GB684073A - Microwave frequency stabilizer - Google Patents

Abstract

684,073. Frequency measurement. STANDARD TELEPHONES & CABLES, Ltd. (Federal Telephone & Radio Corporation). June 8, 1951, No. 13656/51. Class 37. [Also in Groups XXXV and XL (b)] The frequency of a micro-wave oscillator is stabilized at the natural frequency of a cavity resonator by an arrangement of two wave-guide couplers of the kind known as a magic T. The oscillator 5 is coupled to a wave-guide 6 which forms a T-junction with two lateral arms 7, 8, one of which, 7, feeds the load, and the other, 8, forms the input guide to a second T-junction. A third arm 9 lying in a plane perpendicular to the plane of the arms 6 to 8 contains a crystal rectifier. The second T-junction comprises a lateral arm 11 of length l terminating in a short circuit 14, and a lateral arm 12 extending in the opposite direction to a length l+#/8 and terminated by a cavity resonator 15 tunable by a knob 18. The perpendicular arm 13 of the second T-junction also encloses a crystal rectifier. The outputs of the two rectifiers are fed jointly to a D.C. amplifier 19, the output of which is applied as a frequency-regulating voltage to the oscillator 5. Undesirable reflections from the crystals are reduced or eliminated by the provision in front of each crystal of an attenuation or resistor pad 22, 23 which may be of diamond or other suitable shape with their planes parallel to the electric vector. The general arrangement of the double magic T is described in Proceedings of the Institution of Radio Engineers, December, 1947, page 1405.