Variable coupling for microwave sample treatment - has perforated screen isolating cavity and adjustable piston volume

摘要

The variable coupling is for a waveguide based microwave sample treatment cavity. The coupling prevents parasitic secondary modes due to the presence of the sample. The waveguide (35) is coupled into the treatment cavity by a tapered transition section (39) expanding to match the cross-section of the cavity. A perforated screen (3) separates it from the cavity which has a variable position piston (4) closing its other end. The cavity may have a further volume attached to one of its walls (20) and coupled to it by a small slot, the second volume itself having an adjustable piston.