Closed-form low frequency solutions for electromagnetic waves through a frequency selective surface

It is well known that a multiband frequency selective surface (FSS) can be obtained by arranging multiple simple apertures in a periodic array. However, this simple combination can not achieve a perfect resonance response in a wide band due to the restriction of the grating lobe frequency determined by the array. A new type of element, the multi periodicity combined element (MPCE), is presented to solve this problem. Its feasibility on restraining the grating lobes is proven by numerical experiments and theoretical analysis. The electromagnetic performance of the MPCEs was studied. The results show that the MPCE FSSs have much weaker grating lobes than the traditional FSSs and their frequency performance can be well predicted through the properties of the member element FSSs. An approximate formula for predicting the transmission coefficients of the grating lobes is provided.

Frequency Selective Surface (FSS) is a specialized structure used in the field of electromagnetic waves and radio frequency (RF) engineering. It is designed to exhibit selective transmission or reflection properties based on the frequency of the incident electromagnetic waves. This article describes the design, construction, and analysis of a textile-based band-stop frequency selective surface for use in the highly EM-polluted GSM, Wi-Fi, LTE, and WiMAX bands. A full-wave EM solver called CST Microwave Studio was used to develop and simulate the unit cell of the proposed FSS at the relevant frequency. In this study, embroidered and screen-printed textile based FSSs were designed. According to the results of this study, it was demonstrated that both embroidery and screen printing FSSs exhibit resonance at a frequency of 3.5 GHz. The screen printing method yielded the best results in terms of resonance frequency sensitivity, while the embroidery method showed a resonance frequency shift. It was observed that the stitch directions and density are important parameters in the embroidery method. Gaps between the embroidery paths in the production of embroidered FSSs resulted in differences from simulations due to the disruption of the structural integrity of the unit cell. Consequently, textile-based FSSs offer advantages over traditional FSSs. This study highlights the potential of textile FSSs as an effective means of reducing electromagnetic pollution, and suggests that further improvements in the design and production processes of textile FSSs can be made.

This paper presents a multi-functional frequency selective surface (FSS)based on varactor diode and PIN diode loading. It can be realized that when the varactor diode is not loaded with voltage and the PIN is in the on state, the frequency selective surface(FSS) exhibits strong transmittance at 4 GHz, and when the PIN is in the off state, the frequency selective surface(FSS) exhibits strong reflectivity at 4 GHz. In addition, when the PIN is turned on, stable transmission of electromagnetic waves in a wide frequency range from 1.37GHZ-5.66GHZ can be achieved by changing the capacitance of the loaded varactor diode.

in this paper, a novel Frequency Selective Surface (FSS) with polarization staggered bands is proposed. The beams in orthogonal polarization of different frequency bands are divided into a group and transmitted the FSS. The rest are divided into another group and are reflected by the FSS. The FSS with polarization staggered bands is good at separation the bands with narrow transition zone, which realizes transmission and reflection of the incident waves in four different physical mechanisms. What is more, a new frequency separation scheme in quasi-optical feed system is discussed. The FSS with polarization staggered bands, which separate two bands near 90GHz and 108GHz, is fabricated and tested. The reflection coefficient of TM polarization is about 1dB, and the transmission and reflection coefficients in the other band or polarization are less than 0.6dB.

Frequency Selective Surfaces (FSSs) are engineered periodic structures that function as spatial filters, enabling the selective transmission, reflection, or rejection of electromagnetic (EM) waves. These structures are widely utilized in advanced RF and microwave systems for applications such as filtering, electromagnetic shielding, and stealth technology. In this manuscript, we propose an angularly stable and polarization-insensitive band-stop Frequency Selective Surface (FSS) optimized for applications in the lower Ka-band. The proposed FSS is constructed from a periodic two-dimensional array of compact unit cells, each with dimensions of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$5.5 ~\text{mm} \times 5.5 ~\text{mm}$</tex>. This compact configuration supports seamless integration into high-density millimeter-wave (mmWave) systems. Each unit cell incorporates a concentric dual-ring geometry embedded with orthogonally intersecting cross-slots. This unique configuration enhances the EM wave rejection capability of the surface by inducing multiple resonances. As a result, the FSS achieves a wideband stopband response ranging from 20 GHz to 28.5 GHz, corresponding to a notable fractional bandwidth (FBW) of approximately 34%. The dual-ring structure promotes resonance coupling, while the cross-slot inclusions facilitate effective suppression of incident waves, regardless of polarization orientation. The concentric design further contributes to polarization insensitivity, ensuring consistent stopband performance for both vertically and horizontally polarized waves. In addition, the symmetrical layout enhances angular stability, a critical requirement for real-world deployment. To verify the robustness of the design, full-wave electromagnetic simulations were conducted under varying angles of incidence for both Transverse Electric (TE) and Transverse Magnetic (TM) polarizations. The results reveal negligible shifts in the resonance frequency and stable stopband attenuation across angles up to 60°, confirming the angular resilience of the structure. With its compact form factor, wideband rejection characteristics, and strong angular and polarization stability, the proposed FSS is highly suitable for advanced mmWave applications, including EM interference suppression, co-site interference mitigation, and radar cross-section (RCS) reduction in defense, aerospace, and next-generation communication systems.

