[RFI] Sense antenna for ANC-4 power line rfi?

[Dave Cole]

Charles,

You may find that the phase type noise reducers don't work so well on 
power line noise...  It can help-- but mostly it will not be very 
effective for distributed RFI sources.

The source of transmission can be distributed, (not in all cases), along 
several hundred, to several thousand feet of power line.  This means 
that depending on the distance traveled down the power line, the 
distance to your sense antenna, and the distance to your main antenna, 
RFI will arrive at different times, and hence different phase 
relationships to each other, from every point along the power line that 
carries the RFI.

Given that the ANC-4 is a phase cancellation device, (it looks at your 
main antenna, and your sense antenna, and tries to phase cancel an  RF 
signal based on phase relationship), this can cause no end of issues.

Now imagine the signals the ANC will see if your RFI is being 
re-radiated along several hundred, or thousand feet of power line.  You 
will be able to cancel some, but not a lot of the RFI.

If you are lucky, you will have a specular source, and no re-radiation, 
which will allow you to cancel most of the offending signal out...

Your idea is a good one, and might help...  RFI suppression is always 
fun, when it works...  Good luck.  Please do post your results.

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 1/12/21 11:07 PM, Charles Plunk wrote:
> While waiting on my powerline arc to return in force enough to have 
> confidence it will be ongoing when I call TVA in, thought I would play 
> with improving the sense antenna on my Timewave ANC-4. The 3 phase power 
> runs at the edge of my lot up to the suspect pole. So the noise is 
> radiating up this way and all the more reason its strong on me I 
> suspect. I have a storage building underneath the lines. I am thinking 
> about a vertical made for a scanning receiver I came across and mounting 
> it up under the lines on that building. I will tack it up there somehow 
> and move it around to get a sweet spot maybe. Any better ideas?
> 
> Thanks,
> Chuck
> AF4O
> 
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