The input resistance of 1.5 ohms you quote implies an extremely good
ground system. I suspect that very few people, particularly ones putting
up such a short vertical for 160, have the room for that elaborate a
system. As ground loss increases, the fractional loss caused by the
inductor decreases. So I don't agree with your blanket statement that an
inductor with a Q of 1000 will lose that fraction of the power. It
might, if a person had an extremely elaborate ground system, but not
otherwise.

Incidentally, although 30% power loss sounds impressive, it'll reduce
the signal less than 1.6 dB.

So it won't be worthwhile for most people to make heroic efforts to
produce extremely high Q loading inductors. (And, even if they can make
one with a Q of 1000, it would have to somehow be suspended well above
the ground and away from other conductive objects in order to retain
that sort of Q.)

Roy Lewallen, W7EL

Frank wrote:

"Roy Lewallen" wrote in message
...

Frank wrote:

Also the series inductor should have a very high Q for 160 m. A Q of

1000

will loose about 30% of your power.

Can you tell us how you calculated this? How much ground loss did you
assume?

Roy Lewallen, W7EL


I have run a number of NEC models (NEC-Win Pro), for ground mounted
verticals with a radial system, using the Sommerfeld/Norton ground models
(usually in the range of: Sigma = 0.02 S/m Er = 17) -- although not for the
specific dimensions indicated. My models would be approximately 0.001
wavelengths above ground (as per Cebik: Basic Antenna Modeling). The input
impedance calculated is of the order of 1.5 - j1500. From these data it is
relatively trivial to estimate the required Q of a series inductor.

I have been very interested in such antennas, but have never actually gotten
around to building -- just modeling! If the original poster is interested,
I would be very happy to model the specific dimensions.

Frank Meredith (VE6CB)