Topband: rx array proximity to barbed wire fence

[Jeff Blaine]

Tom,

Having fought (and lost) a battle of harmonics from an environmental 
unintended mixer at the last QTH, I really can feel trouble with that 
blasted fence.  The good news is that the transmit antenna is about 100' + 
from the fence, and the other antennas are several hundred feet further back 
yet.

Trying to track down a thing serving as a mixer out in the open where you 
can get too it is a challenge I'm not fretting too much - IF it becomes 
trouble.

73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie

-----Original Message----- 
From: Tom W8JI
Sent: Tuesday, December 11, 2012 5:39 PM
To: Joel Harrison ; Jeff Blaine
Cc: topband at contesting.com
Subject: Re: Topband: rx array proximity to barbed wire fence

While one might claim some theoretical
interaction I have not documented any or identified any performance
degradation as a result.

I see Big Gun Mike, W5UC, has a lot of experience with RX arrays close to
fences has responded as well.>>>>>

The rusty twisted-joint barbed wire fences by my RX antennas were a problem
when I transmitted, but only when I tried to duplex. They were 2000 -3000
feet long and ran right past the TX antennas in a straight line, so I bet
they had a whopping signal level. They generated noise like crazy while I
transmitted.

I think the real problem is all fences and all installations are different.

If the fence has rusty joints and reradiates strong BC station mixing
products, it will be an issue.

If the fence is near power lines and reradiates noise, it can be a problem.

If the fence reradiates propagated signals with significant intensity
compared to over-the-air signals (pretty unlikely), it could be a problem.

It really depends more on the fence and local layout of things than anything
else, so the only way to really know is to just try it.


73 Tom

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