Attenuation

There are two types of losses with a MIL-C-17 coaxial cable. The first results from the dielectric properties of the core and the second is from conductor losses. The use of PTFE as a dielectric provides the lowest dielectric constant and is very stable over a wide range of temperature and frequencies. The conductor losses depend on the base material of the conductor and shield along with the plating of each, especially in higher frequency ranges.

V.S.W.R (Voltage Standing Wave Ratio)

The VSWR is the vector addition of the impedance changes along the length of a cable. The variations can be random or periodic. A resonance can occur at a particular frequency resulting in a VAWR spike. These impedance changes will often be related to a process during manufacturing. Because of the ram extrusion process for manufacturing PTFE dielectrics, most of the dielectric manufacturiog spikes are not present. The VSWR will change with frequency.

Characteristic Impedance

MIL-C-17 coaxial cable are available with characteristic impedance values 50, 75 and 95 ohms. Most systems use 50 ohms because it allows for maximum power transmission with minimum loss. The 75 ohms cables are more common in cable TV transmission where minimum cable attenuation. The 95 ohms cables are typically used for data transmission applications.