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 centre 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.
Low Frequency Coaxial Capacitors and Tuners / 9,344,061
Thursday, May 5, 2016