Abstract

A grounded wire-medium slab has recently been shown to support leaky modes with azimuthally independent propagation wavenumbers capable of radiating directive omnidirectional beams. In this paper, the analysis is generalized to wire-medium slabs in air, extending the omnidirectionality properties to even modes, performing a parametric analysis of leaky modes by varying the geometrical parameters of the wire-medium lattice, and showing that, in the long-wavelength regime, surface modes cannot be excited at the interface between the air and wire medium. The electric field excited at the air/wire-medium interface by a horizontal electric dipole parallel to the wires is also studied by deriving the relevant Green's function for the homogenized slab model. When the near field is dominated by a leaky mode, it is found to be azimuthally independent and almost perfectly linearly polarized. This result, which has not been previously observed in any other leaky-wave structure for a single leaky mode, is validated through full-wave moment-method simulations of an actual wire-medium slab with a finite size.

Highlights

  • THE 1-D wire medium consists of a periodic arrangement of thin perfectly conducting cylinders, infinitely long and parallel, embedded inside a homogeneous host dielectric medium

  • Known as a rodded medium, has been known since the 1950s to be described in the long-wavelength regime by a scalar permittivity with a plasmalike dispersion behavior for waves having the electric field polarized along the axis of the wires [1]

  • We consider the problem of modal excitation and propagation along a canonical planar waveguide, a slab in free space, made of a 1-D wire medium with wires parallel to the air–slab interfaces

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Summary

INTRODUCTION

THE 1-D wire medium consists of a periodic arrangement of thin perfectly conducting cylinders (wires), infinitely long and parallel, embedded inside a homogeneous host dielectric medium Such an artificial medium, known as a rodded medium, has been known since the 1950s to be described in the long-wavelength regime by a scalar permittivity with a plasmalike dispersion behavior for waves having the electric field polarized along the axis of the wires [1]. To consider the excitation of a dominant leaky mode by a horizontal dipole source parallel to the wires, and to study the properties of the resulting near field at the air–slab interface, adopting both a homogeneous model and a full-wave method of moments (MoM) approach.

Homogenized Medium
Modal Dispersion Equations and Surface-Wave Suppression
Electric Field at the Air–Slab Interface
FULL-WAVE MODAL ANALYSIS
Parametric Analysis of Leaky Modes
Findings
CONCLUSION

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