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Summary: This article presents a novel wearable frequency selective surface (FSS) for shielding the communication link of implantable devices with the external environment. The proposed shield blocks a dual‐band frequency operating at 404 MHz and 2.45 GHz in the medical implant communication service (MICS) and industrial, scientific, and medical (ISM) bands. The two distinct stop bands provide a high‐frequency band ratio of 6.02 in an ultra‐miniaturized physical form factor of 0.024λo × 0.024λo, with at least 76.96% miniaturization when compared to the existing art. Each of the unit cells is imprinted on a conformal 50 μm polyester substrate in a symmetrical configuration. The polyester adheres with jean to realize its compatibility with wearable applications. The designed shield system offers a low profile of only 0.00146λo. By suppressing the grating lobe, the proposed shield achieves a high angular stability of 80° and polarization insensitivity of 90° in both transverse electric (TE) and transverse magnetic (TM) modes. The FSS is fabricated and measured results validate its performance. To evaluate the physical insight, an equivalent circuit model (ECM) analysis is done. To ensure durability, the proposed shield system is tested with Amitech SDR04. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to design a suitable guard trace to reduce the electromagentic interference between two closely spaced high frequency transmission lines. A novel cross-shaped resonator combined via fence is passed down to alleviate far-end and near-end crosstalk (NEXT) in tightly coupled high-speed transmission lines. The distance between the adjacent transmission lines is increased stepwise as a function of trace width. Design/methodology/approach: A rectangular-shaped resonator via fence is connected by a guard trace has been proposed to overcome the coupling between the traces that is separated by 2 W. Similarly, by creating a cross-shaped resonator via fence connected by guard trace that reduces the spacing further by 1.5 W. Findings: A tightly coupled transmission line structure that needs separation by a designed unit cell structure. Further research needs to be conducted to improve the NEXT, far-end crosstalk (FEXT) and spacing between the transmission lines. Originality/value: This study portrays a novel method that combines the resonators via fence with a minimum spacing between the tightly coupled transmission lines which reduce the NEXT and FEXT; thereby reducing the size of the routing area. The resultant test structures are characterized at high frequencies using time domain and frequency domain analysis. The following scattering parameters such as insertion loss, NEXT and FEXT of the proposed method are measured as 1.504 dB, >30 dB and >20 dB, respectively. [ABSTRACT FROM AUTHOR]

This paper presents the design of an Ultra‐wide band‐stop Frequency Selective Surface (FSS), the building block of which makes use of a modified Jerusalem cross loop structure. The proposed FSS unit cell has a coupled configuration with a modified Jerusalem cross loop on the top and a square loop on the rear side to operate over an ultra‐wide bandwidth. The proposed FSS design offers band‐stop characteristics over the entire UWB operating bandwidth extending from 2.95 to 12 GHz with a reference transmission loss of 10 dB. The proposed FSS unit cell has a miniaturized profile of 0.05λ˳ × 0.05λ˳ where the λ˳ corresponds to the free space wavelength at the lowest operating frequency. The rotational symmetry of the proposed FSS makes it polarization‐independent under both TE and TM modes of operation. Also, the proposed FSS exhibits a good angular stability response up to 60°. The prototype FSS is fabricated and the simulated results are validated using experimental measurements. Thus, the proposed FSS is a promising candidate for a multitude of applications such as spatial filtering (Bayatpur & Sarabandi, 2010, https://doi.org/10.1109/LMWC.2009.2038517), antenna gain enhancement (Chatterjee & Parui, 2016, https://doi.org/10.1109/TAP.2016.2552543), and electromagnetic shields (Chiu et al., 2008, https://doi.org/10.1109/TEMC.2008.2004560) operating over the UWB spectrum. Key Points: This paper presents the design of an Ultra‐wide band‐stop Frequency Selective Surface (FSS)The proposed FSS design offers band‐stop characteristics over the entire UWB operating bandwidthThe proposed FSS is a promising candidate for a multitude of applications such as spatial filtering, antenna gain enhancement [ABSTRACT FROM AUTHOR]

