Dale,
Short answer: I have almost the exact same setup. It'll work.
How nearly half the readership got onto ground radials and arguing I am not
certain. It does kinda seem that a number of threads on Towertalk and
CQ-Contest fly off the rails fairly quickly often involving adjacent
discussions for reasons that I cannot fathom. You asked a pretty
straightforward question and I hope the answer below will help you.
My example is an HF9V multiband vertical mounted on the back of my shed (on
a side where a gutter would normally be, not on the peak) around the 6.5'
mark AGL.
I then made 2 RESONANT (raised) radials for each band I intended to operate
from. 80, 40,30, 20, 15*, 17, 12 and 10m.
I skipped 6m radials as I use yagis on 6m and I skipped the *15m radials as
I figured the 40m radials would perform double duty at 3 wavelengths on 15m
(seems to work).
In my case the RAISED (resonant) radials were first made as a kind of dipole
then I got my analyzer out, got them in the ballpark after trimming and then
removed the temp. center insulator and attached the pair to the baseplate of
the RAISED HF9V.
I have 2 raised resonant radials extending out roughly 180* apart from one
attachment point for each band, running in the air and over branches in fir
trees and ultimately tied off to the tops of 50yr old cedar fence posts
around the 4' mark in most cases (so sloped down slightly from the multiband
verticals base which is at 6-7' AGL).
The RAISED (resonant) radials start out together and then I fan them out
as well as could be expected but most of them are 6"-12" apart from one
another using air or in some cases super small PVC spacers.(spacing varies a
lot)
I was able to obtain a near perfect SWR on most bands and operation of the
HF9V mounted 6-7' AGL is as to be expected. (some would say radiates poorly
in all directions, hi)
Over the years some of the radials have sagged or fallen (tree branches!)
and I have caught the odd one or two with a tractor or a ladder or some deer
(buck) caught his antlers or whatever and some of them have become slightly
tangled (storms) and I do some half hearted repairs but have never noticed
much degradation in Signal strengths or SWR measurements. It's only a
backup to a backup antenna, so almost never gets used these days. My wire
4-squares are always better (and quieter) so the HF9V, while solid, plays
3rd fiddle now.
Once you do your first "dipole" or two of some of the RAISED (resonant)
radials you can do the math and make subsequent radial pairs with little or
no antenna analyzer measurements needed imo. Bend them, it matters very
little.
GL with it!
Mike - VE9Antenna Antenna
AF7WH asks:
I have a SteppIR BigIR vertical that I am refurbishing. It will be
installed
in a small backyard that does not allow for the normal ground radial system
(such as 60 ea at 33'). I will need to go to 2 ea tuned elevated radials
for
each band (80 thru 10 - 8 bands). My solution (I think the only one I have
due
to lot restrictions) is to run the radials along the vinyl fence. The
vertical
is mounted on a 4x4 post at 5 feet above the ground. One direction has
about
70' of length (straight) but the other direction has a 90-degree turn about
20
feet down from the antenna and then a straight shot the rest of the lengths
so
the radials for 80, 40, and 30 will have a 90-degree bend at that point and
then continue on straight. All the radials will follow the fence line so
they
will not be spaced out is a circular distribution from the antenna. There
will
be about 1 to 2 feet of horizonal spacing in the plane for 4 bands (80, 40,
30
and 20). I will do a similar install for the 17, 15, 12
and 10m bands but will have them be 1 to 2 feet down vertically from the
1st
set of radials. Hopefully, this is clear and not confusing - I do not think
I
am able to post a diagram of what I want to try.
Couple of questions:
Will this work?
What is the minimum spacing horizontally and vertically for the radials as
proposed?
Any other suggestions?
Thanks,
Dale
AF7WH
Mike - Keswick Ridge, NB, Canada
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