US 4,229,676 A · Helical slow-wave structure assemblies and fabrication methods

Abstract

Helical slow-wave structure assemblies including a helical dielectric supporting member are disclosed along with methods for fabricating such assemblies. After the slow-wave structure helix is wound on a mandrel, a masking helix is coaxially wound about the slow-wave structure helix in the same sense as the slow-wave structure helix over the helical space between turns of the slow-wave structure helix and in overlapping relationship with portions of adjacent turns of the slow-wave structure helix. The supporting helix is formed by plasma spraying dielectric material into the helical space between turns of the masking helix. The dielectric material is ground to a predetermined radial dimension, and the mandrel and the masking helix are removed. By utilizing a masking helix of tapered width, a dielectric supporting helix of tapered width may be fabricated to provide a slow-wave structure assembly with a tapered phase velocity. A slow-wave structure helix having a radially outwardly extending longitudinal ridge may be utilized to provide a structure of wide bandwidth.

Claims11

Dependent claims

A method for fabricating a helical slow-wave structure assembly comprising:

winding a first ribbon of an electrically conductive material unsusceptible to etching by a predetermined etchant on a cylindrical mandrel to form a first helix having a predetermined spacing between successive turns thereof;
winding a second ribbon of a material susceptible to etching by said predetermined etchant and having a width greater than said predetermined spacing about said first helix over the helical space between turns of said first helix and in overlapping relationship with portions of adjacent turns of said first helix to form a second helix;
depositing dielectric material unsusceptible to etching by said predetermined etchant over the exposed surfaces of said first and second helices;
grinding the deposited dielectric material to a predetermined radial dimension;
removing said mandrel from the resulting assembly;
removing said second helix from the resulting assembly by chemical etching using said predetermined etchant;
and
mounting the resulting assembly within a tubular housing with the circumferentially outer surface of the dielectric material firmly contacting the inner surface of said housing.

5 more elements

Dependencies are inferred from the claim text.

Helical slow-wave structure assemblies and fabrication methods

Life of this patent

Helical slow-wave structure assemblies and fabrication methods

Life of this patent

Abstract

Claims11