Operation analysis of a novel concept of RF source known as gyromagnetic line

Gyromagnetic nonlinear transmission lines are interesting new devices used for RF generation since they are all solid state, lightweight and compact, neither requiring vacuum nor thermionic filament as in electronic tubes. Experiments with these lines have demonstrated their successful operation at L and S bands, thereby enabling them for applications in UWB pulsed radars in space vehicles and defense systems. There is also a great interest in compact solid-state high-power microwave sources for applications in small defense platforms (boats, trucks, etc.) to destroy the enemy electronic systems. Although the operation of these devices has been demonstrated exhaustively in recent years, their working principle is not quite well understood so far as it has been expected that the precession of the magnetic dipoles in the ferrite material given by the Larmor frequency, which predicts a proportional increase with the magnetic field bias. However, as observed experimentally the opposite occurs and the frequency decreases with the increasing of the magnetic field applied. Thus, the objective of this paper is to address this problem using the Landau-Lifshitz-Gilbert (LLG) equation with boundary conditions on the TEM mode propagation in the coaxial line. The formulation obtained for the precession frequency will be used to compare with experimental data found in the literature.