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We report on a negative-zero-positive metamaterial based on an omega-type microstructure with special attention on the nonvanishing group velocity for a zero refractive index. We first investigate the dispersion characteristics by full wave analysis, by stressing the necessary conditions of equality between the electric and magnetic plasma frequencies which are characteristic of the dispersion of the effective permittivity and permeability. Also, tuning of the gapless transition frequency between the left and right-handed dispersion branches was analyzed when the permittivity of the host substrate is changed. Last, we demonstrate experimentally the balanced composite character of the dispersion by frequency and angle-resolved transmission measurements, carried out at centimeter wavelengths on slabs and wedge-type prototypes, respectively.

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The phase noise generated by a FET device is investigated using transmission and reflection residual phase noise measurements. This approach helps in locating, in the intrinsic device, the low frequency noise sources which are responsible for these phase fluctuations. On the basis of these experiments, a new nonlinear noise model of the FET is proposed. This model is able to describe a phenomenon that has been observed, but never modeled in the past: the dependence of the baseband noise on the microwave input power.