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Message-ID: <003601cc2696$b086dcc0$4001a8c0@lark>
From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <9E1D0F6DD9224C7A86D4227122F486E5@MLB>
Date: Thu, 9 Jun 2011 12:11:48 +0100
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Subject: LF: Re: antenna for 137kHz.
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Hi Martin, I would confirm Hugh's ideas. The idea way for all bands might be
to use the bottom of the remote pole as the feed point of the wire. This
gets the wire away from a lot of the pick-up and also from TV downloads,
house wiring  and things that might pick up from your transmissions.

Dont forget that two or three spaced horizontal top wires will improve your
inverted L even on top-band, but try to keep the wire as far away as is
practicable from walls, trees etc. which will increase the loss. I recommend
a simple aerial bridge for optimising the aerial and ground wires. But
getting it away from man-made noise is a winner, every extra metre helps.
The loop may well be quieter, but not necesarily so, but it will probably
not be a competitor on transmit unless you have an awful lot of tall trees
in that small plot.

Fortunately 137 is a narrow band so you will probably find that you dont
need to keep rushing out to retune.

Best of luck
Alan G3NYK
----- Original Message ----- 
From: "Martin Evans." <books@mollies.freeserve.co.uk>
To: <rsgb_lf_group@blacksheep.org>
Sent: Thursday, June 09, 2011 11:07 AM
Subject: LF: antenna for 137kHz.


> Gentlemen - some advice, please.
>
> My radio room is in a bedroom at the back of my house.
>
> Currently, I use a wire running from the bedroom up to a pole on the
chimney about 35ft (10m) above ground,
> then to a pole at the bottom of the garden about 100ft (35m) away, then
down to the bottom of the pole, where
> it is tied off.
>
> I tried running the wire back to the house (end not connected to anything)
at about 8ft above ground (2.5m)
> but this runs alongside a long building with my office, with electicity
cables, computers, etc, so it picked
> up a lot of noise.
>
> The signals seem "cleaner" when this return run is cut off.
>
> How can I improve this setup?
>
> I am thinking of pulling the far end of the wire over to the other side of
the garden and running it back to
> the house there, probably about 10ft (3m) above ground, then back inside
to make a loop.
>
> I would then have a loop aerial in a 45 degree plane, roughly.
>
> Does this sound as if it could be an improvement over my current setup?
Would lifting the bottom of the loop
> up to be more horizintal be better or worse?
>
> Any other suggestions?
>
> My garden runs roughly East-West. Does my current "Inverted U" aerial have
any directivity at this frequency
> (137kHz)? What would be the directivity of my proposed 45 degree loop?
>
> Thanks for any help & suggestions,
>
> Martin  GW3UCJ deep in the Swansea Valley!
>
>
>
>