In order to make the dual-band frequency-selective surface (FSS) used in the engineering conditions of thick substrate, wide band spacing and large incident angle, an FSS structure with dual-band at Ku-band and Ka-band is presented. The stable filtering condition of the FSS is analyzed by using the grating lobe diagram, and the transmission of the FSS with combination or fractal elements is calculated using the vector modal matching method. The design method of the dual-band FSS with thick substrate is obtained by analyzing the resonance mode of the element and the transmission of the FSS. By using those methods, an FSS with combination elements of the square and Y loops is designed. The simulated and tested results show that the dual-bands of the structure at Ku-band and Ka-band are stable and the transmissions of the two pass-bands are larger than 75% when the incident angle is varied from normal to 45. This paper provides some theoretical and experimental references for the design of the dual-band FSS with thick substrate, wide band spacing and large incident angle.

Frequency selective surface (FSS) is a spatial filter that has frequency selection characteristics for electromagnetic waves with different operating frequencies, polarization states and incident angles. At the same time, frequency selective surface has the advantages of simple structure and easy processing compared with the traditional filters. FSS have been investigated for many decades and extensively utilized in various applications. It can used in radar radomes to reduce the radar cross section (RCS) of an array antenna, as a reflector to transmit and reflect electromagnetic waves in different frequency bands. Normally, electromagnetic waves are incident at an oblique Angle onto the target surface. Therefore, the research of FSS absorbers with stable absorbing performance under oblique incidence has tremendous practical application value. This paper proposes a new design scheme for designing a FSS absorber with stable oblique incident response range from 0° to 70°. A single-square-loop array with lumped resistors and square patch printed on the dielectric substrate is proposed, and it exhibits a characteristic impedance matching for wide incident angles from 0° to 70°. The design scheme of the FSS layer under the condition of oblique incidence is introduced in detail, and the equivalent circuit is adopted to make the design clearer and more direct. The results show the absorption bands with oblique incident angles from 0° to 30°, 30° to 50°, and 50° to 70° reflection coefficients below –10 dB are 3.44 to 9.03 GHz, 4.49 to 9.06 GHz, and 4.87 to 8.96 GHz for TE polarization, respectively. The absorber proposed in this paper will contribute much to the development of ultra-wide-angle oblique incidence.

This paper deals with a novel Frequency Selective Surface (FSS) Electromagnetic shield that operates in the low 5G vertical applications. This FSS is designed for the purpose of serving as an electromagnetic shield to eliminate EMI. The FSS designed operates at a frequency of 5GHz with a bandwidth of 1.45GHz providing a shielding of more than 40dB. The proposed FSS uses a polyester sheet as substrate and uses silver for the metallization of the FSS. Since the proposed FSS is symmetric, it behaves similarly when a Transverse Electric (TE) or a Transverse Magnetic (TM) wave is incident. The structure was designed and simulated using CST software. The results show that this FSS blocks electromagnetic radiation at lower frequencies as intended.

This thesis presents the development and the additive manufacturing of smart antennas and frequency selective surfaces (FSS) for microwave, millimetre wave, and low-Terahertz applications. Numerous fabrications techniques such as etching, low-cost inkjet-printing, Fused Filament Fabrication (FFF) and Aerosol Jet Printing are employed to fabricate the antennas and FSS. Firstly, frequency reconfigurable antennas with close-coupled biasing technique are developed using double-sided etching on a thin mylar substrate for smart current and voltage sensing applications. The frequency tunable antenna also acts as a novel current sensing antenna in a smart sensing system that can sense the alternating current passing through a wire. The design is followed by introducing a low-cost inkjet-printed industry ready solution for frequency reconfigurable antennas where a single antenna aperture solution is utilised to demonstrate frequency reconfigurability in both switching and tuning configurations. Development of Frequency Selective Surfaces using low-cost printing machine is demonstrated in which FSS structures are inkjet-printed as wallpaper posters for Radio Frequency (RF) shielding and signal enhancements for 4G and 5G applications. A novel approach for fully 3D printing an FSS structure is also demonstrated using a low-cost open-source printer, which was modified to print the filament and the conductive inks simultaneously. Widespread investigation of industry-grade Aerosol Jet printing is utilised for additive manufacturing of bandstop and bandpass FSS designs for RF shielding and signal filtering. The bandstop designs are developed for microwave and millimetre-wave applications. The bandpass slot FSS designs are developed for millimetre wave and low-Terahertz applications for futuristic Beyond 5G and 6G systems.

