Background With the continuous advancement of microwave electronic technology, research on power combining technology has attracted increasing attention. Power combining based on conventional vacuum devices such as klystrons represents a typical application case of power combining technology in microwave source systems. However, existing power combining technologies struggle to achieve two functions simultaneously without dismantling and replacing the transmission waveguide: enabling a single klystron to operate independently for microwave power output, and allowing two klystrons to work concurrently at the center frequency to produce combined microwave power output.

Purpose In view of the application requirements of a high-power microwave system, this paper designs a microwave radiation system adopting conventional Ku-band klystrons as power sources.

Methods To achieve this goal, one solid-state pre-stage excitation source is adopted, which outputs two power channels A and B. It can feed excitation signals to a single klystron separately or supply excitation signals to two klystrons simultaneously, integrating the two klystrons into a unified microwave source. A power combiner and a polarization conversion mechanism are deployed. Without disassembling or replacing the transmission waveguide, the system can not only enable a single klystron to operate independently to output. Meanwhile, the polarization conversion mechanism adjusts the rotation angles of two cascaded circular polarizers by regulating three rotary joints, thereby realizing conversion between horizontally and vertically polarized incoming waves, whether linearly polarized or circularly polarized.

Results The results show that when a single klystron is operating, the maximum output power reaches 0.61MW within a bandwidth of hundreds of megahertz. When two klystrons work simultaneously, their respective output powers at the center frequency are 0.53MW and 0.56MW, with a combined power of 1.04MW. A standard microwave receiving antenna is mounted 2.7 meters directly in front of the microwave antenna, and the maximum measured electric field strength is 32kV/m.

Conclusions Therefore, the designed microwave radiation system can realize microwave power output by a single klystron operating independently without removing and replacing the transmission waveguide. Meanwhile, it supports simultaneous operation of two klystrons at the center frequency to output microwave power through power combining, with a power combining efficiency exceeding 95%. This work provides a valuable reference for further research on high-power microwave power combining technology.