electromagnetic waves in composites and improves dielectric properties. In addition, EG with a large specific surface area provides many active sites, further promoting interface and dipole polarization. Benefiting from synergistic effect of NiFe 2 O 4 and EG, magnetic loss and dielectric loss of NiFe 2 O 4 /EG composites have been improved and impedance matching is further enhanced. The results indicate that the minimal reflection loss of NiFe 2 O 4 /EG-4 reaches −53.47 dB at 2.69 mm, and the effective absorption bandwidth reaches 2.97 GHz. In addition, based on the computer simulation technology results, NiFe 2 O 4 /EG can attenuate microwave energy under experimental conditions. This work provides a strategy for synthesizing carbon matrix composites with adjustable dielectric parameters and electromagnetic wave properties. [ABSTRACT FROM AUTHOR]

Highlights: 3D cubic hollow core–shell NiCo2O4@C composites were synthesized. Oxygen vacancies were introduced into the prepared composites. Ultrabroad effective absorption bandwidth of 12.48 GHz was obtained. The absorption performance mechanism of NiCo2O4/C composites was investigated. Cobalt nickel bimetallic oxides (NiCo2O4) have received numerous attentions in terms of their controllable morphology, high temperature, corrosion resistance and strong electromagnetic wave (EMW) absorption capability. However, broadening the absorption bandwidth is still a huge challenge for NiCo2O4-based absorbers. Herein, the unique NiCo2O4@C core–shell microcubes with hollow structures were fabricated via a facile sacrificial template strategy. The concentration of oxygen vacancies and morphologies of the three-dimensional (3D) cubic hollow core–shell NiCo2O4@C framework were effectively optimized by adjusting the calcination temperature. The specially designed 3D framework structure facilitated the multiple reflections of incident electromagnetic waves and provided rich interfaces between multiple components, generating significant interfacial polarization losses. Dipole polarizations induced by oxygen vacancies could further enhance the attenuation ability for the incident EM waves. The optimized NiCo2O4@C hollow microcubes exhibit superior EMW absorption capability with minimum RL (RLmin) of −84.45 dB at 8.4 GHz for the thickness of 3.0 mm. Moreover, ultrabroad effective absorption bandwidth (EAB) as large as 12.48 GHz (5.52–18 GHz) is obtained. This work is believed to illuminate the path to synthesis of high-performance cobalt nickel bimetallic oxides for EMW absorbers with excellent EMW absorption capability, especially in broadening effective absorption bandwidth. [ABSTRACT FROM AUTHOR]

[Display omitted] Due to the rapid growth of electronic equipment technology, efficient electromagnetic shielding materials are needed for equipment and human protection. Among them, foam shielding materials with absorption as the primary mechanism have higher application value than highly reflective materials. Highly absorbing shielding materials can reduce the secondary pollution caused by electromagnetic wave reflection. In this study, we added Fe 3 O 4 @Polyvinyl alcohol (Fe 3 O 4 @PVA) and graphene oxide@silver (GO@Ag) into the polyurethane (PU) matrix and constructed Fe 3 O 4 @PVA and GO@Ag/PU composite foam by foaming. Fe 3 O 4 @PVA and GO@Ag form an excellent network structure in the PU foam skeleton, significantly improving its electromagnetic shielding effectiveness (EMI SE) and mechanical properties. The shielding effectiveness reached 30.9 dB with a specific EMI SE (SSE) of 274.9 dB × cm3 × g−1 at a Fe 3 O 4 @PVA filling of 7 wt%, where the electromagnetic wave absorption accounted for more than 80 % of the total EMI SE, proving absorption as the primary shielding mechanism. The results show that Fe 3 O 4 , as a ferromagnet, has both the dielectric loss of ferroelectric materials and the hysteresis loss of ferromagnetic materials in electromagnetic shielding, effectively improving the wave absorption performance of composite shielding materials. Therefore, this work provides a promising idea for efficient and lightweight wave-absorbing shielding materials in aerospace, portable electronic devices and lightweight wearable devices. [ABSTRACT FROM AUTHOR]

