Distributed window for large diameter waveguides

Coupling apparatus for coupling microwave power between the HE.sub.11 mode in a first waveguide to the HE.sub.11 mode in a second waveguide, said apparatus comprising:

• a vacuum barrier separating said first and second waveguide, said vacuum barrier including a plurality of parallel dielectric strips, each dielectric strip being separated from an adjacent dielectric strip by a metallic cooling strip, the distance between a center line of adjacent dielectric strips being approximately a distance h, where h<.lambda..sub.0, where .lambda..sub.0 is the free space wavelength associated with the microwave power being coupled between said first and second waveguide, and further wherein the thickness of said vacuum barrier is a distance d through said dielectric strips, and is a distance d+2L through the thickest part of said metallic cooling strips, whereby each metallic cooling strip extends perpendicularly out from a plane surface of said dielectric strips a distance L;
• the dielectric strips of said vacuum barrier being oriented so as to be longitudinally perpendicular to an electric field component of said microwave power;
• and further
• wherein opposing surfaces of said dielectric strips are corrugated, said opposing surfaces being those surfaces that front the interior of said first and second waveguides.

A method of forming a vacuum barrier that separates first and second waveguides, said method comprising the steps of:

• (a) forming a plurality of dielectric strips so that the thickness of said vacuum barrier is a distance d through said dielectric strips, and forming opposing surfaces of said dielectric strips to have corrugations, said opposing surfaces being those surfaces that front the interior of said first and second waveguides;
• (b) forming a plurality of metallic cooling strips so that there is a distance d+2L through the thickest part of said metallic cooling strips, each metallic cooling strip extending perpendicularly out from a plane surface of said dielectric strips a distance L;
• (c) adjoining a cooling strip on each side of each dielectric strip, thereby forming a barrier, such that the distance between a center line of adjacent dielectric strips is a distance h, where h<.lambda..sub.0, where .lambda..sub.0 is the free space wavelength associated with the microwave power being coupled between said first and second waveguides;
• and
• (d) mounting said barrier between said first and second waveguides so as to separate said first and second waveguides, and orienting the dielectric strips to be perpendicular to an electric field component of microwave power propagating through said first and second waveguides.