Gobinda Sen

BROADBAND PERFECT METAMATERIAL ABSORBER ON THIN SUBSTRATE FOR X-BAND AND KU-BAND APPLICATIONS

A broadband Perfect Metamaterial Absorber (PMA) on FR-4 Epoxy substrate for X-band and Ku-Band applications is proposed. The unit cell structure is composed of rectangular patches of appropriate shapes and orientation on top of the metal-backed dielectric substrate having a thickness of 2.7 mm (0.16λL). The relative absorption bandwidth is 79% (more than 85% absorption) covering the entire X-band and the Ku-Band of the microwave frequencies. The surface current distributions of the top and bottom planes have been analyzed to elaborate the absorption mechanism of the structure. The broadband characteristics of the design support its claim of being useful to a wide range of applications in both commercial and research sectors. Such applications include military and stealth devices, thermal sensors and electronic-cloaking devices.

Broadband metamaterial absorber on a single-layer ultrathin substrate

Abstract In this article, a broadband metamaterial microwave absorber on a low-cost FR-4 Epoxy substrate is proposed. The unit cell of the absorber consists of a staircase shape metallic patch placed on the top of the metal-backed ultrathin dielectric substrate having a thickness of 1.9 mm (0.07 λ0). The absorption of more than 90% is achieved with this proposed low profile single-layer microwave absorber throughout the operation band from 8.86 to 15.5 GHz. The performance is analyzed for different values of incident angle, polarization angle, substrate height, and dielectric constant. The surface current and the power loss density at the top and bottom planes at the two absorption peaks of 9.46 and 13.90 GHz are also analyzed to elaborate the absorption mechanism of the structure. Experimental result closely follows the simulated one. The broadband characteristics of the design with relative absorption bandwidth (RAB) of 54.51% at both TE and TM polarizations of incident wave for a wide incident angles makes it versatile for applications in the X and Ku bands of microwave frequencies. The proposed work is very compact (unit cell size: 0.22 λ0) with ultrathin substrate height (0.07 λ0) and giving RAB performance of 54.51% comparable with that of others. Thus with this single-layer low-cost substrate material a broadband absorber is achieved.

A dual band metamaterial inspired absorber for WLAN/Wi-MAX applications using a novel I-shaped unit cell structure

This article presents a dual band metamaterial absorber suitable for applications over the WLAN and Wi-MAX frequencies on a metal-backed FR-4 Epoxy substrate utilizing a novel I-shaped unit cell structure for the design. The component shows dual band absorption at frequencies 3.5 GHz and 5.8 GHz respectively with 100% absorption of the incident signal at both the points of observation. The component is developed on a substrate of thickness 1.5 mm that corresponds to a dimension of λ/34 (nearly) for the frequency of 5.8 GHz - that highlights the miniaturized design performance of the structure. The novel I-shaped unit cell structure that consists of two C-shaped oppositely faced rectangular strips with a thin I-shaped patch in between, shows exquisite metamaterial-like performance when examined. A good match of frequency band can be achieved between the performances of the simulations and the experiments. Surface current distributions are investigated to conclude about the reasons for which the structure is acting like a metamaterial absorber and its performances under different incident angles of the incoming signal were studied.

Dual-polarized dual-band CPW-fed slot antenna for WLAN applications

A dual-band dual-polarized CPW-fed slot antenna for WLAN applications is presented. The antenna shows two resonant dips at 3.56 GHz and 5.12 GHz. For the WLAN band (3.6 GHz) the antenna shows a circularly polarized behavior, whereas in case of the other band it is acting as a linearly polarized component. The design geometry consists of a CPW-fed thin slot structure with an LC complimentary resonator loaded at the end of the CPW trace line. The resonator is loaded at an offset of 0.5 mm with respect to the center of the CPW-trace to realize the circular polarization. The structure is simulated and studied for the s-parameters and the axial ratio (AR) values those suggest its characteristics as will be presented through this article. The surface current distributions and the radiation patterns are investigated to conclude about the performances. The simple structure and its dual-band dual-polarized attributes claim its novelty and suggest its wide applicability in the commercial sector for practical operations. The simulated and the measured results for the structure were found to be in good agreement with each other, consequently establishing the usability of the component for commercial production and applications.

Design and gain enhancement of a CPW-Fed dual band slot antenna using a metamaterial inspired superstrate

The design of a Dual band slot antenna using complementary LC resonators is presented. Two complementary dual band LC resonators are used to achieve the response. A metamaterial inspired superstrate is then used to achieve gain enhancement at both the operating frequencies. The paper discusses the steps followed to realize the final design and presents the simulated results for the proposed structure. The novelty of this work lies in the simultaneous gain enhancement performance observed at both the bands of the dual band slot antenna structure using the superstrate.