Dual-band Frequency Selective Surface Research Articles

A Novel Compact Dual-Band Frequency Selective Surface for GSM Shielding by Utilizing a 2.5-Dimensional Structure

Based on 2.5-dimensional (2.5-D) structure, a novel compact dual-band frequency selective surface for GSM shielding is proposed in this letter. The unit cell geometry is designed by knitting double square-loop elements in 2.5-D which realizes the compact dual band-stop characteristics successfully. The size of proposed 2.5-D frequency selective surfaces (FSS) cell is only 0.072 λ0, where λ0 corresponds to free-space wavelength of the lower resonance frequency. The 2.5-D FSS is modeled and simulated by Microwave CST STUDIO SUITE. The simulation result shows that the FSS offers band-stop response at 900 and 1790 MHz with shielding effectiveness of 41.9 dB and 49.2 dB, respectively. Furthermore, the 2.5-D FSS performs a good angle-stability under both TE and TM polarizations. Hence, the designed 2.5-D FSS can be used for GSM shielding effectively. A prototype of proposed 2.5-D FSS is fabricated. The measurement result proves the satisfactory consistency with the simulation results.

High gain dual band slot antenna loaded with frequency selective surface for WLAN/fixed wireless communication

AbstractThis study shows the gain enhancement achieved through dual band slot antenna incorporated with dual band frequency selective surface. In order to do this, at first, a dual band novel 7 × 7 spanner shape FSS is designed, and its operations is analyzed by using the ray tracing method. The second step involves designing the dual band slot antenna resonating at 3.53 and 6.2 GHz, respectively. The designed FSS is then used as superstrate on the slot antenna in which cavity resonance occurs due to multiple reflections and leaked out waves, thereby enhancing antenna's gain significantly on both the bands. Further, the overall gain of slot antenna with the superstrate is achieved as 13.00 and 13.92 dBi on the 2 respective resonant frequencies; this in turn results in a gain enhancement of 8.0 and 6.82 dB at 3.53 and 6.2 GHz, respectively. The measured results coincide verifying the results of the simulated structure. This is followed by a parametric analysis for air gap between FSS and the radiating antennas, which in turn have been designed for wireless and satellite communications.

Compact dual‐band frequency selective surface designed for global system for mobile communications system

In this Letter, a compact dual-band frequency selective surface (FSS) with the smallest size of 0.047λ 0 × 0.047λ 0 for global system for mobile communication system is proposed. This FSS element is composed of two 2.5D square loops, which creates two stop bands resonating at 940 and 1820 MHz with −18 dB bandwidth of 105 and 208 MHz, respectively. Besides, the proposed FSS performs a stable frequency response under different incident angles for the horizontal polarised electric field (transverse electric mode) and vertically polarised electric field (transverse magnetic mode). The detailed design process is illustrated in the Letter. To confirm the full-wave simulation results, a prototype is fabricated and the measured results show good agreements with the simulated ones.

Dual stop band frequency selective surface for C and WLAN band applications

A miniaturized unit cell design of Frequency Selective Surface (FSS) to produce stop band characteristics for two bands is presented. The presented unit cell structure is showing the band filtering characteristics for dual frequency band specifically C-band for satellite communication and Wireless Local Area Network (WLAN). The designed FSS structure is comprised of I shaped and modified I shaped metallic strips. The distinct unit cells of suggested are investigated for band filtering characteristics and finally integrated on a single unit cell for dual-band filtering applications. The I shaped and modified I shaped unit cell is producing band filtering properties at center frequencies like 4 GHz and 5.5 GHz respectively. The presented FSS design is modeled on an FR-4 substrate with dielectric constant of 4.4 and the dimension of the unit cell is 10 × 10 × 1.6 mm3. The fabricated FSS structure is simulated and measured for its characteristics verification like S11 and S21 and it has been found a satisfactory agreement in simulated and measured results.

