Metamaterial based agile frequency selective surfaces

Abstract

In recent years new concepts in synthesis and novel fabrication techniques have allowed the construction of structures and composite materials that mimic known material resposes or that qualitatively have new, physically realizable response functions that do not occur or may not be readily available in nature. Electromagnetic metamaterials are broadly defined as artificial effectively homogeneous electromagnetic structures.An effectively homogeneous structure is a structure whose structural average cell size is much smaller than the guided wavelength (it shold be at least small than a quarter of wavelength). Designing spatial filters (frequency-selective surface) is an important application of metamaterial. Once exposed to the electromagnetic radiation, a frequency-selective surface (FSS) acts like a spatial filter, some frequency bands are transmitted and some are reflected. In a way, an FSS can be a cover for hiding communication facilities. This is probably the first potential application of FSS structures, as they have actually been used as covers named radomes.Radomes are bandpass FSS filters that are used to reduce the radar cross-section (RCS) of an antenna system outside it’s frequency band of operation. FSS characteristics control is a major objective of metamaterial use.The goal is to desing agile FSS, of which it is possible to change the characteristics using an external active control system. We are interested in this thesis, with the FSS agility. The agility is introduced by using agile metamaterials which allow one to adjust the electromagnetic response in real time. this turning ability helps make metamaterial devices more versatile, adapting to shifting input or changing target parameters. Bibliography : [1]C.caloz T.Itoh, «Transmission Line Theory And Microwave Applications :the engineering Approach»,A john Wiley & Sons, inc.,publication,2006 [2]A.K.Sarychev, V.M. Shalaev, « Electrodynamics Of Metamaterials » World Scientific Publishing Co.Pte.Ltd.2007 [3]N.Engheta, R.W. Ziolkowski « Metamaterials : Physics and Engineering Explorations », A JOHN WILEY & SONS, INC.,Publishing, 2008