Search

The study of Frequency Selective Surface (FSS) by Direct ink writing (DIW) has attracted much attention due to the convenience and effectiveness of 3D printing technology. However, the limited printing precision of DIW has heavily restricted its applications as the electromagnetic performance is highly sensitive to it, especially the precision at the microscale. Herein, the ultra-high printing precision of FSS was achieved through DIW by the uniformly dispersed graphene sheets to deeply modify the rheological behavior and the steric hindrance effect. Thus, the highly precision of the printed filament width as thin as 67 μm with a space of only 42 μm were achieved, which is difficult for conventional DIW, and no structural distortion is found after 3D printing, no matter it was 2D printed on a flat surface or the sharply skewed hook face, or even 3D printed to architectural structures. According to the highly improved precision, the electromagnetic performance matching between the designed model and the printed physical FSS device was perfectly achieved, reducing the center frequency error less than 0.3 GHz, and the transmission coefficient error less than 0.046. Our work promises an effective and easy preparation of high-quality FSS from the aid of graphene.

A thin and broadband frequency selective surface (FSS)-based magnetic absorber is presented for low-microwave frequency applications. The design consists of a double-layers of FSS with the combination of two different magnetic substrates, which provides a much broader bandwidth compared to existing single-layered designs. The magnetic materials are in-house made by mixing different ratios of carbonyl-iron powder with silicone elastomer polydimethylsiloxane (PDMS). The simple single-square loop (SSL) structure is used for both FSSs which are printed on a standard FR4 material using lossy resistive sheet. This configuration allows the use of a closed-form equivalent-circuit model for a fast and efficient bandwidth optimization. A genetic algorithm (GA) is utilized to obtain the design parameters for broadband absorption with minimum overall thickness. The measured results confirm that the proposed absorber operates from 0.78 to 4.8 GHz with -10 dB reflectivity. The design achieves 144% fractional-bandwidth with a 10.12 bandwidth-to-thickness ratio.

In this paper, a flexible multifunctional active frequency selective surface (AFSS) with miniaturized units is proposed, and it is simulated, fabricated, and measured. In our design scheme, the flexible AFSS structure adopts PIN diode for function control, realizing the arbitrary selection of electromagnetic wave transmission and reflection functions and polarization selection function in the range of 8-12 GHz. The flexible multifunctional AFSS structure consists of two FSS layers with PIN diodes on the top and bottom, a thin, flexible dielectric layer in the middle, and vias for connecting the FSS layers. The structure we design does not need additional bias feeders, which can reduce the interference to the transmission performance of AFSS. Finally, it is found that the experimental results of the AFSS structure are in good agreement with the simulation results.

A transparent frequency selective surface (FSS) on glass window is proposed for signal selectivity of 5G millimeter-wave communication, based on a transparent and low loss material cyclic olefin copolymer (COC). An FSS based on dual-loop units is designed on both sides of COC, which helps to realize band-pass filtering effect under both normal and oblique-incident conditions in the desired frequency range from 27.5 GHz to 29.5 GHz. The metal-meshed technology is employed to enhance the light transmission of the circuits, and the measured performances with traditional glass show that our proposed concepts can be a potential solution for signal filtering at millimeter-wave on glass windows.

Usually, Radar signature of an object is reduced using microwave absorber surface. Recently, another approach based on time‐modulated frequency‐selective surfaces has been developed to deceive Radar detection by selectively generating harmonics/sidebands. Here, a polarization‐insensitive time‐modulated frequency‐selective surface is proposed that works over a broad frequency range. The design employs a PIN diode‐based switchable frequency‐selective surface to switch between the two states of reflection coefficient. Monochromatic incident electromagnetic (EM) wave, upon reflection from the surface is modulated by a periodic time‐varying reflection coefficient to generate several harmonics/sidebands along with the incident frequency. In the frequency spectrum of the reflected EM wave, the power of the incident frequency component is suppressed below that of the sidebands. The time‐modulated frequency selective surface has the capability to suppress the incident frequency component for any incident EM wave in 2–4 GHz that is S band, as well as generate spurious reflection sidebands.

