Since their invention, negative-refractive-index (NRI) media have been plagued by three primary limitations: narrow bandwidth, high loss and polarization dependence. In this thesis, each of these problems is addressed. First, a new metamaterial topology that achieves negative permeability over a broad bandwidth is introduced. This structure is used to realize a broadband, volumetric NRI medium that is then thoroughly analyzed using multiconductor transmission line (MTL) theory. A homogenized, periodic form of MTL analysis is used to derive a simplified dispersion equation, as well as expressions for the Bloch impedance, permittivity and permeability for an infinite NRI medium.

The analytical methods are supported by both full-wave simulation and measured results. Two broadband NRI lenses are presented: one contained inside a waveguide and the other in free space. Both lenses exhibit super-resolving capabilities: the first at 2.45GHz and the second at 10.435GHz. The transmission and reflection coefficients of the free-space lens are measured using a quasioptical Gaussian beam telescope, and the material parameters of the lens are extracted for these measurements. This lens exhibits a negative index of refraction over a fractional bandwidth of 41.2%. The low-loss performance of this metamaterial lens is experimentally verified. The lens exhibits 0.17dB of loss per unit cell and a figure of merit (FOM = n'/n'') of 31.4 at the operating frequency of 10.435GHz. These properties allow the recovery of evanescent spatial frequencies over a bandwidth of 7.4%. Additionally, the measured focal pattern at the image plane of the lens is accurately predicted using the material parameters obtained from the transmission measurements.

A polarization-independent NRI medium is also reported. The design of this structure uses stereolithography and electroplating to complete the requisite three-dimensional fabrication on a large scale (more than 400 unit cells). The NRI bandwidth of this medium is 24%. A NRI lens that operates at 1.54GHz is designed and fabricated using this isotropic topology. At this frequency, the lens produced a super-resolved focus independent of the type of source and its polarization.