Analysis Of Frequency Selective Surfaces Research Articles

Design and analysis of frequency selective surface embedded broadband high gain miniaturized antenna

SummaryIncorporating the better impedance matching capability of planar curved radiating patch, a miniaturized broadband planar antenna has been designed, analyzed, and integrated with frequency selective surface (FSS) to accomplish higher gain for various short‐range and long‐range modern wireless communication applications. Physical and electrical volume of the presented antenna is 25 × 20 × 1.6  and 0.25 × 0.20 × 0.016, respectively. The proposed radiating patch is constructed from a conventional rectangular patch by transforming the upper side of the patch into a semi‐circular shape and the lower side of the patch into a staircase‐like shape. Measured outcomes of the designed antenna show a very large operating bandwidth of 19.8 GHz (3–22.8 GHz) with a fractional bandwidth (FBW) of 153.5% and bandwidth dimension ratio (BDR) of 3070. An equivalent circuit model (ECM) of the proposed antenna is developed using an advanced design system (ADS) circuit simulator. The frequency responses of the ECM are compared with the simulation done by CST Microwave Studio Suite software and measurement results, which show good agreement. An FSS structure with stop band from 2–28 GHz is positioned beneath the proposed antenna at optimal position (27 mm below the antenna) to enhance the gain up to 8.9 dBi. The presented antenna and FSS are fabricated on FR4 substrate and experimentally verified using standard microwave measurement setup.

Design and Analysis of Frequency Selective Surface for Ism and Lower Ultra-Wideband Antenna

A Compact, dual-layer Frequency Selective Surface (FSS) is presented for electromagnetic shielding applications. The square loop FSS is modified to provide band rejection characteristics for ISM band and lower Ultra-Wide Band (UWB) covering from 2.2 GHz to 7.1 GHz with the bandwidth of (S21 < -20dB) 4.9 GHz. The novel design exhibits symmetric property due to which it achieves polarization-insensitive stable band rejection of the desired frequency band for various angles of incidences up to 60°. The proposed FSS structure has compact dimensions of 0.170λ x 0.170λ x 0.0117λ. The design was fabricated on either side of the substrate made of FR-4 with a dielectric constant of 4.4 and loss tangent of 0.02. The measured results are well per the simulation results. The proposed FSS in this paper has various applications, including the aerospace industry, hospitals, random, and in the scope of electromagnetic filters, etc.

Synthesis analysis of frequency selective surface using the generalized sheet transition conditions

Based on the generalized sheet transition conditions (GSTCs), the surface electric/magnetic susceptibilities of frequency selective surface (FSS) are extracted and analyzed. Key factors that affect the FSS performance, including frequency variations, structure shapes, angular dependent, and bandwidth are studied through the susceptibility parameters. Based on the analysis of four typical FSS structures, potential automatic structure designs are suggested and several illustrative examples are given. Finally, the method is compared with the equivalent circuit method.

Development of Method of Moment Based Programme to Analyze Cross Dipole Frequency Selective Surface and its Verification with Measured Results

Theoretical analysis of frequency selective surface comprising of cross dipole elements has been presented in this paper. Algorithm for theoretical analysis based on method of moment has been implemented by MATLAB programming. Theoretical, simulated and experimental results are compared. Simulated result is obtained by ANSOFT designer version 2.2 software. Experimental result is obtained by standard microwave test bench. Good parity in the results is observed. The presented FSS Structure has relevance in the field of mobile and satellite communication.

Equivalent circuit model for analysis of frequency selective surfaces with ring and double concentric ring apertures

In this study, the authors present two new proposals for representation by the equivalent circuit model for aperture-type circular ring geometries, not yet studied in the literature. The study consists of the frequency response representation of frequency selective surfaces (FSSs) formed by circular ring aperture and concentric circular ring apertures. At first, the authors performed an equivalent circuit analysis for a single cell formed by a single circular ring. Then, they extend the analysis to concentric circular rings, which when used as FSS unit elements, present two passband responses. They compare results of the proposed method with results obtained with the commercial software ANSYS HFSS, showing a good agreement between the results. They built four prototypes and compared measured results with simulated results obtained with the suggested method and it completes the proposed equivalent circuit validation.

