TJ wrote:
On Fri, 29 Jul 2005 16:24:42 +0300, "Kimmo Yliskoski" kimmo.yliskoski
@ gmail.com.invalid wrote:

Kimmo Yliskoski wrote:
Anyone have good tips to homebrew car antenna? No 1" pipe... just
whip... that stays with me when driving 60mph. I'm going to use
magnet mount on my car roof. About 1,5m to 2m would be nice length.
Any advice or site where can find something about it?

Forget to mention that it is going to be used at CB-channels. 11m band.

Why not go to RS and buy one??
A lot easier than building one for 27Mhz.

Only if he's somewhere that has RS or equivalent, which isn't true all
places. I don't find Mr. Yliskoski in the FCC or RAC databases, which
leads me to believe he's not on the North American continent. The name
has a Slavic feel, and anyone, anywhere in the world, can have a gmail
address. It's entirely possible that there's no place near him that
sells brown-n-serve antennas.

Kimmo,

An efficient 11m whip probably is going to be a bit longer than 1.5m;
the rear bumper might be a better choice.

If you really want to do a roof- or trunk- (boot-) mount, there is a rather
sturdy-looking magnetic mount described in the web page at
http://www.qsl.net/n2ffl/ic706kmiig.htm. The page at
http://www.arrl.org/tis/info/Mobile-H.html discusses mobile antenna
design and construction of a bumper-mounted whip that works from 20m
through 6m and will handle 100W output.

It's 99" (2.5m) long at max extension, and is retracted about 60 cm (to
about 1.9m) for 10m. I think that it would need to be just about 2m long to
work 11m, and that's pretty long for a roof-mounted whip. With the coil in
the center, it really would be difficult to keep it in place on the roof,
because of the rotational moment from the forces on the coil, and it would
be a real danger to traffic if it came loose.

Boot lid would be a little safer, but not much: a magnetic mount just is
not as secure as a real mechanical fastening. Please consider the bumper
mount.

Good luck!

73, de

--
Mike Andrews W5EGO

Tired old sysadmin