[Elecraft] KAT500 Antenna Grounding

[Fred Jensen]

Indeed.  We live on a more or less rectangular 5 acres.  A 69 KV tie 
line connecting two hydroelectric power plants N and S of us transits 
the SE corner of the property.  Under it are primary 12 KV distribution 
lines.

When preparing my comments to the FCC during the BPL bruhaha some years 
ago, I noted most of the comments focused on BPL interference *to* ham 
operations.  The other side of that equation is equally troublesome if 
my operations destroys my neighbor's Internet access.

So, I modeled the 12 KV distribution lines and my closest antenna in 
EZNEC-4.  I found that on 80 - 10, the coupling between my antenna and 
the power lines was a fairly constant -28 dB.  On 160, it was -17 dB, I 
think because the lines and antenna are in each other's near field at 
that low frequency.  A -30 dB coupling coefficient means that 1 KW puts 
1 W into the into the power lines, which no doubt would have saturated 
my neighbors BPL modem had BPL actually been deployed around here.

If the "antennas" are in the near fields, the coupling would have put 
around 50 watts into the power lines.  The power lines are essentially 
non-resonant, so yes, a nearby unused antenna can produce significant 
amounts of power just from proximity to a working antenna.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015
- www.cqp.org

On 5/11/2015 9:55 AM, Wes (N7WS) wrote:

> I won't expand on that but will address the real problem that you pose.
> IMHO, whether or not you "ground", "short" or otherwise screw up the
> impedance of the driven element of the inactive antenna, there will be
> interaction between the two antennas.  Regardless of what you do to the
> inactive antenna's DE, all of the elements on both antennas are
> coupled.  To what extent, who knows?