I'm no expert at all on such matters, but it seems to me that chokes
should be placed wherever the current maximums of the undesired signal
would be. Chokes don't do any good at current minimums. The problem,
of course is figuring out where the current maximums are since I'm not
sure you can assume one is at the feedpoint of the antenna. Maybe it is
... I don't know. We're talking the current maximum of the noise, and
I'm not sure that would necessarily be the same point as the current
maximum of the transmitted/received signal.
In any case, if your feedline is long enough there will be multiple
current maximums every half wavelength. I'd also put a choke where the
feedline enters the house just for good measure, to catch whatever noise
might have been picked up between the next closest choke and the house.
Just some thoughts, educated or not.
73,
Dave AB7E
On 10/21/2018 12:31 PM, Tony wrote:
All:
I use an end-fed half wave for portable work and was wondering what
the most effective way would be to reduce the ingress of feed-line
noise? I've compared it to a resonant center fed dipole in the field
and found the receiver noise to be higher on the end-fed: same
location with the same feed line.
I've tried a single choke at different lengths along the feed line
which does seem to reduce the noise to some extent, but I'm wondering
if adding several chokes at some specific interval would be more
effective.
The antenna is usually deployed with one end in a tree with the
feed-point a few feet off the ground. I suspect that grounding the
feed line at the feed point would help, but a ground rod is not
particle in the field.
Thanks,
Tony
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