GB1002537A - Method of, and apparatus for, measuring the power transmitted by a wave-guide - Google Patents

Abstract

1,002,537. Power measurement JOSEPH LUCAS (INDUSTRIES) Ltd. Feb.19, 1962 [Jan. 23, 1961], No. 2561/61. Heading G1U. [Also in Division H1] To measure the power transmitted by a waveguide, a portion of the current carrying part of the waveguide is formed of material of higher resistivity than the remainder of the guide so as to increase the transverse temperature differences which occur in use and are dependent on the transmitted power, and the temperature difference between a point on the portion and a second point at a lower temperature is measured. In one embodiment, a waveguide has a lower wall 3 incorporating a ridge 4, sidewalls 5, 6 and an upper wall 7 to which is secured a plate 8; all parts being copper. A cut away portion 9 in the plate 8, parallel to the ridge 4, is closed by a strip of constantan foil 10, secured to which are a plurality of thermocouples consisting of copper wires 11 and constantan wires 12. The output from the thermocouples is taken through the wires 13,14 and a connector 15. In use the greater proportion of the current transmitted by the waveguide is in and opposite the ridge, producing a marked temperature difference between successive junctions of the thermocouple, this temperature difference being a measure of the power transmitted by the waveguide. The voltage developed by the thermocouple is measured by an instrument which may be calibrated to read power directly. Thermistors may be used instead of thermocouples in order to carry out the temperature measurement. The constantan foil together with the thermocouples may be pre-assembled prior to use in the waveguide.