Traveling-Wave Harmonic Generation Along Nonlinear Transmission Lines

Abstract

A perturbation solution is developed for determining the steady-state response of nonlinear TEM transmission lines and nonlinear cylindrical waveguides of arbitrary cross section. The nonlinear medium which is considered in this analysis is comprised of both nonlinear reactance and nonlinear resistance; and can be physically realized in the ferroelectric ceramic material composed of 73% BaTiO3 and 27% SrTiO3. From the results of the perturbation analysis and the known large signal microwave characteristics of this material, the properties of traveling-wave harmonic generation in ferroelectric ceramics are investigated. To assess the characteristics of ferroelectric traveling-wave harmonic generators, an example is worked out for an S-band rectangular waveguide completely filled with the above mentioned ceramic and excited in the TE10 mode at the fundamental frequency of 3 kMc. The predicted behavior of this device is then compared with the experimental characteristics of a cavity-type ferroelectric harmonic generator in order to determine the advantages and disadvantages of each type of device. The comparison brings out the superiority of the resonant system and indicates ways of improving the distributed system. Finally, based upon the treatment of the waveguide problem, the processes of frequency and mode conversion in nonlinear waveguides are discussed, both in general and with regard to the example of the rectangular guide.