Tunability Enhancement of Ku-Band Oscillator using Distributed Bragg Reflectors

It is possible to improve the tunability range of slow-wave structure oscillators with the use of distributed Bragg reflectors (DBRs). In this paper, an aperiodic DBR made of rectangular surface gratings is applied to a 16GHz (Ku-Band) sheet beam oscillator which previously did not exhibit good tunability when coupled with a single grating reflector. The device operates at the central frequency given an input current of 2.195kA and 178keV beam energy with an axial magnetic field of 1.02T. The designed peak power output is 145MW. The DBR geometry is optimized using CST Studio to achieve the desired reflectivity range. It is observed that the DBR improves the tunable frequency range by 2.85 times, i.e. increase from 350MHz to 1GHz while maintaining an output power of at least 40MW.