Space between radials has to be equal or less than .025 WL.
The tables consider .5WL radials and this numbers lead to the famous 120
radials (>90% efficiency).
Unless the radiator is longer than 1/4 WL there's no need to extend radials
to .4-.5 WL.
Halving the radials lenght and keeping the same .025 distance, the required
number for .025 spacing is 60 .
In theory and in case of a full size quarter wave radiator, with 30 radials
the efficiency drop from 90% to 86% that's an attenuation of 0.25 dB if
compared with the 60 radials case.
73,
Mauri I4JMY
----- Original Message -----
From: "Bill Coleman" <aa4lr@arrl.net>
To: <W8JI@contesting.com>; <towertalk@contesting.com>; <K3BU@aol.com>
Sent: Thursday, January 11, 2001 4:39 PM
Subject: Re: [TowerTalk] Re: Radials over salt water
> On 1/10/01 15:35, Tom Rauch at w8ji@contesting.com wrote:
>
> >> Thinking and analyzing the situation, there should
> >> be improvement if using many (>60) elevated (or on ground) radials vs.
few
> >
> >Fact Yuri. When the radials are less than .025 to .05 wl apart at
> >the open ends, they look like a solid screen. Using more radials
> >than that is a waste of wire.
>
> Hmm. 1/4 wave radials means a circle of 1/2 diameter. That's a perimeter
> of pi/2 wavelength, which divided by .05 yeilds about 31 radials.
> Similarly, .025 spacing at the ends is about 63 radials.
>
> If >63 radials is like a solid screen, I wonder why there's so much in
> the amatuer literature about installations with 120 or so radials.
>
> Bill Coleman, AA4LR, PP-ASEL Mail: aa4lr@arrl.net
> Quote: "Not within a thousand years will man ever fly!"
> -- Wilbur Wright, 1901
>
>
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