Giant Microwave Windows
A major problem currently plaguing experimental cosmic microwave background research is the small size of the window located at the microwave receiving end of the instrument. The window must be made of materials that are completely transparent to microwaves, and at least one material must block infrared radiation completely. The window must also mechanically support itself against atmospheric pressure. Shown below is a model of an instrument used to measure the cosmic microwave background radiation emanated by the universe. The window is the gateway for microwaves to reach the detectors; it is also the zone where warm, pressurized air is separated from the cold (<1 K), vacuum environment.
Our goal is to design a giant microwave window. Designing a larger window would let more microwaves reach the detectors of an instrument, and allow a greater number of sophisticated detectors to be used. To date the majority of ground and balloon based cosmic microwave background experiments have utilized instruments with a window that is 6 inches or smaller in diameter. We are combining mechanically strong, microwave transparent fabrics in novel mechanical configurations with infrared blocking, microwave transparent foam to build a window that is at least 20 inches in diameter.