[Elecraft] Contact your Representatives (BPL)

[Michael E Dobson]

Well my antenna is located 10 feet from both the power lines and the pole
where the BPL repeater would in all likelihood be located for the four
houses that get power from that transformer.  I suspect that at that
distance resonance would not matter at all.  I'm using a 102 ft G5RV
about 25 feet off the ground.  It is arranged broadside to the power pole
and at a 30 degree angle to the power lines on the street.  It runs
roughly parallel to the lines feeding the house.  I would expect rather
good coupling which probably explains why I have trouble getting a good
match on certain frequencies.

Mike WA3KYY

On Tue, 30 Sep 2003 10:29:01 -0700 (PDT) "John A. Magliacane"
<kd2bd@yahoo.com> writes:
> --- "Guy Olinger, K2AV" <olinger@bellsouth.net> wrote:
> > 5 watts in band on the antenna of a spread spectrum receiver will
> > certainly swamp it. Spread spectrum overcomes that kind of
> > interference when it's at the SAME power level as it's desired 
> receive
> > signal.
> 
> Hmmm...  I'm not fully convinced that's true.  Remember, these are
> digital signals, presumably sent with enough redundancy to tolerate
> certain errors.  If the transmission system is adaptive, then 
> perhaps
> it could even compensate for interference of this sort.
> 
> I do agree that 5-watts into the front-ends of MOST receivers would
> overload them to the point of being pretty useless.  But coupling
> 5-watts of RF into a power line ain't easy!
> 
> 5-watts is only about 26 dB below the 1500-watt FCC Part 97 power 
> limit.
> Assuming a frequency of 30 MHz, we could induce 5-watts of RF into 
> a
> RESONANT antenna from a 1500-watt transmitter at a distance of 
> about
> 60 feet.  (Reference: Isolation vs. Antenna Separation - 
> http://www.guerrilla.net/reference/quick_ref/dplx_ant_sep.html)
> 
> Lower frequencies could achieve this at larger distances.  If the
> distance is halved, the amount of coupling increases by 3 dB.
> 
> But the point is that these figures assume a RESONANT receiving
> antenna.  For the majority of situations, a power line is anything
> BUT a resonant receiving antenna.  Therefore, it would take a LOT
> closer spacing between power line and antenna to achieve this 
> amount
> of coupling -- so much so that it would probably throw your antenna
> out of resonance.
> 
> I don't believe many amateur stations fall into this situation.
> 
> 
> 73, de John, KD2BD
> 
> 
> =====
> -=-=-=-=-=-=-=-=- John A. Magliacane, KD2BD 
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