Microwave Investigation of Constitutive Electromagnetic Parameters of Some Left-Handed Structures M. G. Banciu, A. Ioachim Group of Physics of High Frequency Materials and Devices National Institute of Materials Physics Magurele, Jud. Ilfov, Romania gbanciu@infim.ro I. A. Mihai, N. Militaru, G. Lojewski Department of Communications, Faculty of Electronics, Telecommunications and Information Technology University POLITEHNICA of Bucharest Bucharest, Romania george.lojewski@munde.pub.ro Abstract—Microstrip structures with left-handed properties are investigated in time and frequency domain. A method of extracting material effective parameters from the two-port scattering parameters is developed and applied to the proposed left-handed structures. Keywords-left-handed materials, microstrip, constitutive parameters. I. INTRODUCTION Recent researches showed that interaction of the electromagnetic waves with artificial structured materials having such electromagnetic parameters as electrical permittivity, magnetic permeability, refraction index taking negative values, leads to exotic phenomena as negative Doppler shift, reversed Cerenkov effect, growing of the evanescent waves or the negative refraction, etc. [1-3]. The super-lens made of such artificial material focus both the propagating and evanescent components of the electromagnetic waves and enables sharper, subwavelength size imaging [4]. The anti-parallelism of phase and group velocities is another interesting physical phenomenon of such structured materials. One of the practical applications of these features allows the control of the signal phase and of the dispersion characteristics in telecommunications systems. II. PULSE PROPAGATION Let us consider the propagation of a TEM Gaussian pulse through a 20 mm thick material sample. When the sample is of a conventional material with positive relative electric permittivity ε r and relative magnetic permeability μ r , the transmitted and reflected signals are sums of undistorted multiple delayed replicas of the Gaussian pulse (Fig. 1). When ε r = 3 and μ r = 1, the first reflected pulse has a negative sign, compared to the initial pulse. On the contrary, for ε r = 1 and μ r = 6, the first reflected pulse has the same sign as the initial pulse. It can be observed that, after 1.6 ns, the amplitude of the transmitted and reflected signals can be neglected. Figure 1. Pulse propagation through a conventional material: a) input Gaussian pulse; b) output signal for εr = 3 and μr = 1; c) reflected signal for εr = 3 and μr = 1; d) output signal for εr = 1 and μr = 6; e) reflected signal for εr = 1 and μr = 6. Figure 2. Magnitude of scattering parameters of a two-port with conventional material: a)|S21| for εr = 3 and μr = 1; b) |S11| for εr = 3 and μr = 1; c) |S21| for εr = 1 and μr = 6; d) |S11| for εr = 1 and μr = 6.