| 摘要 |
<p>942,712. Directional couplers. SANDERS ASSOCIATES Inc. Aug. 18, 1961, No. 29860/61. Heading H1W. A variable directional coupler for twoconductor transmission lines comprises means for varying the spacing of the conductors of the respective lines within a coupling section. The invention may be applied to the type of strip line comprising a single inner strip conductor arranged between a pair of broad outer conductors forming a common " ground." As shown, the inner conductors 30, 36 (Figs. 2, 3), of the coupled lines share the same pair 22, 24 of ground conductors and variation in coupling (max. of 3 db.) is obtained by lateral movement of the conductor 36 between the positions shown in whole and broken lines (Fig. 2). As the conductor 36 approaches the conductor 30 the capacitance of both lines increases within the coupling section causing mismatch between this section and the output and input sections. In order to avoid this, conductor 36 is associated with a fixed compensatory conductor 27 and conductor 30 with a compensating conductor 26 which moves with the conductor 36. Thus, as the coupled conductors approach each other they withdraw from the region of their compensatory conductors and the capacitance within the coupled section remains constant. The fixed and movable conductors, respectively 27, 30 and 26, 36, may be mounted on dielectric blocks 18, 20 (Figs. 6, 7), arranged within relatively movable, recessed, conductive members 42, 44 which provide the common ground planes of the coupled lines. The member 42 forms the lid of a box 46 and the member 44 is arranged for lateral movement within the box. This is effected by means of a lead-screw and cam mechanism 82, 86. Terminals 56, 58 for the two lines are arranged on the lid 42, the terminals 58 associated with the movable line being connected to sliding contacts 60. Contact pressure between members 42 and 44 is provided by a pair of short resilient tubes (Fig. 5, not shown), mounted between member 44 and the base of the box. The tubes are arranged with their axes perpendicular to the direction of motion of the member 44 and have sufficient resilience to permit this motion.</p> |
