WAVEGUIDE FOREIGN OBJECT DAMAGE PREVENTION WINDOW

A waveguide system for passing microwave energy while blocking foreign particles from a moving gas passing through the system is provided. The system includes first and second waveguide sections and a low loss microwave window disposed between the waveguide sections to allow microwave energy to pass from the first waveguide section through the window to the second waveguide section. The system also includes a gas bypass filtration system having a first port in communication with the first waveguide section, a filter element in communication with the first port, and a second port in communication with the filter element and with the second waveguide section. The system of the invention having these features blocks, by means of the window, a gas flowing through the first waveguide section and forces that gas to flow through the gas bypass filtration system so that it enters the second waveguide section only after passing through the filter. A system designed to include a pillbox window is also provided.