The most common dielectrics are Polyethylene (PE) and Polytetraflouroethylene (PTFE or Teflon). PTFE and polyethylene is available in solid and low-density forms: foamed, splined, and perforated or expanded tape wrap (micro-porous). Low-density dielectrics are used for low loss and/or phase stable applications. If the application is for a specific time delay, low loss cables may not be advantageous since the velocity of propagation is higher, requiring additional length for a given delay time. (Table 2)

Table 2