[TowerTalk] Re: short radials, spacing

[Ken Hirschberg]

Hello, All -
A good working number for spacing is 0.015 wavelengths.  As the radials
diverge, install a connecting circle of wire connected to each of the
radial wires at the radius where they have gotten to be 0.015 wavelength
apart.  From that circle outward, install additional radial wires between
the original radials.  Continue until the spacing again becomes 0.015,
install another circle, and so on, to any desired radial length.  This
technique insures an adequate ground plane / screen density, and will be
only about 0.1 dB down from a solid ground screen.

73, Ken, K6HPX
CAL-AV LABS

Jan.E.Holm@telia.se wrote:

>      I have lernt from books and antenna gurus that whats
>      interesting is the distanse betwen the ends of each
>      radial, if it´s close enough the antenna will "see" the
>      wires as a  homogen shield. Think the magic number
>      was 0.05 wl but I´m not dead sure.
>      Bottom line is, don´t worry about the number of radials
>      but instead worry about the distance betwen the ends of
>      each radial.
>
>      73, Jim SM2EKM
>
>      PS: This is ofcourse also what Mauri is saying below in a
>      different way.
> --------------------------------
>
> -----Ursprungligt meddelande-----
> Från:   i4jmy@iol.it [SMTP:i4jmy@iol.it]
> Skickat:         den 6 november 2000 12:49
> Till:   towertalk@contesting.com
> Ämne:   Re: [TowerTalk] short radials, spacing
>
> The only reason why radial have to be more when longer, is that the
> distance between them, at a considerable distance from the base,
> becomes progressively bigger althought spacing in degrees would be the
> same.
> In term of current density and typical quarter wave verticals, the area
> close to the antenna and extending to 0.125 wl is maximally important.
> There is nothing to lose (but probably to gain) keeping an higher
> radials number, althought they are shorter than canonical lenghts.
>
> 73,
> Mauri I4JMY
>
> > ---------- Initial message -----------
> >
> > From    : owner-towertalk@contesting.com
> > To      : towertalk <towertalk@contesting.com>
> > Cc      :
> > Date    : Mon, 06 Nov 2000 06:34:44 +0000
> > Subject : [TowerTalk] short radials, spacing
> >
> > We all know that if the radials for a vertical are short then it
> > does no good to have a lot of them. Reference The ARRL Antenna Book,
> > 17th Edition, Table 3 on page 3-13, and ON4UN's Low-Band DXing, 3rd
> > Editiom, Table 9-1 on page 9-10.
> >
> > So for 60 radials .2 wl long the radials would be spaced 6 degrees.
> > Likewise, for 36 radials .15 wl long they would be spaced 10 degrees.
> >
> > Now consider an 80m 4-square array. Assume each vertical will have 60
> > radials .2 wl long (6 degree spacing). In the interior of the array
> > the radials will be much shorter than .2 wl. (Ranging .125 to
> > .17 wl). Question: Can (should) there be fewer interior radials since
> > they are shorter? Or should the 6 degree spacing be maintained?
> >
> > Kris N5KM
>
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