Metamaterials (MMs) are periodic and/or non-periodic subwavelength structures with a unique response to electromagnetic (EM) waves compared to conventional materials. MMs possess negative permittivity and/or permeability; the combination of both negative is not found in conventional materials. The shape, dimensions, and materials used in the MM determine its ultimate working frequency and response. Owing to their peculiar properties, MMs have found new-age applications such as cloaking, perfect absorber, hyperlenses, modulators, holography, etc. Graphene is a remarkable material with distinctive properties, including excellent thermal and electrical conductivity, very high mechanical strength, along with having a zero bandgap. Further, one of the most important properties of graphene, which has enabled it to be widely used as/along with MMs, is its tunable response to EM waves via a change in conductivity when its chemical potential is varied by applying a bias or doping. Frequency selective surfaces (FSSs), or flat MMs, and MMs utilizing graphene, find applications for defense and security systems in infrared, terahertz, and microwave frequency range. The broad areas of application include stealth, communications, and imaging. Stealth applications aim to prevent radar detection by absorbing or dissipating the incoming EM waves using graphene MMs or FSSs [which act as radar absorbing surfaces (RASs)]. Another important stealth application, although a futuristic one, is cloaking. Fast, secure, and high volume data transfer is critical for any security system, and graphene MMs can improve upon the existing technologies, particularly in the terahertz frequency range. Graphene MMs can be used to develop lenses, mirrors, hyperlenses, modulators, etc., for infrared (thermal) and terahertz imaging systems. In the current chapter, the basic properties of graphene, the working of FSSs and RASs, and applications of graphene-based MMs in defense and security systems are discussed.

The propagation of electromagnetic and magnetoelastic plane waves in ferrimagnetics was discussed in the last chapter; however, the analysis did not take into account the effect of interfaces (of ferrimagnetics with other media) which are significant in realistic situations. This chapter presents a discussion of the propagation (reflection and transmission) of electromagnetic and magnetoelastic plane waves in structures having plane interfaces between dielectrics and ferrimagnetics. Such a study is useful in understanding more complicated wave propagation phenomena and also has direct applications for some devices. The reflection and transmission of electromagnetic waves are discussed in Part A while that of magnetoelastic waves is considered in Part B.

We try to thin the thickness of a λ/4 electromagnetic(EM) wave absorber with inserting a frequency selective surface (FSS) into the spacer in order to control the phase in the spacer. For this reason, we focus on the impedance characteristics of the FSS. Furthermore, we design and fabricate the λ/4 wave absorber using the FSS and measure its absorption characteristics. The result shows that the absorber with the spacer of half thickness of the general absorber is obtained. We have also provided the useful data of the frequency and oblique characteristics of the proposed absorber.

In this article, a via‐based 2.5‐dimensional (2.5D) frequency selective surface (FSS) is proposed to realize a quasi‐elliptical bandpass response with high frequency selectivity. Each FSS element is composed of two parts. Part A is a double‐layer metallic circular patches, which are etched on both sides of a thick substrate and connected by a central big metallic via and several small vias. Part B is a single layer metallic circular patch etched on a thin substrate. The proposed FSS features several transmission/reflection zeros, exhibiting a flat transmission in the passband and fast roll‐off out of band. By investigating the electric field distributions, two paths of electromagnetic wave (EMW) propagation are observed, and the physical mechanism of the transmission/reflection zeros of the FSS is obtained. A prototype of the FSS is fabricated to verify the design, and the measured transmission responses agree with the simulated ones.

In this article, we present the results of a comparative study of three different types of superstrates used to enhance the directivity of a microstrip patch antenna. The three superstrates are frequency selective surface (FSS) with dipole elements; a dielectric slab; and a double negative (DNG) slab. We find that microstrip antennas (MPAs) covered either by an FSS or a plain dielectric slab superstrate provide higher directivities than that realized by using a DNG superstrate. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 327–331, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24898

In this paper, the transmission of the electromagnetic waves in the waveguide filled with the anisotropic epsilon-near-zero (ENZ) metamaterials with dielectric cylindrical defects embedded is investigated. The anisotropy is taken into consideration, and the sandwich structure is put forward to achieve total transmission and total reflection. Despite of the anisotropy and the impedance mismatch compared with the matched impedance zero-index metamaterials, both the analytical and the numerical results show that the total reflection and the total transmission can be achieved. Furthermore, some factors that own potential effects on the transmission of the electromagnetic waves are also discussed, and it is interesting to find that the radius of the embedded dielectric cylindrical defect could greatly affect the bandwidth of total transmission and total reflection. By removing the dependence on isotropy and impedance matching, our work can facilitate the applications of the ENZ metamaterials in the waveguide.