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In this paper, a new metamaterial absorber (MMA) is presented that exhibits peak absorptions at 3.26 GHz, 11.6 GHz, and 17.13 GHz within S, X, and Ku bands. The unit cell of the proposed MMA is constructed on an FR4 substrate having an electrical dimension of 0.144λ × 0.144λ, where wavelength, λ is calculated at the lowest absorption frequency. The unique structural design of the unit cell consists of two concentric copper rings with which dumbbell-shaped structures are attached. The rotating symmetrical structural design of this MMA provides around 93.8%, 96.47%, and 99.95% peak absorptance in the mentioned frequencies, which is invariable with the change of incident angle as well as polarization angle. The metamaterial properties of the proposed absorber are studied along with the surface current analysis. The MMA shows single negative behaviour and it also exhibits high-quality factors (Q factor) of 21.73, 41.42, and 51.90 at maximum absorptance frequencies. The MMA is analysed by it's equivalent circuit to understand the resonance phenomenon, which is verified through simulation in Advanced Design Systems (ADS) software. The testing is done on the developed prototype of the proposed MMA. Measurement results are in close proximity to the simulation results. Due to its high Q factor, high EMR, and insensitivity to polarization and angle of incidence, it can be utilized as a part of miniaturized microwave device. In addition, the proposed MMA can exhibit high sensing performance and flexibility to differentiate different oils in S, X, and Ku bands. [ABSTRACT FROM AUTHOR]

In this article, a simple metamaterial absorber (MMA) is presented aiming absorption of microwave signals from Wi-Fi frequencies of 2.4 GHz, and 5 GHz. The MMA unit cell constructed on 20 × 20 mm2 FR4 substrate provides maximum absorption of 99.2% and 99.9% at 2.4 GHz and 5 GHz with the flexibility of on-design tuning of maximum absorption frequencies. The tuning metallic stubs connected with the outer ring provide the provision of frequency adjustment from 2.34 GHz to 2.45 GHz, whereas middle ring stubs along with the innermost ring assists for frequency tuning from 4.68 GHz to 5.1 GHz. Due to symmetrical structure, excellent angular stability up to 60° is achieved with near zero cross-polarization effect for both transverse electric (TE) and transverse magnetic (TM) modes of excitation. The measured result of the proposed MMA is analyzed that shows good similarity with the simulated one. Due to its simplistic design within nominal dimension, high absorption, flexibility to frequency tuning, wide angular stability, and no cross-polarization effect, this MMA can be a good candidate for absorber applications in wireless communication systems, especially for wave shielding from Wi-Fi frequencies. [ABSTRACT FROM AUTHOR]

A symmetric engineered high polarization-insensitive double negative (DNG) metamaterial (MM) reflector with frequency tunable features for fifth-generation (5G) antenna gain and directivity enhancement is proposed in this paper. Four identical unique quartiles connected by a metal strip are introduced in this symmetric resonator that substantially tunes the resonance frequency. The proposed design is distinguished by its unique symmetric architecture, high polarization insensitivity, DNG, and frequency tunable features while retaining a high effective medium ratio (EMR). Moreover, the suggested patch offers excellent reflectance in the antenna system for enhancing the antenna gain and directivity. The MM is designed on a Rogers RO3010 low loss substrate, covering the 5G sub-6GHz band with near-zero permeability and refractive index. The performance of the proposed MM is investigated using Computer Simulation Technology (CST), Advanced Design Software (ADS), and measurements. Furthermore, polarization insensitivity is investigated up to 180° angles of incidence, confirming the identical response. The 4 × 4 array of the MM has been utilized on the backside of the 5G antenna as a reflector, generating additional resonances that enhance the antenna gain and directivity by 1.5 and 1.84 dBi, respectively. Thus, the proposed prototype outperforms recent relevant studies, demonstrating its suitability for enhancing antenna gain and directivity in the 5G network. [ABSTRACT FROM AUTHOR]

