GB839992A - Improvements in or relating to arrangements for measuring the power of electromagnetic oscillations transmitted along a waveguide - Google Patents

Abstract

839,992. Power measurement. GENERAL ELECTRIC CO. Ltd. Feb. 25, 1958 [March 15, 1957], No. 8713/57. Class 37. In apparatus for measuring the electromagnetic power transmitted along a waveguide 1; a body of material 11, spaced from but terminating the waveguide, absorbs substantially all the transmitted power; and is disposed in thermal contact with the hot junctions of a plurality of series connected thermo-couples 6; whereby the thermo-couple potentials are applied additively across a pair of output terminals 24, 25. A rectangular waveguide 1 is brazed into a circular metal plate 2 screwed to a cylindrical metal casing 3; and a block 4 of synthetic resin, screwed to the base thereof, is pierced by a hole 5 over both ends of which are wound, e.g. 25 turns of wire, each turn constituting a thermo-couple by copper-plating one half thereof, the junctions being disposed in series alternately at the top and bottom of the block 4; the upper, or hot, junctions being in thermal contact through a mica sheet 10 with a carbon wedge 11. A window 26 in the waveguide screens the wedge from draught, and a “ wave-length slot 27 in the inner face of the plate 2 acts as a choke to reduce electromagnetic leakage into the cylinder 3. Terminals 16, 17 may supply a calibrating current to heat the wedge 10.