The design, development, fabrication, and testing of a wideband reflectarray antenna with a novel concentric ring element operating over Ku/K band frequencies is presented in this paper. The element characterization is performed using the infinite array approach and is inferred that the proposed unit cell offers a higher phase variation of 643° by changing the size of the concentric rings. The proposed reflectarray antenna has a circular geometry and is constructed using 437 elements with an element separation of 0.43λ0. The proposed reflectarray offers a 3 dB gain bandwidth of 35% (15–21 GHz). The aperture efficiency is estimated to be 58.78% at 16.5 GHz. The prototype reflectarray is fabricated and tested to validate the simulation results. The measured peak gain of the reflectarray is 28.4 dBi with a side lobe level of −17.6 dB. The measured cross‐polarization level is less than −32 dB. Furthermore, it is inferred that the proposed unit cell has a reduced maximum phase sensitivity of 246°/mm with a gain selectivity of 6 dB at the lowest operating frequency. The proposed broadband reflectarray with enhanced performance characteristics is suitable for application in satellite communication and aeronautical radio navigation. [ABSTRACT FROM AUTHOR]

The design, fabrication, and testing of an integrated polarization diversity antenna array for maximizing the wireless channel link in vehicular networks are presented in this paper. The diversity antenna is constructed using unit cell radiators that provide two operating modes. The mode transition is achieved using a pair of PIN diodes. In one state, the antenna provides multiband operation centered at 2.4, 3.5, and 5.8 GHz. In the other state, the antenna covers the entire ultra-wideband (UWB) spectrum. The unit cell radiators are distributed in the horizontal and vertical plane to achieve polarization diversity. Apart from offering a polarization diversity antenna, the orientation of antennas offers a reliable link with the communication devices. The prototype antenna array is fabricated and tested for diversity performance. The performance metrics such as envelope correlation coefficient, diversity gain, and mean effective gain under isotropic, indoor, and outdoor conditions are evaluated and presented. [ABSTRACT FROM AUTHOR]

This paper presents a miniaturized frequency selective surface (FSS) with stop band characteristics at the resonant frequency of 5.12 GHz. The unit cell size of the proposed FSS design is in the order of 0.095 λ×0.095 λ. The proposed unit cell is obtained by convoluting the arms of the basic swastika structure. The design provides fractional bandwidth of 9.0 % at the center frequency of 5.12 GHz in the 20 dB reference level of insertion loss. The symmetrical aspect of the design delivers identical response for both transverse electric (TE) and transverse magnetic (TM) modes thereby exhibiting polarization independent operation. The miniaturized design provides good angular independency for various incident angles. The dispersion analysis is done to substantiate the band stop operation of the convoluted swastika FSS. The proposed FSS is fabricated and its working is validated through measurements. [ABSTRACT FROM AUTHOR]

A low profile flexible linear to circular polarizer made of paper substrate is proposed in this paper. The polarizer is constructed from frequency selective surface (FSS) comprising of crossed dipole unit cell elements. The polarizer converts the linearly polarized incident electromagnetic wave to circular polarized wave at 7.0 GHz. The polarizer provides the advantage of use in conformal system, which is substantiated using bending analysis. The proposed reflective polarizer provides a 3 dB axial ratio bandwidth of 13% at the center frequency of 7.0 GHz. In addition, the proposed flexible polarizer provides stable response for angular incidences up to 30°. Prototype of the flexible FSS polarizer is fabricated and its simulation results are validated with experimental measurements. [ABSTRACT FROM AUTHOR]

A novel single layer miniaturized frequency selective surface made of circular unit cell elements is presented in this article. The frequency selective surface (FSS) unit cell measures 0.055λ0 × 0.055λ0, where λ0 corresponds to its free space wavelength. The proposed FSS offers band stop characteristics with bandwidth of 137.5 MHz centered at 1.39 GHz. The symmetrical structure of the unit cell elements provides polarization independency. The miniaturized unit cell elements help achieving angular independency for both TE and TM mode of polarization. The miniaturized design provides excellent angular independency with negligible frequency shift for varying incident angles. A prototype of the FSS is fabricated and its simulation results are validated using measurements. [ABSTRACT FROM AUTHOR]