Nigel Molesworth wrote:
A little OT for this group, but I figure you guys are the experts!

I've got a boat, it has an VHF FM Car Radio with a car aerial. The first
problem is that there is no ground plane, the boat is GRP. It is also lying
horizontally, it is too long to be vertical.

I want to replace the aerial something a bit more suitable. Modern cars seem
to have much shorter aerials, so is there a coil involved?

Any suggestions on making or buying a replacement?

BTW, the radio has a DIN antenna socket, so 150 Ohms I think?


IME,Most car radios are sensitive and selective enough to pull in local
stations with only a short wire hanging out of the antenna socket. I've
routinely checked them out on the bench,and just stuffed a piece of
hookup wire in the antenna jack,works fine.
Maybe you could just run a wire up some vertical-surface of the boat?

There *IS* a ground plane-The water. When the boat is in the water,the
water itself is the ground plane.

On Sun, 28 Dec 2008 12:10:57 -0800, PhattyMo wrote:

Maybe you could just run a wire up some vertical-surface of the boat?

What about 1/4 wavelengths, and all that stuff?

Nigel Molesworth wrote in
:

On Sun, 28 Dec 2008 12:10:57 -0800, PhattyMo wrote:

Maybe you could just run a wire up some vertical-surface of the boat?

What about 1/4 wavelengths, and all that stuff?

Powerboat or sail? I recommend a quarter wave for sail, but 5/8 should
work on most powerboats. If you can mount atop a metal mast 1/4 wave
should easily do the job. I get really good broadcast FM reception on my
FT897D from my dual band mobile antenna out on the back deck. For receive-
only with good broadcast signals, impedance matching is not that much of a
concern. If you're trying to DX, that's another story, involving yagis.




--
Dave Oldridge+
ICQ 454777283