High-power millimeter wave output window testing and aging device and method

The invention provides a high-power millimeter wave output window testing and aging device, which comprises a high-power millimeter wave source, an absorption load, a reflection grating, a dielectric window sheet, a reflector M1 and a reflector M2; the metal reflection grating is used for performing beam splitting on high-power electromagnetic waves propagating in a quasi-Gaussian mode, and a part of wave beams are extracted to form a traveling wave resonant ring; the traveling wave resonant ring is adjusted to work in a resonant state, so that the dielectric constant of the dielectric window sheet is calculated; meanwhile, the dielectric window sheet is screened and aged under the condition that the equivalent power is higher than that of a microwave source by utilizing the gain effect of the traveling wave resonant ring. Parameter measurement can be directly carried out on a dielectric window sheet or a dielectric window assembly which is actually used under a high-power condition, and a measurement result