In-line waveguide calorimeter for microwave power measurement

摘要

987,649. Power measurement. UNITED STATES ATOMIC ENERGY COMMISSION. April 16, 1963 [May 14, 1962], No 14812/63. Heading G1U. Apparatus for measuring the average microwave power in a waveguide comprises heat-sink means for regulating the temperature along a portion of the waveguide and temperature-sensing means for indicating the temperature change in the regulated temperature upon passage of microwave power through the waveguide. In Fig. 1 the measuring section of waveguide 12 is provided at each end with flanges 14 and 16 which are cooled by the passage of coolant fluid through passageways provided in them. Resistances 32 and 38 are wound round the waveguide adjacent the flanges 14 and 16, and resistances 34 and 36 are wound round the centre of the waveguide. The four resistances are connected in a bridge circuit to give a measure of the temperature difference between the centre and the ends of the guide, this temperature difference being proportional to the power of the microwaves within the guide. The waveguide should be an integral number of wavelengths long and should be of lossy material such as stainless steel or may be of copper coated internally with stainless steel or graphite. The temperature may be measured by thermocouples instead of resistances. In a modification, Fig. 4 (not shown), the heat sinks are adapted to be clamped about an existing waveguide.