[Mobile-Portable] Mobile antenna tuner questions

[MELVYN EVANS]

--- Dick Flanagan <dick at twohams.com> wrote:

> At 11:23 AM 2/9/2006, JV wrote:
>  >
>  >    Sorry, I am going to disagree with you on your
> statement that a 20 M
>  >mobile antenna
>  >only radiates 30 watts. I county hunt with a
> modified Hustler and at the
>  >base of the antenna I have
>  >100 watts from my IC-706MKIIG. The antenna is
> mounted on the roof in the
>  >center of my Cherokee.
> 
> I think the question relates to how many of those
> 100 watts actually 
> radiate as RF as opposed to heat.  This "radiation
> efficiency" is 
> depressingly low in mobile installations where poor
> grounds, inductive 
> loading and electrically short (as a function of
> operating wavelength) 
> antenna elements are the norm.
> 
> If JV's antenna system is able to realize a 30%
> radiation efficiency on 20 
> meters, I applaud and envy him.  Once you get
> further down to the lower 
> frequencies (80, 160 M) radiation efficiencies in
> the single-digits quickly 
> become the norm.
> 
> 73, Dick
> --
> Dick Flanagan K7VC NV SM
> E-mail: k7vc at arrl.org
> 
> ----
> Your Moderator: Dick Flanagan K7VC,
> mobile-portable-owner at mailman.qth.net
> 
Hello Dick,

Can I quote you information on mobile antenna's from
an old Radio Society of Great Britain Handbook which
as you know is a knowlegeable sort of organisation
when it comes to discussing amateur radio

160 m. 32 watts output/ Efficiency 0.25%/ radiated
power 80 mw

80 m. 100 watts output/ Efficiency 1.0% / radiated
power 1 watt

40 m  100 watts output/ Efficiency 7%   / radiated
power 7 watts

20 m  100 watts output/ Efficiency 10%  / radiated
power 10 watts

Sorry Dick, my memory was more optimistic than the
fact ! The figures are even worse than I remembered. I
hope I haven't spoiled your day.

Kind Regards,  73,  Mel