Operation of a Gyromagnetic Line at Low and High Voltages With Simultaneous Axial and Azimuthal Biases

A great interest has been devoted to the study of nonlinear transmission lines (NLTLs) for radio frequency (RF) generation since they have been used with great success in RF generation by producing a train of oscillatory waves along the line and at its output. There are two configurations of NLTLs. The first one is a dispersive line consisting of LC sections with nonlinear components, and the second one is a continuous ferrite loaded nondispersive line generally biased by an axial magnetic field, known as gyromagnetic line. In this paper, the focus of the study is on the second one, since gyromagnetic lines can operate in a broader frequency range (0.3-2.0 GHz) with higher conversion efficiency (20.0%) when compared to lumped NLTLs, generally limited up to 300 MHz with less than 10.0% of efficiency, because of their dielectric losses and stray impedances on line structure. Different models have been used along the years by several authors with different approaches to study the gyromagnetic phenomenon by means of numerical simulations based on analytical models to predict the precession movement of the electron magnetic dipole of the ferromagnetic material. Thus, the goal of this paper is to analyze the gyromagnetic NLTL behavior through the effects on the line operation. The novelty herein is to use two biases simultaneously to study continuous gyromagnetic NLTLs, focusing on the pulse rise time compression and RF generation caused by the precession of the magnetic dipole. An experimental setup is described and tested for low- and high-voltage operation for a 20-cm gyromagnetic line loaded with NiZn ferrite beads. The novelty of this paper is to use two biases simultaneously to study continuous gyromagnetic NLTLs, such techniques can be useful in the design of continuous lines for RF applications in space and mobile defense platforms of compact size.