Efficient numerical analysis of finite FSS with multilayered media by MLACA

In this study, an efficient numerical technique for transmission characteristic analysis of finite planar frequency selective surface (FSS) with multilayered media is presented by using the multilevel adaptive cross approximation (MLACA). The computational scheme is based on the mixed-potential electric field integral equation (MPIE) with multilayered media Green's functions (MLGFs). The three-level modified discrete complex images method (DCIM) is presented for the spatial-domain MLGFs without any quasi-static and surface-wave extraction. For electrically large-size FSS structures, the MLACA method is then employed to alleviate the high computational complexity and memory requirement of method of moments. Numerical results are presented to demonstrate the accuracy and efficiency of the proposed method.

EM Design and Analysis of Frequency Selective Surface Based on Substrate-Integrated Waveguide Technology for Airborne Radome Application

In this paper, a bandpass frequency selective surface (FSS) based on substrate-integrated waveguide (SIW) technology is presented for airborne radome application. The proposed FSS element consists of a tapered cross-slot on either side of the substrate surrounded by metallic vias. The structure selectively allows the impinging electromagnetic (EM) wave through it in the specified frequency band. The element shows very stable frequency response for oblique incidence and the sharp roll-off performance characteristics at the edges of operating region in the rejection band. The −10 dB relative bandwidth (BW) of the element is 12.8% from 9.5 to 10.8 GHz with a very good insertion loss (IL) of 0.1 dB. Furthermore, the spectacular advantages of the FSS element based on SIW have been used for modeling the airborne radome application. The proposed radome structure is operating at 10 GHz with a relative 10 dB BW of 25.0% (8.20–10.6 GHz) with maximum (IL) better than 0.1 dB in its passband. The behavior of the FSS radome has been analyzed at different conformal sectors and thickness is optimized for optimal performance. The key parameters of radome such as transmission performance, radiation efficiency, and radar cross section (RCS) have been studied. Experimental verifications are carried out to prove the validity of the estimated results. The results show promising performance of the proposed FSS based on SIW technology for airborne radome application.

Multiband FSS Analysis and Synthesis Based on Parallel Non Coupled Metallic Strips Using WCIP Method

A novel parallel coupled Metallic strips frequency selective surface (FSS) is presented. The design is based on a filter composed of horizontal and vertical metallic strips. The structure has the advantage of simplicity and gives multi resonant frequencies easily controlled by a simple variation in the strips length. The proposed FSS rejects frequencies at 7GHz, 9.4GHz with bandwidths of 0.646GHz, 0.793GHz respectively when the structure is excited with an x polarized plane wave, and two frequencies at 9.1GHz and 11.2 GHz with bandwidth of 280.3MHz, 63MHz respectively when the structure is excited with a y polarized plane wave. To suppress frequencies ideal diode on reverse bias are inserted. The simulated results obtained using WCIP (Wave Concept Iterative Method) are compared to the COMSOL Multiphysics 4.3b software results, and measurements, a good agreement is observed. Then, an FSS synthesis approach based on non coupled parallel metallic strips is presented. It allows the synthesis of FSS for resonant frequencies ranging from 4.5GHz and 12.25 GHz for strips lengths inversely varying from 5mm to 19mm. To validate the synthesis approach, measured resonant frequencies are used as desired resonant frequencies to determine the metallic strips lengths. As a result the metallic strips FSS dimensions are extracted. Then the WCIP method is used to characterize the synthesized FSS. Three FSSs are synthesized based on the fabricated FSS and good agreement between measurements and synthesized FSSs results is recorded.

Prediction and validation of electromagnetic performance of curved radar-absorbing structures based on equivalent circuit model and ray tracking method

In this study, an equivalent circuit model and ray tracking method were used to predict the electromagnetic characteristics of curved radar-absorbing structures (RASs) applied with a frequency selective surface (FSS). After performing an electromagnetic analysis of FSS using a unit cell model, an equivalent circuit model reflecting the characteristics of the FSS was constructed. The equivalent circuit model of the FSS was applied to an equivalent circuit model for the RAS to evaluate the absorption performance as a function of the curvature and incident angle. Electromagnetic characteristics of the curvature structure were predicted by estimating the path of the electromagnetic wave using the ray tracking method. The calculated results were compared with the experimental results using free space measurements. Through this study, it was possible to estimate an equivalent circuit model reflecting the electromagnetic characteristics of the RAS with respect to the incident angle and curvature of the FSS. In addition, the electromagnetic performance of the entire curved structure was evaluated using the ray tracking method.

