The scattering from a thin PEC cylinder is solved by means of a semi-analytical method. In azimuth, the surface current is expanded into a standard Fourier series, while an expansion into Chebyshev polynomials is used in the longitudinal direction. For an, in principle, arbitrary incident electromagnetic field, the expansion coefficients are determined using a Galerkin method. The numerical part involves solving Sommerfeld type integrals in the spectral domain. Given the expansion coefficients, analytical expressions for the scattered fields are derived. Numerical results are compared with the wire antenna with midpoint delta-gap feeding, and for plane wave illumination. Extensions to cylinders with surface resistance and multiple section cylinders are presented.

A mode-matching formulation is presented and used to analyze the dispersion properties of twist-symmetric transmission lines. The structures are coaxial lines periodically loaded with infinitely thin screens, which are rotated with respect to each other to possess twist symmetry. The results obtained using the proposed formulation are in good agreement with those of commercial simulators. Furthermore, using the presented mode-matching formulation, it is demonstrated that the propagation characteristics in the twist-symmetric structures are linked to the scattering and coupling of the higher order modes. The physical insight offered by this analysis is valuable for the design of various electromagnetic devices, such as filters, antennas, and phase-shifters.

This paper studies the propagation characteristics in twist-symmetric structures by means of a mode-matching approach. The studied structures are coaxial transmission lines periodically loaded with 1- and 3-fold twist-symmetric infinitely thin sectorial sheets. The mode-matching formulation is validated with the commercial software CST Microwave Studio. In addition, the impact of adding twist symmetry to a coaxial line on the coupling of the higher order TM modes is discussed.

The new discovery of the extraordinary properties of meta-surfaces possessing higher symmetries is encouraging new studies to better understand the fundamental role of the symmetry, as well as to produce efficient numerical methods for enabling a fast optimization. Here, we propose a mode matching technique to explain the operation of glide-symmetric fully-metallic surface made of holes of arbitrary shape. The mode-matching is formulated to take into account the glide symmetry of the unit cell and isolate its impact. This formulation leads to a reduction of the computational domain to a half cell, and to derive the symmetry properties of the modal fields propagating in the metasurface. Numerical results from commercial software are employed to validate our method.

Twist symmetry provides an additional degree of freedom to control the wave propagation in periodic structures. However, real twist-symmetric structures are cylindrical structures that have a high cost of manufacturing. In addition, they are not compatible with the available, low-cost and flat technologies, such as microstrip technology. Here, we investigate the possibility of mimicking the dispersion properties of twist symmetry in flat structures.

The wave propagation along a plasmonic holey metasurface when a metallic plate is located in its proximity has been analyzed using a mode matching technique. With this analysis, we demonstrate that decreasing the distance between the metallic plate and the holey surface excites nonresonant higher order modes in the structure. Therefore, considering only the dominant mode inside the holes, as the previous simpler models assumed, is not sufficient to analyze this type of metasurfaces.

In this letter, wave propagation in 2-D doubled corrugated metasurfaces, including glide-symmetric corrugated metasurfaces, embedded in a thin parallel plate waveguide have been analyzed using the mode matching method. The general dispersion equation for propagation at different directions is derived and dispersion surfaces have been obtained for three different cases. The results are in good agreement with reference results obtained using CST Microwave Studio. Moreover, the method is accurate and computationally much faster than CST Microwave Studio and similar commercial software.

We consider the inverse problem of reconstructing the shape of a deformation in one of the broad walls of a rectangular waveguide. Assuming a small deformation, resulting in weak scattering, the direct problem is solved using a first order perturbation approach. Hence, the inverse problem becomes linear and is formulated as an equation system for a set of expansion coefficients. The illposedness of the inverse problem is handled with regularization, by adding a penalty term which weight is determined by the L-curve method. The theory is tested on experimental reflection data, using the dominant mode of the waveguide. The reconstructed shape is in qualitative agreement with the true shape, but a detailed resolution cannot be obtained due to insufficient quality of the experimental data. Extensions and improvements of the method are discussed.

New high-frequency 5G and satellite communication systems require fully-metallic antennas and electromagnetic components. These components can be implemented with truncated versions of periodic structures. In order to achieve the desired performance of these future devices, it is of crucial importance to have a precise control of the propagation properties, i.e. the frequency dispersion behavior and stop-bands. Here, we demonstrate the potential use of higher symmetries to diminish the frequency dispersion of periodic structures and control the width of stop-bands with a new type of fully-metallic transmission line, which is loaded with holes on a twist-symmetric configuration. Simulated and experimental results confirm the intrinsic link between the propagation characteristics and the symmetries of a periodic structure. Additionally, we provide a definitive explanation of the recently discovered polar glide symmetry and its potential combination with twist symmetries to produce low-dispersive materials and reconfigurable stop-bands. The promising properties of these structures are demonstrated with a fully-metallic reconfigurable filter, which could be used for future high-frequency 5G and satellite communication systems.

The mode matching method for analysing two dimensional doubled corrugated metasurfaces, including glide-symmetric corrugated metasurfaces, embedded in a thin parallel plate waveguide is presented. This method is accurate, fast, and without any limitations on the parameters.