This work presents a dual band epsilon negative (ENG) metamaterial with a bilateral coupled split ring resonator (SRR) for use in C and X band wireless communication systems. The traditional split-ring resonator (SRR) has been amended with this engineered structure. The proposed metamaterial unit cell is realized on the 1.6 mm thick FR-4 printed media with a dimension of 10 × 10 mm². The resonating patch built with a square split outer ring. Two interlinked inner rings are coupled vertically to the outer ring to extend its electrical length as well as to tune the resonance frequency. Numerical simulation is performed using CST studio suite 2019 to design and performance analysis. The transmission coefficient (S21) of the proposed unit cell and array configuration exhibits two resonances at 6.7 and 10.5 GHz with wide bandwidth extended from 4.86 to 8.06 GHz and 10.1 to 11.2 GHz, respectively. Negative permittivity is noted at frequencies between 6.76-9.5 GHz and 10.5-12 GHz, consecutively, with near-zero refractive index and permeability. The optimal EMR value depicts the compactness of the proposed structure. The 1 × 2, 2 × 2 and 4 × 4 arrays are analyzed that shows similar response compared to the unit cell. Measured results of the 2 × 2 array shows the close similarity of S21 response as compared to simulation. The observed properties of the proposed unit cell ascertain its suitability for wireless communications by enhancing the gain and directivity of the antenna system. [ABSTRACT FROM AUTHOR]

• This manuscript proposed a unique mirror symmetric µ-near-zero wide band-stop metamaterial shield for EMI shielding applications in the C- and X-band. • The proposed design intends to employ a shared metamaterial structure to serve two distinct microwave bands with extended shielding bandwidth. • The wide band-stop characteristics as well as frequency and bandwidth modulation flexibility make the structure unique for EMI shielding applications. • The simple shorting metallic strip in the proposed structure can control the shielding spectrum from C-band to X-band with an outstanding band-stop enhancement capability of 170.63%, which significantly outperforms the existing state-of-the-art metamaterials. • The proposed metamaterial prototypes are fabricated and experimentally verified their shielding performance and show promising results for wideband EMI shielding applications. In this paper, a µ-near-zero wide band-stop metamaterial (MM) shield is conducted for electromagnetic interference (EMI) shielding purposes in the C- and X-band. The proposed design intends to employ a shared MM structure to serve two distinct microwave bands with extended shielding bandwidth. The proposed structure consists of metal strip coupled four identical quartiles based unique mirror symmetric resonator and designed on a low-loss Rogers 5880 substrate within a compact physical dimension of 7.5 mm × 7.5 mm × 1.575 mm. The speciality of the proposed MM is its wide band-stop functionality with maximum shielding bandwidth and effectiveness of 4.33 GHz and 66.6 dB, respectively. Moreover, four shorting metal strips among adjacent quartiles can control the shielding spectrum from C-band to X-band with an outstanding band-stop enhancement capability of 170.63 %, which significantly outperforms the existing MMs. Therefore, the proposed MM structure can be utilized for two distinct wide frequency spectrums shielding by introducing simple shorting metallic strips. The electromagnetic radiation shielding phenomena are also explained using surface current and electric and magnetic field distribution. The proposed MM prototypes are fabricated and experimentally verified with numerical results. The promising shielding performance of the developed MM demonstrates the potentiality for shielding undesired electromagnetic radiation. [ABSTRACT FROM AUTHOR]