Design and Analysis of Frequency Selective Surface at Ka/K/Ku Band

Design and Analysis of Frequency Selective Surface at Ka/K/Ku Band

Critical analysis of frequency selective surfaces embedded composite microwave absorber for frequency range 2–8 GHz

Radar wave absorbers are important for the reduction of radar cross section of the target for stealth applications. Earlier the radars were available in the frequency range 8–12 GHz (X-band) and 12–18 GHz (Ku-Band). Due to recent advancement in radar technology, radars are now available from 2 to 18 GHz frequency range. So there is an urgent need to develop such a material that can work as radar wave absorber in the lower frequency band of the microwave spectrum i.e., 2–8 GHz. For this purpose the selection of material is an important criterion as the radar wave absorption depends primarily upon the material characteristics i.e., complex permittivity and complex permeability. For lower frequency radar wave absorption, the material must also possess the conducting property along with dielectric and magnetic properties. Therefore, an attempt has been made to develop a radar wave absorbing nano-composite material by selecting constituent materials with such inherent properties that can work for the absorption of radar wave in the lower frequency range. It is observed that the developed composite give good absorption in the lower frequency range but with narrow radar wave absorption bandwidth (4–7 GHz). So we have explored the possibility of the efficient use of an advanced electromagnetic technique like frequency selective surface to enhance the radar wave absorption bandwidth in the lower frequency region of the microwave frequency spectrum and precaution has been taken such that complexity due to FSS can be avoided. It has been observed that the synthesised single layer absorber with single square loop, cross dipole and Jerusalem cross FSSs provides radar wave absorption bandwidth in the frequency range 2–8 GHz.

X-band Band-pass Frequency Selective Surface for Radome Applications

A low profile multi layer miniaturized unit cell frequency selective surface (FSS) with second-order band-pass response is design. The metallic layers in the form of capacitive patches and inductive grids are separated by dielectric substrates. The non-resonant sub-wavelength unit cells with unit cell dimensions and periodicities on the order of 0.15λ. The overall thickness of approximately 0.03λ is designed which is useful at lower frequencies with long wavelengths. The FSS exhibit a stable frequency response to different angles of incidence and polarizations. The analysis and synthesis of the FSS is done using equivalent circuit method and simulated using CST microwave studio at X-band.

Analysis of finite frequency selective surfaces backed by dielectric substrate using sub-entire-domain basis function method

Purpose – Analysis of the frequency selective surface (FSS) is of great significance. In the method of moments, when the electric size of the FSS increases, huge in-core memory and CPU time are required. The purpose of this paper is to efficiently analyze the finite FSS backed by dielectric substrate utilizing sub-entire-domain (SED) basis function method. Design/methodology/approach – Different types of SED basis functions are generated according to the locations of the cells in the entire structure, and a reduced system is constructed and solved. The couplings of all cells of the FSS are taken into account by using Green’s function and Galerkin’s test procedure. The spatial Green’s function is obtained with the discrete complex image method. The reflection and transmission coefficients of the FSS are calculated using the far field of the FSS and the metallic plate with the same size. Findings – Moderate problems of the finite FSS backed by dielectric substrate are solved with the SED basis function method. The original problem can be simplified to two smaller problems. It enables a significant reduction to the matrix size and storage, and efficient analysis of FSS can be performed. The band-stop type of FSS can be composed of periodic conductive patch cells on the dielectric substrate, and shows total reflection property at the resonant frequency. Originality/value – The SED basis function method is mostly used to analyze periodic PEC structures in free space. The layered medium Green’s function is successfully employed and several dielectric substrate backed finite FSSs are discussed in this paper. The calculation of reflection and transmission coefficients, which are more effective rather than far field scattering of the FSS, are described.

Numerically Efficient Modeling of Frequency Selective Surfaces in Broad Frequency Range

Fast and accurate simulation of the electromagnetic field around frequency selective surfaces (FSSs) are needed for the design and optimization of devices based on the use of FSSs. The authors recently published a computationally efficient calculation method for the analysis of FSSs where the current distribution in the conducting parts are locally approximated by currents associated to electromagnetic waves propagating perpendicularly to the surface of the FSS. In this paper, an improved version of this method is presented. Here, in addition to the described assumption, local plane wave distribution of the current density is imposed also with respect to that surfaces being perpendicular to the surface of the FSS. By this modification, the error of the described calculations becomes very small in a very broad frequency range while the computational burden remains low, consequently the method can be advantageously applied for the solution of design and optimization problems.

