An -band ferrite coaxial line modulator

A new L-band modulator is described which utilizes low saturation magnetization ferrites to achieve a high percentage modulation over an eight per cent bandwidth. The device is designed in 7/8" coaxial line and modulation is effected by alternately biasing the ferrite element into-and away from-gyromagnetic resonance using a longitudinally applied magnetic field. The ferrite element is a thin walled tube of ferrite aluminate located concentrically on the coaxial line center conductor. Its saturation magnetization is such that operation is from zero field to resonance. Two concentrically wound coils are used to independently achieve ferrite biasing at the midpoint of the resonance curve and to achieve amplitude modulation. Design theory leading to the development of the modulator is presented. Information is likewise included on the pertinent physical and electrical characteristics of the modulator.