Date: Fri, 12 Aug 2016 11:46:17 -0400
From: Hans Hammarquist <hanslg@aol.com>
To: towertalk@contesting.com
Subject: [TowerTalk] Fwd: Fwd: Stacking question - another reality
data point
Message-ID: <1567f6eb796-2629-fd8@webprd-m103.mail.aol.com>
Content-Type: text/plain; charset=utf-8
I realize that the idea probably has been discussed before. I don't have the
possibility to test it (yet) but was wondering if it would enhance the
communication better than elevating a single beam at different heights.
Switching with relays etc is faster than mechanically running a bean up and
down. Two (3, 4, 5) beams will also give better signal than one (I hope).
Hans - N2JFS
-----Original Message-----
From: StellarCAT <rxdesign@ssvecnet.com>
To: Hans Hammarquist <hanslg@aol.com>; towertalk <towertalk@contesting.com>
Sent: Thu, Aug 11, 2016 2:07 pm
Subject: Re: [TowerTalk] Fwd: Stacking question - another reality data point
Seymour, W6CCP does this ... or at least did at one time. He had 2 I believe
6 element 20's spaced horizontally on two different towers and played with
phasing (line length) to get them to work together. He said it was a real
barnstormer.
Gary
K9RX
-----Original Message-----
From: Hans Hammarquist
Sent: Thursday, August 11, 2016 11:48 AM
To: towertalk@contesting.com
Subject: [TowerTalk] Fwd: Stacking question - another reality data point
I have had an idea for some time: When you feed all these stacked antennas
in phase you will have optimum radiation to the horizon (or just above). My
idea is to add switchable delay lines to the higher located antennas. (You
could rather easily replace the damping networks in an attenuator with some
coax do make this.) Thereby you will be able to get optimum angle for
"higher up" propagation. You should select the steps to be small enough not
to get "gaps".
### With antennas stacked side by side, and FIXED in direction, NON rotatable,
the
beamwidth can be steered or slewed + / - by a fair amount. If you look at
the SW HF
broadcast, curtain arrays, where they put the low freq portion on one side of
the screen reflector,
and the high freq portion on the opposite side of the screen reflector, The
high freq portion
can be slewed + /- 30 degrees. The low freq portion can be slewed + / -
15 degs. Thats
coming right from the makers of such arrays. They dont mention being able to
slew in the
vertical plane. The low freq portion typ consisted of ants, stacked 3
high..and 4-8 wide. Typ
height of the 2 x supporting towers was 330 ft. Lowest freq used was the 49m
band, or 5.9 – 6.3 mhz.
## In Bob heils book, which I cant find in my library, misplaced or lost some
where, Bob described
an interesting 40m array, where he stacked 2 x 40m dipoles, and both fed to a
LC network. The take
off angle could be adjusted up / down by adjusting the phase between the
antennas. Dunno if bob used
coax..or open wire line in his phasing scheme.
## For typ BOP use on 2 x stacked yagis, a simple electrical half wave of
coax is inserted into EITHER
leg. If a half wave = 180 degs, then using a mess of relays, the extra line
being inserted, could be switched,
using several different length lines, so phasing could be varied from 0-180
degs in several increments, say
every 30 degs, so 6 x different coax lengths. Im sure it could also be done
via caps + coils. Now whether
it buys you anything or not is another issue.
## BOP results in a take off angle that is always higher than the lowest ant.
A buddy tried BOP on his 2 x 40m
yagis, with top yagi at 180 ft..and bottom yagi at 90 feet. It was a total
failure. Only once did he find a single instance
where BOP actually worked...and that was a station on 40m, that was less than
500 miles away, during the daytime. Loads
of other stations that were 300-800 miles away were louder when in BIP
mode...go figure.
At the time, the pair of 40m yagis was stuck in BIP mode, fed with a L network.
IE: individual yagis could not be selected.
So all he had was BIP...or BOP. Since the array was stuck in BIP mode, the
thought was to add BOP capability, as a cheap
and easy way to obtain a higher take off angle.
## two each lengths of coax used to each yagi. The extra electrical hale wave
of coax that gets inserted into either leg
just consists of one piece of coax, and one spst relay. The relay just shorts
the center conductors of the BOP line, since the
line is just a loop, with the ends brought close together inside the box.
Simple to implement.
Thinking about it, a 40m yagi @ 90 ft is like a 20m yagi @ 45 ft. And 45 ft
on 20m is
pretty low to begin with. I cant see any case where a 20m yagi @ 45 ft would
be too high..at least not on the west coast.
Jim VE7RF
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