Probably the most common coaxial cable is the simple flexible coaxial cable which is mostly used by the common person to connect video equipment. This cable has a metal inner conductor, a flexible plastic polymer dielectric tube surrounding it, a braided/woven conducting metal shield around the dielectric and lastly a jacket covering to protect the interior from environmental damage such as moisture, puncture and abrasion or breakage of the shield.

For extreme flexibility, a stranded copper central conductor is used with a surrounding dielectric tubing of PE (polyethylene) foam that is then surround by an Al tape outer conductor combined with a tinned copper braided shield.

Flexible Coaxial Cable

When less flexibility is needed, somewhat higher performance characteristics are obtained when solid wire (bare copper, bare copper clad aluminum) or even copper tubing is used as the inner conductor. For higher frequency performance, the inner conductor may be silver-plated such as SPCW (silver plated copper wire) or silver plated copper clad steel. Braids and foils may also be silver-plated.

As a substitute to PE foam, more water resilient but less flexible solid polymer dielectrics such as LD PTFE (low density polytetrafluoroethylene) are used. Cables can be jacketed with smoke retardant PE polymer coatings. The maximum fire resistant rating is given to cable jacketed with FR PVC combined with PTFE dielectrics.

One of the disadvantages of highly flexible coaxial cable is the use of a braided shield that is not a smooth surface and bending causes variations in the actual electrical characteristics of the cable. Very sharp bends or even kinking of the shield can seriously affect transmission power and integrity. Similar results occur from bending of the stranded inner conductors. A solid conductor with a coating to smooth the surface and the use of a film shield within the braided shield are improvements but not ideal.

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