Inductive reactance Xl = 2(pai)fL, hence the voltage drop would be considerable with very poor voltage regulation and considerable noice, in transmission on EHV lines..

Generally MV and LV have only transformers to boost or step down the voltage and no switching circuits. Hence there is no need for special circuits in the BPL needed to remove these switching noises. If you are talking about HVDC or FACTS (Flexible AC)the way for some compensations respectively. This introduces good noise and it is very difficult to remove such noises which are due to continuous switching in HVDC and FACTS. More over this BPL is useful only for remote places where communication facility is not there. Today based on the mobile/satellite technologies, it is easy to implement one such Base station rather than trying BPL if you need lot of communication/networking features.

It may be conditioned by the forceful increasing of interference in the radio-frequency band in high-voltage power transmission lines in comparison with low and medium-voltage ones.

In case of HV power lines there is usually a ground wire present, which, today is mostly so called OPGW, incorporating an optical fibre core with e.g. 96 threads. This gives inexpressable bandwidth compared to any other technologies.