School of Engineering and Sustainable Development, De Montfort UniversitySchool of Engineering and Sustainable Development, De Montfort UniversityChorleySchool of Engineering and Sustainable Development, De Montfort University
Recent IWCS conference publications from the authors have evaluated the Cavity Perturbation Technique for the measurements of dielectric constant of Ethernet cable dielectrics. Marked changes in both dielectric properties and transmission performance of Ethernet cable and its dielectrics as a consequence of thermal variation have been noted and reported. Thermal variations in twisted pair Ethernet cables are commonly associated with Power over Ethernet delivery as well as changes in the cabling operating environments. To date, only changes in the transmission parameters of the Ethernet cables and the real part of the dielectric permittivity have been reported. This paper reviews previous work and reports further progress in the dielectric measurements. Firstly, the dielectric properties of Fluorinated Ethylene Propylene (FEP) and High-Density Polyethylene (HDPE) used fin Ethernet cabling were examined at an elevated room temperature to compare their dielectric constant at 1GHz, 2.4GHz and 5GHz. After that, a continuous 30-day heating at ～65℃ without cooling was carried out on the FEP to observe the effect of prolonged heating on its dielectric constant at 2.4GHz and 5GHz. And lastly, FEP was thermally cycled between the room temperature and ～65℃ to study the effect of intermittent and prolonged heat cycling on its dielectric constant (ε_r) and loss tangent (tanδ). The ε_r of FEP was found to be lower when compared to that of HDPE at room temperature. Furthermore, the evaluation of the ε_r of FEP at 5GHz based on constant heating of ～65℃ suggests that the ε_r may initially decrease but later increase permanently based on prolonged heating. Whereas, at 2.4GHz, the ε_r of FEP may likely decrease progressively as a consequence of prolonged heating. However, due to thermal cycling of the FEP at 2.4GHz, the ε_r decreased due to the effect of temperature at 60℃ but increased based on the cooling at 25℃. Progressive increase in the tanδ of the FEP was also observed during the heating and cooling cycles.
Cable Performance;Degradation;Dielectric Constant;Dielectric loss;Dissipation factor;Twisted Pair;FEP and HDPE