[CQ-Contest] [TowerTalk] stacking 2 different beams

[Mark Beckwith]

N4GG wrote a really good article in the NCJ about this topic within the past 
year or two.  He concluded:

1. a lot of people do it
2. some people get unexpected results
3. there IS a "sweet spot" using different feedline lengths, but it's not as 
intuitive as only compensating for horizontal Driven Element offset.

Off the top of my head I cannot tell you how you find the sweet spot. 
Usually when I wonder about stuff like this I ask N4GG for help  :)  Start 
by reading the article.  It is a great article.

Jerry K4SAV brings up some good points, but I think he's splitting hairs to 
some extent.  Having the two antennas will definitely increase your options 
and make your station more flexible.  Also, he is 100% correct that your 
operating will benefit from being able to switch between the two antennas - 
or at least if you set it up that way you can develop confidence in what the 
array can and cannot do.  I am confident you will be pleased by it, after 
you get the feedline lengths right.

I'm not so fast to say rotate your moxon is required.  You didn't tell us 
what you have on 40 in other directions :)

I would also not arbitrarily set the spacing to where you put the lower 
antenna 15M below the upper antenna - I am assuming that changing the height 
of the top antenna is pretty much not an option, right?  But that you can 
put the lower one maybe "wherever is the best place" - ?  I would look at 
putting it more like a quarter wave below the top one.

I would model all this beforehand.  You really should find a way to model 
antennas, Daniel, it will totally change your life.

So yes, by all means it is a good idea and it certainly will be better than 
using only one or the other of the antennas for some of your international 
QSOs.

73 - Mark, N5OT


----- Original Message ----- 
From: "Daniel Glanc" <ok1dig at seznam.cz>
To: <towertalk at contesting.com>
Cc: <ok1dvm at centrum.cz>
Sent: Monday, August 17, 2009 7:13 AM
Subject: [TowerTalk] stacking 2 different beams


> Hi everyone,
>
>
>
> I am considering to stack the 40 m 2 element moxon beam  below my existing
> 40 m 4 el  40M4LLDD @ 30m agl.
>
> I am not sure if this is a good idea. I can't model the situation.  My 
> idea
> is to put it @ 15m agl beaming into one direction (NA).
>
> I would appreciate any comments or hints form the community.
>
>
>
> Thanks in advance
>
>
>
> Daniel / OK1DIG ( also OK7M and OL6X )
>
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