Re: [Swprograms] OT: FCC BPL Meeting

[Joe Buch <joseph.buch@xxxxxxx>]

Yes, the ARRL, National Science Foundation, NTIA and others have noted the 1/D field strength argument.  Radiation from a point source decays as 1/D^2 where D is the distance from the emitter.  An infinite line source causes the field to decrease at 1/D where D is the perpendicular distance to the wire.  An interesting extrapolation is that perpendicular to an infinitely large conducting plane the field does not decrease at all.  How about that.  Build an infinitely large copper plate and you would have a way to transmit power very efficiently.  Where is Tesla when we need him? 

The counter argument from the manufacturers is that the concern is irrelevant because the wires don't radiate appreciably at all.  There is a second wire running parallel to the first wire which is fed with an equal and opposite phase polarity signal.  Because the wires are spaced closely together in terms of the wavelength at HF, the fields effectively cancel each other at a distance of 10 times the line spacing or so.  Just like an open wire transmission line will have no radiation if the currents in each wire are balanced and 180 degrees out of phase.  

In theory the manufacturers are right.  In practice they are full of BS because the load on each phase is not constant so the BPL transmitter is always looking at an unbalanced, time-varying load.  Consequently the currents in each wire from the BPL transmitter are never truly balanced and so the wires do radiate as every honest test has demonstrated.

At 09:20 AM 9/27/04 -0400, Richard Cuff wrote:
>Had the chance to hear the Canadian saga of BPL on Sunday.  One of the ODXA
>guys was able to obtain the architecture of the Sault St. Marie test loop
>that was run earlier this year.
>
>One of the interesting elements that came out of the testing up in Sault was
>that the point source distance-squared model of radation decay is
>technically inappropriate since the radiator is a wire, not a point.  As a
>result, the radiation decayed on a linear distance basis, not a
>least-squared basis, in the vicinity of the wire.
>
>We also saw pictures of what BPL injection / removal connections looked
>like, so it's a bit easier to spot BPL installations from the ground.



~*-.,_,.-*~'^'~*-.,_,.-*~'^'~*-.,
Joe Buch
-*~'^'~*-.,_,.-*~'^'~*-.,_,.-*~'^


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