[TowerTalk] Stacking question - another data point

[Tim Duffy]

Hello John,

The K3LR stack has been optimized as a 3 high in phase array for best
pattern control (both AZ/EL). Optimizing for best rear rejection (over 180
degrees)and eliminating high angle radiation (lots of noise up there) takes
some doing. HFTA was also used to determine best heights.

As W6NL says "Experience trumps theory".

The 3 high stack at K3LR works very well for DX Contest work.

73,
Tim K3LR

-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of
john at kk9a.com
Sent: Friday, August 19, 2016 1:33 PM
To: towertalk at contesting.com
Subject: Re: [TowerTalk] Stacking question - another reality data

 

That is a good question Jim. 72' stacking distance works well with small
40m beams however K3LR's 4el OWA antennas are anything but small. I
believe that he has three which puts the top one at 262 feet. I too
would think equally spacing them down the tower would be better but I
have not modeled this scenario. 

John KK9A

[TowerTalk] Stacking question - another reality data
from [Jim Thomson] [Permanent Link][Original]

"Tim Duffy K3LR said:

I 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's
up in the air and using them for many years here at K3LR - these are the
stacking distances that have worked very well at this Western PA QTH:

Lowest Yagi height:
40 meters - 118 feet
Then - stacking distances by band:
40 meters - 72 feet

## How did the 118 ft for the lowest height for 40m come about ? That
and the
72 ft stacking distance on 40M ? That would put the upper 40m at 190 ft.

72 ft spacing on 40m is like 36 ft spacing on 20m. 

## I would have thought that a 95 / 190 stack on 40m....with 95 ft
spacing 
would
have been the ticket. 

Jim VE7RF
 
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