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Date: Fri, 20 Dec 2002 11:02:11 +0100
Message-ID: <2D280BB697C7EE4C979C5C89925418EF1BF5A5@TNS-FBU-2E-003.corp.telenor.no>
Thread-Topic: LF: Big vs small RX antennas
Thread-Index: AcKnidoTkGYJBU+oRIWJ9iV0rQFCAgAgzncg
From: jan-martin.noding@telenor.com
To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: Big vs small RX antennas
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Can't see any arguments against my version. But apart from telling that you disagree,
you don't give any related reasons.

I already agree to the balance, but using a balanced amplifier for a balanced 
antenna is only amateur nonsense.
 
And using the amplifier is nonsense when it doesn't improve for anything -
only increase an already strong enough signal. The only argument is that it is
more complex, and it is worth some money if you sell it.

My loop has center grounded, it is at least necessary for the varicap tuning, 
and I use a coupling loop of 1/100 of the totalt antenna area

73 es merry xmas,
Jan-Martin
LA8AK

-----Opprinnelig melding-----
Fra: Ashlock,William [mailto:William.Ashlock@edwards.boc.com]
Sendt: 19. desember 2002 19:02
Til: 'rsgb_lf_group@blacksheep.org'
Emne: RE: LF: Big vs small RX antennas


I don't buy this. The reason for the balanced connection (or center tap) to
the loop is to reduce the so called 'antenna effect'. Without the balance
the antenna will be sensitive to the E-field of the intended signal as well
as all the other unwanted signals and noise in the area, coming from all
directions. Also, the desired null off the side, typically 40db for a well
balanced loop, will be greatly reduced if the loop is connected simply to
one side.
 
One common way to achieve a 'balance' is to isolate the tuned winding from
the input to the amplifier with a one or two turn isolated pickup winding. A
ferrite core can also be used that couples one turn from the main winding to
the amplifier or receiver. John Andrews uses this approach. I call both of
these a 'floating connection' rather than a balanced connection', but they
achieve the same thing because neither is effected by E-field signals.   
 
Bill A

 
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