Circuit-Model Analysis of Frequency Selective Surfaces With Scatterers of Arbitrary Geometry

An equivalent-network model is here proposed to characterize two-dimensional planar periodic arrays of arbitrary scatterers/apertures embedded in a layered environment. The model is an extension of the approach previously developed by some of the authors, which only considered simple rectangular scatterers. A key underlying assumption in the present approach is that the current/field distribution in the scatterer can be factorized so that the spatial profile is independent of the frequency in the considered range of interest. This approximation is proven to work properly for a great variety of useful planar scatterer/aperture patterns, even at frequencies within the diffraction regime. The spatial current/field profile is determined from a full-wave simulation at a single and low frequency value. Our numerical results are validated through comparison to commercial simulators for very wide frequency ranges as well as with previously proposed circuit-model approaches.

IMPROVEMENT OF THE EQUIVALENT CIRCUIT METHOD FOR ANALYSIS OF FREQUENCY SELECTIVE SURFACES USING GENETIC ALGORITHMS AND RATIONAL ALGEBRAIC MODELS

In this paper, we propose an enhancement of the Equivalent Circuit Method (ECM) for analysis of frequency selective surfaces (FSS) with square loop geometry of the unit cell. For this, genetic algorithms and rational algebraic models are used to obtain a more accurate value of the effective electrical permittivity (eeff ). We use simulated data obtained with a commercial software to adjust some parameters. So, genetic algorithm is used to obtain a better value of an exponent that calculates eeff minimizing the rational algebraic models. In this paper, this is done for the square loop geometry, but the methodology can be extended to any geometry. Finally, prototypes are built and the technique is validated.

Application of AIM and MBPE Techniques to Accelerate Modeling of 3-D Doubly Periodic Structures with Nonorthogonal Lattices Composed of Bianisotropic Media

An efficient methodology is introduced for rapid analysis and design of three-dimensional (3-D) doubly periodic structures over a wide frequency range based on hybrid finite element boundary integral (FEBI) methods. The 3-D doubly periodic structures can be represented as nonorthogonal lattices composed of general inhomogeneous bianisotropic media with arbitrarily-shaped metallic patches. Based on Floquet theory and periodic boundary conditions, the original stated problem that involves infinite periodic structures can be converted into a single unit cell. Using the equivalence principle, the derived BI equation formulation is applied to the top and bottom surfaces of the unit cell, which results in a perfectly reflectionless boundary condition for the FE-based approach. Then, the unit cell was meshed using triangular prismatic volume elements, which provide a great deal of flexibility in modeling complex planar geometries with arbitrary shapes in the transverse direction. The adaptive integral method (AIM) was employed to accelerate the calculation of the matrix-vector product for the BI portion within the iterative solver. Furthermore, a model-based parameter estimation (MBPE) technique was proposed for the wide-band interpolation of the required impedance matrix elements in the BI part for near field components that were used in the AIM procedure. The accuracy and efficiency of the proposed hybrid algorithms are demonstrated by the presented numerical results (e.g., in comparison with analytical solutions). Several simulation results are presented to illustrate the flexibility of the proposed methods for analysis of frequency selective surfaces with arbitrarily-shaped metallic patches, bianisotropic materials, and nonorthogonal lattice configurations.

Study on the lumped parameters of FSS in terms of the transfer function

Equivalent circuit method is a principal one to analyze the active frequency selective surface (FSS). Extracting its lumped parameters is the key to the equivalent circuit method. We have constructed the transfer function based on the traditional equivalent circuit method and the transmission line theory. A matrix equation composed of lumped parameters is set up utilizing the relationship between the equivalent impedance and transmission peak. The equivalent lumped parameters are solved by the least square method, and the FSS frequency response curves are obtained from the transfer function. Compared with the full wave analysis method, the calculated results are in good agreement with that of simulation. Such results verify the accuracy and reliability of the method presented in this paper, and provide a theoretical reference to active FSS analysis using the equivalent circuit method.

Software for project and analysis of frequency selective surfaces

This paper presents a numerical investigation for a double screen frequency selective surface (FSS) with perfectly conducting rectangular patch elements. The analysis uses a full wave technique to obtain the scattering characteristics. The analysis combines the immitance approach and the method of moments to obtain the scattered fields and, consequently, the scattering characteristics of the structure. For validation of the analysis, numerical results are compared with measured and numerical results presented by another authors. A good agreement was obtained with experimental results.

Software for project and analysis of frequency selective surfaces

In this paper, a software for design and analysis of frequency selective surfaces (FSS) based on the equivalent circuit model is presented, with emphasis on teaching students in the interaction between FSS parameters. Tools to design FSSs and a tutorial with theoretical elements of the equivalent circuit method, applied to FSS, compose this software. The software can be used at FSS analysis and design course to consolidate the first theoretical and illustrated concepts.