Shock front development in ferrite-loaded coaxial lines with axial bias

Application of an axial magnetic field to ferrite-loaded coaxial lines used as pulse sharpening elements is found experimentally to reduce leading edge shock front rise-times to 100-200 ps. The paper presents a novel physical model for axially biased lines. The 3-D gyromagnetic magnetisation equations for the ferrite are coupled with TEM-mode transmission-line equations in the time domain. The role of induced radial and axial magnetic field components in the magnetisation and shock front propagation process is outlined. Predicted and experimental results are compared for lines using both MgMn and NiZn ferrite types. General characteristics of axially biased ferrite lines are explored using the model