Claims
- 1. A coaxial cable assembly with a discontinuous outer jacket, said assembly comprising:
a coaxial cable having a central conductor, an outer conducting sheath, and insulation material disposed therebetween, a section of said coaxial cable having a portion of its outer sheath removed to expose the central conductor along a gap having a selected length; and a stub having an internal conductor, an outer conductor, and a dielectric material separating said internal and outer conductors, said stub having an effective electrical length of a predetermined value; said outer conductor having a section of enlarged diameter overlapping a portion of said internal conductor and a necked-down section remote from the enlarged diameter section, said overlapped portion of the stub internal conductor and said necked-down section being adapted to match the outer diameter of the coaxial cable outer sheath; said outer conductor and said internal conductor of the stub being electrically connected to said outer sheath of said coaxial cable on opposite sides of said gap; whereby said stub is secured in a position along said coaxial cable such that one end of the dielectric material of said stub is positioned over said gap in the coaxial cable.
- 2. The coaxial cable assembly of claim 1 wherein said stub has a length L, measured from the midpoint of said gap to the end of the stub remote from said gap, whereby said length L is adjusted in accordance with measurements of standing wave ratio of the transmitted signal of said cable.
- 3. The coaxial cable assembly of claim 1, wherein said gap approximately 1.27 mm in length.
- 4. The coaxial cable assembly of claim 1, wherein said dielectric material comprises commercially available 7070 glass, fired to make the stub hermetic.
- 5. The coaxial cable assembly of claim 2 wherein the length of the stub is equal to a quarter wavelength at a selected operating frequency.
- 6. The coaxial cable assembly of claim 5, wherein said stub has the impedance of an open circuit at its open end transforming to zero ohms at the end of said stub positioned over said gap, whereby at the selected operating frequency said gap is transparent to signals at said selected operating frequency while effectively blocking DC and lower frequency signals.
- 7. A coaxial cable assembly with a discontinuous outer jacket, said assembly comprising:
a coaxial cable having a central conductor, an outer conducting sheath, and insulation material disposed therebetween, with a portion of the outer sheath removed to form a gap having a predetermined length; a quarter wavelength stub electrically connected to said outer conducting sheath and bridging said gap, said stub having inner and outer conducting sleeves with dielectric material therebetween, said outer conducting sleeve having a section of enlarged diameter overlapping a portion of said inner conducting sleeve and a necked-down section of reduced diameter adapted to match the outer diameter of the coaxial cable outer sheath; whereby the open circuit end of said stub transforms to a closed circuit at said gap for signal frequencies in a limited range about the coaxial cable transmission frequency such that DC, signal frequencies below said range and thermal energy are blocked by said gap.
- 8. The coaxial cable assembly of claim 7 wherein the stub is electrically connected to the coaxial cable sheath by welds between the respective sleeve portions and the outer sheath of the coaxial cable.
- 9. The coaxial cable assembly of claim 7 wherein said stub is formed to establish an electrical length of the stub equal to a quarter wavelength at a selected frequency of operation.
- 10. The coaxial cable assembly of claim 9 wherein the length of the stub in meters is established in accordance with the following equation:
- 11. The coaxial cable assembly of claim 10 wherein the selected frequency of operation is 4 GHz and the dielectric insulation of the stub is commercially available 7070 glass.
- 12. In combination:
a coaxial cable having a discontinuity in its outer jacket forming an open circuit gap along said cable; and a quarter wavelength stub having an electrical length of a quarter wave at a selected transmission frequency; the stub being electrically connected to the coaxial cable on opposite sides of said discontinuity to electrically bridge said gap for signals in a selected range of transmission frequencies, said stub being positioned with a first end of the stub coupled to said gap and having a second end of open circuit impedance transforming to zero impedance at the first end for a range of frequencies about said selected transmission frequency; whereby the combination enables the coaxial cable to transmit signals in said frequency range while blocking DC and frequencies below said range and thermal energy.
- 13. The combination of claim 12 wherein the coaxial cable comprises a central conductor and an outer conducting jacket with dielectric material between them.
- 14. The combination of claim 13 wherein a portion of the outer jacket and a corresponding portion of the coaxial cable dielectric are removed over the length of said gap.
- 15. The combination of claim 12 wherein said stub comprises an inner sleeve and an outer sleeve with dielectric material between them, the inner sleeve having an inner diameter matching the outer diameter of the jacket and being electrically connected thereto on one side of the gap and the outer sleeve having a necked-down portion with an inner diameter matching the outer diameter of the jacket and being electrically connected thereto on the side of the gap remote from said inner sleeve.
- 16. The combination of claim 14 wherein the gap is formed with a predetermined gap length.
- 17. The combination of claim 16 wherein the gap is formed by the removal of said predetermined length of outer jacket.
- 18. The combination of claim 17 wherein the fabrication of said gap further involves removal of the coaxial cable dielectric material for said predetermined length.
- 19. The combination of claim 12 wherein the electrical length of said stub is predetermined in accordance with the equation:
- 20. The combination of claim 19 wherein the thickness of the dielectric material in the stub is equal to the length of the gap.
- 21. The combination of claim 20 wherein the length of the gap is 1.27 mm, the dielectric insulation in the stub is commercially available 7070 glass, and the selected operating frequency is 4 GHz.
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional Application No. 60/175,662, filed Jan. 12, 2000.
Provisional Applications (1)
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Number |
Date |
Country |
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60175662 |
Jan 2000 |
US |