In this paper a novel FSS array is proposed, that provides dynamic band-gap in C-band. Inside the band-gap, the FSS acts as a bandstop filter. Outside the band-gap the amplitude of the reflected wave from the FSS array decreases. Therefore, the outside band is very useful in radar cross section (RCS) reduction. In this paper, at first a new FSS unit cell is designed, then in order to achieve the maximum bandwidth (1.2 GHz), dimensions of the cell are optimized. In the next step, the FSS cell is equipped with PIN diodes. Turning the diodes ON or OFF, shifts the resonant frequency of the band-gap electronically. When diodes are OFF, the resonant frequency and −10 dB bandwidth of the FSS are 5.23 and 0.9 GHz respectively. When the diodes turn ON, the resonant frequency shifts to 4.75 GHz over a bandwidth of about 1 GHz. While the band-gap is shifted dynamically, the bandwidth is kept wide, which is the novelty of this paper. In order to validate the design process, an array of active cells consisting of 128 pin diodes was designed, fabricated and then tested. Finally, the simulation and measurement results are compared with each other and a good agreement is observed between them.

A dual-band frequency selective surface (FSS) employing Ti3C2Tx deposited on a polyethylene terephthalate (PET) layer is proposed for Wi-Fi applications. The structure can afford dual-frequency pas...

The work presented in this paper concerns a method for the miniaturized frequency selective surface (FSS) based on the meander lines. A miniaturized dual-bandstop FSS structure based on meander lines with spiral-shape is proposed and simulated. The equivalent circuit and current distributions are introduced to explain the FSS performance. The size of the unit cell is 10 mm, which is about 0.037 wavelength at the first resonant frequency. Simulation results indicate that the proposed FSS has a frequency shift smaller than 1% for different polarizations with an oblique incident angle of 60°. A prototype of the FSS is fabricated and measured. The measurement results show that the FSS is polarization-insensitive and angle-insensitive.

In the communication, a monopolarized and a dual-polarized polarization-rotating frequency-selective surfaces (PR-FSSs) are designed successively. The two PR-FSSs are both a three-layer aperture-coupled-patch periodic structure. When they are interpreted as an array of antenna-filter-antenna (AFA) modules, because polarization directions of the upper and lower antennas in each AFA module are orthogonal to each other, they can both realize polarization rotation and frequency selection at the same time. The monopolarized PR-FSS is designed first, its relative bandwidth reaches up to 13.58% although there is a maximum insertion loss of 0.8 dB in the band. The final-designed dual-polarized PR-FSS can be regarded as the combination of two orthogonal monopolarized one, so it can work under both $x$ - and $y$ -polarized incidences, its relative bandwidth is still up to 9.81%; moreover, the maximum insertion loss in the passband is very low. The performances of the two PR-FSSs are both verified by simulations and experiments.

In this paper, a miniaturized bandstop frequency selective surface (FSS) with high angular stability is presented. Each FSS element consists of four sets each consisting eight octagonal concentric interconnected loops. The four sets are connected with each other through outermost octagonal loop. The unit size is miniaturized to 0.066 λ0 at the resonant frequency of 1.79 GHz. The proposed configuration achieves excellent angular stability (only 0.025 GHz resonant frequency deviation is observed upto 83° oblique angles). The working mechanism of FSS is explained with the help of equivalent circuit model (ECM), electric field distribution, and corresponding surface current distribution. A prototype of the designed bandstop FSS is fabricated to verify the simulated frequency response. The experimental results are consistent with the simulation results. Simple geometry, low profile, high angular stability, and compact cell size are prominent features of the proposed structure.

In this paper, the Minkowski fractal is used to design the geometry of a frequency selective surface (FSS) unit cell, which resembles the shapes found in nature. The proposed FSS unit cell has both angular and polarization stabilities of incident wave. For the miniaturization of FSS and decrease of resonance frequency, interdigital capacitances (IDCs) are devised in the FSS structure, which do not eliminate angular and polarization stabilities. The dimensions of the unit cell are 5 mm × 5 mm and miniaturized 0.095λ0×0.095λ0. The resonance frequency is specified as 5.75 GHz with 155 MHz bandwidth. An equivalent circuit is derived for the unit cell to evaluate its frequency responses. The effects of variations of the geometrical dimensions of the FSS unit cell on its performance are studied. A prototype model of proposed FSS is fabricated and measured. The performance of its full‐wave computer simulation results and measured data are compared and are shown to be in good agreement.

Aiming at the problems of low-frequency coverage, angle and polarization instability of ultra-wideband (UWB) frequency selective surface (FSS) in practical application, this paper introduces the ad...

In this paper, pixelated Frequency Selective Surface (FSS) layer embedded in two carbonyl iron-filled silicon rubber (CISR) sheets are used for design of broadband microwave absorber in frequency r...

This work focuses on designing a low-profile frequency selective surface transmitarray antenna at 12 GHz using a four-layer Split Ring Resonator structure. The parametric analysis shows a high tran...

