Jerusalem Cross Frequency Selective Surface Research Articles

PEEC Model Based on a Novel Quasi-Static Green's Function for Two-Dimensional Periodic Structures

A quasi-static periodic Green's function (PGF) is proposed for modeling and designing metasurfaces in the form of two-dimensional (2D) periodic structures. By introducing a novel quasi-static approximation on the full-wave PGF in the spectrum domain, the quasi-static PGF is derived that can retain the contribution from propagating and evanescent modes below resonant frequency by a second-order polynomial of frequency. Unlike full-wave PGF, the proposed quasi-static PGF polynomial coefficients are frequency-invariant. Consequently, it can save the modeling time significantly by calculating the coefficients only once for a frequency band of interest. Moreover, a quasi-static PEEC model is developed from the proposed quasi-static PGF. It circumvents the breakdown problem around near-zero frequencies since the singularity in PGF is separated in the quasi-static PGF and eliminated analytically in model development. Therefore, both the time- and frequency-domain analysis can be conducted easily using a SPICE-like solver on the PEEC model. Two examples are given, one of which validates the accuracy of the proposed quasi-static PGF in a 2D periodic unit cell working at 0–12 GHz; the other demonstrates the superior performance in terms of model efficiency and stability by a Jerusalem-cross frequency selective surface (FSS) working at 0–20 GHz. The numerical results show that the proposed method is accurate and efficient in a wide band for metasurfaces made of two-dimensional periodic structures.

Conformal Multifunction FSS With Enhanced Capacitance Loading for High Angle Stable Stopband Filtering and Microwave Absorption

This article presents a new method of enhancing the capacitance of a single-layer conformal frequency selective surface (FSS) for multifunctional operation. The unit cell of the FSS consists of gridded square loop-loaded modified Jerusalem cross (JC) element. End capacitance of the conventional JC FSS is enhanced by placing parallel diagonal strips, resulting in a pair of reflection zeros near the sidebands. The modified geometry provides high selective stopband filtering that reflects the signal at 20.16 GHz with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> < −10 dB stopband bandwidth of 20.52%. The FSS shows stable stopband reflection up to a high incidence angle of 85°. The stability in the filter response is also achieved at various conformal angles. The proposed FSS is optimized for dual-band near-perfect absorption. At two resonances 12.76 and 22.54 GHz, the absorption are 99.88% and 99.1%, respectively. Prototypes of the stopband FSS and the dual-band absorber are fabricated to verify the feasibility of the proposed concept. The measured filter and absorber responses are found consistent with the simulated results. As a conformal multifunctional structure, the proposed FSS has the merits of electromagnetic interference shielding and radar cross section reduction in stealth application.

A Graphene-Based Stopband FSS with Suppressed Mutual Coupling in Dielectric Resonator Antennas.

A novel stopband frequency-selective surface (FSS) made of high-conductivity graphene assemble films (HCGFs) for reducing the mutual coupling between dielectric resonator antennas (DRAs) is investigated and presented. The FSS is a “Hamburg” structure consisting of a two-layer HCGF and a one-layer dielectric substrate. A laser-engraving technology is applied to fabricate the FSS. The proposed improved Jerusalem cross FSS, compared with cross FSS and Jerusalem cross FSS, can effectively reduce the size of the unit cell by 88.89%. Moreover, the FSS, composing of 2 × 10-unit cells along the E-plane, is proposed and embedded between two DRAs, which nearly has no effect on the reflection coefficient of the antenna. However, the mutual coupling is reduced by more than 7 dB on average (7.16 dB at 3.4 GHz, 7.42 dB at 3.5 GHz, 7.71 dB at 3.6 GHz) with the FSS. The patterns of the antenna are also measured. Therefore, it is suggested that the proposed FSS is a good candidate to reduce mutual coupling in the multiple-input–multiple-output (MIMO) antenna system for 5G communication.

