In this article, a novel binary Wind Driven Optimization (WDO) algorithm is presented for the synthesis of six-band Metamaterial Absorber (MA). Synthesis of the unit cell structure of MA is done by optimizing the presence of each unit pixel of pixelated Frequency Selective Surface (FSS). Numerical simulation of this optimized absorber shows six discrete bands of absorptions at 7.6, 10.1, 13.3, 14.7, 15.8 and 16.7 GHz with more than 90% absorptivity under normal incidence of the wave. The proposed absorber is ultra-thin, polarization insensitive and has good performance over a wide angle of incidence. The numerical simulation and experimental results are in close agreement.

A six-band ultra-thin polarization-insensitive pixelated metamaterial absorber using a novel binary wind driven optimization algorithm

A novel triple-band ultrathin metamaterial absorber (MA) with polarization independence is designed, characterized and realized in this study. The designed absorber consists of three layers. The top metallic patch is patterned in an ultrathin dielectric substrate that is backed with a ground metallic plate. The numerical simulation results show that the presented metamaterial absorber exhibits three distinct absorption peaks of 99.95%, 99.28% and 96.36% under normal incidence at frequencies of 8.115, 11.4 and 15.12 GHz, respectively. Due to its fourfold symmetry, the absorbing properties are independent of the polarization of the incident radiation angle. Moreover, in the cases of TE and TM polarization modes, the proposed absorber displays an outstanding absorption response over a wide range of incident angles up to 60◦. The physical mechanism of the absorption performance is explained by investigating the normalized input impedance, surface current and field distributions at three distinct absorption peaks. Furthermore, the presented absorber is practically validated by the excellent agreement observed between the experimental and simulated results. The designed absorber has an ultrathin thickness of 1mm, which is 0.027λ0 with respect to the lowest peak absorption frequency, and can be useful for several potential applications, such as electromagnetic compatibility, stealth technology and super lenses.

Triple-Band Polarization-Independent Ultrathin Metamaterial Absorber

This article introduces a novel, binary version of wind driven optimisation (WDO) called binary WDO (BWDO), which can be specifically used for solving binary valued problems such as antenna array and metasurface synthesis. Validation of proposed algorithm is done with standard benchmark functions. To demonstrate the efficiency of BWDO, examples of thinned antenna array and metasurface synthesis are considered. Thinned antenna array problem is solved by formulating single and multi-objective optimisation problems which achieve minimum SLL of −22.30 dB and −20.28 dB respectively, as compared to −13.2 dB by periodic array. Further, the proposed BWDO algorithm is interface with Ansys-HFSS and three design examples of metasurfaces such as MPA and AMC are further considered to exemplify the proficiency of BWDO. Simulation of optimised MPA exhibits five discrete bands of high absorptions at 8.7, 9.7, 14.6, 15.3 and 16.5 GHz with simulation reflection co-efficient value of −11.46, −10.00, −12.17, −16.19 and −20.58 dB which is less than −10 dB reflection under normal incidence of wave. Synthesised single and dual band AMC has in-phase reflection bandwidth of 0.58 and 0.34, 0.16 GHz at central frequency of 5.21 and 5.07, 6.49 GHz respectively. The measured results almost matched with the respective simulated results with slight variation due to fabrication tolerance.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-map.2018.5051

BWDO algorithm and its application in antenna array and pixelated metasurface synthesis

A new design of a metamaterial absorber (MMA) with two broad-bands is simulated, fabricated and experimentally investigated in this paper. The MMA structure unit cell consists of combination of eight rings with two pair of concentric split rings and two pair of concentric continuous rings placed diagonally opposite. The proposed MMA has x-y symmetrical copper unit cells with middle layer of FR-4 substrate and copper laminated ground plane. The simulated and measured absorption peaks as well as the absorptance of the proposed MMA exhibits insensitivity to change in polarization and incidence angle of electromagnetic waves. The metamaterial behavior of the studied MMA is confirmed by extracting effective permeability, μ eff(f), effective permittivity, e eff(f), and effective refractive index, η eff(f), from the measured S-parameters. The proposed MMA has resonance peaks at 7.6 GHz, 8.9 GHz, 12.3 GHz, and 12.8 GHz with measured absorptance of 94%, 99.9%, 96%, and 96% at respective frequency bands. The first absorption broad-band extends from 7.36 GHz to 9.36 GHz and the second broad-band extends from 11.9 GHz to 13 GHz. The high electromagnetic wave absorptance from 7.36 GHz–9.36 GHz and 11.9 GHz–13 GHz makes this MMA suitable for satellite, mobile and radar applications.

https://iopscience.iop.org/article/10.1088/2053-1591/aadd83/pdf

Wide incidence angle and polarization insensitive dual broad-band metamaterial absorber based on concentric split and continuous rings resonator structure

The manuscript presents a log-periodic microstrip antenna with a defective ground structure (LPMADGS). The antenna is simulated, designed, and validated for C-band applications. The design of the antenna consists of three layers with upper most layer consisting of log-periodic, copper patches with a thickness of 0.035 mm; the middle layer is a 2 mm thick dielectric layer of FR-4 substrate; and the bottom layer is a defected ground structure (concentric ring resonators of 0.035 mm thickness). The suggested antenna design is simulated with a complete ground plane, without ground plane, and with a defective ground plane. The proposed antenna with optimized design is fabricated by wet etched method. The simulated results are approximately similar to the experimentally measured results. The experimentally measured results show transmission peaks at 7.65 GHz and 7.90 GHz. The resonating effect of log-periodic patches with a defected ground structure results in wide-band of 0.91 GHz (−10 dB bandwidth). The proposed antenna structure exhibits a wide bandwidth transmission which mostly resonates in frequency range that lies in C-band. It has future applications for mobile as well as wireless communication.

/pdf/wide-band-log-periodic-microstrip-antenna-with-defected-46dyrfsqtd.pdf

Wide-Band Log-Periodic Microstrip Antenna with Defected Ground Structure for C-Band Applications

Simulation and experimental measurement of a new design of an oblique incidence and polarization insensitive metamaterial absorber with multiband absorption is presented in this paper. The unit cell of the proposed metamaterial absorber comprises concentric continuous rings of different radii and widths placed in four different quadrants with identical pair of rings placed diagonally opposite, with each ring responsible for high absorption. The calculated dispersion behavior of MM absorber in terms of effective permittivity (εeff ), effective permeability (μeff ), and refractive index (ηeff ) shows the metamaterial characteristics. The surface current and field distributions in MM absorber are simulated to understand the occurrence of absorption bands. The measured results show the absorption peaks of 99.5%, 99.8%, 99.5% and 99.9% at 7.20 GHz, 9.3 GHz, 12.61 GHz, and 13.07 GHz, respectively. The simulated results are well supported by the experimentally measured performance of the fabricated metamaterial absorber. It offers multiband absorption with bands lying in C-band, X-band and Kuband for mobile communication, satellite communication and radar applications. With merged third and fourth absorption peaks, the proposed metamaterial absorber structure exhibits a broadband absorption.

and Ashutosh Singh

Papers

Oblique Incidence and Polarization Insensitive Multiband Metamaterial Absorber with Quad Paired Concentric Continuous Ring Resonators