GB635769A - Apparatus for determining the characteristic values associated with the presence of an obstacle in a guide for electromagnetic waves - Google Patents

Abstract

635,769. Electric tests. COMPAGNIE GENERALE DE TELEGRAPHIE SANS FIL. Jan. 17, 1947, Nos. 1636 and 1637. Convention dates, Jan. 18, 1946, and July 6, 1946. [Class 37] [Also in Group XL (b)] Apparatus for determining the reflection coefficient of an obstacle in a wave-guide comprises two sections of wave-guide forming extensions of the guide containing the obstacle, a movable probe for detecting the electric field in one extension guide, a movable piston in the other extension guide, means for simultaneously moving the piston and the probe, and means for marking the positions of the piston and the probe. As shown, a movable probe 7 projects into an extension of a waveguide containing an obstacle 0. A movable piston 10 is provided in an extension of the other end of the guide. The probe 7, and piston 10 are coupled by means of a cable 11 and screw 9 to move in the same direction, or by cable 11 and screw 8 to move in opposite directions. The probe and piston are first moved together and two adjacent standing wave zeros marked. The probe is then moved midway between these zeros when the piston and probe will be equally spaced from the electric phase of symmetry of the obstacle. Screw 9 is now loosened and screw 8 tightened so that the piston 10 and probe 7 move symmetrically. The distance between two adjacent standing wave zeros, and the distance between the piston and probe when the latter is midway between the two zeros are now measured. The reflection coefficient of the obstacle may be determined from these measurements. A crystal or suitable detector is mounted on the carriage of the probe. In a modification (Fig. 3, not shown), the piston and probe are carried by members driven by two oppositely threaded screws. Adjustable shoes engaging one or other of the threaded rods enable the relative direction of movement of the piston and probe to be changed. Coarse adjustment is effected by means of a rotor and reversing clutch. In another embodiment (figs. 4-8, not shown), the probe carriage is provided with grooved wheels running in extensions of the sides of the wave-guides. The detector circuit is completed through the wheels which are pressed against the rails by adjustable springs.