Characterization of RF Micro-Coaxial Cable Insertion Loss Degradation
RF micro-coaxial insertion loss escalates through skin-depth resistance, dielectric loss tangent shifts, mechanical flex displacement, and atmospheric oxidation.
ePTFE Dielectric
Meaning
Expanded fluoropolymer insulation provides a low density medium for signal propagation in high frequency transmission lines. Often used in high performance coaxial cables, eptfe dielectric combines air with polytetrafluoroethylene to create a material with a low dielectric constant. It allows signals to travel faster and with less energy loss than solid plastics.
The boundary of its use is defined by the mechanical pressure it can withstand before the air pockets collapse and the electrical properties shift.
Phase Stability
Consistent electrical performance depends on the density of the material remaining stable across a range of temperatures. Because eptfe dielectric contains a high percentage of air, it undergoes less thermal expansion than solid insulators. This stability keeps the signal timing accurate in phased array antennas or high speed data links.
Porosity Control
The manufacturing process stretches the base resin to create a web of nodes and fibrils. By adjusting the expansion ratio, the supplier controls the exact volume of air inside the eptfe dielectric layer. Higher porosity leads to lower capacitance and improved signal velocity.
Mechanical Integration
Softness in the insulation requires careful handling during the termination of the cable. If excessive crimp force is applied, the eptfe dielectric compresses and changes the impedance of the connection. Protective jackets or tapes usually surround the expanded core to provide the necessary crush resistance for field installation.