A low profile metasurface, which rotates the polarisation of incident electromagnetic wave upon reflection, is presented in this study. The design, which works over a large bandwidth of 67%, is achieved by combining the effect of a circle and a triangle forming a unit cell. By proper modification, the array is found to be useful in RCS reduction over a broad frequency range. Unlike many earlier designs, this structure is of single layer and can be fabricated using standard process on a thin substrate which is inexpensive and easily available. The results are presented with simulation and experiment. [ABSTRACT FROM AUTHOR]

Electromagnetic wave refraction and reflection at the interface between vacuum and lossy metamaterial with zero real part of permittivity are analytically described by macroscopic classical electrodynamics. The analytical model is based on exact solutions of electromagnetic boundary problems. We have good reason to believe that in lossy metamaterial with zero real part of permittivity, the values of the magnetic field and energy flow are nonzero due to the crucial role of losses in epsilon-near-zero metamaterials. It is shown that the significant transmission of waves occurs for almost all incident angles. Moreover, the transmission coefficient increases with increasing loss for TE and TM wave polarizations. Numerical results are presented to show that the optical characteristics of waves at the interface of the metamaterial are highly sensitive to the losses and polarization of waves. The effect of the losses is most pronounced for transverse electric waves. The main contribution of this article is the characterization of the role of losses in the optical properties of epsilon-near-zero metamaterials that differs from some analogs known in the literature. [ABSTRACT FROM AUTHOR]

A new approach to the problem of the passage of the extraordinary wave through the region of the electron–cyclotron resonance in inhomogeneous plasma was considered in the framework of the full set of Maxwell's equations, taking into account the effects of spatial dispersion and resonance dissipation. For the model one-dimensional geometry, field distributions were calculated in the vicinity of the cyclotron resonance at the second harmonic for the normal incidence of the extraordinary wave and the reflection, transmission, and absorption coefficients were found depending on the parameters of the resonance region. As a result, the fine effect of the reflection of electromagnetic radiation from the cyclotron resonance region in transparent plasma was described and the results were compared with the observations of this effect in the experiments on the microwave heating of the plasma at the L-2M stellarator. [ABSTRACT FROM AUTHOR]

Lightweight, flexible, and electrically conductive thin films with high electromagnetic interference (EMI) shielding effectiveness and excellent thermal management capability are ideal for portable and flexible electronic devices. Herein, the asymmetric and multilayered structure Ag-MXene/ANFs composite papers (AMAGM) were fabricated based on Ag-MXene hybrids and aramid nanofibers (ANFs) via a self-reduction and alternating vacuum-assisted filtration process. The resultant AMAGM composite papers exhibit high electrical conductivity of 248,120 S m−1, excellent mechanical properties with tensile strength of 124.21 MPa and fracture strain of 4.98%, superior EMI shielding effectiveness (62 dB), ultra-high EMI SE/t (11,923 dB cm2 g−1) and outstanding EMI SE reliability as high as 96.1% even after 5000 cycles of bending deformation benefiting from the unique structure and the 3D network at a thickness of 34 μm. Asymmetric structures play an important role in regulating reflection and absorption of electromagnetic waves. In addition, the multifunctional nanocomposite papers reveal outstanding thermal management performances such as ultrafast thermal response, high heating temperatures at low operation voltage, and high heating stability. The results indicate that the AMAGM composite papers have excellent potential for high-integration electromagnetic shielding, wearable electronics, artificial intelligence, and high-performance heating devices. [ABSTRACT FROM AUTHOR]

La-Sr co-doped Ba1−x(La0.5Sr0.5)xCo2Fe16O27 (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0, respectively) hexaferrites were prepared by the solid-state method. W-type hexaferrite single phase structure with space group P63/mmc was obtained when the doping amount was x < 0.4 and an M-type hexaferrite and a spinel phase with smaller grains gradually replaced the W phase as the primary phases when x ≥ 0.6. The maximum Ms is 76.2 emu/g and the minimum Hc is 60 Oe at x = 0.4, as obtained by VSM analysis. The magnetoelectric properties of the samples were tested at 1–18 GHz with a vector network analyzer and the reflection loss was calculated based on transmission line theory. It was found that the introduction of an appropriate amount of La-Sr provides a large number of porosity defects while increasing the grain size, which can effectively improve the reflection of electromagnetic waves inside the material and dissipate more energy. At the same time, co-doping also makes the resonance frequency of the samples shift to lower frequency, resulting in tunable absorption properties in the C, X and Ku bands. When x = 0.2, the minimum reflection loss is −40.61 dB at 1.5 mm thickness, with the effective absorption bandwidth of 5.76 GHz in the X band; when x = 0.4, the minimum reflection loss is −37.45 dB at 2.5 mm, with the bandwidth of 4.97 GHz in the C band; when x = 0.6, the material has good absorption in both the X and Ku bands with the thickness less than 2 mm. The simple preparation method and good performance make La-Sr co-doped Co2W ferrite a promising microwave absorbing material. [ABSTRACT FROM AUTHOR]