Design and Analysis of Fractal Based Monopole Antenna Backed with Modified Jerusalem Cross Frequency Selective Surface for Wireless Personal Area Communications

This paper presents a low profile Single-layer Modified Jerusalem Cross Frequency Selective Surface (SMJC FSS) which functions as a band-stop filter to shield the 2.45 GHz Industrial, Scientific and Medical (ISM) band with a unit cell size of 0.249λg × 0.249λg × 0.027λg. Compared to JC FSS, 50% size reduction is achieved by the effect of capacitive and inductive loading. The proposed FSS exhibits a fractional bandwidth of 14.69% and fractional bandwidth dimension ratio (FBDR) of 8775.4, which is one of the highest among the single layer FSS. The Koch curve inspired fractal monopole antenna is backed by 5 × 5 FSS array, which contributes enhanced gain and fractional bandwidth of 6.28 dB and 23.75% respectively and has a net dimension of 75 × 75mm ×31.2 mm. The specific absorption rate (SAR) is analyzed on human arm model where proposed antenna attains 0.183 W/Kg, which makes it appropriate for the application of body area communication. The measured results agree well with the simulated results and hence it is validated for wireless personal area communications in the ISM band at 2.45 GHz.

Multiband FSS with Fractal Characteristic Based on Jerusalem Cross Geometry

This paper proposes a new device with modifications on the Jerusalem Cross (JC) geometry to provide a multiband Frequency Selective Surface (FSS). Fractal iterations are created by introducing concentric self-similar JC copies in the original unit cell. This modification results in new dipoles at the structure which allows for the appearance of new bands proportional to these diploles' lengths, while maintaining total unit cell size. Four iterations of the JC FSS are studied in this paper. Simulation results for the insertion loss (S 21 ), surface current distribution and measurement results are presented.

Design and measurement of an EM composite material frequency selective surface in C band

An investigation of frequency selective surface made from composite material with cross and Jerusalem cross patches for C band application is presented. The design method selection and its basic theory for analysing the frequency selective surface are introduced. The simulated results from the simulation and measurement results of a designed frequency selective surface array obtained in an anechoic chamber are presented. Their comparison shows a good agreement. The designed composite material frequency selective surface presented in this paper has good electromagnetic characteristics. The 5 dB transmission bandwidth of a single layer cross frequency selective surface is 1 GHz. The double layer frequency selective surface has a better transmission bandwidth than the single one while the Jerusalem cross frequency selective surface design also performs well in terms of frequency responses.

A Quasi-Yagi Antenna Backed by a Jerusalem Cross Frequency Selective Surface

A quasi-Yagi antenna is developed to operate at 2.4 GHz (ISM band) presenting a low profile and off-axis radiation when packaged over a metal ground plane. The off-axis radiation is realized by incorporating a Jerusalem cross frequency selective surface (JC-FSS) as the ground plane for the antenna. A JC-FSS is preferred because of its frequency stability in the operating band for a large angular spectrum (≈70°) of TE- and TM-polarized incident waves. In this research, the substrate of the antenna flush-mounted on top of the FSS is added to the JC-FSS model and allows for a smaller cell grid. The prepared quasi-Yagi antenna over the JC-FSS offered 260 MHz of functional bandwidth and 54° of beam tilt towards the end-fire direction. To the best of the authors’ knowledge this is the first instance that these two structures are combined for off-axis radiation. Additionally, to support the preferred use of the JC-FSS, the quasi-Yagi is backed by a square patch (SP) FSS for comparison purposes.

The Analysis of Periodic Structures With 2-D-Staggered Grid by FDTD Algorithm

According to the characteristics of the periodic structures with 2-D-staggered grids, two new effective construction methods dealing with periodic boundaries based on the finite-difference time-domain (FDTD) algorithm are developed in this work. The two proposed staggered periodic boundary conditions (PBC) arrangement methods can be implemented combining the existing boundary data mapping techniques. Applying these arrangements, coordinate change and additional ladder boundary grids can be avoided during the modeling process, so that the simulation accuracy of the FDTD algorithm can be maintained. The performance and the applicable conditions of the two staggered PBC arrangement methods are discussed and compared with the common nonstaggered PBC arrangement method. The validity of the two staggered PBC arrangement methods is verified through the numerical examples of an infinite dielectric slab and Jerusalem cross frequency selective surface with 2-D-staggered girds.

A NOVEL AMC WITH LITTLE SENSITIVITY TO THE ANGLE OF INCIDENCE USING 2-LAYER JERUSALEM CROSS FSS

A novel artificial magnetic conductor (AMC), i.e., high- impedance surface (HIS), is proposed. The structure, which utilizes the well know Jerusalem Cross Frequency Selective Surface (JC-FSS), is a novel 3D AMC. It offers stable resonance frequency with respect to the incidence angle of both TE and TM-polarized plane waves, very compact size and acceptable bandwidth.