This paper presents a compact ultra-wideband frequency selective surface (FSS) with band stop response. The proposed single layer FSS is printed on FR-4 substrate with a unit cell periodicity of 0.138λ_0 × 0.138λ_0, corresponding to its lowest operating frequency. The developed FSS exhibits stable response for plane waves with normal and oblique incidence with TE and TM polarization for angles varying from 0° to 60°. The FSS offers -10dB bandwidth of 141 % covering the entire ultra-wideband frequency range from 2.39 GHz to 13.67 GHz. The structural parameters are optimized, and an equivalent circuit is modelled to analyze the performance of FSS. The simulated results are validated by the measured values.

In this paper, a metamaterial-based novel antenna-mutual-coupling reduction structure is proposed and demonstrated. The structure consists of a three-layer metamaterial frequency selective surface (MFSS) superstrate with split-ring resonators and metal grids. The MFSS means metamaterial frequency selective surface that has the metamaterial performance along the substrate and the frequency selective characteristic on the normal direction of the antenna array simultaneously. A 1×2 MIMO antenna that has a short edge-to-edge distance (0.037λ0) is designed as an illustration to demonstrate the validity of the meta-surface for mutual. When loaded with the proposed MFSS, the mutual coupling between the antenna elements is significantly reduced and the gain of the antenna array is improved by 2.5 dBi.

In this paper, a low-profile quad-band frequency selective surface (FSS), designed as a sub-reflector for satellite communication is presented. This single layered FSS employs non-concentric open l...

In this letter, a dual-polarized 3-D frequency selective surface (3-D FSS) based on square metallic waveguides (SMWs) is proposed, which produces a flat passband with two transmission zeros in a relatively wide rejection. Because all resonances occur along propagation direction without complex resonators, a small unit cell size and simple geometry is achieved, resulting in good angular stability and easy implementation. By an equivalent circuit model, its operating principle is explained. At last, the measured results of an implemented FSS show that a stable response under the incident angles up to 60° for dual polarizations is realized.

In this study, a pattern for an active frequency selective surface (AFSS) applicable to stealth radomes was designed and manufactured. Subsequently, its effectiveness was verified via measurements of its electromagnetic performance, and its mechanical performance was numerically evaluated in an actual flight environment. An AFSS equipped with a PIN diode was designed to have a transmission frequency in the X-band using only one side of a surface. To evaluate the mechanical performance when the designed AFSS was applied to a stealth radome, flow analysis was performed on the basis of the shape of the F-35 combat aircraft. Moreover, structural analysis of the stealth radome was performed using the pressure distribution at the maximum velocity of the F-35, as determined via the flow analysis. On the basis of the structural analysis results, the mechanical performance of the designed stealth radome was evaluated via analysis of the stress distribution of the AFSS diode. Through this study, an AFSS pattern applicable to stealth radomes was proposed, and its mechanical/electromagnetic performance was evaluated to verify the feasibility of stealth radomes incorporated with AFSSs.

Single‐layer ultrathin absorber patch elements are analysed under normal and oblique incidence. A compensation technique for impedance variation with an angle of incidence (θ) is proposed. An equivalent‐circuit model is formulated that provides a realisation for the absorption response (in terms of resonance frequency and absorption ratio) of non‐complicated rectangular patch absorbers using simple equations. The design methodology proposed is based on using multiple subcells of simple patches to add another degree of freedom for the design equations and keep the ultrathin planar feature. Previously reported techniques realising a wide angle of incidence are applied for fair comparison with the proposed methodology. The developed structure features angular stability, polarisation insensitivity, and a planar non‐complicated configuration compared with that of structures reported in literature. Moreover, a prototype is fabricated and measured to validate the proposed approach.

A single-layer miniaturized tri-band frequency selective surface (FSS) for bandstop filtering applications has been proposed in this work. The metallic layer with four-branched meandered pattern connected in the center is engraved on a dielectric FR-4 substrate. The three stopbands operating at 2.6, 5.6, and 7.1 GHz provides −10 dB bandwidth of 437, 447, and 552 MHz respectively. The size of the unit cell is 0.067 λ∘ × 0.067 λ∘, where λ∘ is the wavelength of the first resonance frequency. As a figure of merit, the symmetric FSS structure provides the advantage of polarization independence. The proposed compact FSS structure exhibits a stable angular response up to 60° in TE and TM mode. Moreover, measurements obtained from the fabricated prototype are compared with the simulated results and are found to be in close agreement.

A dual-band high-gain linearly polarized antenna for wideband operation using a defective frequency selective surface (DFSS) is proposed and demonstrated experimentally. The designed antenna consis...

