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This article reports on a single layer penta‐bandstop frequency selective surface (FSS) for multiband shielding applications. The proposed unit cell incorporates five independent resonant elements that are realized on a single‐sided FR4 substrate to suppress GSM ‐ 0.9 GHz, GPS ‐ 1.5 GHz, GSM ‐ 1.8 GHz, Wi‐Max ‐ 3.5 GHz, and Wireless Local Area Network (WLAN) ‐ 5.7 GHz frequency bands. The proposed single layer unit cell has compact lattice periodicity of order 0.11 λo × 0.11 λo. The design is not only polarization‐insensitive, but it also offers high angular stability up to 45°. A detailed parametric analysis is conducted to establish a relationship between geometrical parameters and FSS spectral response. Additionally, an equivalent lumped circuit model is also derived to further elaborate on the underlying resonance mechanism. A prototype is fabricated and tested to validate the performance of the proposed FSS. The measured results are in good agreement with simulated ones. The proposed FSS has the uniqueness of suppressing 0.9 GHz GSM band that has never been reported in a pentaband design. The proposed FSS is a potential candidate for radio frequency (RF) shielding, electromagnetic wave suppression, and data security applications in secure installations. [ABSTRACT FROM AUTHOR]

This study reports on a highly miniaturised polarisation selective surface (PSS) for dual-band Wi-Fi and WLAN applications. The proposed unit cell consists of two independently tuneable square loops. The outer loop is split with a gap of 0.2 mm to introduce polarisation selectivity and miniaturisation for lower-frequency band of 2.5 GHz. The inner square loop is inductively loaded with arms to suppress 5.45 GHz frequency band. These configurations have resulted in a unit element size of $\lambda _{\circ }/14$λ∘/14 at 2.5 GHz, which is not presented before to the best of the authors' knowledge. A wide rejection bandwidth ($-10\,{\rm dB}$−10dB) of more than 600 and 1180 MHz is obtained around 2.5 and 5.45 GHz, respectively. Furthermore, the proposed PSS exhibits an excellent polarisation selective characteristic by generating two stopbands at 2.5 and 5.45 GHz when illuminated by horizontal (TM) incident waves, whereas vertically (TE) polarised incident waves result in the generation of passbands for these two frequencies. Numerical validation through equivalent circuit modelling of the proposed PSS has also been carried out. A finite prototype containing $31 \times 33$31×33 elements is fabricated and tested. The measured results demonstrated that the PSS has excellent potential for applications that employ polarisation separators and wave generators. [ABSTRACT FROM AUTHOR]

A compact four‐element multiple‐input‐multiple‐output (MIMO) antenna for ultra‐wideband (UWB) applications with WLAN band‐notched characteristics is proposed here. The proposed antenna has been designed to operate from 2 to 12 GHz while reject the frequencies between 4.9 to 6.4 GHz. The four antenna elements are placed orthogonal to attain the polarization diversity and high isolation. A thin stub connected to the ground plane is deployed as a LC notch filter to accomplish the rejected WLAN band in each antenna element. The mutual coupling between the adjacent elements is at least 17 dB while it has low indoor and outdoor envelop correlation (<0.45) and high gain with compact size of two boards, each measuring 50 × 25 mm2. To validate the concept, the prototype antenna is manufactured and measured. The comparison of the simulation results showed good agreement with the measured results. The low‐profile design and compact size of the proposed MIMO antenna make it a good candidate for diversity applications desired in portable devices operating in the UWB region. [ABSTRACT FROM AUTHOR]

This article reports on a dual band, polarization insensitive Frequency Selective Surface (FSS) for Wi-Fi and WLAN shielding applications. The design incorporates concentric square and circular loops loaded with log periodic directors and passion crosses, respectively. The proposed design is completely polarization insensitive. Also, the design has angular stability up-to 45° for both Transverse Electric (TE) and Transverse Magnetic (TM) polarizations. The FSS offers measured suppression of 38 dB at 2.4 GHz and 32 dB at 5.9 GHz. The detailed analysis of all parameters has been carried out. Equivalent lumped circuit model has also been proposed. The design is highly miniaturized with the unit element size of 0.1λ 0 only. The complementary bandpass FSS has also been investigated. The measured results are in good agreement with the simulated response. The design has excellent potential for EM field suppression and security applications. [ABSTRACT FROM AUTHOR]

This article reports on a compact dual band, Frequency Selective Surface (FSS) based spatial filter for Wi-Fi and WLAN shielding applications on a transparent glass surface with optical transparency of 70%. The unit cell comprises an outer square loop resonator with a disconnected and concentric annular ring resonator. To introduce frequency tuning and compactness T shape stubs are strategically loaded on these resonators and it is ensured that the mutual coupling remains minimal. The outer square resonator suppresses the 2.4 GHz band, and the inner circular ring resonator stops the 5.4 GHz band. The unit element is four-fold symmetric thus it offers complete polarization independence. A detailed parametric and electromagnetic field analysis has been conducted to elucidate the significance of different sections of the unit element. An equivalent lumped circuit model is also derived for the proposed unit element to better explain the underlying working mechanism. A finite prototype of 15 × 11 elements is fabricated on a soda lime float glass by using ordinary adhesive copper foils with a standard chemical etching process. Polarization independence and angular stability up to 45° are measured and compared with the simulated responses. The FSS shield offers frequency suppression up to 45 dB and 43 dB for 2.4 GHz and 5.4 GHz bands respectively. With high optical transparency, the design allows maximum light through it and causes no extra burden on energy consumption for indoor applications. The compact dual band design and the possibility of direct application on host surfaces like glass windows and doors make this design an excellent candidate for data security and privacy applications in secure installations with an esthetically pleasing outlook. [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents a four elements frequency reconfigurable ultrawideband (UWB) multiple-input-multiple-output (MIMO) design, capable of rejecting on-demand WLAN band ranging from 4.8 to 6.2 GHz. The proposed design consists of two U-shaped monopole UWB radiators and two circular slotted-monopole radiators. These monopole radiators are placed orthogonally with respect to each other to exploit polarization diversity, whereas the PIN diodes are used to connect the band-stop design with the ground plane to introduce the on-demand band rejection feature. An isolation of better than 17 dB between the four UWB-MIMO elements is achieved in the 2.7-12 GHz frequency range for the both PIN diodes biased and unbiased states. The simulations and measurements results showed good agreement over the band of interest. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:270-276, 2016 [ABSTRACT FROM AUTHOR]