Implementation of the circuit showing the characteristics of the double negative materials

Abstract

In 1968, Veselago proposed the material that had simultaneously negative permittivity ε and permeability μ, which means ε < 0 and μ < 0 [1], and hence, this material has been called as double negative (DNG) material [2]. Veselago proved its unusual characteristics which does not exist in nature, such as a negative refractive index (NRI), negative wave vector k, negative group velocity v <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</inf> , left-handed set (k, E, H), backward-wave (k is anti-parallel to Poynting vector S), and negative group velocity v <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</inf> . After about three decades, periodic structures comprised of split-ring resonators [3] and conductive strips have been developed by Smith [4] and verified as having a NRI and negative group velocity within very narrow band around resonant frequency [5], but being lossy. Other approaches using series capacitors and shunt inductors (C-L configuration) [6] have been extensively studied by Itoh [7] and Eleftheriade's groups [8]. Theses C-L networks having NRI are broad band and low loss, but do not provide the negative group velocity of Veselago's DNG material, which is discussed later. Recently, Mojahedi's group [9] has proposed a transmission line made of the C-L configuration and the embedded RLC resonator circuits that has presented a NRI and negative group velocity, but heavily mismatched and lossy because of its embedded resistor.