Low attenuation high frequency coaxial cable for microwave energy in the gigaHertz frequency range

In a low attenuation high frequency coaxial cable for carrying microwave energy in the gigaHertz range having a central conductor and an outer conductor spaced from and concentric with the central conductor and having dielectric in the region between the central and outer conductor, the improvement comprising:

• said dielectric comprising an inner portion of low density of PTFE material and an outer portion of high density PTFE material,
• said inner portion comprising a plurality of layers of low density PTFE material,
• each of said layers having abutting edges, the abutting edges of each layer being located on the opposite side of the central conductor from the abutting edges of an adjoining layer, and
• said outer portion comprising at least one layer of high density PTFE material encircling the low density material and with its edges overlapping for holding it firmly in place and being applied in its unsintered state and being sintered in place.

A low attenuation high frequency coaxial cable for carrying microwave energy in the gigaHertz range and having a center conductor extending along the axis of the cable comprising:

• dielectric surrounding said center conductor including at least four layers of low density PTFE dielectric material, having a specific gravity of about 0.7 and a dielectric constant of about 1.45 and each layer is about 10 mils (about 0.010 of an inch) thick,
• at least one layer of high density PTFE dielectric material having a specific gravity of about 2 and a dielectric constant of about 2.1 surrounding and holding said layers of low density PTFE dielectric material around said center conductor,
• a plurality of longitudinally extending, parallel, adjacent conductive wire strands which are in electrical contact with each other forming an outer conductor encircling said high density PTFE dielectric material,
• said conductive wire strands having a slight helical lay along the axis of said cable,
• means holding said strands in place, and
• a protective outer jacket surrounding said holding means.

A low attenuation high frequency coaxial cable for carrying microwave energy in the gigaHertz range and having a center conductor extending along the axis of the cable comprising:

• dielectric surrounding said center conductor including a plurality of layers of low density PTFE dielectric material,
• at least one layer of high density PTFE dielectric material surrounding and holding said plurality of layers of low density PTFE dielectric material around said center conductor,
• a plurality of longitudinally extending, parallel, adjacent conductive wire strands which are in electrical contact with each other forming an outer conductor encircling said high density PTFE dielectric material,
• said conductive wire strands having a slight helical lay along the axis of said cable,
• means holding said strands in place, and
• a protective outer jacket surrounding said holding means,
• each of said layers of low density dielectric material comprising a tape extending longitudinally of the cable with its edges abutting in edge-to-edge relationship,
• the abutting edges of each layer of low density material being located on the opposite side of the center conductor from the abutting edges of an adjoining layer, and
• said layer of high density dielectric material comprising a tape of unsintered PTFE material extending longitudinally of the cable and encircling the underlying low density dielectric layers and with its edges overlapping and which is sintered in place after being applied over the underlying low density dielectric layers.

A low attenuation high frequency coaxial cable for carrying microwave energy in the gigaHertz range and having a center conductor extending along the axis of the cable comprising:

• a dielectric surrounding said center conductor including at least four layers of low density PTFE dielectric material, and each layer being about 10 mils (0.010 of an inch) thick,
• at least one layer of high density PTFE dielectric material surrounding and holding said plurality of layers of low density PTFE dielectric material around said center conductor,
• a plurality of longitudinally extending, parallel, adjacent conductive wire strands which are in electrical contact with each other forming an outer conductor encircling said high density PTFE dielectric material,
• said conductive wire strands having a slight helical lay along the axis of said cable,
• a jacket of uncured high density PTFE material applied over said wire strands and then cured in place, and
• a tight wire braid around said jacket for applying compressive force around said jacket for pressing the conductive wire strands of said outer conductor inwardly together around said layer of high density PTFE dielectric material of said cable and thereby further reducing the attenuation of said cable.

A low attenuation high frequency coaxial cable for carrying microwave energy in the gigaHertz range and having a center conductor extending along the axis of the cable comprising:

• a dielectric surrounding said center conductor including a plurality of layers of low density PTFE dielectric material,
• at least one layer of high density PTFE dielectric material surrounding and holding said plurality of layers of low density PTFE dielectric material around said center conductor,
• a plurality of longitudinally extending, parallel, adjacent conductive wire strands which are in electrical contact with each other forming an outer conductor encircling said high density PTFE dielectric material,
• said conductive wire strands having a slight helical lay along the axis of said cable,
• a jacket of uncured high density PTFE material applied over said wire strands and then cured in place,
• a tight wire braid around said jacket for applying compressive force around said jacket for pressing the conductive wire strands of said outer conductor inwardly together around said layer of high density PTFE dielectric material of said cable and thereby further reducing the attenuation of said cable,
• each of said layers of low density dielectric material comprising a tape extending longitudinally of the cable with its edges abutting in edge-to-edge relationship,
• the abutting edges of each layer of low density material being located on the opposite side of the center conductor from the abutting edges of an adjoining layer, and
• said layer of high density dielectric material comprising a tape of unsintered PTFE material, extending longitudinally of the cable and encircling the underlying low density dielectric layers and with its edges overlapping and which is sintered in place after being applied over the underlying low density dielectric layers.