Topband: "Missing" Buried Radials for a Monopole

[Richard Fry]

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