Frequency Selective Surface Geometry Research Articles

Design of single layer bowtie wide band-stop frequency selective surface with angular stability for C-band applications

This paper presents the design and analysis of a single-layer wide band-stop frequency selective surface (FSS) tailored for C-band applications. The proposed FSS design employs a modified bow-tie unit cell structure that enhances band stop characteristics, resulting in improved performance compared to traditional FSS geometry. The design process involves numerical simulations and optimization techniques to achieve the desired frequency response. A modified bowtie element with FR4 substrate comprises the proposed FSS which exhibits a resonant frequency of 6.0 GHz with a wide bandwidth of 4.84–6.96 GHz (35.93 %) and act as a band stop filter. The FSS is analyzed in terms of its transmission coefficients, providing insight into its filtering properties. In addition, parametric studies of the unit cells are done. Furthermore, the angular stability of the proposed FSS is simulated with incident waves at various angles between 0° to 60° for both TE and TM modes. The proposed FSS presents C-band applications of WLAN, ISM/WiMAX, satellite communications, radar systems, shielding and communication devices, also enhancing filtering capabilities and system performance. The simulation results are well correlated with measurement results.

A Novel Double-layer Low-profile Multiband Frequency Selective Surface for 4G Mobile Communication System

A novel double-layer multiband, low-profile frequency selective surface (FSS) for IMT-Advanced (4G) mobile communication system is presented in this article. On aspired to a minimum transmission coefficient of −10 dB for surface materials when the frequency bands targeted for blocking are stopped. For this project, we chose the dielectric substrate FR4 (loss-tangent = 0.02; dielectric constant = 4.54) and a thickness of 1 mm. Dodecagonal rings, upright bars, and square frame make up the FSS unit cell. The desired frequency responses of the FSS were intended to avoid being changed according to the angle of incidence of the electromagnetic waves. The FSS design is proposed as a symmetrical structure to make it polarization-independent and is aimed to stop 800, 900, 1800, 2100, and 2600 MHz frequencies to prevent harmful effects to human health and interference effects at these frequencies. With a cell size of 0.17λ, the planned FSS is quite small and, thus, has a low sensitivity at the angle of the incident wave. In addition, FSS geometry was manufactured by a printed circuit board (PCB) and measured in a non-reflective environment after being studied in Ansys high-frequency structure simulator (HFSS) software. By comparing the analysis and measurement results of the design, the success of the FSS to the frequencies to be stopped has been verified. The effect of each patch on different frequencies has been examined by drawing the surface current density graphs of the design.

Hybrid ECM Blended Whale Optimization Derived Frequency-Selective Conformal EMI Shielding Structure Using Ferrite Substrate

In this work, both planar and conformal novel electromagnetic interference (EMI) shielding structures with customized properties are developed using a unique coupling of frequency-selective surface (FSS) and magnetic substrate. A hybrid equivalent circuit model (ECM) blended whale optimization (WO) technique is offered in the quest of customized shielding of L-, S-, C-, X-, and Ku-bands using a simple FSS geometry. The proposed structure is designed to shield L-, S-, C-, X-, and Ku-bands with a fractional bandwidth of 66.67%, 66.67%, 66.67%, 50.2%, and 40.50%, respectively. The frequency-dependent complex dielectric permittivity ( ε'- jε") and complex magnetic permeability ( μ'- jμ") of ferrite are measured using a waveguide measurement setup at X-band. The measured electromagnetic parameters are utilized in the modeling of planar and conformal ferrite-based frequency-selective shielding structures. An optimal ferrite coupled FSS shielding structure is fabricated, and its performance is evaluated using a non-destructive free-space microwave measurement setup. The measured results are found in congruence with the full-wave simulation and WO results. Besides, the conformal configuration of the proposed shielding structure is peculiarly investigated for inward and outward curved shielding structures for different values of radius of curvature. The proposed technique is intended to achieve a customized, simple, wideband, polarization-insensitive, and angular stable structure in the desired frequency regime, thus verifying the potential of the aforementioned technique for shielding applications.

Numerical Model of the Effective Permittivity for Square-Loop Frequency Selective Surfaces

This paper presents a model, obtained through numerical simulation and curve fitting, for the dielectric effective permittivity of frequency selective surfaces (FSSs). The numerical model is based on the permittivity and thickness of the dielectric layer supporting the FSS metallic elements, as well as on the period and on a factor dependent on the FSS geometry. The model is developed for square-loop FSS, using a given geometry reported in literature as a reference case. The results from electromagnetic simulations with the finite-element method are used for developing the numerical model.

An iterative full‐wave method for designing bandstop frequency selective surfaces on textile substrates

ABSTRACTThis work presents an investigation of frequency selective surfaces (FSSs), with cross dipole, square loop, and triangular patch elements printed on textile substrates which exhibit some advantages over typical dielectric substrates used in FSS structures, such as high flexibility, low weight, low cost, and ease fabrication. Among these advantages, flexibility is certainly the most important one, allowing the FSS geometry to be used in many microwave circuit applications. Simulated results are obtained using both an implementation of the wave concept iterative procedure and Ansoft Designer commercial software for comparison purpose. Furthermore, textile FSS prototypes are built and measured to validate the simulated results. Good agreement is reported between simulated and measured results. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:383–388, 2014

Frequency selective surface filters with polarized band pass/band reject performances

ABSTRACTThis work presents a wave concept iterative procedure design of a frequency selective surface (FSS) structure, which elements are composed by integration of square ring and cross dipole conducting patch elements. The proposed FSS geometry allows the development of a band pass or band reject filter, depending of the incident wave polarization. Simulated and measured results for the transmission coefficient are compared and a good agreement is observed. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:483–487, 2014