http://ieeexplore.ieee.org/iel7/7569814/7569815/07569878.pdf

Electromagnetic Shielding

The intent of this paper is to provide an overview of basic concepts, types, techniques, and experimental studies of the current state-of-the-art Frequency Selective Surfaces (FSSs). FSS is a periodic surface with identical two-dimensional arrays of elements arranged on a dielectric substrate. An incoming plane wave will either be transmitted (passband) or reflected back (stopband), completely or partially, depending on the nature of array element. This occurs when the frequency of electromagnetic (EM) wave matches with the resonant frequency of the FSS elements. Therefore, an FSS is capable of passing or blocking the EM waves of certain range of frequencies in the free space; consequently, identified as spatial filters. Nowadays, FSSs have been studied comprehensively and huge growth is perceived in the field of its designing and implementation for different practical applications at frequency ranges of microwave to optical. In this review article, we illustrate the recent researches on different categories of FSSs based on structure design, array element used, and applications. We also focus on theoretical breakthroughs with fabrication techniques, experimental verifications of design examples as well as prospects and challenges, especially in the microwave regime. We emphasize their significant performance parameters, particularly focusing on how advancement in this field could facilitate innovation in advanced electromagnetics.

Frequency Selective Surfaces: A Review

Progress in frequency selective surface-based smart electromagnetic structures: A critical review

In this paper, a low-profile broadband frequency selective surface (FSS) is presented for wideband shielding. The FSS consists of periodic patterns of circular loops connected among themselves through varactor diodes, which exhibit tunable operation. The novelty of the proposed design lies in its wideband tuning, where the bandstop response can be varied from 0.54 to 2.50 GHz under the reverse bias voltage, thereby exhibiting a tunable range of 363%. Moreover, the structure exhibits a wide 1.28 GHz stopband (fractional bandwidth of 152%), which is maximum as compared to other wideband FSSs. Additionally, the design is polarization-insensitive and angularly stable for both TE and TM polarizations. A prototype of the proposed structure has been fabricated where the varactor diodes are biased through a novel biasing technique. The sample is measured using parallel-plate waveguide setup as well as the free-space technique, where the measured results show good agreement with the simulated responses.

Broadband Polarization-Insensitive Tunable Frequency Selective Surface for Wideband Shielding

A new dielectric resonator antenna (DRA) for a millimeter-wave (mm-wave) multiple-input–multiple-output system is presented. Two approaches are exploited to reduce the mutual coupling between two antenna elements. First, a frequency selective surface (FSS) wall is inserted between the DRAs to reduce the free-space radiation. Then, two slots with different size acting like an $LC$ resonator are etched from the common ground plane of the structure to reduce the surface current. The designed FSS has a wideband characteristic from 40 to 70 GHz. The FSS is optimized for the desired frequency of 57–63 GHz. A high isolation of −30 dB is achieved when both FSS wall and slots are used. A prototype of the structure is fabricated and measured. The results give a low correlation coefficient ( $e$ –6) and a good agreement with simulation ones, indicating that the proposed antenna can provide spatial or pattern diversity to increase the data capacity of wireless communication systems at mm-wave bands.

Low-Mutual-Coupling 60-GHz MIMO Antenna System With Frequency Selective Surface Wall

An efficient approach to achieve the shielding effectiveness (SE) by using a frequency-selective surface (FSS) is presented. This FSS, which consists of cross dipoles and rings printed on the opposite sides of a single-layer FR-4 substrate, exhibits a wide, 7.5-GHz stopband to provide simultaneous shielding in both X- and Ka-bands. Experimental results confirm SE of the prototype over an ultra-wide band with more than 20-dB measured attenuation. The design is compact and suitable to provide shielding against the radiation interference caused by license-free and other radio systems.

Irfan Sohail Syed

Papers

A Single-Layer Frequency-Selective Surface for Ultrawideband Electromagnetic Shielding