In this paper, a new octagonal close ring resonator (OCRR)-based dumbbell-shaped tuning fork perfect metamaterial absorber for C- and Ku-band applications is presented. This design is a new combination of an octagonal ring close ring resonator with two dumbbell-shaped tuning forks metal strips integrated on epoxy resin dielectric substrate. The proposed perfect metamaterial absorber (PMA) is assessed by finite-integration technique (FIT)-based electromagnetic simulator-Computer simulation technology (CST) software. The anticipated assembly reveals dual resonance frequencies of 6.45 GHz and 14.89 GHz at 99.15% and 99.76% absorption, respectively, for TE incidence. The projected design is augmented through various types of parametric studies, such as design optimization, the effect of the octagonal ring resonator width, and varying the split gap of the double tuning fork. The numerical results are also investigated and verified using the equivalent circuit model, another electromagnetic simulator high frequency structural simulator (HFSS), and different array combinations that showed very negligible disparity. The TE polarization wave is applied to analyze the absorption separately and oblique incidence angle showing polarization insensitivity up to $30°$ and wide incident angle up to $60°$. The presented metamaterial absorber is suitable for satellite communication bands, stealth-coating technology, and defense and security applications.

A triple-band epsilon-negative (ENG) metamaterial based on a split ring resonator (SSR) with a modified hexagonal-shaped metal strip proposed in this study is a new combination of a single slit square resonator and a modified hexagonal-shaped metal strip. The desired unit cell FR-4 (lossy) that was selected as the substrate was 1.6 mm thick. Following the assessment of the unit cell, a high-frequency electromagnetic simulator like the computer simulation technology (CST) microwave studio was applied to assess the S-parameters. The proposed design exhibited resonance at 2.89, 9.42, and 15.16 GHz. The unit cell also demonstrated negative permittivity in the frequency ranges 2.912–3.728 GHz, 9.552–10.144 GHz, and 15.216–17.328 GHz, along with a negative refractive index. An effective medium ratio (EMR) of 11.53 is an indicator of the goodness of the metamaterial unit cell. It is deliberate at the lowermost resonance frequency of 2.89 GHz. Moreover, the simulated results that were validated using HFSS and equivalent circuit model indicated slight variations. The proposed design was finalised based on several parametric studies, including design optimisation, different unit cell sizes, various substrate materials, and different electromagnetic (EM) field propagations. The proposed triple band (S, X, and Ku bands) negative permittivity metamaterial unit cell can be utilised for various wireless applications, such as microwave communication, satellite communication, and long-distance radio communication.

This study presents a double-inverse-epsilon-shaped, triple-band epsilon-negative (ENG) metamaterial with two split ring resonators (SRRs). The proposed unit cell comprises a single slit two SRRs with two inverse-epsilon-shaped metal bits. Rogers RT6002, of dimension 10 × 10 × 1.524 mm³, is used as a substrate. An electromagnetic simulator CST microwave studio is used to investigate the effective medium parameters of the material. The proposed metamaterial shows three resonance peaks that are demarcated at the frequencies 2.38 GHz, 4.55 GHz and 9.42 GHz consecutively. The negative permittivity of the metamaterial is observed at the frequency ranges of 2.39–2.62 GHz, 4.55–4.80 GHz and 9.42–10.25 GHz. The goodness of the material was presented by the effective medium ratio (EMR) of the unit cell at 12.61. In addition, the simulated results are authenticated by using different electromagnetic simulators such as HFSS and ADS for the equivalent circuit model, which exhibits insignificant disparity. The anticipated scheme was finalised through some parametric analyses, together with configuration optimisation, different unit cell dimensions, several substrate materials, and altered electromagnetic (EM) field transmissions. The proposed triple band (S-, C- and X-bands) with negative permittivity (ε) metamaterial is practically used for numerous wireless uses, for instance, far distance radar communication, satellite communication bands and microwave communication.

A commercially viable metal–dielectric–metal configured triple-band metamaterial absorber is offered in this paper. It is an aggregation of four compact symmetric circles, with a swastika-shaped metal structure, which are bonded by two split-ring resonators (SRRs). Copper (annealed) of electrical conductivity 5.8 × 10⁷ Sm⁻¹ is used for the ground plate and resonator portion of the top layer and an FR 4 dielectric of permittivity 4.3 is used as a substrate. The structural parameters of the unit cell were determined by a trial and error method. FIT-based 3D simulation software (CST microwave studio, 2019 version was used to characterize the proposed perfect metamaterial absorber (PMA). Three resonance peaks were observed at frequencies 3.03, 5.83 and 7.23 GHz with an absorbance of 99.84%, 99.03% and 98.26%, respectively. The numerical result has been validated by some authentic validation methods. Finally, a microwave network analyzer (PNA) of Agilent N5227 with waveguide ports were deployed for measurement. The simulation and experimental results show better harmony. The proposed PMA has a unique design and a small dimension with higher absorption compared to other contemporary studies. This special type of polarization, insensitive S- and C-band PMA, is designed for a telecommunication system via full-time raw satellite and radar feeds.

A split-ring resonator (SRR)-based power tiller wheel-shaped quad-band ℇ-negative metamaterial is presented in this research article. This is a new compact metamaterial with a high effective medium ratio (EMR) designed with three modified octagonal split-ring resonators (OSRRs). The electrical dimension of the proposed metamaterial (MM) unit cell is 0.086λ × 0.086λ, where λ is the wavelength calculated at the lowest resonance frequency of 2.35 GHz. Dielectric RT6002 materials of standard thickness (1.524 mm) were used as a substrate. Computer simulation technology (CST) Microwave Studio simulator shows four resonance peaks at 2.35, 7.72, 9.23 and 10.68 GHz with magnitudes of −43.23 dB −31.05 dB, −44.58 dB and −31.71 dB, respectively. Moreover, negative permittivity (ℇ) is observed in the frequency ranges of 2.35–3.01 GHz, 7.72–8.03 GHz, 9.23–10.02 GHz and 10.69–11.81 GHz. Additionally, a negative refractive index is observed in the frequency ranges of 2.36–3.19 GHz, 7.74–7.87 GHz, 9.26–10.33 GHz and 10.70–11.81 GHz, with near-zero permeability noted in the environments of these frequency ranges. The medium effectiveness indicator effective medium ratio (EMR) of the proposed MM is an estimated 11.61 at the lowest frequency of 2.35 GHz. The simulated results of the anticipated structure are validated by authentication processes such as array orientation, HFSS and ADS for an equivalent electrical circuit model. Given its high EMR and compactness in dimensions, the presented metamaterial can be used in S-, C- and X-band wireless communication applications.