Analysis of FSS with Koch Island patch elements using the wave concept iterative procedure

In this paper, a rectangular metallic ring FSS (Frequency Selective Surfaces) with parallel metallic strips for multi band applications are characterized by the WCIP (Wave Concept Iterative Procedure) method. The proposed FSS structures are made of metallic elements that are simultaneously independent in the spatial domain and uncoupled in the spectral domain. Thus the FSS multiband behavior can be achieved only by a building process based on independent metallic elements in both domains. The resonant characteristics of the proposed FSS are determined. The structure shows three resonant frequencies when the incident wave is x-polarized and three resonant frequencies when the source is polarized in the orthogonal direction. A variation in the length of the strips and the rectangular ring allows a fine tuning in the FSS resonant frequencies to give raise to tuned bandwidths. The suppression of a resonant frequency can be insured either by the elimination of the responsible metallic strip or by the insertion of a PIN diode switch. Three FSS structures are manufactured and characterized. The FSS bandwidth can be enhanced in both perpendicular FSS exciting source directions by only varying the strips lengths and the ring dimensions to the corresponding resonant frequencies. A good agreement is obtained when the WCIP results are compared with the simulations of COMSOL Multiphysics software and experiment.

This work presents an analysis of frequency selective surfaces (FSSs) with Dürer's pentagon pre-fractals patch elements. The proposed FSSs are composed by a 2-D periodic array of metal pre-fractals elements printed on a dielectric substrate. A parametric analysis is performed using Ansoft Designer commercial software in terms of the FSS periodicity and of the fractal iteration number used in the FSS elements. The structures are proposed to behave like stop-band spatial filters and exhibit interesting features to be used in the design of compact FSSs with broadband or dual band responses.

We have studied a frequency selective surface (FSS) for a U-shaped geometry by a method called the Wave Concept Iterative Procedure (WCIP). The development of this method based on Fast modal transformation (FMT), for the FSS frequency response is presented in the results of a single resonance obtained by the WCIP method exhibit a resonance frequency at 5.6 GHz with a bandwidth of 2.75 GHz, when the structure is excited in the x direction by a plane wave at normal incidence, a resonance frequency at 11.6 GHz with a 414.61 MHz band when the structure is excited in the y direction. The simulation of the results obtained by the WCIP method are compared to the HFSS results and a good agreement is to score.

This paper presents an analysis of the characteristics of the frequency selective surface (FSS) by means of equivalent circuit models. In order to determine the circuit element parameters of the FSS with resonant elements of arbitrary shape, the eigenvalue problem of the matrix equation is solved and the Q curve of each resonance is derived from the frequency dependence of the reactance obtained from the characteristic current distributions at resonance. By equating this Q curve with that for the equivalent circuit, the circuit parameters are derived. As an example of analysis by the present method, the circuit element parameters of patch-type resonant elements designed by us using the genetic algorithm (GA) are derived. The characteristics of the dielectric-loaded FSS for the C/Ka band are analyzed by means of the equivalent circuit. The usefulness of the proposed method is verified by comparison of the frequency characteristics obtained by the method of moments and by the equivalent circuit. © 2005 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 88(6): 9–17, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20162

In this paper a modified method based on FDTD method is used to analyze frequency selective surfaces with periodic boundary condition. Computation results are compared to that from other scholars. Good agreement has been observed. Multiplexer, which consists of two sheets of FSS, is simulated and good performance has been obtained over a band from 100 GHz to 450 GHz.

A loaded gridded Jerusalem cross element is analyzed and predicted its plane-wave transmission/reflection characteristics for a normal and oblique angle of incidence using an equivalent circuit model. Further, the structural behaviour of its conformal bent is analyzed by bending the structure at a conformal radius of 25 mm. The modes of resonance of the structure are examined, current is largely confined at the E-plane arm at the resonance frequency. The deviation in the EM performance of planar and conformal structures have been studied for different design parameters. A Commercial full-wave simulator is employed to validate the designed analytical expressions of the element and for further analysis.

A novel approach to analyze FSS structures is used whereby the Ewald transform technique, in conjunction with a particular choice of basis function, is shown to reduce the complexity of the problem formulation and greatly improve the convergence rate of the MoM solution for periodic structures. In particular, we consider wire-type geometries, which need not be confined to a single plane configuration, to demonstrate the effectiveness of this method.

In this paper, combined elements method is introduced to achieve dual stop-band frequency selective surface (FSS). Later, a dual-band WLAN antenna is designed and the centre frequency is at 2.4GHz and 5.4GHz which accord with the FSS in this paper. We use FSS as dual-band WLAN antenna's reflection plan to improve the performance of antenna. The analysis and results of antenna and FSS are given. The results show that antenna's gain can be improved after the FSS is placed as the reflection plane. This is a new research area which have great prospect in the design of antenna combined with FSS.

This paper presents a design of dualband frequency selective surface (FSS) element design based on SIW cavity (SIWC) technology and its performance analysis. The proposed dualband FSS is modelled using a combination of two FSS elements. A cross-slot element has been enclosed by a square slot to design the proposed shape. The structure shows dualband response at two different frequency bands C- and Ku-bands with sharp roll-off performance characteristics. The performance of the structure has been estimated using commercial CST Microwave studio. The simulation results show the higher selectively, very good isolation between the bands and stable performance characteristics compared with its equivalent conventional planar version.