Dual band, low profile and compact tunable frequency selective surface with wide tuning range

In this paper, a dual polarized, dual band, low profile, embedded bias network, and compact tunable varactor band pass frequency selective surface (FSS) is designed with a wide tuning range. The proposed FSS is composed of two metallic layers printed on both sides of the substrate, where the top side has two cross strips with different dimensions encircled with high pass grids, whereas the bottom side includes a proper bias network. The loaded varactors between the grids and the cross strips with a designed bias network achieve two independent tunable pass bands. Moreover, an equivalent circuit of the FSS is extracted, which show good agreement with the full wave simulation results. The proposed FSS can operate from 2.28 GHz to 4.66 GHz and from 5.44 GHz to 11.3 GHz by proper tuning of the varactors loaded in the large and small cross strips. The tunable range of the low and high pass bands are about 70% with respect to the center frequency of each pass band. The electrical dimensions of the proposed FSS are about 0.05λ × 0.05λ, where λ is the free space wavelength at a lower pass band (2.28 GHz). Moreover, the proposed FSS works properly up to 60° incident angles.

A glass based dual band frequency selective surface for protecting systems against WLAN signals

A polarization independent, double layer frequency selective surface on glass substrate is proposed that can transmit 900MHz and 1.8GHz GSM bands but inhibit transmission of wireless local area network (WLAN) bands, 2.4–2.5GHz and 4.98–5.825GHz. A parametric analysis is conducted to tailor the resonance frequencies at WLAN bands and the effect of each geometrical parameter on band stop response is investigated. Band stop responses of each FSS layer and the double layer final design are presented both numerically and experimentally. The simulation results showed a good agreement with the experimental results and supported the polarization independent behavior. In particular, very wide rejection bands are obtained (−10dB bandwidths more than 1.75GHz) for the 5GHz band, both numerically and experimentally, for vertical and horizontal polarizations, under normal incidence. The design can be used in double layer window glasses for protecting systems against interference with WLAN signals in indoor environments and buildings.

An FSS Structure Based on Parallel <italic>LC</italic> Resonators for Multiband Applications

An frequency selective surface (FSS) structure based on parallel LC resonators is proposed to achieve multiband bandpass filtering responses. The parallel LC resonator, implemented by a via-connected metallic line and a parallel-plate capacitor (PPC), serves as the basic element for intentionally constructing FSS unit cell, which exhibits a single-band bandpass filtering response. As a result, the proposed FSS structure can provide a multiband performance by introducing multiple VCMLs and PPCs with different resonance frequencies. Because of the compact resonator resulting from a PPC, the proposed FSSs feature miniaturized unit cell size inherently, for example, the single-band FSS element is as compact as 4.8% of the operating wavelength. Moreover, this kind of FSS structure is also beneficial for independent control of the frequency performance under different polarizations, efficient optimal design of desired resonance frequencies, and easy realization of multiband response with wideband ratio range (e.g., 1.13 to 3.32 for the dual-band FSS). Equivalent circuits of these FSSs are established for explaining the resonating mechanisms and precisely modeling the frequency performances. Finally, prototypes of the dual- and tri-band FSSs are fabricated and measured. The measured results exhibit stable filtering performance under different polarizations and incidence angles (up to 60°).

A Miniaturized Dual-Band FSS With Controllable Frequency Resonances

A novel dual-band miniaturized frequency-selective surface (FSS) is proposed in this letter. The proposed FSS is composed of cross dipole aperture element combined with meandered monopole aperture element. The single layer FSS provides two pass-bands centered at 5.13 and 8.85 GHz with bandwidth of 1.27 and 1.33 GHz, respectively. The two pass-band frequencies of the designed FSS can be controlled independently by simply changing structure parameters of the unit cell. In addition, the dual-band FSS designed using the miniaturized element exhibits excellent resonance stability for different polarizations and incident angles. A prototype of the proposed FSS is fabricated and measured. A good agreement between the simulation and the measured results is obtained, which demonstrates the stable performance of the FSS.

건물 내 WLAN 대역 전파환경 개선을 위한 이중 대역 주파수 선택 구조의 설계

건물 내 WLAN 대역 전파환경 개선을 위한 이중 대역 주파수 선택 구조의 설계

Design and analysis of infrared frequency selective surface with dual-stopband

A dual-band frequency selective surface (FSS) with double screen was designed to cover the mid-infrared atmospheric window (3 μm~5 μm) and the far-infrared atmospheric window (8 μm~14 μm). This structure is com-posed of hexagonal metallic mesh and hexagonal resonant ring array. Simulation results show that the average transmission of FSS in atmospheric window is lower than 5%, and this structure is insensitive to the incident angle. The effect of the parameters on transmission properties was analyzed. The results show that adjusting the size of hexagonal ring structure can effectively adjust the -10 dB stopband bandwidth in 3 μm~5 μm, and increasing the size of metallic mesh can move the stopband in 8 μm~14 μm to long wave direction.

