Stan
Yes, for each one db improvement on RDF you can expect 2 or more dB on signal
to noise ratio. One simple solution for you is to phase two or 4 delta flags,
it will provide over 14 db RDF and only 50m long.
73’s
JC
N4IS
From: Stan Stockton <wa5rtg@gmail.com>
Sent: Saturday, December 15, 2018 3:28 PM
To: n4is@n4is.com; topband@contesting.com
Subject: Re: Topband: Waller Flag
Thanks, JC. Based on what you said and what I know about the location, I think
I probably have enough noise that I shouldn't have to worry about how much gain
the preamp might have relative to the negative gain of the smaller antenna.
My plan would be to install it horizontally at about 64 feet above a tribander.
If I can make it all work, it would be the greatest improvement to my little
station that could possibly be made. I have worked VU2 and some other good
stuff with what I have tried in the past, but there is no question that I
transmit a lot better than I receive on 160m.
I see in the model I have that going to 750 feet high increases gain by about
17 dB and RDF by about 3 as compared to where I can put it.
I would be very pleased to make a noticeable improvement over the little
triangle antenna and have something that is on my tower that I could rotate.
73...Stan.
On Sat, Dec 15, 2018 at 2:04 PM <n4is@n4is.com <mailto:n4is@n4is.com> > wrote:
Hi Stan
There are two very important numbers to consider, first is horizontal or
vertical, the horizontal signal is zero at ground level and maximum at 1.5
wave length height , vertical signal is maximum at ground level and minimum
at 1.5 wave high. The second is the gain, the local noise limits the gain,
if you are on a very quiet location bigger loops can dig weaker signal out
of the noise.
Vertical WF can be small, 6 or 8m are common, you only need a low noise
preamplifier 2db or better, gain is not important , 20 db external gain is
enough on 160m. Horizontal is more challenging you need a < 1db NF.
I am working on a project using two SDR receivers to phase the loops by
software, it should be possible to reduce the size of the boom. But not the
height necessary because the limitation is the horizontal receiver signal
intensity. For horizontal average performance on 160m it is necessary 20 m
above the ground, 10m high for 80m. Good performance on 160m it is necessary
30 to 40 m above ground, and it shows no limitation on performance. Higher
is always better.
Check vertical W8VVW (8m) WF or WX4D ( 10m) original WF.
Regards
JC
N4IS
-----Original Message-----
From: Topband <topband-bounces@contesting.com
<mailto:topband-bounces@contesting.com> > On Behalf Of Stan Stockton
Sent: Saturday, December 15, 2018 2:15 PM
To: topband@contesting.com <mailto:topband@contesting.com>
Subject: Topband: Waller Flag
I am curious to know if anyone on here has scaled a Waller Flag to a smaller
antenna and had any success with whatever might be available for preamps to
bring the gain up enough to start to hear band noise.
At my location on Cayman Brac I could probably get by with a 20 foot boom
but not much larger. According to my model, one with a 50 foot boom is
about -48 dB, one with a 30 foot boom is about -65 dB and one with a 20 foot
boom, like I would lilke to put up, is about -79 dB.
I guess a lot to do with how successful the antenna might work for me will
have to do with how much preamplifier gain I will need at my particular
location to start to hear noise. I wanna use it on 160, 80 and 40 and the
gain of the 20 foot boom one is enough for 80 and 40 using a 30 or 40 dB
preamp.
Any help would be appreciated.
73 and Merry Christmas...Stan, K5GO/ZF9CW _________________ Searchable
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