A linear phase shifter using cyclotron waves

A new phase shifter is described which provides wide-angle phase modulation at UHF and microwave frequencies. Suitable for modulation rates from DC to VHF, it achieves phase excursions up to several cycles with excellent linearity. The device is a simple electron beam tube. Fast cyclotron waves are impressed upon a beam by an input coupler and extracted by an output coupler. Between these two elements the beam passes through a tiny solenoid mounted inside the envelope. Control current in this solenoid generates a local magnetic field which adds algebraically to a uniform magnetic field applied externally. Output phase varies linearly with control current.