A Study of Ultra-Thin Single Layer Frequency Selective Surface Microwave Absorbers With Three Different Bandwidths Using Double Resonance

In this paper, a high gain ultra wideband (UWB) antenna by employing a single layer frequency selective surface (FSS) as a reflector is presented. The impedance bandwidth of the proposed antenna is 155% (1.9 to 15.2 GHz) with peak gain 5.9 dBi. Further the gain of the proposed UWB antenna has been improved by placing a frequency selective surface (FSS) array reflector underneath the UWB antenna. The unit element of FSS is a circular loop structure and further modified in to 5X5 element array. The UWB antenna with FSS reflector showed the enhancement in gain from 5.9 dBi average peak gain to 9.2 dBi and it's almost stable in the higher band. The comparative analysis of gain and radiation patterns of antenna with and without FSS has been discussed to observe the effect of FSS on the antenna performance. The full wave EM simulation has been carried out by using CST MWS.

This study proposed the use of coplanar waveguide Ultrawide-band strawberry artistic shaped printed monopole (SAPM) antenna with a single-layer frequency selective surface (FSS) as the metallic plate to improve the gain of antenna application. The intersection of six cylinders is used to structure the strawberry artistic shaped radiating element, which leads to enhancing the antenna bandwidth. The proposed FSS reflectors used a $10\times10$ array with the unit cell of 6mm $\times6$ mm in introducing a center-operating frequency. This study used the FR4 substrate with coplanar waveguide (CPW) fed to print the proposed antenna, which provided a wide impedance bandwidth of 8.85 GHz (3.05–11.9GHz) that covers the licensed Ultrawide-band. The proposed FSS transmitted a stop-band transmission coefficient, which is below −10 dB with the linear reflection phase over the bandwidth in the range from 3.05 GHz to 11.9 GHz. The UWB SAPM antenna with FSS reflector showed an improvement from 1.65 dB to 7.87 dB in the lower band and 6.3 dB to 9.68 dB in the upper band with an enhancement of 6.22 dB. The gain value is enhanced by the gaping between the antenna and FSS, which has an approximately constant gain response through the band, the gain is sustained among 7.87 dB to 9.68 dB. The total dimension of the antenna is 61mm $\times 61$ mm $\times 1.6$ mm. The proposed antenna structure provides the directional and balanced far-field pattern, which is suitable for Ultrawide-band (UWB) applications and ground-penetrating radar (GPR) applications.

This work presents an electromagnetic optimization technique that blending full-wave method, artificial neural network, and population-based search algorithms for optimal design of frequency selective surfaces (FSSs) with fractal motifs. We consider a simple application of this technique in a single-layer FSS with Sierpinski island fractal patch elements. The optimization technique replaces the computational intensive full-wave method of moments simulations by a fast and accurate multilayer perceptrons neural network model of FSS spatial filter, which is used to compute the cost (or fitness) function in the search algorithms iterations. In the FSS optimization with specific resonant frequency and bandwidth, we use: bees algorithm, continuous genetic algorithm, and particle swarm optimization. A FSS prototype is built and measured for a first level of Sierpinski island fractal. The accuracy of the proposed optimization technique is verified through the excellent agreement (0.9%) obtained by means of comparisons between theoretical and experimental results. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:827–831, 2014

In this article, a 3-D frequency-selective surface (FSS) with high selectivity and large angular stability of 70° is proposed. The equivalent circuit model of the single-layer FSS is first presented and analyzed, offering physical support to the operating principle using the odd- and even-mode analysis method. By cascading two single-layer FSSs, the resulting 3-D double-layer FSS operates as a fifth-order bandpass filter. The filling design of dielectric block, metal block (MB), and waveguide wall makes the 3-D FSS produce different magnetic coupling effects in parallel and perpendicular to the electromagnetic wave propagation direction to obtain an electromagnetic filtering response with broadband and good roll-off characteristics. By introducing the outer dielectric bonding to the 3-D FSS, the angular stability is greatly improved from an angle of 0°–70°. Finally, the veracity of the design is verified by physical processing and testing.

