Patent GB-580085-A (GB)
Title: Improvements in wave-meters
IPC: G01R23/04
Filed: 1942-10-26
Abstract: 580,085. Coil-less resonators. GENERAL ELECTRIC CO., Ltd., BOURNE, W. A., and CLAYTON, R. J. Oct. 26, 1942, No. 15039. [Class 40 (iii)] [Also in Group XXXVI] A wave-meter for oscillations having a wavelength of the order of 10 cm. consists of a concentric line closed at one end and provided with a bridge which is movable along the line by a fine and coarse adjustment. Oscillations are excited in the part of the line between the bridge and the closed end and means are provided for measuring their amplitude. The bridge is adjusted to positions at which this amplitude is a maximum, the wavelength being twice the distance between successive positions. Fig. 1 shows the wave-meter in section, the lower half of the Figure being a continuation of the upper half to the right. The outer member 1 of the concentric line is closed by a cap 3 carrying the inner member 2. The line is coupled to a source of oscillations by means of a pick-up probe 5 which is carried on a sleeve 6 sliding on the inner member 2 and projects through a hole 7 in the cap 3, the amount of projection varying the coupling. A side tube 8 is provided for receiving a sleeve 9, Fig. 6, which carries a measuring loop consisting of a strip 10 and a capsule 11 containing a rectifying crystal. The capsule 11 has end pins 12, 13, of which the former engages the bent-over end of the strip 10 and the latter fits into the lower end of an insulated metal cylinder 14. This cylinder has a side hole for receiving the central conductor 17 of a cable 16 which is held in place by a pin 18 carried by a nut 19 on the top of the sleeve 9. The cylinder 14 and sleeve 9 form a condenser associated with the rectifier. The outer conductor 16 is in contact with a side tube 20 on the sleeve 9. The cable 16 leads to an ammeter for measuring the rectified current. The bridge 4 is a sleeve carried by the inner conductor 2 and is slightly smaller in external diameter than the bore of the outer conductor 1 and slightly larger in internal diameter than the inner conductor 2. The part facing the cap 3 is hollow and its open end bears tightly at 22, 23 on the outer and inner conductors. The length of the hollow part is about one quarter of the mean wavelength to be measured. The bridge 4 is carried by a hollow plunger 24 which is slidable in the conductor 1 and can be clamped in any position by a milled head 26 on the end of the conductor 1. For fine adjustment, the outer end of the plunger 24 has a milled head 27 by which a tube 28 can be rotated. The inner end of this tube acts as a nut 29 on a screwed part 30 of the bridge 4. The position of the bridge is measured by means of a strip attached to it carrying a scale which co-operates with a vernier marked on the edge of a window in the outer conductor 1 through which the scale is exposed. In a modification for measuring shorter wavelengths, the bridge is prolonged by a sleeve extending to the rear of the outer conductor 1 and the screw adjustment is arranged behind this. The pick-up probe 5 may alternatively pass through an insulating sleeve in the cap 3 and can rotate and slide in and out. There is no permanent attachment to the inner conductor 2, but a spring finger is carried by the inner end of the probe and can, by rotation of the probe, be made to bear against either of the conductors 1, 2 or to lie between them. Specification 572,511 is referred to.