Abstract: A method of forming a composite metal-ceramic helix structure suitable for TWT application. The method includes concentrically joining a metal cylinder disposed within a ceramic cylinder to form a high strength hermetic bond therebetween having good thermal conductivity. Prior to joining the cylinders a predetermined quantity of heat vaporizable liquid is disposed within the metal cylinder and its ends are sealed off. During the brazing process the liquid vaporizes ensuring intimate contact between the concentric cylinders. Thereafter the metal cylinder ends are removed and the resulting concentric structure machined into a helical shape.

Abstract: The substrate is ladder shaped and is located between a serpentine metallic meander line conductor and a metallic ground plane. Conductive shields are disposed in slot-like openings of the substrate between adjacent parallel transverse segments of the meander line to decrease dispersion and increase the bandwidth to a full octave.