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Warren,
I've buried out the article which was pubished
in QST Oct 2010
and carefully studied again.
Below you see a short excerpt from the text:
-----------------------------------------------
"Results:
Forward gain with 180 feet of feeder,
assuming a 2:1
VSWR, was predicted to vary
from -28.6 dBi at 1.8 MHz to -6.4 dBi at
10.1 MHz and this appears to have been
achieved. On all bands noise from
the OS
antenna exceeded that due to the receiver.
Additional
amplification above that from the
preamplifier in the radio may not have
been
necessary if the antenna was only used in the
forward direction. In
this application, while
receiving off the back, an additional
ampli-
fication stage may be needed, especially on
the lower
bands."
--------------------------------------------------------
One point of G3LNP's approach is in fact -as I said -
to use the orthogonally steerable null
to suppress an interfering station which arrives on
the same bearing (and frequency),
but at a different vertical angle than the desired
station.E.g. he could separate Polish stations
from German stations on 160m because their signals
arrived at different vertical angles yet
on the same bearing.This special feature is only usable
when the antenna is receiving off the back.
The second point is that in the normal forward
mode the *range* of the steerable vertical angle
of the backward null can be extended..
While the standard variable resistance can change the
angle between 85° and ~40°
the variable rectance can extend this range to zero
degrees.
73
Clemens
DL4RAJ
----- Original Message -----
Sent: Monday, May 14, 2012 1:26 AM
Subject: Re: LF: Cardioid RX antenna for
LF...
Clemens,
The G3LNP reactance tuned
loop receives off the front so it has
the same output level as a similar
sized K9AY etc, the vertical angle
of the rear facing null is steerable by
varying the reactance.
73 Warren K2ORS
On Sun, May 13, 2012 at
6:26 PM, Clemens Paul <[email protected]> wrote:
>> BTW,
Tony Preedy G3LNP published an article last year in QST which
>> had a
loop with variable reactance and resistance termination, by
>> varying
the reactance one could adjust the vertical angle of the main
>>
lobe.
>
>
> If_I_recall_it_correctly this design uses the
*backside* lobe of the K9AY
> for vertical beam steering which is as we
know a lot, 20dB-30dB,even weaker
> than the low gain frontside
lobe.
> 73
> Clemens
> DL4RAJ..
> ----- Original Message
----- From: "Warren Ziegler" <[email protected]>
> To:
<[email protected]>
>
Sent: Sunday, May 13, 2012 11:37 PM
>
> Subject: Re: LF: Cardioid RX
antenna for LF...
>
>
>
--
73 Warren
K2ORS
WD2XGJ
WD2XSH/23
WE2XEB/2
WE2XGR/1
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