In plain language: Coaxial cable carries RF between concentric conductors: the wanted differential fields remain mainly between the center conductor and the inside of the shield.
Why an operator notices it
That geometry provides controlled impedance and shielding, but current can still flow on the shield exterior. Coax does not guarantee common-mode isolation by itself.
Decisions that matter
- Match characteristic impedance to the radio system.
- Choose loss, power, flexibility, shielding, and environmental rating for the job.
- Use connectors designed for the exact cable.
A useful field check
- Protect bend radius and jacket.
- Strain-relieve connectors.
- Test the finished assembly at the frequencies that matter.
Common wrong turns
- Confusing shield coverage with zero exterior current.
- Using audio cable for RF because the connector fits.
- Ignoring dielectric damage after crushing.
Technical foundation
This lesson translates established transmission-line and antenna practice into a field decision. Use the current equipment datasheet and Chameleon product guide for changing loss, power, connector, installation, and compatibility limits.
