Terahertz waveguide comprising an outer copper layer laminated with an inner dielectric layer to form a rolled guide tube which is encased by a support tube

An overmoded dielectric-lined waveguide, particularly for the 0.03 to 3 terahertz frequency range, is disclosed with performance advantages relative to prior dielectric-lined waveguides, cost and size advantages relative to corrugated waveguides, and with coupling, bandwidth, and cost advantages relative to micro-structured-fiber waveguides. The waveguide comprises a single-clad flexible microwave laminate rolled into a cylinder with said copper surface on an outside of said guide tube and said dielectric surface on an inside of said guide tube. The rolled laminate is supported inside a metal tube. The same method of achieving the structure needed for efficient guiding of HE11 mode may be applied to a conical tube to make a low-cost efficient overmoded tapered waveguide transition for the 0.03-3 THz range.