That would take some more sophisticated modeling software to see just how
the delayed signals would interact with the ground reflections, they may not
result in exactly what you want. In free space or on vhf/uhf/mw radar or
communications systems that is a common method of beam steering but in those
cases they are usually ignoring ground reflections... and to do that hams
usually use elevation rotors to steer the beams up for satellites or
moonbounce. I have been considering something like that for a 4-square or
larger vertical array to steer the beams, that was essentially how the old
sonar arrays on submarines generated beams from a series of hydrophones
wrapped around the hull.
David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net:7373
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Hans
Hammarquist via TowerTalk
Sent: Thursday, August 11, 2016 15:48
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".
Any taker? (K1TTT?)
Hans - N2JFS
-----Original Message-----
From: Tom_N2SR via TowerTalk <towertalk@contesting.com>
To: towertalk <towertalk@contesting.com>
Sent: Wed, Aug 10, 2016 9:49 am
Subject: Re: [TowerTalk] Stacking question - another reality data point
I used to operate at N3RS, who has 5/5/5 on 20, 5/5/5 on 15, and 5/5/5 on
10. I forget the specific stacking heights/distances, but IIRC, they are
20: 37/77/117 feet, 15: 47/77/127 feet. 10: 25/50/87 feet. I am using 2
C31XR tribanders at 40 and 80 feet, with separate feedlines. On 10, I have
added a 5 element 10 at 25 feet, so while the distances are a compromise, I
will have 3/3 @ 40/80 on 20, 4/4 @ 40/80 on 15, and 5/5/5 @ 25/40/80 feet.
Which seems very similar to Tim's and well as Sig's stacking distances and
heights. I used HFTA not for the gain numbers, but as someone else pointed
out, to eliminate or move the nulls for the arrival angles from Europe
(mainly) and other directions. As John also pointed out, I only have 1
tower, and the C31XR's are just above the guy wires. So that's what I have,
and I have no plans to take the tower down to reconfigure the guy wires. I
know some guys have tribanders at 30/60/90 feet, but I chose not to do that.
Tom, N2SR
From: "john@kk9a.com" <john@kk9a.com> To: towertalk@contesting.com
Sent: Wednesday, August 10, 2016 7:58 AM Subject: Re: [TowerTalk] Stacking
question - another reality data point These are logical stacking distances
and will definitely work well formost stations. Most of us do not have
dedicated towers for each band andwe have to adjust the spacing and heights
to clear guy wires and otherantennas. Fortunately spacing distance is not
overly critical. I usesimilar but slightly larger spacing and similar low
antenna heights toK3LR except on 40m.John KK9ATo: <k1ttt@arrl.net>,
<towertalk@contesting.com>Subject: Re: [TowerTalk] Stacking question -
another reality data pointFrom: "Tim Duffy" <k3lr@k3lr.com>Reply-to:
k3lr@k3lr.comDate: Tue, 9 Aug 2016 21:06:54 -0400I have 41 years
experience in stacking 2, 3 and 4 Yagi's high.After many hours behind the
HFTA and NEC model engines - then putting Yagi'sup in the air and using them
for many years here at K3L
R - these are thestacking distances that have worked very well at this
Western PA QTH:Lowest Yagi height:40 meters - 118 feet20 meters - 50 feet15
meters - 40 feet10 meters - 33 feetThen - stacking distances by band:40
meters - 72 feet20 meters - 60 feet15 meters - 40 feet10 meters - 33 feetAll
OWA Yagi's on all bands at K3LR have booms that are 48 feet long (itmakes a
difference).73,Tim
K3LR________________________________________________________________________
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