> Didn't Dud Charman's indoor antenna circus demonstrate the truth of the
> axiom that a small antenna has the same radiation pattern as a very
> small antenna?
I also believe that all short verticals have the same basic radiation
pattern (the upper hemishere of a doughnut, with low angle suckin if
ground loss is significant).
I was privileged to see Dud Charman's aerial circus in the 1960s as
a schoolboy. For those who do not know, he had a large copper
tray with a coax socket in the centre. He would then feed miniature
antennas with UHF or microwaves and demonstrate their radiation
pattern with a hand-held RF detector driving a lightbulb. Seeing a
text book radiation pattern demonstrated in such a practical way
was really amazing.
The flaw in this demonstration, however, is that it assumes little or
no ground loss. I am sure that with practical levels of ground loss,
the lowest angles are attenuated more on very short verticals than
on taller ones.
Mike, G3XDV (IO91VT)
http://www.dennison.demon.co.uk/activity.htm
|
