page 4Coaxial cables

LOW LOSS COAXIAL CABLES

To have low loss coaxial cables it is possible to act in these ways:

- Increase the diameter of the cable (increase the size of cable)
- Improve the skin effect of conductors (decrease the attenuation due to conductor)
- Increase the percentage of air in the dielectric (improve the quality of the dielectric)

Increase the size of the cable has a practical limit beyond which, cost, weight, handling etc... become unsustainable, by further increasing the diameter there is a reduction of the cutoff frequency.

The skin effect is optimized to the maximum by using silver plated conductors or using a solid central conductor or both of them.

Increase the amount of air into the dielectric is the best solution to decrease attenuation. Years ago the problem was solved in TV antenna connection using as dielectric the cheap foam, in fact, these cables are still considered with the lowest loss. The trick is to use a cheap dielectric and easily made by adding a high concentration of air (inert gas) , obviously the scarce specifications necessary for the consumer TV field does not make them suitable for industrial uses. For the industrial purpose are available foam corrugated cables (for example Cellflex cables) and foam not corrugated 10 mm cables like RG8-FOAM, Ecoflex10, WBC400, RT5020, H1000, LMR400 etc..., and 5.5 mm cables like LMR240, WBC240, H155, etc..., these cables are suitable for industrial applications at a reasonable cost.

For more complex microwave applications it is available a Huber+Suhner S_04272_B cable with 5.5 mm diameter

FLEXIBLE COAXIAL CABLES SELECTION GUIDE

SEMI-RIGID/HANDY-FORM COAXIAL CABLES SELECTION GUIDE