Coaxial cable assembly with a discontinuous outer jacket
AssigneeMeggitt Safety Systems Inc.
InventorsVahid Badii, Farzad Kialashaki
Life of this patent
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Abstract
A coaxial cable structure incorporating a physical interruption in the outer jacket or sheath of the cable. This interrupts the continuity of the outer conductor and serves to block DC (direct current) and low frequency electrical signals. Also, it greatly reduces heat transmission along the cable. The interruption is achieved by placing a specially fabricated stub in series with the coaxial cable. The resulting coaxial cable assembly acts like a band-pass filter which, although blocking DC and lower frequency electrical signals, is able to transmit RF (radio frequency) signals at selected frequencies. The entire assembly, including the stub, can be made hermetic.
Claims21
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.
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.
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.
Dependencies are inferred from the claim text.