Patent ID: 8720040

Claim:
A method of manufacturing a hollow waveguide including a metal pipe and a hollow region formed inside of the metal pipe, said method comprising: preparing a first metal pipe comprising a first metal material; preparing a second metal pipe comprising a second metal material different from the first metal material and having an outside diameter smaller than an inside diameter of the first metal pipe; inserting the second metal pipe into the first metal pipe; pressure-bonding the first and second metal pipes to directly bond the fast and second metal pipes with each other to form a metal-clad pipe comprising an inside metal layer and an outside metal layer; polishing a surface of the inside metal layer; and forming a dielectric layer on the polished surface of the inside metal layer, wherein an alloy layer is formed by the pressure bonding at an interface between the inside metal layer and the outside metal layer, wherein the inside metal layer comprises aluminum, wherein the dielectric layer comprises aluminum oxide, and wherein the dielectric layer has a thickness of 0.1 μm or less.