[TowerTalk] Fwd: Stacking question - another reality data point

n1rr at comcast.net n1rr at comcast.net
Thu Aug 11 14:27:55 EDT 2016 

Hans, 
This idea of lobe steering or tilt is also used on commercial collinear / stacked dipole VHF/UHF verticals to 
apply an up-tilt or a down-tilt in the main lobe of the vertical to solve terrain/coverage issues. 

I have three comments on this for HF stacked yagi lobe steering: 

#1 For a DXer on the highbands, it might allow for a small improvement in signal to a single station, but you 
have to remember that as you move the lobe away from natural ZERO-TILTED standard phasing state, 
the gain figure of the main lobe will decrease and it likely will decrease at nearly or greater than the 
increase in TX/RX signal strength resulting in no improvement or a negligible loss/gain. 
(This can also be seen when side-stacking [horizontal stacked pair] when BOP splits the forward lobe but 
the gain is cut by 3 to 10db. I'd love to play with a pair of long boom yagis when the higher bands open again 
while trying to cover the pacific and Asia from here without a rotor but using lobe steering.) 
This kind of control is very precise, whereas HF propagation over a typical opening covers a broader set of 
wave angles then the granularity that 1 degree tilt would provide in a contest running/CQ-ing operating scenerio. 
If you did try this, I'd model it with a 2-stack using very long yagis which would have a narrow and higher gain lobe 
to control from the beginning and I would test it on the highest band that offers F-layer prop which will delay the 
start of your on-air testing until 2026..... 

#2 The use of a BOP antenna phasing position - 
Tim-K3LR has only implemented that on two bands: 20M & 15M. 
And it is likely only to improve the short skip signal strength to fend off frequency incroachers or to work 
short-skip close-in Canadian Ops or e-skip. Maybe Tim or some of his ops on those bands like DG/UA/RV etc 
can comment on what conditions the BOP is useful for longer haul propagation. Those would be enlightening stories. 

#3 There's been some work published that covers using lowband gain arrays and lobe steering them. This might 
be another area for you to investigate. If you come up with any ideas that Dave or I could try, I'd enjoy talking 
with you about them next time I come up to Peru. 

-Charlie N1RR 
----- Original Message -----

From: "David Robbins" <k1ttt at arrl.net> 
To: "Hans Hammarquist" <hanslg at aol.com>, "reflector -tower" <towertalk at contesting.com> 
Sent: Thursday, August 11, 2016 12:16:43 PM 
Subject: Re: [TowerTalk] Fwd: Stacking question - another reality data point 

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 at arrl.net 
web: http://wiki.k1ttt.net 
AR-Cluster node: 145.69MHz or telnet://k1ttt.net:7373 


-----Original Message----- 
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Hans 
Hammarquist via TowerTalk 
Sent: Thursday, August 11, 2016 15:48 
To: towertalk at 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 at contesting.com> 
To: towertalk <towertalk at 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 at kk9a.com" <john at kk9a.com> To: towertalk at 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 at arrl.net>, 
<towertalk at contesting.com>Subject: Re: [TowerTalk] Stacking question - 
another reality data pointFrom: "Tim Duffy" <k3lr at k3lr.com>Reply-to: 
k3lr at 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 
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