The inner conductor (also known as the core) is usually a rigid copper conductor. This has different diameters depending on the design of the coaxial cable. The inner conductor is surrounded at a constant distance by a hollow cylindrical outer conductor and can be made of different materials.
An overview of the different materials:
| Cu solid | Solid copper |
| Cu stranded wire | Copper stranded wire |
| AlCu stranded wire | Copper stranded wire with aluminium core |
| CuAg stranded wire | Silver-plated copper stranded wire |
