Application of Azimuthal Prepolarization in GNLTL for High-Power RF Generation

The gyromagnetic nonlinear transmission line (GNLTL) is a compact, solid-state source of high-power microwaves (HPMs), consisting of a coaxial transmission line (TL) partially filled with ferrite material. The nonlinearity inherent in the material arises from the interaction between azimuthal and axial magnetic fields. In the present study, the influence of the azimuthal prepolarization field on GNLTL performance is investigated at different levels of axial magnetic field and input pulse amplitudes. It is shown that the azimuthal prepolarization field is not only added to the magnetic field created by the input pulse current but also premagnetizes the ferrite material, thereby altering the initial conditions for RF generation. In our experiments, the generated RF power rises with an increase in prepolarization current. When the axial magnetic field value is low and insufficient for the GNLTL operation, adding the azimuthal magnetic field enables the generation of RF oscillations at the output of the line, thereby expanding its operating mode. A mathematical model based on telegrapher’s equations and the Landau-Lifshitz–Gilbert equation for the GNLTL is used to interpret the obtained results. This work describes a new technique for increasing the generated RF power and expanding the operating mode of GNLTL.