A single beam-driven dual-band transit-time oscillator based on harmonic operation

Dual-band high-power microwave (HPM) sources, combining the distinct advantages of different frequencies (e.g., penetration depth, energy deposition efficiency, and target coupling), are highly valuable for military, industrial, and scientific applications. However, existing dual-band HPM systems typically require complex setups with two separate electron beams, posing significant challenges in beam control and thermal management. This paper proposes a compact, single-beam-driven dual-frequency coaxial transit-time oscillator that generates simultaneous Ku- and Ka-band outputs using cascaded extractors to efficiently extract energy from both the fundamental wave (14 GHz) and its second harmonic (28 GHz). Unlike conventional single-frequency devices, this design maintains a simple structure while delivering dual-band operation with enhanced power and efficiency. At 490 kV and 9.6 kA under a 0.83 T magnetic field in simulation, the device achieves 1.7 GW at 14 GHz (Ku-band) and 0.35 GW at 28 GHz (Ka-band), with a total output power of 2.05 GW and an efficiency of 44.6%.