Single-layer dual-band frequency selective surface for coverage-enhancing applications in millimeter-wave 5G

A method for designing miniaturized frequency selective surface (FSS) using equivalent circuit model (ECM) and multi-objective particle swarm optimization (MOPSO) algorithm is proposed in this paper. In the proposed method, ECM describing the desired frequency response is established, and parameters of the ECM are determined using the MOPSO algorithm. Combining the ECM analysis and the MOPSO algorithm, the requirements of desired frequency response can be converted into the constraints of equivalent circuit parameters, which simplifies the optimization process of FSS design. For verification, a single-layer bandstop-bandpass FSS composed of convoluted elements with the unit cell size of 0.073λ 0 × 0.073λ 0 is designed. Simulation results show that the −15 dB bandwidth is from 2.62 to 2.83 GHz, and the −0.5 dB bandwidth is from 3.84 to 5 GHz. Meanwhile, the resonant frequency is stable at different incident angles (up to 80°) under TE and TM polarization. Finally, the proposed FSS prototype is fabricated and measured. The measured results agree well with the simulated ones.

An electronically switchable, single layer frequency selective surface designed for 60GHz millimeter-wave applications is presented. The design is based on modified elliptical patch geometry with a single GaAs PIN diode that switches between transparent and opaque modes of operation. The FSS surface does have single polarized operation with broad transmission band from 53GHz to 67GHz. The theoretical studies indicate that a transmission loss up to 57dB at 60GHz when the PIN diode is OFF. The proposed structure can be utilized for beam-steering applications by employing as a spatial filter around an omnidirectional antenna operating at millimeter-wave band.

A polarization-selective and reconfigurable Fresnel zone plate consisting of frequency selective surfaces (FSS) loaded with varactor diodes is devised for compact vehicular wireless communication devices. The unit cell constituting the impedance zone exhibits rapid impedance transitions from 0 ohm (electrically-opaque) to 377 ohm (electrically-transparent). An I-shape configuration is employed for the resonant unit cell structure, featuring high compatibility with DC bias voltage network. In addition, double-sided FSS is employed on the top and bottom faces for polarization-selective beamforming. The FSS comprise of a dielectric with near zero thickness ( λ /250 of 2.40 GHz) resulting in intentionally high mutual coupling between the layers. The devised unit cell is designed using an equivalent circuit model analysis and optimized using finite element solver, achieving over 30 dB impedance switching. The proposed unit cell is experimentally confirmed in both vertical and horizontal polarizations. By configuring the DC voltage bias lines, the unit cells of the FSS are transformed into electrically-driven impedance zones formulating alternating and repetitive gratings. The width and the interval of the grating manipulate the constructive and destructive interference resulting in beam scanning range of 30° in both vertical and horizontal polarizations. The proposed approach can provide concise and compact beamforming solutions for future vehicular communications.

Presented here a Frequency Selective Surface FSS that attenuates the cellular phone signals of 0.8, 0.9, 1.8 and 1.9 GHz bands, but transmits the Wi-Fi 2.45 GHz signals. It consists of two co-centric rings printed over a float-glass and can be used to isolate the intensive care rooms of hospitals from mobile phone calls, yet it supports Wi-Fi feature, enabling doctors to share the confidential medical reports to communicate with outside world.

This paper has developed a multiband single-layer frequency selective surface (FSS) designed by using the optimization technique (micro-genetic algorithm). The characteristics of the designed FSS are superior to those of the Fractal FSS in the close dual-band separation and to those of the convoluted double square loop FSS in the bandwidth. We design the FSS for transmitting L and S bands and reflecting Ku and Ka bands. The agreement between the calculated and measured transmission responses for the designed FSS proves the validity of the present method.

