High power dual mode coupled-cavity TWT

The purpose of this work was to develop a gridded, dual-mode amplifier TWT suitable for the output tube of a multimode airborne radar. The required 10:1 power ratio in the two modes was achieved in the tube design at the maximum drive available of 1 watt. The PPM-focused tube was designed with the use of a computer program which calculates gain, stability, and efficiency of coupled-cavity TWTs. The measured results from the tube agree very closely with the analysis and demonstrate the value of being able to accurately calculate coupled-cavity TWT performance. A comparison of the calculated and measured results for the dual-mode TWT is presented.