John,
Thanks for responding to query.
I would like to discuss further a few points.
1)" A series-resonated loop is not a high-impedance antenna."
I guess I am misunderstanding The RJELOOP program. The program predicts
that the loop impedance will be 1580K ohms and the 1 turn loop(my feed
point) is 1.8 K ohms at resonant frequency. Am I missing something?
Bill's (WA) loop is 50' on a side using 1 turn. Mine is 7' on a side using
30 turns.
What did I forget her John?
2)"Area enclosed by the loop is the key. But in this case, Paul, I believe
you
may be asking the wrong question. DO you really want to do that? If you're
planning to put the transmitter at the loop, fine. But remember that the
regulations under which we work here currently limit us to a total antenna
of
15 meters--INCLUDING transmission line, which in your current setup is
already 110m."
I agree that I am out of compliance with the 110 meters of transmission line
feeding the antenna.
When fully implemented however this feed line will supply only the drive to
the 1 watt input final.
Did you make your above comments because you think that he feed line may be
radiating?
A test was preformed with W1VD at the receive end and the loop has a front
to side ratio of approx of 22db
Not optimum for sure but I don't think the feed line is radiating all that
much.
Another test performed was to mistune the antenna and record results using a
HP Selective Voltmeter.
Out of resonance the RX sig dropped in excess of 40 DB
So I guess I would Yes I do want the loop to radiate.
Thanks you and anxiously awaiting yours and any other comments on this post
Paul
Paulc
W1VLF
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-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of [email protected]
Sent: Monday, February 11, 2002 4:51 PM
To: [email protected]
Subject: Re: LF: Loop questions
In a message dated 2/11/02 2:09:07 PM Eastern Standard Time, [email protected]
writes:
<< Here are my questions.
1) Does this "high impedance antenna?" suffer from the same problems as a
high "Q" vertical such as absorption from trees, ground etc? So that
removing it from this environment might increase signal strength? >>
A series-resonated loop is not a high-impedance antenna. As should be clear
from Bill Ashlock's experiments, transmitting loops are less immediately
affected by some aspects of their environment; but they are affected by
close
proximity to any somewhat conductive surface, as you found out by raising
your loop above ground.
<< 2) Would I benefit from using Litz wire? >>
Maybe.
<< 3) Does higher "Q" neccessarily mean more radiated signal? >>
Not absolutely, but it does indicate reduced losses, which is generally more
conducive to radiated signal strength.
<< 4) In most cases I don't belive we want the coil to radiate but in this
case
I want to increase it. Any ideas on how to do that? >>
Area enclosed by the loop is the key. But in this case, Paul, I believe you
may be asking the wrong question. DO you really want to do that? If you're
planning to put the transmitter at the loop, fine. But remember that the
regulations under which we work here currently limit us to a total antenna
of
15 meters--INCLUDING transmission line, which in your current setup is
already 110m.
73,
John
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