High-Power X-Band and Ka-Band Microwave Generation With a Coaxially Nested Dual-Frequency Relativistic Transit Time Oscillator

Driven by the increasing demand for light-weight, compact, and versatile dual-frequency high-power microwave (HPM) sources, this article explores the design and performance of a novel dual-frequency HPM source based on a relativistic transit time oscillator (RTTO). The proposed dual-frequency RTTO features a nested design that integrates the Ka-band within the X-band using a shared solenoid magnetic field, achieving reductions in energy consumption, system size, and weight. Particle-in-cell (PIC) simulations were conducted using CHIPIC under both ideal and practical pulse power system voltages, with detailed parameters ensuring model accuracy and relevance to realistic conditions. Under ideal conditions of 460 kV and a solenoid magnetic field of 0.6 T, the X-band (8.42 GHz) achieves an average power of 2.0 GW with an efficiency of 40.0%, while the Ka-band (30.62 GHz) reaches an average power of 0.9 GW with an efficiency of 39.5%, demonstrating stable operation without mode competition. Under realistic voltage conditions ranging from 410 to 510 kV, the X-band average power increases from 1.35 to 2.22 GW with a peak efficiency of 39.4%, and the Ka-band average power rises from 551.2 to 976.2 MW with a peak efficiency of 38.1%, highlighting its consistent performance and practical viability. Moreover, the device supports the flexibility potential of both simultaneous and time-division dual-frequency HPM output, making it a promising solution for advanced dual-frequency HPM applications.