Mike Dennison wrote:
Further to my note on Radiation Resistance formulas, the highly
respected 160m expert ON4UN uses 1450 instead of "160 (or 60)
multiplied by pi squared" in his excellent book Low Band DXing.
This figure is lower than 160 x pi sq (1580) but nowhere near as low
as 60 x pi sq (592). I assume that he must have done some
practical measurements which gave him a better figure than that
calculated in the 1920s.
My first reaction is that (shock, horror) Terman and many others
are wrong and the Admiralty was almost right.
And my ERP is definitely (probably, perhaps) 44mW.
The LF Experimenter's Source Book shows a method of estimating ERP
using Roy Lewallen's antenna modelling software, EZNEC. The results
correlated well with signal strength measurements made by G3YGF and
by calculations made by Rik, ON7YD.
The technique was also described at the LF Forum of last year's HF
Convention. Has anyone else tried the EZNEC program? It might show
which of the formulas is nearest to reality.
--
Regards, Peter, G3LDO
<[email protected]>
|