An innovative four‐bit second order multifunction active frequency selective structure controlled via four PIN diodes with nine different combinations is introduced . The proposed design is equipped with electromagnetic switching, frequency switching and polarization selection at two passbands. The coding states 0000 and 1111 offer transmission to the passbands centred at 1.96 and 4.98 GHz frequencies and shield to the bands centred at 4.98 and 1.96 GHz for transverse electric (TE)/transverse magnetic (TM) waves, respectively. The coding state 1010 offers transmission to the TE and TM waves at 1.96 GHz and 4.98 GHz, respectively and shields the TM and TE waves at 1.96 GHz and 4.98 GHz, respectively. Contrarily, the coding state 0101 offers transmission to the TE and TM waves at 4.98 GHz and 1.96 GHz, respectively and shields the TE and TM waves at 1.96 GHz and 4.98 GHz, respectively. The coding states 1000/0100 and 1101/1110 allow transmission to the TE wave at 1.96 and 4.98 GHz frequencies, respectively and shield to both the passbands at TM wave. Conversely, the coding states 0001/0100 and 1011/0111 allow transmission to the TM wave at 1.96 and 4.98 GHz frequencies, respectively and shields to both the passbands at TE wave. The coding state 1100/0011 provides shield to all the frequencies below 7.7 GHz. The designed structure is validated through the measured response of the fabricated prototype.

This article presents a dual notched Frequency Selective Surface (FSS) using a compact structure. Four sub-cell square split ring resonators (SSRRs) are imprinted over 8×8 mm2 FR-4 substrate in a 9...

In this paper, a design method for tunable liquid crystal (LC)-based metamaterial absorber (MMA) with the compact unit cell and the wideband absorption is proposed. A compact LC-based MMA unit cell...

In order to realize wide-band, high-efficiency and flexible electromagnetic wave absorption, an effective method is the combination of different electromagnetic functional materials. How to use and make the multilayer materials with individual absorption, reflection and selective transmission characteristics is very important. In this work, multilayer composite flexible absorbing fabrics made of a frequency selective surface (FSS), carbonyl iron coated fabrics (CIFs) and copper-nickel plated conductive woven fabrics (CWFs) were prepared. The layered composite materials have a thin thickness, good flexibility and adjustable absorption band, which provide a reference for the development of lightweight and efficient electromagnetic wave absorbing materials. The influence of the resonance point, wave absorbent content and conductive layer on the absorbing properties were studied. CIF-3 with a surface density of 2046.9 g/m2 has the best absorption performance with a minimum reflectivity of –20.52 dB at 12.56 GHz. A one-layer FSS can broaden the absorption bandwidth; the broadening degree varies with the resonance point of the FSS, which also makes the absorption band adjustable. The bandwidth of f12/CIF-3 with reflectivity of less than –10 dB can reach 5.68 GHz. Besides, CWF is beneficial to increase the absorption intensity, and the best reflectivity of CIF-3/CWF can reach –27.73 dB. Furthermore, three-layer composites can improve the absorption strength and bandwidth of CIF at low frequency. Compared with CIF-3, the reflectivity of f14/CIF-3/CWF decreases 8.06 dB at 11.28 GHz, and the bandwidth is 4.72 GHz, which widens by 0.32 GHz.

To establish a successful future generation cellular communication system in the Terahertz (THz) regime, there is a need to design high-directivity antennas, which will allow the signal to propagate beyond 0.1 km. Simultaneously, design wide bandwidth (BW) antennas to facilitate transmitting the information at a data rate up to 0.1 Tb/s. Two sets of microstrip array antennas have been designed, optimized, and simulated with the CST MWS simulator, in a hybrid fed with uniform amplitude distribution technique, the $$1{\text{st}}$$ one without frequency selective surface (FSS) feature and $$2{\text{nd}}$$ one with the FSS feature for further enhancing the antenna gain. To verify the simulation results of the $$1{\text{st}} - 2{\text{nd }}$$ antennas design, which simulated with the CST MWS simulator, these designs have been validated with the ANSYS HFSS simulator, and the simulation results obtained out of both simulators were close to each other. These antennas can establish a successful short-range 6G cellular communication system at the THz band.

This paper conceptualizes the development of a frequency selective surface (FSS) with 3-D unit cells. The FSS unit cells individually present a three-dimensional structure, whereas collectively the...

A rigorous full wave technique based on the Transverse Wave Concept Iterative Procedure (WCIP) is used to design a complex Frequency Selective Surface (FSS). These surfaces include a periodically arrangement of identical circuit. There are used as filters and reflector antenna as well as deep-space exploration for multi-frequencies operations. A simple FSS structure is studied in the first stage to validate our approach. In the second stage two different complex structures are studied. The good agreement between simulated and published data justifies the design procedure.

