"4nec2" wrote in message
oups.com...
When someone asks me what's the optimal radial ground screen, I mostly
answer: "120 radials with a length of 0.4 lambda".

This answer is somehow fixed in my mind, based on a study and
experiments undertaken long time ago by ...?

Does anybody have a pointer/link/url to this study or can someone
deliver me more details ?

I already did some Googling, but could not find the article I once
red.

Thanks in advance,
Arie Voors.


Hi Arie,
thanks for all the work on 4NEC2!!!!

Let me just bring to attention that just about all the radial studies deal
with either 1/4 wave or shortened radiators and current distribution in
their radials - typically showing higher current concentration close to the
base and reasoning that one needs only shorter radials, so many good enough,
etc.

When dealing with longer radiators, say 3/8 to 1/2 wavelength and using
longer radials, situation is different. Longer radiator has longer and
higher current portion radiator and is "looking" further out than its own
base for the radials and good ground. This, combined with good ground or
sloping terrain helps significantly with pulling the lobe down and increased
gain at low angles.

This works in reality very well, I have observed it when operating from
W8LRL, using his 200 ft vertical with 360 radials 200 ft long. When low
angle propagation prevails, this is beating "regular" 4 squares, (contrary
to W8JI claims of being "impossible"). The same goes for long Beverages of
some 3.5 wave long.

Interesting question is how well can modeling capture this effect and the
transition from radials to "far field ground" condition or its extension by
longer radial field and elevated radiator current distribution.

73 Yuri, K3BU.us