Enhancement of Bandwidth of an Extended Interaction Klystron by Symmetric Loading

A novel technique was developed for broadbanding of the interaction structure of an extended interaction klystron (EIK) through symmetric loading of the top and bottom shorting cavities while maintaining the periodicity of the ladder circuit the same. A 3-D electromagnetic analysis was carried out on a W -band structure in order to demonstrate the efficacy of the loading in broadbanding. The loading is found to marginally reduce the ohmic quality factor and the characteristic impedance of the structure. Measurements were also carried out on frequency scaled-down structures at X -band for validating the simulation. Symmetric stagger tuning of the circuit is facilitated through this loading and particle-in-cell analysis shows an enhancement in the 3-dB hot-bandwidth of the EIK by around 400% in comparison to an unloaded device.