Abstract
Metallic strip gratings (MSG) have different applications, ranging from printed circuits to filters in microwave domains. When they are under the influence of an electromagnetic field, evanescent and/or abnormal modes appear in the region between the traces, their utilization leading to the development of new electromagnetic nondestructive evaluation methods. This paper studies the behavior of MSGs in the sub-subwavelength regime when they are excited with TEz or TMz polarized plane waves and the slits are filled with different dielectrics. The appearance of propagating, evanescent and abnormal modes is emphasized using an electromagnetic sensor with metamaterials lens realized with two conical Swiss rolls, which allows the extraction of the information carried by the guided evanescent waves. The evanescent waves, manipulated by the electromagnetic sensor with metamaterial lenses, improve the electromagnetic images so that a better spatial resolution is obtained, exceeding the limit imposed by diffraction. Their theoretical and experimental confirmation opens the perspective for development of new types of sensors working in radio and microwave frequencies.
Highlights
The metal strip grating is a periodic planar arrangement of parallel metal strips with infinite length and infinitesimal thickness
This paper proposes a theoretical and experimental study of the eigenmodes that appear in a metallic strip grating having thick metallic strips from silver, operating in sub-subwavelength regime; this implies the constant of strip grating much smaller than the wavelength of incident electromagnetic field
The case of a metallic strip grating made from silver strips having 10 μm thickness, the width of strips being xm = 0.6 mm and the width of slits being xd = 0.4 mm is analyzed, considering that the wavelength of the incident field is = 0.6 m
Summary
The metal strip grating is a periodic planar arrangement of parallel metal strips with infinite length and infinitesimal thickness. This paper proposes a theoretical and experimental study of the eigenmodes that appear in a metallic strip grating having thick metallic strips from silver, operating in sub-subwavelength regime; this implies the constant of strip grating much smaller than the wavelength of incident electromagnetic field This approach is new for stratified structures (MSG, dielectrics and metamaterials) in subwavelength regime and can be integrated into a new class of sensors with performances able to open new domains of applications in electromagnetic evaluation of composite and nanocomposite materials. Both TEz and TMz polarized plane waves are used as incident to metallic strip grating. A good agreement between theoretical and the experimental results is found
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