The characteristic impedance of a half wave radiator is infinite.=20
Matching it to a 50 ohm coax is not trivial. I used a commercial model=20
(through the windshield glass) on the 2 meter Amateur band from=20
1985-1994 that used a capacitive matching device that did very little.=20
The best I could do with it was to have a helper watch a field strength=20
meter (about half scale on the meter) while I transmitted and turned the=20
knob. It did not work all that bad, but it never performed as well as a=20
19" whip. It made no difference in the long run, since my son had his=20
Ham license by then I gave him the car, radio included, with more than=20
100,000 miles on it. The last time I saw it the antenna was still=20
installed and a friend still had it.

The J-Pole is just about bullet proof as far as operation. Keeping it=20
from getting involved in mechanical damage may be another problem.=20
perhaps a break-away mount or at least a spring base. 50 watts on the=20
water to a J-Pole will definitely reach a little past the actual horizon!

On 6/4/2014 5:25 PM, Joe McCauley wrote:
> I'll have a look at that stuff John, thanks. Meanwhile both boats are out=
 on the water as of this evening so I brought a portable spectrum analyser =
& repeated my tests. No difference,so I guess the presence of water does no=
t matter. Both antennas have a loading coil built into the bottom. The ante=
nna I've been testing with at home is a J pole type & as I said, it seems t=
o work better. It is of course longer. I'll probably try that antenna in th=
e boat next.
>
> Joe

--=20
John Ferrell W8CCW

"Travel is fatal to prejudice, bigotry and narrow-mindedness=94
  Mark Twain


--=20
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