Abstract: A screen for a dipole-mode waveguide is described. The screen is in the form of a metal cylinder, with or without longitudinal gaps, and this screen is useful with the type of dipole-mode waveguide formed by a generally cylindrical structure of elongated parallel spaced apart conductors. External radial vanes and an internal diametric vane for the structure are also described for suppressing unwanted modes at the launching point, as is a slot launching arrangement for launching the dipole mode without exciting unwanted modes.

Abstract: Waveguides for the dipole mode are described which are of rectangular cross-section with conductive walls and contain one or more longitudinal conductors, or groups of conductors. Where a plurality of conductors are employed they are usually arranged in planes parallel to one wall and are positioned nearer to this wall than the opposite wall. With one conductor or a group of conductors near one wall the dipole mode propagates principally between the conductor or conductors and the nearer wall while the evanescent part of the transverse field is allowed to decay substantially without interference before reaching the far wall.

Abstract: Hollow circular or rectangular waveguides for supporting electromagnetic waves in the dipole mode are disclosed. Special surface impedances are required for such waveguides and examples are given. The waveguides may or may not have a central member also with a special surface impedance. Means for launching the dipole mode in waveguides of this type are described.