In order to solve the problem that the stability of general frequency selective surface (FSS) is bad when the electromagnetic wave is irradiated by large incident angle, a tripole type FSS structure with large angle stability is designed. The frequency response characteristics of the FSS for different incident angles are simulated. The results show that the novel structure has good stability of large angle in X band. It has good practical value in the fields of curved radome.

Beam steering is one of the prevailing functions performed by electromagnetic metasurfaces. Its efficiency depends on a large number of physical parameters associated with resonant elements comprising the metasurface and is thus notoriously difficult to optimize. Here we formulate a theoretical model for evaluating the diffraction efficiency of an array of lossy resonant elements whose spectral response is dominated by the coupling between a leaky eigenmode and a single incoming/outgoing channel. We use it to deduce a formula for the maximum attainable diffraction efficiency and the gradient parameter profile for which it is achieved. The optimization procedure is demonstrated on the example of an electrically tunable liquid-crystal terahertz beam steering metasurface. Finally, the proposed model is benchmarked against rigorous metasurface simulations. © 1995-2012 IEEE.

Frequency selective surface (FSS)-based intelligent spatial filters are capturing the eyes of the researchers by offering a dynamic behavior when exposed to the electromagnetic radiations. In this manuscript, a concept of creating complementary structures which stems from Babinet’s principle is illustrated. A hybrid complementary pair of FSS (CPFSS) comprising double square loop FSS (DSLFSS) and double square slot FSS (DSSFSS) on either side of the dielectric substrate is proposed. DSLFSS offers band-pass behavior and can be placed as a superstrate, whereas DSSFSS behaves as a band-stop intelligent spatial filter that blocks the radiations falling on it, thus making them applicable for use as a substrate. The technique utilized for analyzing DSLFSS and DSSFSS structures is based on the equivalent circuit modeling and transmission line methodology. The CPFSS structure offers the design simplicity, hence, suitable for placing them with the printed patch antenna radiators in wireless networking devices operating in sub-6 GHz 5G spectrum. DSLFSS offers band-pass behavior ranging from 2.99 to 5.56 GHz, whereas DSSFSS offers band-stop behavior ranging from 2.85 to 5.42 GHz covering all n77 (3.3–4.2 GHz), n78 (3.3–3.8 GHz), and n79 (4.4–5 GHz) bands of FR1 spectrum of sub-6 GHz 5G range. The passband and the stopband offered by the two structures of CPFSS geometry are stable to oblique angles of incidence and the proposed design also offers polarization-independent behavior. The thickness of the dielectric region existing within the pair of designed structures is critical for the location of the passbands and the stopbands. The impact of the overall thickness of the dielectric substrate on the passbands and stopbands is also reported in this article.

Dynamic control of the absorption frequency and intensity of metamaterial absorbers has attracted considerable attention, and many kinds of tunable metamaterial absorbers have been proposed. Unfortunately, due to the integration of separate resonant unit and tunable unit, these designed metamaterial absorbers suffer from complex structure and low sensitivity. We numerically and experimentally demonstrate a tunable metamaterial absorber composed of artificial dielectric atoms as both resonant and tunable unit arrayed periodically in the background matrix on the metallic plate. Polarization insensitive and wide incident angle absorption band with simulated and experimental absorptivity of 99 % and 96 % at 9.65 GHz are achieved at room temperature. The absorption frequency can be gradually modulated by temperature, however, the absorption intensity at working frequency remains near unity. The dielectric atoms based tunable metamaterial absorbers with simple structure have potential applications as temperature sensors and frequency selective thermal emitters.

Frequency selective surfaces (FSSs) achieved a great height in various applications like satellite communication, mobile phone communication, frequency filtering. In this survey paper, we described about some existing designs, substrates used for those designs, different layers involved in FSSs and their simulated results. This paper also projects the effect of Transverse Electric (TE) polarization and Transverse Magnetic (TM) polarization. Some design failed to achieve the required output for a particular application. This is due to large dimensioned structure. Different ways to overcome this problem are also discussed in this paper.

A single layer novel compact frequency selective surface which is used in reflector antenna is designed and simulated. The proposed unit cell reflects electromagnetic waves in K and Ka band with maximum reflection occurring at 22.62 GHz and 35.44 GHz respectively. The designed FSS find its application in satellite communication. A crossed dipole structure in center and two-legged structure in corners with square loop in each quadrant makes the FSS unit cell structure. The FSS is designed with oblique incidence for transverse electric and transverse magnetic polarization with return loss 0.3 dB in 22.62 GHz and less than 0.5 dB in 35.44 GHz. The proposed work shows frequency independence against oblique angle of incidence. The simulated result from CST microwave studio is compared with other similar works.