A Unicontrol Radio Receiver for Ultra-High Frequencies Using Concentric Lines as Interstage Couplers

A new type of radio receiver for frequencies between 100 and 300 megacycles per second is described. This receiver differs from conventional designs in that it utilizes quarter-wave concentric transmission lines as coupling impedances between amplifier stages. A method of using a single line per stage and means for varying the effective line length for unicontrol tuning is shown. The deviation of the line length from the actual full quarter-wave length over the frequency range of the receiver is given. Measurements showed an amplification of the order of two per stage at 300 megacycles, six per stage at 200 megacycles, and nine per stage at 175 megacycles. With four stages of radio-frequency amplification and a detector, an effective over-all amplification of the order of 100,000 may be expected at 200 megacycles. The paper gives the circuit arrangement for a receiver consisting of four stages of radio-frequency amplification and a detector. This receiver uses four concentric lines with ganged tuning plungers for varying the effective line lengths in unison. The lines are arranged with their major axes about a common center.