Patent GB-1019939-A (GB)
Title: A wave guide junction
Inventor: WALKER RICHARD MARION
IPC: H01P5/20
Filed: 1963-04-17
Abstract: 1,019,939. Waveguide hybrid Junctions. MICROWAVE ASSOCIATES Inc. April 17, 1963, No. 15190/63. Heading H1W. The symmetrical arms of a waveguide hybrid junction meet at an acute angle and co-linear H and E arms are connected to a common junction space at the apex. In the first embodiment (Fig. 2), the symmetrical arms 18, 19 are parallel and have a common narrow wall 12. The symmetrical arms communicate with a common rectangular cavity 23 extending from the edge 22 of the septum 12 to an end wall 24À2. The wide dimensions of the cavity are progressively reduced in the direction of the end wall by conductive inserts 31, 32 forming a stepped transformer. Also communicating with the cavity 23 are H and E arms, respectively 13, 17, arranged on a common longitudinal axis normal to the broad walls of the cavity with their corresponding minor axes at right angles to each other. TE 01  mode energy propagated in the E arm 17 is transformed into TE 02  mode energy in the cavity 23. Because of the restriction in width of the cavity, this energy can only propagate towards the symmetrical arms 18, 19 along which it is propagated as two TE 01  mode waves mutually in anti-phase. TE 01  mode energy from the H arm 13 is propagated in the cavity 23 in the form of two TE 01  waves of opposite phase one travelling towards the wall 24À2 and the other towards the arms 18, 19. Since the distance between the common axis of the H and E arms is chosen to be #g/2 at the working frequency, the whole of this energy is coupled into the arms 18, 19 where it propagates at two TE 01  waves in phase with each other. The E and H arms are matched to the junction by means of narrow iris members arranged on the narrow walls near the junction. These arms may be in the form of apertured blocks equal in width to'the broad walls of the cavity 23. Full-height, instead of half-height (as shown), waveguides may be used for the symmetrical arms 18, 19. In the second embodiment (Fig. 13), the symmetrical arms 50, 51 are parallel and have a common broad wall in the form of a septum 52. The co-linear H and E arms, respectively 53, 57, are connected to the outer narrow walls of the arms 50, 51 with a broad wall of the H arm arranged in the same plane as the edge 62 of the septum 52. The septum may overlap the junction of the E arm 57 as shown, or may be curved to avoid this overlap. The distance of the end wall 64 from the common axis of the H and E arms is arranged to be such that the junction space behaves as a short-circuited half-wave stub for TE 01  mode energy from the E arm 57. Hence, this energy propagates as two in-phase TE 01  modes in the arms 50, 51. TE 01  mode energy from the H arm 53 is divided into two anti-phase components because of the presence of the edge 62 of the septum. These waves propagate in the symmetrical arms 50, 51 as two TE 01  mode waves in mutual anti-phase, but destructive interference prevents their propagating towards the end wall 64. The E and H arms may be provided with iris matching elements and the common junction space may be provided with a matching transformer such as is shown in Fig. 2.