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[Towertalk] Radial "fan out"/forking - MMANA model wanted

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Subject: [Towertalk] Radial "fan out"/forking - MMANA model wanted
From: (Don Havlicek)
Date: Thu, 28 Feb 2002 15:00:14 -0500
I've been following this thread since it began.
Sorry, but I don't understand WHY anyone would want to go through all
the trouble of doing this.  
My reasoning is this:  
IF you intend to 'fan' the radials .. that would cause the 'fan'
elements to be CURVED or BENT to keep them from crossing OTHER 'fan'
radial ends.  Draw a diagram of it on a piece of paper.  If you intend
to put, let's say, 12 radials from the base of the vertical, each sector
between radials would be 30-degrees.  That limits ANY 'fan' to
15-degrees.   In fact, to keep the radials spaced 'evenly', that means
they would be required to fit in a 10-degree sector.  Remember, the
space between two radials connected to the vertical base must be SHARED
by 'fan' wires from neighboring radials... I don't like the prospect of
the messy arrangement.  
Go ahead and 'model' it .. but I think you're wasting valuable time,
energy, money, and copper!
Now you say you're going to elevate the vertical, with the radials
sloping from 15' to ground .. At 30-degrees, that means the radials will
meet the ground approximately 26' from the base of the vertical. 
Doesn't seem to give you much room for 'bending under them'.
I totally agree with those who have said "put the radials on/in the
ground".  That's what has been most successful for me.  
I have a 3-element 40m vertical array with 36 1/4-wavelength radials,
spaced 10-degrees, beneath the 'main' vertical .. and an insulated, 60'
tower [no antennas on it] that is my 80m vertical, that has 60
1/4-wavelength radials, spaced 6-degrees, with an additional 10 radials
at smaller spacings .. placed to the NE for Europe, SE for the
Caribbean, NNW for Japan, and W for VK/ZL.

Pat Rundall wrote:
> For me at least, this remains in my mind as
> an "unsolved antenna mystery". A few have
> asked "why bother messing around with the
> forked radials idea - just put down 60 1/4 wl
> radials and get it over with?"
> In my case, I'm considering forked radials (at
> least, a minimal amount of wire and "stuff to
> duck under when mowing the lawn) for a Butternut
> vertical on a mast mount (at ~10' to 20' height)
> with the radials sloping to ground. 60 .25wl
> radials sloping to ground at ~30 degrees from a
> height of 15' turns a simple secondary antenna
> into a rather complex one. Assuming that
> because it is mast mounted and off the ground
> (the radials are somewhat elevated to begin
> with), perhaps a greatly reduced number of radials
> eminating from the mast would suffice.
> I'd like to eventually model this, but the only
> modeling package that I have at the moment is
> the FREE one - MMANA (a fun free modeler - check
> out which
> probably isn't ideal for this sort of thing.
> Once I get around to it, I'd like to model
> "standard forking"...
> where A=B=C=D=(~.125 wl) and A slopes to ground
> from 10' at the mast (M) at ~40 degrees.
>                /
>             B /
>              /
>       A     /   C
>   M-----------------
>             \
>              \
>             D \
>                \
> "multiband forking"...
> where A=.125 wl on say 40m and ~.06 wl on 80m,
> B=.19wl on 80m (to finish the 1/4 wl), C=.125wl
> on 40m, etc.
> "upclose forking"...
> where A is very close to the mast (a 45 degree
> slope) and forks as soon as A hits the ground.
> and finally "reverse forking"...
> I doubt this makes any sense at all.
>          ^
>        A/ \
>        /   \
>   C   /  D  \
> -----<------->M
>       \     /
>        \   /
>         \ /B
>          V
> In fact, I have my doubts about quite a bit of
> this (especially the multiband forking - which
> electrically needs a lot of work), but it should
> give me something to do while waiting for the
> ground to thaw to actually try this stuff.
> Pat, N0HR
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