[NLRS] Yagi Spacing Q.. - MORE questions

[John (JK) Kalenowsky, K9JK]

Not to questions Jim's response...BUT, and _particular_ to Scott's 
specific antennas.

Since the 124WB and A449-6S are end mounted designs...wouldn't there 
be 'less' worry about such interaction with the mast and/or coax?

In Cushcraft (Laird?) pictures (with the antennas by themselves), they 
are shown with a mast (presumably metal) only inches behind the 
reflector.

ALSO, Cushcraft (Laird?) makes (made?) the A2706S and A27010S Dual 
Band Yagis where elements are on the SAME boom, essentially 'minimal' 
spacing between the two antennas.

So I guess my questions would be...

1. IS a "rear" mast out of the 'capture area' for the antenna or not?

2. Has anyone done an evalation of those Dual Band Yagis? How DO they 
perform with, basically, TWO antennas on the same boom? Probably 
seeking a "more thorough" assessment than "just" max. forward gain as 
is typically done at conference antenna ranges, e.g. 'cleanliness' of 
pattern, any "odd" nulls in the forward direction, and the like.

73, JK
----- Original Message ----- 
From: "Jim Froemke" <jim.k0mhc at earthlink.net>
To: "'KB0NLY'" <kb0nly at mchsi.com>; "'NLRS'" <nlrs at mailman.qth.net>
Sent: Thursday, October 23, 2008 11:00
Subject: RE: [NLRS] Yagi Spacing Q.. - response


>
>
> Hi Scott
>
> For your application (vertical polarization) a bigger issue is the
> proximity of each antenna to the vertical metal mast. For best 
> performance
> you'll want to keep the vertical metal mast OUTSIDE of the capture 
> areas of
> both antennas. This means your horizontal spacing along your 
> horizontal mast
> between each antenna and the vertical mast should be AT LEAST 1/2 
> the
> diameter of each antenna's capture area.
>
> You could use a non conductive vertical mast (if it's strong enough)
> but when your coax makes a 90 degree angle to descend down the 
> vertical mast
> it also becomes a vertical conductor located on the vertical mast 
> between
> the two antennas so you'll still have this problem.
>
> 73, Jim
> K0MHC
>
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