An Analytical Study of Electromagnetic Deep Penetration Conditions and Implications in Lossy Media through Inhomogeneous Waves.

Paolo Baccarelli,Nicola Tedeschi,Fabrizio Frezza,Patrizio Simeoni

doi:10.3390/ma11091595

Paolo Baccarelli, Nicola Tedeschi + Show 2 more

Open Access

https://doi.org/10.3390/ma11091595

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Abstract

This paper illustrates how the penetration of electromagnetic waves in lossy media strongly depends on the waveform and not only on the media involved. In particular, the so-called inhomogeneous plane waves are compared against homogeneous plane waves illustrating how the first ones can generate deep penetration effects. Moreover, the paper provides examples showing how such waves may be practically generated. The approach taken here is analytical and it concentrates on the deep penetration conditions obtained by means of incident inhomogeneous plane waves incoming from a lossless medium and impinging on a lossy medium. Both conditions and constraints that the waveforms need to possess to achieve deep penetration are analysed. Some results are finally validated through numerical computations. The theory presented here is of interest in view of a practical implementation of the deep penetration effect.

Highlights

The achievement of electromagnetic deep penetration is of extreme importance in many applications, e.g., detection of buried or immersed objects, information transmission in lossy media, material analysis and microscopy, and interaction with biological tissues
Based on the preliminary results presented in [7], the analysis performed in this paper provides a complete description of the deep penetration phenomenon by means of inhomogeneous plane waves at the planar boundary between a lossless medium and a lossy one
We are going to demonstrate that only one direction of the attenuation vector of the incident wave allows for deep penetration, and the one corresponding to the angle +90◦; the other solution, i.e., relevant to the angle −90◦, produces, instead, an attenuated transmitted wave

Summary

Introduction

The achievement of electromagnetic deep penetration is of extreme importance in many applications, e.g., detection of buried or immersed objects, information transmission in lossy media, material analysis and microscopy, and interaction with biological tissues. A variety of techniques are commonly employed to improve the penetration, depending on the field of application, which, in turn, is strongly dependent on both the frequencies and the media involved. An alternative approach may consist of improving penetration by designing structures able to generate inhomogeneous plane waves with specific properties that will be discussed here. This approach could lead to an increase in penetration without reducing frequency, and, resolution [5,6]. Based on the preliminary results presented in [7], the analysis performed in this paper provides a complete description of the deep penetration phenomenon by means of inhomogeneous plane waves at the planar boundary between a lossless medium and a lossy one.

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