| 摘要 |
1,216,880. Negative resistance apparatus. VARIAN ASSOCIATES. 8 Aug., 1968 [23 Aug., 1967], No. 37981/68. Heading H3T. A solid state negative resistance device such as an avalanche diode 8 (or a Gunn effect or L.S.A. device) is supported in a closed resonator 10 defined at least in part by portions 7, 37 of a post structure, a capacitive gap 11 between the portions being in series with the selfinductance of the post structure and coupling the resonator to a wave supporting structure 2. The wave supporting structure is a channel in an aluminium block 1 carrying the post structure, the channel being closed at one end by a wall (3, Fig. 2, not shown) constituting a shorting plane, and connected at the other end to a waveguide (not shown). The portion 7 of the post structure is a hollow aluminium sleeve and contains a copper plug 13 whose end 23 is surrounded by a conductive cap 21 and is secured to one end of the diode 8 whose other end is secured to the post portion (plunger) 37 which is insulated at 39. The assembly of the plug 13, diode 8 and plunger 37 is axially movable against a spring 66 by rotation of the plug 13, to vary the capacitive gap 11 thereby varying the centre frequency, and also the coupling to the wave-supporting structure (channel). Folded chokes are formed between plug end 23 and sleeve 7, and between plunger 37 and a sleeve 49 around it, whereby these parts are shorted to the block 1 at microwave frequency. The diode is mounted in an alumina ceramic body 33 on a copper stud 35, connections to a plug 55 being made via the spring 66 and the block 1. In a modification (Fig. 4, not shown), the sleeve 7 and plug 13 are replaced by a single post portion (81) having a hollow end (6) containing the diode (8) and defining the resonator with the plunger (37), tuning being effected by a tuning screw (83) in the portion (81), the upper part (85) of the screw being of a dielectric material. In a further modification of this (Fig. 5, not shown) a conductive stud (87) fixing the diode to the plunger (37) has its length (1) selected to give initial approximate tuning. |
