Low frequency coaxial capacitors and tuners

摘要

A new type of variable coaxial, low frequency capacitor uses two cylindrical blocks, which are interdigitally insertable into each-other to create an adjustable capacitance. Each block is made using a conductive (aluminum, brass or copper) strip which is mounted vertically on a conductive basis and is wound in spiral form around a center axis. The blocks are guided coaxially into each-other and the relative orientation angle allows approaching the surfaces of the conductive strips from a maximum distance, which is half the width of the spiral gap, to full galvanic contact. The block penetration is motor controlled and a cascade of three or four such capacitors and associated lengths of coaxial cable is used to make wideband impedance tuners operating in the low MHz frequency range.

主权项

1. A variable capacitor comprising two parts in form of cylindrical blocks, a top block and a bottom block, each mounted on a conductive base plate,
each said block comprising a single conductive strip which is wound in spiral form around a centre axis and is mounted perpendicularly on said conductive base plate, said top block spiral being insertable vertically and interdigitally into said bottom block spiral without creating a galvanic contact.