Patent GB-599487-A (GB)
Title: Improvements in or relating to a resonator wavemeter
IPC: G01R23/04
Filed: 1943-03-03
Abstract: 599,487. Electric resonators. SPERRY GYROSCOPE CO., Inc. March 3, 1943, No. 3537. Convention date, Dec. 12, 1941. [Class 40 (iii)] [Also in Group XXXVI] A resonator wave-meter of the variable volume cavity type has a movable end wall by which its volume is varied to obtain a resonant condition therein, and includes means for introducing short wave electromagnetic energy, whose wave-length is to be measured in such a way as to obtain a desired mode of oscillation in which the lines of electric force are situated in parallel relation with respect to the movable end wall and wavelength indicating means movable with the end wall. A conducting cylindrical wall 1, Fig. 1, is closed at one end by a fixed conducting end wall 2 and at the other by a conducting end wall 3 carried by a rod 5 by which it can be moved axially in the cylinder 1 so as to alter the volume of the resonator cavity. At the periphery of the wall 3 is a flange 4 of external diameter very nearly equal to the internal diameter of the cylinder 1. Concentric line transmission leads 6, 6<1> with coupling loops 7, 7<1> are provided for the introduction of the ultrahigh frequency energy whose wavelength is to be determined and for the removal of a portion of the energy for the measurement of the field strength produced. A conducting rod 8 mounted in the end wall 2 supports wires 9, 10, 11 which are tensioned by springs 12. These wires have a resistance of the order of 30 ohms and damp out any mode of vibration whose lines of magnetic flux link the wires. The wires 9, 10, 11 are placed so as to be at right angles to the electric field of the preferred mode of oscillation so that no currents are induced in the wires by such oscillations. More than three damper wires may be employed and they may be otherwise arranged. A number of interchangeable end walls 2 of different thicknesses may be provided in order to change the frequency range. The rod 5 is threaded at its outer end to take a nut 14<1> which is prevented from longitudinal movement by a bearing 18 clamped in a stationary housing 19 by a flange 21. Backlash is prevented by a compression spring 17 and a nut 15, which is slidably engaged by rods 16 fixed to the nut 14<1> so that both turn together. The nut 14' is provided with a knurled head 22 which has a scale 23 reading against a fiducial mark 24 on the housing 19. The rod 5 carries a pointer 25 which extends through a slot 26 in a tube 27 which is fastened at one end to the housing 19 and held at the other by a fixed support 29. The pointer 25 co-operates with a scale 28 to give a rough reading, fine measurement being effected by the scale 23. The rod 5 is prevented from rotation and is provided with a bearing near the wall 3 by the means shown in Fig. 2. The rod 5 is supported concentrically with the tube 27 by hardened balls 38, 39 in the ends of set-screws 34, 35. A key 30 on the rod 5 bears against a hardened ball 40 in a set-screw 33, firm contact being insured by a wire 32 and spring 36. The movable end wall 3 of the resonator is made exactly concentric with the cylinder 1 by adjustment of the set screws 34, 35. Specification 508,392, [Group XXXVI], is referred to.