Novel Passive and Active Transmission Line Metamaterial Devices
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0919-J02-03
Novel Passive and Active Transmission Line Metamaterial Devices Christophe Caloz Electrical Engineering, École Polytechnique de Montréal, 2500, ch. de Polytechnique, Montreal, Québec, H3T 1J4, Canada
ABSTRACT This paper presents a number of metamaterial (MTM) structures and devices, with emphasis on the so-called transmission line (TL) MTMs, which have lead to most practical applications so far. Both results obtained from 2002 to mid-2005 [1] and recent advances over the past few months are described. INTRODUCTION The fact that electromagnetic metamaterials (MTMs) [1,2] constitute a new field in science and technology is largely recognized today. After only six years from their first experimental demonstration, they have generated to over 2000 publications (including in around 10 special issues), they occupy an important position in all major conferences on electromagnetics, and have drawn the attention of the entire scientific community. Beyond the academic arena, many companies, forseeing in MTMs the potential for a novel generation of microwave and optical devices, have started to show strong interest and motivation for investment in this new direction. MTMs are artificial electromagnetic effective (i.e. electromagnetically uniform) structures exhibiting interesting and useful properties not readily available in nature. They include, lefthanded (LH) or negative refractive index (NRI) MTMs, but are not restricted to these media. Any artificial effective structure with exotic properties (e.g. artificial magnetism in the THz/optics) can be termed MTM. In the opinion of the author, structures designed to operate in the Bragg-regime (e.g. photonic crystals) should not be called MTMs, although this is commonly done, because Bragg structures are not effective, and have been known from Newton and Brillouin under the simpler and more convenient name of periodic structures. Today’s MTMs may be classified in two categories, resonant-type (thin-wire / split ring resonator structures) and TL-type MTMs. While the former have been more popular in the physics community, the latter have lead to a larger range of practical applications; the present paper deals mostly with them. Resonant-type and TL-type MTMs are related in several ways and share many physical phenomena. TRANSMISSION LINE (TL) METAMATERIALS (MTMs) TL-MTMs [1] originated in 2002 from the simple observation that a hypothetical transmission line with series capacitance and shunt inductance would result into a propagation medium with negative propagation constant or, equivalently, anti-parallel phase and group velocities, which are the attributes of a LH or NRI medium. It was later realized that naturally
right-handed (RH) parasitic were also necessarily present and contributed to the overall response of a TL medium in a very significant and interesting manner. This gave raise to the concept of composite right/left-handed (CRLH) MTMs, which has lead to wealth of novel electromagnetic concepts and applications [1].
MONO-DIMENSIONAL STRUCTURES, PASSIVE F
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