On Jun 13, 11:45*am, bpnjensen wrote:
On Jun 13, 7:22*am, Krypsis wrote:



On 13/06/2010 4:30 AM, DEFCON 88 wrote:

OK, this deviates somewhat from the topic, but I've always wondered
about window antennas. My Mitsubishi Galant has an antenna embedded in
the rear window. It's not one of those dipoles that you used to (or
still?) see embedded in the front windshield of GM cars. Rather, it
has a peculiar folded design that's hard to describe. It works very
well. I get exceptional reception, especially on AM. In fact, one of
the reasons I chose the Galant is because it had the best AM reception
of all the cars I test drove. What's the theory on these window
antennas? Do they have a pre-amp ahead of the radio?

The theory is they are simple and vandal proof! They also lessen the
effect of an external aerial on the aesthetics and the aerodynamics of
the car. No wind whistles on these window aerials!

Krypsis

I don't think the windshield-internal dipoles work as well on FM as a
good external vertical whip of the proper dimension. *They are not
omnidirectional, nor are they vertically polarized, both of which are
helpful for FM in a moving car. *The folded ones may have different
characteristics that overcome these drawbacks, I don't know for sure.

- Moreover, they are not likely the AM antennas
- at all almost every car AM radio since dirt has
- used a ferrite- or air-core coil antenna;

H U H ?

- far more effective than a whip or wire ever could be. *
- Especially the ferrite, it gets you what a whip cannot
- ~ full wave resonance and high relative gain.
-*Match that with a quality AM radio and you'll
- have a nice MW DX machine in your car.
-*I love listening to stations on the Great Plains
- when driving overnight to Yellowstone :-)
-
- Bruce Jensen