Resonant-slot hybrid junctions and channel-dropping filters

A type of four-port resonant-slot hybrid junction, which is realisable in a number of waveguide configurations, is described. Matching of the junction may be achieved by correctly locating the position of the slots in the respective guides; design equations are derived. The absence of the usual matching posts and irises is an advantage in millimetric construction. Suitable slot-manufacturing techniques for these wavelengths are outlined. The principal application of the junction is in constant-resistance channel-dropping filters, in which the junction permits a low reflection coefficient to be obtained. The design of filters for both broad- and narrow-band use is discussed. The new types of six-port junctions are briefly described.