[Mobile-Portable] Mobile antenna tuner questions

[Dick Flanagan]

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