A generalization of the wave concept iterative procedure method is proposed and used in the analysis of finite size and nonuniform frequency selective surfaces (FSS). The nonuniformity of the FSS is obtained by mixing different shapes of elements in the finite size FSS structures consisting of circular patch elements with and without radial slits. The shapes of the radial slit elements are defined according to a fractal-like formation rule, where the circular patch without radial slits is the generator. Single or multiband frequency performances can be obtained, enabling the design of reconfigurable FSS. In addition, a high stability of the incidence angle of the plane wave is confirmed. A good consistency is observed among theoretical, simulation, and experimental results.

When a load is applied to a structure reinforced by composite materials, the mechanical behavior is different from the one without composites. As the technology in which the surface of structure is reinforced by fiber reinforced plastics (FRP) is used widely to prohibit the reduction of strength caused by cracking, it is necessary to establish the method of fracture simulation applicable to the reinforced structure. Therefore, a computer program of fracture simulation for the cement mortar reinforced by CFRP or AFRP has been developed in this paper. In order to evaluate the computational results, three point bending tests on mortar beams were carried out. The cement mortar beams whose surface is reinforced by FRP sheet are superior in strength to those of cement mortar only. The computational results have a good agreement with the experimental ones. As a result, it is clear that the developed computer program of fracture simulation is very useful for design of structures with composites.

Frequency selective surface (FSS) is a two-dimensional periodic structure. It exhibits total reflection and transmission in the neighborhood of the element resonances. As it performs as a filter, FSS is widely used in the fields of microwave and optics. In this paper, the finite element method is used to analysis frequency selective surface and study on the feasibility of Ansoft HFSS software for frequency selective surface simulation. Hexagonal element of frequency selective surface is as an example to explore the simulation method and the process of Ansoft HFSS. Through the comparison of the simulation curves and the measured curves of hexagonal element frequency selective surface film by photoetching technology, the simulation method of Ansoft HFSS software for frequency selective surface is correct. At the same time, this paper further verified the reliability of the simulation through the example of the ring and the cross unit structure.

Frequency Selective Surface (FSS) is a specialized structure used in the field of electromagnetic waves and radio frequency (RF) engineering. It is designed to exhibit selective transmission or reflection properties based on the frequency of the incident electromagnetic waves. This article describes the design, construction, and analysis of a textile-based band-stop frequency selective surface for use in the highly EM-polluted GSM, Wi-Fi, LTE, and WiMAX bands. A full-wave EM solver called CST Microwave Studio was used to develop and simulate the unit cell of the proposed FSS at the relevant frequency. In this study, embroidered and screen-printed textile based FSSs were designed. According to the results of this study, it was demonstrated that both embroidery and screen printing FSSs exhibit resonance at a frequency of 3.5 GHz. The screen printing method yielded the best results in terms of resonance frequency sensitivity, while the embroidery method showed a resonance frequency shift. It was observed that the stitch directions and density are important parameters in the embroidery method. Gaps between the embroidery paths in the production of embroidered FSSs resulted in differences from simulations due to the disruption of the structural integrity of the unit cell. Consequently, textile-based FSSs offer advantages over traditional FSSs. This study highlights the potential of textile FSSs as an effective means of reducing electromagnetic pollution, and suggests that further improvements in the design and production processes of textile FSSs can be made.

This work proposes the inverse design of bandstop Frequency Selective Surface using a Graph based Conditional Variational Autoencoder (G-CVAE) integrated with a Physics-Informed Neural Network (PINN). This inverse design involves the prediction of FSS geometry that exhibits ultra-wide stopband characteristics. Initially, the graph convolutional network precisely extracts the topological and spatial relationships within the FSS geometrical design. The features of the graph and simulation results of the FSS dataset are used to train the CVAE, which maps the FSS physical structure and its electromagnetic behavior. The trained CVAE predicts the FSS geometries with desired frequency responses, while the PINN is incorporated to ensure physical feasibility. By monitoring the average relative error values, the simulated and predicted transmission coefficients are brought closer to each other. Also, similar approach is followed to enhance the angular stability and to achieve polarization independence in both TE and TM modes. A G-CVAE-PINN is constructed and trained using various random combinations of graph attributes and simulation outcomes, achieving an average inaccuracy of 3%. Further, one of the best designs from the predicted FSS designs is chosen for experimental validation. This predicted and experimentally validated bandstop FSS exhibits wide band rejection of 20 GHz ranging from 8 GHz to 28 GHz. The fabricated design exhibits polarization independence up to 75°in both normal and oblique angles. Thus, the predicted FSS designs are ideal for radome, EMI shielding, and satellite communications, providing efficient frequency filtering for 5G and beyond 5G networks.

This paper introduces a compact dual band frequency selective surface (FSS) absorber designed using FR-4 substrate to achieve high absorption efficiency at frequencies of 4.09 GHz and 8.23 GHz, with absorption coefficients of 99.53% and 99.94%, respectively. The absorber is characterized by polarization insensitivity, ensuring consistent performance for both TE and TM polarizations. Additionally, it demonstrates strong angular stability, maintaining effective absorption at oblique incidence angles of up to 60°. An analysis of the surface current distribution offers insights into the electromagnetic behavior at the resonant frequencies. The unit cell is miniaturized, measuring <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.13 \lambda_{0} \times 0.13 \lambda_{0}$</tex>, where <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\lambda_{0}$</tex> denotes the freespace wavelength associated with the first resonance frequency. Due to its high absorption, compact size, and stability, this proposed FSS absorber is a promising candidate for applications in radar cross section (RCS) reduction, stealth technology, and electromagnetic shielding.