Applications may require cable assemblies that are trimmed to a specific electrical length, which may change with temperature, flexure, or other environmental factors. Solid Teflon dielectric, for instance, has a much more pronounced phase shift (change in electrical length) around room temperature than a micro-porous or air-articulated Teflon dielectric. (Figure 8) A tighter bend radius will increase phase change, and increasing the number of flexures will also increase phase change. Phase changes over frequency can be considered a linear response, although some cables will have more significant change at higher frequencies.
Figure 8 - Phase vs. Temperature Relationship