Tunable power absorbing termination for a waveguide transmission line

A tunable power absorbing termination for a waveguide transmission line comprising:

• a section of waveguide having a power feed front end and a power extraction back end, and guidewalls extending behind the front end thereof toward the back end thereof, the front end of the section of waveguide have a rectangular form such that the guidewalls extending behind the front end of the section of waveguide are comprised of opposed broad guidewalls and opposed narrow guidewalls,
• a coolant circulating dielectric taper having a coolant feed base end and a point end, the coolant feed base end of the dielectric taper being engaged in the back end of the waveguide section such that the dielectric taper extends into the section of waveguide in an inclined orientation toward a narrow guidewall of the section of waveguide and such that the point end of the taper extends substantially to the front power feed end of the waveguide section, a free volume of space being provided adjacent the dielectric taper behind the front power feed end of the waveguide section,
• a tuner element disposed in the free volume of space behind the front power feed end of the waveguide section, the position of the tuner element being adjustable within the free volume of space through a rotation arc centered on a pivot axis located proximate the narrow wall of the narrow guidewall opposite the narrow guidewall toward which the dielectric taper is inclined.