W8JI wrote:
>At my present QTH on 40 meters, somewhere around 15 evenly spaced radials
>flattened off the measured field strength improvement. Even 60 radials
>would have been a waste of wire.
The number and length of equally-spaced buried radials needed for a monopole
depends rather heavily on the conductivity of the earth in which they are
buried, and how close the operator needs/wants to approach theoretical
perfection for that system.
The link below shows how loss in the r-f ground connection for 32 x 1/4-wave
buried radials is a function of earth conductivity, other things equal.
For earth of high conductivity the r-f loss in that radial system is less
than 1 ohm, which is rather difficult to improve upon. The only reasons
preventing near-perfect radiation efficiency from the antenna system are the
loss in the loading coil needed to resonate the short monopole, and the low
radiation resistance of a monopole of that height on that frequency.
http://i62.photobucket.com/albums/h85/rfry-100/10m_Vert32Buried_Radials.jpg
R. Fry
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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