Tapered airline directional coupler

A tapered airline directional coupler comprising:

• a housing having a length with an input end and an output end disposed at opposite ends of the length, the housing having a slot formed therein extending between the input end and the output end, the slot having a lower section with a generally round cross-section and an upper section with a generally rectangular cross-section, wherein a width of the upper section of the slot tapers from a larger width adjacent to the input end of the housing to a smaller width adjacent to the output end of the housing;
• a main conductor disposed within the lower section of the slot and extending between the input end and the output end of the housing, the main conductor being in electrical communication with an input port connector mounted on the housing at the input end thereof and with an output port connector mounted on the housing at the output end thereof, the main conductor having a generally circular cross-section regardless of where the cross-section is taken along the length of the housing, and wherein the diameter of the main conductor has a taper from a larger diameter toward a middle of the length of the housing toward smaller diameters toward both the input end of the housing and the output end of the housing;
• and
• a coupled conductor disposed within the upper section of the slot and spaced apart from the main conductor, the coupled conductor being in electrical communication with and extending between a forward coupling port connector mounted on the housing adjacent to the input end thereof and a reverse coupling port connector mounted on the housing adjacent to the output end thereof, the coupled conductor having a generally rectangular cross-section regardless of where the cross-section is taken along the length of the housing and wherein a height of the coupled conductor tapers from a larger height adjacent to the input end of the housing to a smaller height adjacent to the output end of the housing.