Online measuring device and method for high-power microwave TMOn mixed mode

The invention relates to an online measuring device and method for diagnosing a high-power microwave TMOn mixed mode output by high-frequency high-power microwave sources including X, Ku and Ka. The measuring device is composed of a reference coupler, a length-adjustable straight waveguide, a measuring coupler and a horn radiator, wherein the output port of the reference coupler is connected with the input port of the length-adjustable straight waveguide, the output port of the length-adjustable straight waveguide is connected with the input port of the measuring coupler, and the output port of the measuring coupler is connected with the input port of the horn radiator. According to the measuring device and method, design and structure are simple, power and capacity are high, the disadvantage that slits are small and the coupling amount is hard to calibrate accurately in the high-order mode is overcome, and the device and method can applied to diagnosis on the high-power microwave TMOn mixed mode.