Some Advances in the Circuit Modeling of Extraordinary Optical Transmission

The phenomenon of extraordinary optical transmission (EOT) through electrically small holes perforated on opaque metal screens has been a hot topic in the optics community for more than one decade. This experimentally observed frequency-selective enhanced transmission of electromagnetic power through holes, for which classical Bethe\'s theory predicts very poor transmission, later attracted the attention of engineers working on microwave engineering or applied electromagnetics. Extraordinary transmission was first linked to the plasma-like behavior of metals at optical frequencies. However, the primary role played by the periodicity of the distribution of holes was soon made evident, in such a way that extraordinary transmission was disconnected from the particular behavior of metals at optical frequencies. Indeed, the same phenomenon has been observed in the microwave and millimeter wave regime, for instance. Nowadays, the most commonly accepted theory explains EOT in terms of the interaction of the impinging plane wave with the surface plasmon-polariton-Bloch waves (SPP-Bloch) supported by the periodically perforated plate. The authors of this paper have recently proposed an alternative model whose details will be briefly summarized here. A parametric study of the predictions of the model and some new potential extensions will be reported to provide additional insight

Equivalent Circuit for Double Annular Aperture Frequency Selective Surfaces

In this work a double annular aperture frequency selective surface is analyzed from an equivalent circuit perspective. A comparison between full wave numerical solution and the proposed equivalent circuit results is provided for different examples. A very good agreement is obtained endowing the equivalent circuit with great potential as a very powerful and efficient design tool for advanced space filters

Application of the array scanning method to 1D periodic microstrip lines

The Array Scanning Method (ASM) is employed to analyze the excitation of 1Dperiodic microstrip lines by a nonperiodic source. It should be noted that the nonperiodic nature of the source preclude the direct application of the Floquet’s theorem. However, a combination of the ASM with the Method of Moments allows for the computation of the current density launched on the line. Some results are presented showing the current excited by a delta-gap voltage source at frequencies corresponding to passband as well as to stopband regimes of the periodic microstrip line

Fast numerical analysis of a 1D array of microstrip patches

This paper compares between different efficient and accurate techniques for the numerical analysis of a 1D periodic printed structure with the method of moments (MoM). Both a hybrid spatial/spectral and a purely spectral approach are examined, the former via the discrete complex image technique (DCIT) and the latter through suitable asymptotic extractions and numerical acceleration schemes. These fast formulations are particularly suitable for studying the excitation of the considered structure by a-periodic sources via the array-scanning method (ASM) in the work of Munk and Burrell (1979). As is known, the ASM requires as intermediate steps the solution of many Floquet-periodic problems, which can be efficiently treated with the proposed MoM approaches

Efficient hybrid full-wave/circuital approach for stacks of frequency selective surfaces

International audienceThis letter shows an efficient hybrid method to study stacks of identical frequency selective surfaces (FSSs) separated by possibly different dielectrics. The method takes advantage of the ability of the equivalent circuit approach to create a Π-network for a pair of coupled FSSs and combines it with full-wave simulations involving a single FSS. This way, the solution of the complete problem of N stacked surfaces only involves full-wave simulations of a single periodic layer. Three scenarios have to be simulated where the surface is either standalone, or backed by perfect electric or perfect magnetic conductors. The proposed approach is validated through the analysis of several examples. © 2002-2011 IEEE

Circuit-model approach for polarizing surfaces based on stacked meander-line gratings

International audienceThis manuscript reports the design of polarizers consisting of stacks of several meander-line gratings for axial-ratio enhancement. Analysis and design are carried out with analytical equivalent circuits that fully characterize periodic meander-line architectures. The advantage of using the analytical equivalent-circuit approach lies on its accuracy as well as in the better physical insight of the structure's behavior provided by this approach. Extension to the case of oblique incidence is also carried out. Comparisons between results obtained by a commercial software and by the circuit model will evidence the good accuracy of the proposed approach. © Institution of Engineering and Technology.All Rights Reserved

Annular Apertures in Metallic Screens as Extraordinary Transmission and Frequency Selective Surface Structures

A 2-D periodic array of annular apertures (or ring slots) is studied using an accurate circuit model. The model accounts for distributed and dynamic effects associated with the excitation of high-order modes operating above or below cutoff but not far from their cutoff frequencies. This paper allows to ascertain the substantial differences of the underlying physics when this structure operates as a classical frequency selective surface or in the extraordinary-transmission (ET) regime. A discussion of two different designs working at each regime is provided by means of the equivalent circuit approach (ECA), full wave simulation results, and experimental characterization. The agreement between the equivalent circuit calculation applied here and the simulation and experimental results is very good in all the considered cases. This validates the ECA as an efficient minimal-order model and a low computational-cost design tool for frequency selective surfaces and ET-based devices. Additional scenarios such as oblique incidence and parametric studies of the structural geometry are also considered

Efficient network representation of grounded patch-based FSS

The disposal of an equivalent network representation to characterize the frequency behavior of grounded periodic arrays of printed patches is here combined with the assistance of full-wave electromagnetic simulator to achieve a very efficient method for analysis/design. The basic restriction of the present procedure is that the frequency band cannot be extended much beyond the first fundamental resonant frequency of the scatterer. Although this limitation can be important in some cases, it covers a great number of practical situations. © 2014 European Association on Antennas and Propagation