Abstract-Volumetric left-handed metamaterials made up of an array of split-ring resonators (SRRs) and wires exhibit negative index of refraction in a very narrow bandwidth due to the resonant nature of SRRs. We investigate the possible bandwidth enhancement by adding resonances to the system using fractals. The operating bandwidth of the system is increased when the additional resonances are placed close enough to each other. The Sierpiński-carpet fractal pattern is chosen as the distribution for the SRRs. The principle is demonstrated through simulations, and prototypes are fabricated and tested to verify consistency with simulations.

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The design and implementation of a 120 GHz monostatic tracking interferometer with near diffraction limited focal spot size, used to measure line-averaged plasma density in the source of a plasma opening switch (POS), is described. Physical dimensions of the switch source place an upper limit on the focal spot size. Focusing quasioptics utilize a standard pyramidal horn and a pair of cylindrical lenses that are easily fabricated. The combination of the two cylindrical lenses transforms the asymmetric and approximately Gaussian beam produced by the pyramidal horn into a small focal spot. The circuit utilizes a tracking receiver configuration to track oscillator frequency drifts, which allow for full heterodyne quadrature operation, while avoiding the added complexity of phase or frequency locking of the sources. In order to reduce system noise in the POS pulsed power environment, all sources and amplifiers are battery powered and other noise-reducing techniques are employed. Finally, an improved Gaussian optics design methodology, which tracks the phase center of the Gaussian beam, is proposed. While not critical to this application, this method may yield improvements in systems with short focal lengths.

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