With the spread of airborne corner reflector (ACR) in the field of shipborne equipment, radar guided anti‐ship missile is facing new challenges. In order to achieve the mastery of the jamming principle of this apparatus, the paper studied its motion properties and sequential Radar Cross Section (RCS) properties. Firstly, the motion model of the ACR was obtained under certain constraints, by deriving the centroid dynamics equation and rotation dynamics equation according to the theoretical mechanics. Then, the dynamic sequential RCS model of ACR array was established by combining the motion model with the modified geometric optics method and coherent synthesis method. Through the simulation and analysis of the motion model, it was found that the flight process of the ACR can be divided into two stages: fast falling and steady falling. In the fast falling stage, the variables of the ACR system change rapidly, while the ACR rotates slowly and falls smoothly in the steady falling stage. From simulation of dynamic sequential RCS model, the results showed that the obvious depolarisation effect is occur in the fast falling stage. Further statistical analysis showed that, the omnidirectivity of single ACR is well from the dynamic perspective, meanwhile array placement can effectively enhance RCS amplitude and improve the probability density distribution. [ABSTRACT FROM AUTHOR]

The KINX and VENUS codes were used for simulation of the baseline inductive and steady-state scenarios of the ITER tokamak operation. The perturbations of plasma electron density and magnetic field caused by the Alfvén modes were calculated in the flux coordinates for these scenarios. The perturbation fields obtained were converted into the engineering coordinates in order to calculate the propagation of probe electromagnetic radiation of the reflectometer using the two-dimensional full-wave TAMIC RτX code in the expected geometry of the experiment. The calculations performed show that for the baseline inductive scenario, in the case of reflection of the extraordinary wave at the lower cutoff frequency from the high magnetic field side, the electric field relative perturbations of the reflected reflectometer signal correspond to the margin of linear range of the diagnostics operation or even go out of this range. It was found that in a number of scenarios, not only the electron density perturbations, but also the magnetic field perturbations significantly contribute to the total signal perturbations that makes even more difficult the further data interpretation. Another possible problem is the narrow frequency range of probing frequencies where the Alfvén mode can be observed. In addition to simulating the reflection of electromagnetic waves from plasma, it was analyzed also the possibility of measuring the Alfvén modes parameters when the extraordinary wave pass through the plasma in the transparency window between the upper and lower cutoff frequencies of the extraordinary wave (refractometry). It is shown that at the fundamental frequency, the phase perturbations range from 3 to 60 degrees, which makes it impossible to use the amplitude-modulated refractometer for analyzing signals. The "synthetic diagnostics" approach was used, which showed itself well for simulating the operation of reflectometers at plasma facilities. [ABSTRACT FROM AUTHOR]

Abstract A broadband dual‐polarised reconfigurable frequency selective surface (RFSS) based on general dual‐branch parallel circuit model is proposed by the authors. The specific circuit model is constructed to feature the switchable functions of transmission and reflection characteristics by introducing a parallel branch. It is beneficial to clarify the operating mechanism and provide an effective guidance to satisfy the switching bandwidth requirements of the desired RFSS. In order to validate the proposed concept of the dual‐branch parallel circuit model, a broadband dual‐polarised RFSS prototype has been designed, fabricated and measured. A satisfactory agreement can be reached between the synthesis, simulation and measurement. The experimental results exhibit the merits of low insertion loss, broad switching bandwidth and good angular stability for different polarisation and different incident angles.