[Elecraft] Radials for vertical

[Fred Jensen]

On 6/29/2014 12:07 PM, Doug Person via Elecraft wrote:
>
> So now I have all this aluminum wire that I would hate to throw away. So
> I'm thinking of making a really good ground plane and putting up a
> vertical of some kind.  I have enough scrap tubing to make about 38' or
> so.  I was thinking of putting a remote tuner at the base of the
> vertical as the length of coax to reach it will probably be at least 150'.

I assume you mean a ground-mounted vertical?
>
> So I'd be interested in comments on how to configure the radials in
> terms of length and number.  I know there's some guys on this reflector
> that real know a lot about this sort of thing.

I know just about enough to get in trouble.  That said,

There is a small "Cult of the 43 ft Vertical" in ham radio ... 
ground-mounted, ATU remoted at the base, with a ground-plane.   If "38' 
or so" means getting to 43 ft, great.  If not, there really isn't a huge 
amount of magic in 43 except that it's a prime.  You have two choices:

1.  Bury [like 6 inches deep] as many wires as you can, radiating out 
from the base of the antenna in all directions.  Length is not critical 
but at least 1/4 wave on your lowest frequency is good, nor do they all 
need to be the same length.  They don't even need to be straight. 
Ground planes for AM broadcast stations will often have one radial every 
degree around the vertical.

2.  Elevate them a foot or two off the ground.  In this case, length 
*does* matter, you'll need a few [like 4?] a little over 1/4 wave long 
for each of the bands you'll be using it on.  This will likely also trip 
your cows.

Ground-mounted verticals, at frequencies where they are about 1/4 wave 
high will have fairly low angle radiation.  On higher frequencies where 
they are substantially longer electrically, they'll squirt your RF in 
several lobes, not all of which are useful.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2014 Cal QSO Party 4-5 Oct 2014
- www.cqp.org