An epsilon negative metamaterial (MTM) is presented in this article that bears a symmetrical structure and shows a transmission coefficient (S 21) resonance at 2.78 GHz. The proposed MTM unit cell comprises an outer square ring with horizontally oriented splits, connected along the vertical axis to a circular inner ring featuring vertically oriented splits, forming an interconnected structure. The electrical dimension of the MTM cell is 0.08λ × 0.084λ, and here wavelength, λ is determined at 2.4 GHz. The MTM shows negative permittivity, near zero permeability as well as refractive index. The electric field, Magnetic field, and current distribution have been analyzed to realize resonance behavior. The compactness of the MTM is identified through an effective medium ratio (EMR) of 12.2. Moreover, an equivalent circuit is modeled and Advanced Design Systems (ADS) is utilized to confirm its performance. The prototype of the metamaterial is developed and a measured result is taken that exhibits a well-matching with the simulation result. Application of this metamaterial is checked through designing and developing an antenna and MTM is used as a superstrate over the antenna. Both the simulation and measured results reveal that as a superstrate, MTM helps to increase the antenna gain by more than 100% with less effect on the bandwidth. Thus, this new metamaterial can be a good candidate as an antenna element for increasing performance. Moreover, the proposed antenna-MTM system can be utilized for wireless power transmission as it provides an adequate gain in a compact 3D structure. • A new symmetrical epsilon negative metamaterial (MTM) with resonance at 2.78 GHz is demonstrated. • The MTM cell provides effective medium ratio (EMR) of 12.2 indicating its compactness. • The metamaterial's characteristics are investigated through analysis of electric field, magnetic field, and current distribution. • By integrating the MTM as a superstrate over an antenna, more than 100% increase in antenna gain is attained. • The proposed antenna-MTM system holds potential for wireless power transmission applications due to its compact 3D structure and substantial gain. [ABSTRACT FROM AUTHOR]

• A novel modified asymmetric circular split ring resonator-based metamaterial is presented for absorber applications in the microwave regime. • The designed metamaterial absorber provides absorption peaks of 97.9%, 99.1%, 99.5% and 99.95% at 4.1 GHz, 6.86 GHz, 11.3 GHz and 13.45 GHz respectively. • Unique characteristics of this absorber is that it exhibits high quality factor and effective medium ratio (EMR) which can be used for sensing and detection purposes. • Metamaterial and absorber properties are explained thoroughly using surface current, electric field, and magnetic field analysis. • Due to miniaturized metamaterial absorber with good EMR, high quality factor and average 99% maximum absorption, this metamaterial absorber can be used for multiband microwave applications. This article presents a metamaterial based on a modified asymmetric circular split ring resonator for absorber applications in the microwave regime. This metamaterial absorber (MMA) exhibits four absorption peaks to cover C, X, and Ku band applications. The MMA unit cell is formed on a low-cost FR4 substrate with electrical dimensions of 0.106 λ 0 × 0.106 λ 0 , for which wavelength, λ 0 is calculated at 4.1 GHz. The resonator of the unit cell is structured with three concentric intercoupled circular split rings with dimensions modified to obtain maximum absorption peaks of 97.9%, 99.1%, 99.5%, and 99.95% at 4.1, 6.86, 11.3, and 13.45 GHz, respectively. Metamaterial and absorber properties are investigated in the analysis of the surface current, electric, and magnetic fields. The unit cell exhibits single negative metamaterial properties with an effective medium ratio (EMR) of 9.15 and quality factor (Q factor) greater than 20. Beyond that, the equivalent circuit of the MMA unit cell is modeled and validated by comparing S 11 obtained from Advanced Design System (ADS) and CST software. The MMA array's absorption properties are also examined in the simulations. Measured results of the unit cell and array correspond well with the result of simulation in terms of absorption at intended frequencies. Given its good EMR, superior quality factor, and high maximum absorption, the MMA can be a good candidate for a multiband absorber in microwave applications like sensing, detecting, notch filtering and to decrease the indirect reverberation and reflections caused by the metallic part of the radar and satellite antennas. [ABSTRACT FROM AUTHOR]

