The physical shape of an insert is defined by its upwardly and downwardly extending wall portions. This normal horizontal positioning is achieved by engaging the throat surfaces with the adjacent surface of the slot flanges 39 and 44. The engagement between these surfaces locks the insert into its installed position. In addition, the physical shape of the slot can be modified to accommodate an inserted device. For example, the slot throat of a ball valve can be modified by using a slot insert. Gbo4d

The illustrated slot is formed by machining a face 12 of a panel. The slot 13 runs horizontally. In the illustrated embodiment, the slot has a modified T-shape with a back or base wall surface 16 and stepped side wall surfaces 18. The throat area is defined by the converging end and return areas of the slot. The throat area includes the throat. The slots in a panel have a wide range of possible configurations.

A phasing/compression plug coupled to a waveguide with a slot throat is also advantageous. The phasing/compression plug comprises several passages, each extending from an input aperture to the corresponding outlet apertures. Each passage is substantially parallel to the major axis of the slot and the outlet apertures. The area of the outlet apertures is less than the area of the inlet apertures. The horn may be a single or multiple-channel device.

The input throat of the horn is rectangular and the output region 46 of the plug 14 defines the slot throat of the horn. The horn can be coupled with the driver through a diffraction slot in the narrow rectangular throat. This reduces the need for an external transition coupler and internal round-to-rectangular transition. These characteristics make slot throats ideal for multicell amplification. And it is possible to connect two different drivers using a single slot throat.