[TowerTalk] H frame for 10 or 15m

Stein Roar Brobakken s-roabr at online.no
Wed Aug 17 15:51:01 PDT 2011

Thank you all guys for sharing thoughts and ideas with this subject.

Will start with 4 over 4 on 10m first... then we will see what we can do on
15m and in future on 10m.

73s and see yaa in contest 

In contest LN5O/LA5O from Ringsjoen Contest Club

Best Regards  from [73s de Rag LA6FJA]
Stein Roar Brobakken
Pobox 5 
NO-2853 Reinsvoll

Radio Amateur callsign : LA6FJA K3RAG SO5RAG DV1/K3RAG
skype:la6fja  #  mailto:la6fja at nrrl.no  #  http://la6fja.eu #  Telephone :
+47 48 22 44 21 / +47 45 211 654
Member of NRRL http://nrrl.no , ARRL,PARA, WWYC and Ringsjoen Contest Club
LA5O LN5O, DX1M Magelan,CWOpst #933

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Jay Kesterson K0GU
Sent: Tuesday, August 16, 2011 3:37 AM
To: towertalk at contesting.com
Subject: Re: [TowerTalk] H frame for 10 or 15m

On 8/15/2011 1:30 PM, Stein Roar LA6FJA-K3RAG wrote:
> Hi
> does anyone have ideas sizes for a H frame for 4-5 el yagies for 10 m and
15m ?
> is it 1/2 wl , 3/4 wl or 1 wl spacing ??
> I saw one from http://www.arraysolutions.com/Users/h2a.jpg Arraysollution
from PY5EG
> 73 LA6FJA Rag

   Your best bet if possible is to model the antennas and look at the 
gain compared to one antenna and the patterns. The wider the horizontal 
spacing the bigger your first side lobes. That may not be a problem if 
you can't stack them very far apart horizontally. But if you can stack 
them far apart then you need to possibly chose a bit more gain vs a 
better pattern.

   I have a model of a Hy-Gain 105CA (24' boom) for my antenna modeling 
program. And I am a bit bored so here goes...

   Just to get the feel for how the horizontal and vertical stacking 
distance affects the antenna I first model only two antennas.

Single 105CA = 8.24 dbd

Two 105CAs stacked vertically spaced

20 feet = 10.50 dbd
24 feet = 10.84 dbd
28 feet = 11.12 dbd
32 feet = 11.30 dbd
36 feet = 11.35 dbd

   As far as vertical spacing is concerned somewhere around 24-28 feet 
looks pretty good. There is less interaction between the antennas as the 
stacking distance gets larger. More than 28 feet produces little 
advantage and a fair amount of extra wind load..

Two 105CAs stacked horizontally spaced

20 feet =   9.72 dbd (first side lobes are ~37 db down)
24 feet = 10.27 dbd (first side lobes are ~30 db down)
28 feet = 10.66 dbd (first side lobes are ~22 db down)
32 feet = 10.95 dbd (first side lobes are ~16 db down)
36 feet =  11.11dbd (first side lobes are ~16 db down)

   This will depend on how much you value gain compared to pattern. I 
would likely choose 28 feet vertically and 24 or 28 feet horizontally. I 
like a nice tight pattern. Not a lot of advantage beyond 28 feet.

4x H-Frame array of 105CAs spaced

20' high - 20' wide = 12.00 dbd
20' high - 24' wide = 12.46 dbd
24' high - 24' wide = 12.71 dbd
28' high - 24' wide = 13.09 dbd
28' high - 28' wide = 13.53 dbd

   The first azimuth side lobes are essentially the same value on the 4 
stack as the 2 horizontal stack. This model is based on a 24 foot boom 
10m yagi. A shorter boom will require a bit less spacing and a longer 
boom more spacing.

73,  Jay  K0GU


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