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Based on the transmission-line code, a 1-D circuit model for the transmission-line impedance transformer with an arbitrary impedance profile is developed, and the simulation results are compared with those of the existing literatures. By using this model, the power efficiencies and pulse compression ratios of the transformers (with Gaussian, exponential, and linear impedance profiles) were quantified as functions of Ψ (the ratio of the output impedance to the input impedance of the transformers) and Γ (the ratio of the pulsewidth to the one-way transit time of the transformers). The simulation results indicate that the exponential transformers have the maximum power efficiencies and pulse compression ratios. However, in the limit h <; 0.05 (where h is the Gaussian parameter), the Gaussian transformers almost have the same power efficiencies and pulse compression ratios as the exponential ones. Finally, the performances of a radial transformer line in smoothing the arrival time variations in the forward-going power pulses were studied. The simulation results show that, for the cases considered, the rise time (0-1.0) of the output pulse is prolonged by about half of the maximum difference in the time at which the pulses are launched, and the reduction of the peak output power is less than 2% when the maximum difference is 30 ns.
Date of Publication: Nov. 2011