Analytical modeling and experimental verification of coupling between transmission lines in gap-waveguides

Modeling of gap-waveguide structures with single and multiple transmission lines is performed using spectral domain Green's functions approach. The approach is extended using even/odd mode analysis in order to also estimate the crosstalk levels between neighboring transmission lines. The results of this analysis are compared with the results of a commercial electromagnetic solver and with the measured results

Construction of Green's functions of parallel plates with periodic texture with application to gap waveguides - A plane wave spectral domain approach

This study presents Green's functions of parallel-plate structures, where one plate has a smooth conducting surface and the other an artificial surface realised by a one-dimensional or two-dimensional periodic metamaterial-type texture. The purpose of the periodic texture is to provide cut-off of the lowest order parallel-plate modes, thereby forcing electromagnetic energy to follow conducting ridges or strips, that is, to form a gap waveguide as recently introduced. The Green's functions are constructed by using the appropriate homogenised ideal or asymptotic boundary conditions in the plane-wave spectral domain, thereby avoiding the complexity of the Floquet-mode expansions. In the special case of a single ridge or strip, an additional numerical search for propagation constants is needed and performed in order to satisfy the boundary condition on the considered ridge or strip in the spatial domain. The results reveal the dispersion characteristics of the quasi-transverse electromagnetic modes that propagate along the ridges or strips, including their lower and upper cut-off frequencies, as well as the theoretical decay of the modal field in the transverse cut-off direction. This lateral decay shows values of 50-100 dB per wavelength for realisable geometries, indicating that the gap waveguide modes are extremely confined. The analytical formulas for the location of the stopband of the lowest order parallel-plate modes obtained by small-argument approximation of the dispersion equation are also shown. To verify the proposed analysis approach, the results are compared with the results obtained with a general electromagnetic solver showing very good agreement

Simple Boundary Condition for Canonical EBG Surface: PMC-Backed Uniaxial Medium

A simple-to-use replacement model for isotropic electromagnetic bandgap (EBG) surfaces such as mushroom surfaces is investigated. Properties of EBG surfaces strongly depend on the incidence angle of the incoming plane wave. The suggested model takes this behavior into account and actually represents the ideal EBG surface. The model is based on uniaxial representation of a thin DB layer backed by a perfect magnetic conductor (PMC) plate. We investigate how this model behaves in comparison with a realistic mushroom surface, and when it can be applied. The results show that the proposed model can be used for both far field calculations and antenna coupling evaluation

Evaluation of cross-coupling inside gap-waveguides

With the introduction of new transmission line technology called gap-waveguides it is necessary to develop analytical solutions for various interactions between lines and other elements within the structure. Here we focus on the interaction or cross-coupling between neighboring transmission lines as a first step towards the analysis of gap-waveguide fed aperture arrays. Analysis is performed in the spectral domain using the Green\u27s functions approach, with the crosstalk current on the unexcited (victim) transmission line calculated using even-odd transmission line approach. The analysis results are verified by comparison with measured results obtained from the developed prototype

Metasurfing: Addressing Waves on Impenetrable Metasurfaces

4nonenoneMaci S.; Minatti G.; Casaletti M.; Bosiljevac M.Maci, Stefano; Minatti, Gabriele; Casaletti, Massimiliano; Bosiljevac, M

Design considerations for implantable and wearable antennas

This contribution gives a review of our results characterizing the propagation in lossy biological tissues. These results were mainly obtained using a simplified spherical model allowing a description in spherical wave decomposition. This model is of course simple, but has the advantage of providing rapidly a deep insight in the main loss mechanisms linked to implanted or wearable antennas, and thus derive efficient design rules for BAN antennas