Within the class of electromagnetic bandgap structures, periodic surfaces printed in stratified dielectric media occupy an important role. Solutions have been devised for antenna applications, often oriented to realization of compact antennas, or to suppression of surface- and space-wave propagation for reducing diffraction lobes. From the literature, a different application also emerges which uses the same printed periodic surface technology for gain enhancement (H.D. Yang and D.R. Jackson, IEEE Trans. Ant. Propag., vol. 48, no. 4, pp. 556-564, 2000; T. Zhao et al, AP-S Symp. Digests, vol. 3, pp. 248-252, 2001). The basic mechanism to use for the gain enhancement is the excitation of weakly attenuated leaky waves, the same type as that described in the past for unbounded layered media with high dielectric contrast (D.R. Jackson et al., IEEE Trans. Ant. Propag., vol. AP-41, pp. 344-348, 1993). The excitation and leaky-wave propagation can be obtained by printing over a grounded slab a frequency selective surface (FSS). Within the bandwidth where the FSS resonates, the structure behaves as a weakly transparent parallel-plate waveguide. A point-source (dipole or slot) can thus excite a cylindrical leaky wave, thus implying a large phased aperture-field distribution on the FSS. The radiation of this large aperture produces a directive conical beam. For an appropriate design of the slab thickness, the leaky-wave phase velocity approaches infinity and the conical radiation collapses into a broadside beam. In this paper, a systematic procedure for the antenna analysis is presented, which uses a synthesis of the FSS via equivalent network, based on the data obtained by full-wave analysis.

This paper describes an antenna design for wideband high directivity operation using an aperture coupled patch antenna as the feeding source and an FSS (frequency selective surface) based structure as the superstrate for high directivity. The new antenna device combines the wideband characteristic of the aperture coupled antenna and the desirable characteristics of the FSS structure as a superstrate for high performance operation. A coplanar waveguide (CPW) feed design is used to obtain wideband performance for the feeding antenna. Both single layer and double layer based FSS designs are studied for improvement of directivity. The performance is further enhanced by using an air gap between the patch on a thin film substrate and the CPW and aperture structures on an FR4 substrate and also between the layers of a double layer FSS design. The air gaps can be produced using micromachined PMMA rims for low cost construction. An impedance bandwidth in excess of 50% has been obtained for a centre frequency of 10 GHz. The antenna device exhibits a directivity of about 13.6 dBi. A 1-dBi ripple radiation bandwidth as high as ∼42% has been achieved.

A method is presented, for the efficient derivation of the dispersion equation associated with electromagnetic bandgap (EBG) structures composed by lossless frequency selective surfaces (FSS) printed on stratified dielectric media. The method, valid for the range of frequency where a single propagating Floquet mode occurs, is based on Foster's reactance theorem applied to an equivalent transmission line network. This theorem implies that the admittance functions of frequency which represent the FSS satisfy the pole-zero analytical properties of the driving point LC admittance functions. By these basic properties and by the full-wave identification of the FSS resonances, an analytical form of the dispersion equation is obtained. This equation is next solved for both surface wave and leaky wave modes by a conventional numerical technique. The results are successfully compared with those from a full-wave analysis.

This paper proposes a reconfigurable frequency selective surface (FSS) operating in the X band composed of triangular elements periodically placed on a single FR-4 dielectric layer. The reconfiguration of the proposed FSS allows a quasi-linear variation of the rejecting resonant frequency as function of the incident wave angle. The variation of the incident wave angle is provided by rotation of the FSS structure from 0° to 40°, for the TE mode, and can be used in cognitive radio technology through a micro-controlled interface.

This work reveals the Design and development of Dual wide band frequency selective surfaces (FSS). Dual-band FSS based on single and multi layers with or without or extra discrete components has been discussed and analyzed. Dual wide band-pass FSSs has been designed and developed by using two metallic layers for the wide targeted pass band frequency bands range of 3.53-5.3 GHz and 3.53-4.21 GHz. In the initial step of Development ultra thin double layer slotted FSS has been used. These generate resonance at 4.0 GHz and 4.8 GHz. Furthermore Hilbert shaped slotted resonator increase pass band width enhancement. Lastly the opposite alignment of similar FSS metallic plate to form the proposed dual layer FSS which exhibit the bandwidth enhancement of the frequency bands.