A BROAD-BAND MICROWAVE CALORIMETER OF LARGE CROSS-SECTION

A flat calorimeter of large cross-sectional area (1200 cm(2)) designed to measure 3-60-GHz single-pulse microwave energy ranging from 0.025 to 500 J is described. Ethanol is used as the essential material of th e calorimeter, and the quantity measured is the increment in its volum e that results from heating by the absorbed microwave energy. The calo rimeter is installed outside a vacuum volume to measure the total ener gy of a microwave pulse. The absorption coefficient is 0.88 +/- 0.09 i n the 4.5-53.5-GHz frequency band. The calorimeter can be used as an a ttenuator of large cross section with an attenuation coefficient of 10 -30 dB.