抄録
This paper describes calculation method of equivalent relative dielectric constant εs of VVF cable. For Power line communication (PLC), VVF cables in homes are used as 2M to 30MHz high frequency transmission media. As they are not designed and installed for such transmission media, there are many branches and impedance mismatch points that cause PLC signal reflections and standing waves. In order to estimate such standing wave generation and estimate undesirable PLC signal radio wave leakage, the length of cable and relative dielectric constant εs is important. However the insulator of VVF cable is thin and not symmetric, it is not easy to calculate εs mathematically. In this paper, equivalent εs is calculated numerically using PC soft EXCEL by dividing the electromagnetic field lines and analyzing the effect of insulator for each field line. The calculation result of VVF cable considering the limited insulator area around the conductors shows that the equivalent εs is about 13% less and transmission speed is 7% faster than the insulator is full space around the cable.
