Resonator Measurements of Magnetic Microwave Absorbers at Cryogenic Temperatures

This paper details a basic measurement technique of material losses using a cavity resonator. Magnetic losses can be determined using the TE<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">011</inf> mode of the resonant cavity. Microwave absorber materials containing ferrite and iron were tested at ambient and cryogenic temperatures. It was found that the ferrite sample generated higher loss when cooled, whereas the iron samples did not show much variation.