GB896770A - Hybrid junction coupling arrangement - Google Patents

Abstract

896,770. Microwave hybrid junctions. WESTERN ELECTRIC CO. Inc. Dec. 14, 1960 [Dec. 28, 1959], No. 43014/60. Class 40(8). A microwave hybrid junction uses strip transmission lines of the "sandwich" type comprising two parallel ground planes 11 spaced on either side of a configuration of strip conductors. These may be printed or otherwise deposited on the inner faces of slabs of dielectric material arranged between the ground planes. A first branch 13 of the circuit is of U configuration, the limbs of the U being joined at their extremities to second and third branches 15, 16. Each of these comprises two parallel strips short-circuited at their ends to the ground planes by elements 20. The three branches 13, 15, 16 are each of one quarter-wavelength long so that the open and short-circuit impedances between various elements at the extremities of the branches are inverted at the common junction. Two further branches 18, 19 are connected to this junction. Between the parallel elements of branches 15, 16 extends a coupling conductor 21 having a central conductive bridging portion 31 which spans the extremity of the branch 13 and is insulated from it by a piece of dielectric material 32. Energy delivered to the end 22 of the branch 13 is divided equally between the branches 18, 19 in phase (i.e. the branches are in parallel). Energy delivered to either extremity of the coupling conductor 21 is divided equally between the branches 18, 19 in antiphase (i.e. the branches are in series). In a modification, the strip conductors are duplicated and form two identical, parallel layers which are electrically connected at intervals. In this case the elements of the limbs 15, 16 and the coupling conductor 21 are arranged between the ground planes 11 in the manner shown in Fig. 3.