To add to Dennis' comments: you can never have too many antennas
(very important exception: unless they interfere with each other).
Very large arrays such as 8 circle arrays form their deep nulls in the
far field which may be many hundreds of yards away from the array.
Very large arrays are not as effective for suppressing very close RFI sources.,
they're fantastic for more distant RFI sources and especially for
ionospherically propagated interference of all kinds.
Small receiving antennas such as the K9AY or SAL may be more
effective for suppressing nearby RFI.
73
Frank
W3LPL
----- Original Message -----
From: "Dennis" <egan.dennis88@gmail.com>
To: topband@contesting.com
Sent: Monday, October 16, 2017 6:43:20 PM
Subject: Re: Topband: RDF for Transmit 4 Square vs 8 Circle Array
Chuck
Having used both at a number of stations, I can speak with some
experience here.
The biggest virtue I have found of an 8 Circle array is the ability to
put a bothersome
station or noise in a null. Most of the time, you can hear a station in
the 4-square beamed
direction as well on the 4-square as on the 8 Circle. You might even be
able to put
a bothersome station or noise in a null with the 4-square, but now he
doesn't hear you either.
The 8 Circle allows you to steer the null and maybe find a spot where
the SNR is better,
and I've found both as valuable as the direction of maximum gain.
So, yes, you can hear things on an 8 Circle that you might not hear on a
4-square, but to
me its more a question of nulls (of both other signals and noise) rather
than a stronger
signal.
Dennis W1UE
On 10/16/2017 2:26 PM, Chuck Dietz wrote:
> I was always told that, if one had a 4 square, there would be no need for a
> receive array. I am finding this to be untrue when looking at the list of
> RDFs. (Receive Directivity Factor) I have snooped through the archives
> reading about RDF.
> Can anyone verify this from actual experience? Can you actually hear stuff
> on an 8 Circle that can't be heard on the transmit 4 square? I would think
> the difference might be more than marginal with the difference in RDFs of
> 2.48 db. I'm not sure of the difference in takeoff angles. That could be
> important too.
> As a practical matter, the 8 Circle is huge and expensive for a single
> band antenna...
>
> Chuck W5PR
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