Astro wrote in message news:opshy5fcl1v1dc2q@athlon2600...
When you run high frequencies through any wires, you'll get radiation. I
suspect the frequencies used for BPL (mhz), combined with the waveforms
used, will lead to radiation at a variety of frequencies due to the
harmonics.

Not really. Depends on their efficiency as an antenna. Consider
coax. Cat-5 (UTP) is rendered a lousy antenna by the pairwise
twisting. Cogitate as follows:
Say a pair is carrying waveform, and length per full twist is l. l is
much shorter than wavelength on cable. A section of cable of length
l/2 propagates electromagnetic radiation to cancel that of adjacent
l/4-length sections.

Not to mention the very low-voltage (fractional volt) signal and hign
forward impedance.

HTH,
John