An angular-stable miniaturized frequency selective surface with controllable frequency band ratio using lumped elements

A novel dual-band miniaturized-element frequency selective surface (MEFSS) using lumped elements is proposed to achieve angular-stable response and controllable frequency band ratio. The MEFSS consists of two metal layers of the same period for the unit cell. The operating principle and the synthesis procedure of the MEFSS are analyzed based on the equivalent circuit model. The prototype of the MEFSS is simulated, fabricated, and tested, and the simulation results have a good agreement with the measurement results. To further reduce the element size and achieve a controllable band ratio, inductors and capacitors are, respectively, loaded on the top layer and the bottom layer of interlayer substrate to decrease the resonant frequency. Choosing the values of loaded lumped components properly, the resonance frequencies and the band ratio can be controlled. The unit size of this modified MEFSS is consumedly miniaturized to , where represents the resonance wavelength in free space. Compared to the previous works, the proposed MEFSS has a better miniaturization performance. The results show that the modified dual-band MEFSS has a large band ratio and high stability in the scope of incidence angles of 80° for TE and TM polarization.

GSM filtering of horn antennas using modified double square frequency selective surface

In this work, a dual-band frequency selective surface (FSS) is proposed to be placed perpendicularly into the apertures of horn antennas for prefiltering 900 and 1800 MHz GSM signals interfering during the signal reception, with the enhanced return loss, gain, and directivity at the desired frequencies. For this purpose, the microstrip double square loop MDSL is modified in the first stage. As for the second stage, an FSS array (2 × 2) is built up arranging the unit MDSLs in a periodic structure and finally these FSS unit arrays are fixed perpendicularly covering the aperture of a ridged horn antenna which is a part of the available radar system operating between 0.5 and 3 GHz in our laboratory, to construct an integrated module having both bandstop prefilter and horn antenna called “filtenna.” The simulated and experimental results are agreed that the proposed FSS structure attenuates GSM signals at the 900 and 1800 MHz through the high reflection and very poor transmission mechanisms meanwhile enhances return loss characteristics, radiation pattern, and gain of the horn antenna in the desired band. Thus, it can be concluded that these simple microstrip FSS structure can be effectively adapted to the horn antennas which need the GSM prefiltering.

A Novel Simple Convoluted Geometry to Design Frequency Selective Surfaces for Applications at ISM and UNII Bands

In this paper, we use a novel convoluted geometry to design a dual-band Frequency Selective Surface (FSS) with angular stability and independent polarization operation. The geometry allows the design of a dual-band FSS to block ISM and UNII radio bands. We performed a parametric study with the commercial software ANSYS HFSS. A prototype of the designed FSS was built and its transmission characteristics were measured and compared with simulated results. We observed good agreement between numerical and experimental results. The FSS realized a dual-band response at the required bands and it had angular stability and polarization independence.

An Angularly Stable Dual-Band FSS With Closely Spaced Resonances Using Miniaturized Unit Cell

A novel miniaturized-element dual-band frequency selective surface (FSS) with closely spaced resonance is presented in this letter. The proposed FSS comprises of meander lines printed on a single-layer dielectric substrate to provide dual stopband characteristic. Compared to previously published spatial filters, the proposed FSS has better miniaturization characteristic having the unit-cell size of $0.065\lambda _{0} \times 0.065\lambda _{0}$ , where $\lambda _{0}$ corresponds to free space wavelength of the lower resonance frequency. In addition, the operating bands are closely located exhibiting the frequency ratio as low as 1.29. The surface current distribution and the equivalent circuit model are illustrated to explain the resonance behavior of the designed FSS. Furthermore, the proposed structure is polarization-independent and angularly stable for both TE and TM polarizations. A prototype of the dual-band FSS is fabricated and measured, which validates the simulated responses under normal and oblique incidence.

A Novel Dual-Band Ultrathin FSS With Closely Settled Frequency Response

This study presents a novel ultrathin dual-band frequency selective surface (FSS) for X-band applications. The proposed single-layer FSS operates as a band reject filter at 8.47 and 10.45 GHz. The ratio of these two operating bands has small value such as 1.23, and it points out that the proposed FSS has closely spaced characteristic. In addition, the designed dual-band single-layer FSS has an ultrathin thickness of 0.021* ${{\boldsymbol{\lambda }}_{\boldsymbol{l}}}$ , where ${{\boldsymbol{\lambda }}_{\boldsymbol{l}}}$ is the wavelength of the lower operational frequency. The stable frequency responses are sufficiently achieved for the transverse electric and transverse magnetic polarizations by using the proposed FSS. The validity of FSS is obtained by comparing measurements and simulations.

