Magnetic Tuning of Resonant Cavities and Wideband Frequency Modulation of Klystrons

General expressions are obtained for the perturbation of transmission cavities at microwave frequencies by the magnetic properties of ferrites. Experimental results are given for a number of ferrite slabs and magnetic field orientations. The frequency shift of the cavities is given for the range of magnetic field strength from 0 to 1,000 oersteds and slab thicknesses of 0.010 to 0.100 inch. The microwave permeability of a ferrite in the direction of the applied magnetic field is also determined. Two magnetically-tuned x-band klystrons are described for applications requiring very wide-band frequency modulation with low amplitude modulation. Linear frequency deviations as large as 240 mc are obtained with only 13 per cent change in amplitude. This deviation can be extended by proper magnet design.