• A novel cross coupled interlinked split ring resonator (CCI-SRR) based epsilon negative (ENG) metamaterial has been designed for multi band microwave applications. • The unique symmetric structure of CCI-SRR provides three resonances at C, X and Ku-bands. Due to symmetric nature, the array of unit cells is less prone to harmonics and noise. • The permittivity, permeability, refractive index and impedance have been extracted by using the NRW method. Metamaterial exhibits negative permittivity and near zero refractive index. • The interaction of electromagnetic wave between ENG and double positive media is investigated where ENG media shows evanescent wave properties. • Symmetric structure, small size, negative permittivity, near-zero refractive index and high EMR make this metamaterial suitable for devices used in Radar and Satellite communications. In this paper, a cross coupled interlinked split ring resonator based (CCI-SRR) based metamaterial has been presented. Epsilon negative (ENG) with a highly effective medium ratio (EMR) is attained in this metamaterial. The metamaterial unit cell consists of one square shaped split ring resonator and two rectangular rings. The rectangular rings reside within the outer square split ring. Two internal rings are coupled together by using a cross-shaped metal segment. These inner rings are also interlinked to the outer ring by using metal strips. Coupling causes to increase the electrical length and modifies the inductance of the unit cell. Multiple resonances covering C, X and Ku-band are achieved due to the interconnection of rings. The symmetric nature of the CCI-SRR unit cell exhibits unique quality to minimize noise and harmonics effect. The unit cell is designed on FR4 substrate with a thickness of 1.6 mm. The overall dimension of the unit cell is 0.124λ × 0.124λ, where λ is the wavelength calculated at a lower resonance frequency of 4.15 GHz. Three resonances are obtained for |S 21 | at frequencies of 4.15 GHz, 10.38 GHz and 14.93 GHz performing numerical simulation in CST microwave studio. Permittivity, permeability, refractive index and impedance are explored by using the Newton-Ross-Weir (NRW) method. ENG performance is observed in frequencies ranging from 3.95 to 5.65 GHz, 9.57–11.46 GHz, 13.68–16 GHz. Near-zero refractive index is attained within the frequency ranges, 4.16–5.75 GHz, 10.16–11.58 GHz, 14.46–16 GHz. An LC equivalent circuit is designed, and component values are achieved by Advanced Design Software (ADS) justifying |S 21 | with CST result. The study of electromagnetic wave interaction between the unit cell and the double positive medium reveals that the unit cell exhibits evanescent wave properties. The compact nature of the unit cell is confirmed by calculating EMR with a value of 8.03. The electromagnetic coupling effect is examined for 2 × 2 array in various orientations. The |S 21 | performance of 2 × 2, 4 × 4 and 8 × 8 is matched with the unit cell. Due to symmetric patterns, near-zero refractive index, negative permittivity and high EMR, the proposed unit cell can be used to enhance the performance of microwave devices used for C, X and Ku-bands, especially Satellite and Radar communications. [ABSTRACT FROM AUTHOR]

In this paper, coupled ring split-ring resonator (CR-SRR) based epsilon negative (ENG) metamaterial with high effective medium ratio (EMR) is designed and investigated for microwave applications. The metamaterial unit cell is a modification of the conventional split-ring resonator, which consists of three major outer split rings with two face to face horizontal E segments placed at the center. All the rings are intercoupled with each other to increase the electrical length. The coupling effect is clearly observable as it provides multi-frequency resonances and a higher value of the effective medium ratio. The electrical length of the proposed unit cell is 0.064λ × 0.064λ, where λ is the wavelength calculated at the lowest resonance frequency (2.24 GHz). The designed unit cell is fabricated on a FR-4 substrate, having a thickness of 1.5 mm. Negative permittivity is observed at frequencies ranging from 2.15 to 2.3 GHz, 4.4–4.95 GHz, 5.7–6.1 GHz, 8.46–9.2 GHz, and 10.6–10.98 GHz. It also exhibits near-zero refractive indexes in the vicinity of these frequency ranges. The equivalent circuit is also designed for the proposed unit cell. The values of the lumped components are optimized by using Advanced Design Software (ADS). This circuit also demonstrates similar multi-band resonances. A high effective medium ratio (EMR) of 16.74 at 2.24 GHz indicates the compactness of the proposed unit cell. Array performance is also investigated by using 1 × 2, 2 × 2, and 16 × 16 array of unit cells. Multiband resonances of the transmission coefficient, |S 21 | are also noticed from these arrays. For high EMR and small size, the proposed metamaterial is suitable for S, C, and X-bands applications in wireless communications. [ABSTRACT FROM AUTHOR]