Design of a Dual-Band Dual-Polarization Transparent Frequency Selective Surface

A dual-band frequency selective surface (FSS) with different polarizations is proposed in this letter. The unit cell of the FSS is composed of three metallic layers and two intermediate dielectric layers. Each metallic layer has a square loop and a circular patch with a twisted slot. When the incident wave illuminates the surface, the polarizations of the transmission waves in the two bands are different, i.e., one is copolarization and the other is cross polarization. The performance of the surface has been validated by both the simulated and measured results that are in good agreement.

Novel Dual-Band Miniaturized Frequency Selective Surface based on Fractal Structures

Abstract A novel single-layer dual-band miniaturized frequency selective surface (FSS) based on fractal structures is proposed and analyzed in this paper. A prototype with enough dimensions is fabricated and measured in anechoic chamber, and the measured results provide good agreement with the simulated. The simulations and measurements indicate that the dual-band FSS with bandstop selectivity center at 3.95 GHz and 7.10 GHz, and the whole dimension of the proposed FSS cell is only 7×7 mm2, amount to 0.092λ0×0.092λ0, that λ0 is free space wavelength at first resonant frequency. In addition, the center frequencies have scarcely any changes for different polarizations and incidences. What’s more, dual-band mechanism is analyzed clearly and it provides a new way to design novel miniaturized FSS structures.

Polarization and angle insensitive dual-band bandpass frequency selective surface using all-dielectric metamaterials

In this paper, we demonstrate a dual-band bandpass all-dielectric frequency selective surface (FSS), the building elements of which are high-permittivity ceramic particles rather than metallic patterns. With proper structural design and parameter adjustment, the resonant frequency can be tuned at will. Dual-band bandpass response can be realized due to the coupling between electric and magnetic resonances. As an example, a dual-band bandpass FSS is designed in Ku band, which is composed of two-dimensional periodic arrays of complementary quatrefoil structures (CQS) cut from dielectric plates. Moreover, cylindrical dielectric resonators are introduced and placed in the center of each CQS to broaden the bandwidth and to sharpen the cut-off frequency. Theoretical analysis shows that the bandpass response arises from impedance matching caused by electric and magnetic resonances. In addition, effective electromagnetic parameters and dynamic field distributions are presented to explain the mechanism of impedance matching. The proposed FSS has the merits of polarization independence, stable transmission, and sharp roll-off frequency. The method can also be used to design all-dielectric FSSs with continuum structures at other frequencies.

A Low-Profile Paper Substrate-Based Dual-Band FSS for GSM Shielding

A low profile dual-band frequency selective surface (FSS) for shielding the GSM applications is presented in this paper. The proposed FSS contains the unit cell made of modified double square loop elements with paper as its substrate. The overall thickness of the proposed FSS measures only 0.55 mm. The FSS offers band stop response at 930 and 1720 MHz with 18 dB shielding effectiveness for a bandwidth of 100 and 173 MHz, respectively, thus shielding the GSM signals. Additionally, the modified double square loop element-based FSS is symmetrical providing the advantage of polarization independency. It also exhibits angular stability up to 60° for both the horizontal polarized electric field (TE mode) and vertically polarized electric field (TM mode). A prototype of the proposed dual-band low profile FSS is fabricated. The simulation results are compared with the experimental results and are found to be in congruence with each other.

New approach to design dual-band frequency selective surface based on frequency response tunning of each individual layer

In this article, a new approach (not new technique) was introduced for designing frequency selective surfaces (FSSs). They tried to compose the desired frequency response using the frequency response of each constituent FSS. Also, a new dual-band miniaturized frequency selective surface was proposed. In contrast to the conventional FSS design technique, the presented structure took advantage of non-resonance elements and had unit cells with a miniaturized dimension. The proposed FSS cells were composed of two complex and inductive planes that acted as a dual-band filter through the pass of electromagnetic wave propagation. The performance of this structure toward various angles of incident waves and different polarizations was stable; hence, the practical application of this structure would be guaranteed. One prototype of the proposed FSS with FR-4 substrate was built and tested, the results of which could prove the idea proposed in this article. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1423–1429, 2016