The wire medium is a type of complex artificial material we conceptually envision as many identical finitelength, parallel, thin wire inclusions embedded within a host medium. It is representative of a class of novel artificial materials characterized by long thin inclusions. Unlike some conventional artificial material, the inclusions of this class are not necessarily electrically short. Here, we present our theoretical analysis for wire media and by studying certain salient features of plane-wave propagation through these media, introduce equivalent medium parameters that depend, among other parameters, on the direction of wave propagation. The approach we use separates the artificial material into its elementary planes and then uses periodic moment method techniques to individually characterize each elementary plane. Analytic formulas from periodic structure theory are then used to determine the effective wavenumber for the overall medium and the transverse impedance at the midpoint between adjacent elementary planes. Our examples show that some realizations of these media are spatially dispersive and may exhibit interesting features such as "angular windows of propagation" and other properties that are dependent on the polarization, frequency and direction of wave propagation. Disciplines Electrical and Computer Engineering AbstractThe wire medium is a type of complex artificial material we conceptually envision as many identical finite-length, parallel, thin wire inclusions embedded within a host medium. It is representative of a class of novel artificial materials characterized by long thin inclusions. Unlike some conventional artificial material, the inclusions of this class are not necessarily electrically short. Here we present our theoretical analysis for wire media and, by studying certain salient features of plane wave propagation through these media, introduce equivalent medium parameters that depend, among other parameters, on the direction of wave propagation. The approach we use separates the artificial material into its elementary planes and then uses periodic moment method techniques to individually characterize each elementary plane. Analytic formulas from periodic structure theory are then used to determine the effective wavenumber for the overall medium and the transverse impedance at the midpoint between adjacent elementary planes.Our examples show that some realizations of these media are spatially dispersive and may exhibit interesting features such as "angular windows of propagation" and other properties that are dependent on the polarization, frequency, and direction of wave propagation.

In this paper, an idea for a new class of complex media that we name feedforward-feedbackward (FFFB) media is presented and some of the results of our theoretical work in analyzing plane wave propagation in the axial direction through these media are described. The concept of FFFB media, as introduced here, was inspired by the theoretical research of Saadoun and Engheta on a variation of artificial chiral media. Like chiral media, to our knowledge there are no naturally occurring FFFB media for the microwave frequency band; for this reason we introduce an idea for artificial FFFB media. The focus of this paper is on one conceptualization of such media, namely dipole-dipole FFFB media. First, we present the calculation of the necessary constitutive parameters for studying axial plane wave propagation. Then we solve the macroscopic Maxwell equations in the k domain for axial plane wave propagation in an unbounded source-free crossed-dipole FFFB medium. Finally, we present the dispersion equation for this medium in this case, discuss some of the physical properties of its roots and certain features of the polarization eigenstates, and briefly speculate some of the potential applications of this medium.