In this article, a novel metamaterial is presented that is constructed with split ring resonators (SRR) arranged in a nested square configuration. The proposed metamaterial unit cell is constructed over a 1.5 mm thick FR-4 substrate with electrical dimensions of 0.11 λ × 0.11 λ, where λ is the wavelength calculated at 2.8 GHz. The resonating patch contains five interconnected nested squares, including two square split ring resonators (SSRRs). The unit cell exhibits three distinct frequencies at 2.8 GHz, 5.8 GHz, and 11.2 GHz, with corresponding magnitudes of −45 dB, −50 dB, and −30 dB, respectively. Negative permittivity (ε-Negative) is observed in frequency ranges of 2.3–3.20 GHz, 4.4–6.9 GHz, and 10.8–11.30 GHz, with near-zero refractive index. The simulated outcome acquired in CST microwave studio is subsequently confirmed using analogous circuit modeling in Advanced System software (ADS). Moreover, the prototype of the proposed metamaterial is developed that shows similar resonances obtained in the simulation. The effective medium ratio (EMR) of the unit cell is calculated and a high EMR of 8.3 expresses the compactness of the metamaterial. Due to its structural compactness, this new metamaterial with ε-negative, near zero refractive index, and triple band resonance properties holds significant potential for wireless applications such as radar systems, satellite communications, and wireless sensor networks. • Novel structure featuring nested squares and SSRRs for triple-band ε-negative properties. • Achieves an EMR of 8.3 with five linked squares and two SSRRs in the design. • Operates at 2.8 GHz, 5.8 GHz, and 11.2 GHz, catering to S-, C-, and X-bands. • Utilizes a 1.5 mm FR-4 substrate, ensuring affordability and accessibility. • Experimental, CST, and ADS analysis confirm predicted outcomes and potential applications. [ABSTRACT FROM AUTHOR]

This article describes a metamaterial (MTM) based on a symmetric square ring resonator (SSRR) that exhibits epsilon negative (ENG) and near-zero index (NZI) properties. A 0.035 mm thick copper resonator is used to construct the proposed asymmetric MTM structure, designed on a 1.5 mm thick FR-4 substrate for microwave applications. The MTM structure attained optimum resonance at frequencies corresponding to the microwave frequency range of the S, C, and X bands, 2.88 GHz, 4.78 GHz, and 10.9 GHz, respectively. The near-zero index characteristics are realized in the frequency ranges 2.22–3.17 GHz, 4.52–5.10 GHz, and 9.63–11.36 GHz, while the ENG characteristics are realized in the frequency ranges 2.1–3.2 GHz, 4.57–5 GHz, and 9.7–11.4 GHz. The electrical dimensions of the structure are 0.139λ × 0.139λ × 0.014λ, corresponding to an estimated wavelength of 2.88 GHz. The effective medium ratio (EMR), which for this construction is 7.194, indicates the compactness of the design structure. Using CST 2019 simulation software, the proposed structure is designed and developed before its construction and performance evaluation. The circuit was validated by comparing the S 21 response using the Advanced Design System (ADS) software. The response of S 21 from the proposed MTM structure was almost identical when it was tested through simulation (using CST and ADS software) or actual measurements. The compact size, substantial electromagnetic response (ER), negative permittivity, almost zero permeability, and refractive index of this MTM make it perfect for wireless applications in S-, C-, and X-bands. • A novel metamaterial based on a symmetric square ring resonator (SSRR) is proposed for S-, C-, and X-bands wireless applications. • The metamaterial exhibits epsilon negative (ENG) and near-zero index (NZI) properties, making it suitable for various microwave frequencies. • The structure is compact, with an effective medium ratio (EMR) of 7.194, indicating its high electromagnetic response. • The proposed metamaterial is validated through simulation and actual measurements, showing almost identical responses in terms of S21 characteristics. • With its negative permittivity, almost zero permeability, and refractive index close to zero, the metamaterial is ideal for wireless communication in S-, C-, and X-bands. [ABSTRACT FROM AUTHOR]