"dave" wrote in message
. ..
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?

Mine are crossed active loops at MF frequencies. Folded dipole at FM
freqs.

The old window antennas weren't dipoles at all. Both "elements" were
connected to the center of the lead-in. The only reason for the dipole
appearance was symmetry, which helped to make them less of a distraction to
the driver.

On Jun 12, 2:55*pm, "Brenda Ann"
wrote:
"dave" wrote in message

. ..

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?

Mine are crossed active loops at MF frequencies. *Folded dipole at FM
freqs.

The old window antennas weren't dipoles at all. Both "elements" were
connected to the center of the lead-in. The only reason for the dipole
appearance was symmetry, which helped to make them less of a distraction to
the driver.

The embedded Wire Windshield Antennas used
two very thin parallel wires and the two created
a larger signal capture area plus the two provided
some redundancy if one should break.

The newer Printed-On Window Wire Antennas
{Circuit Trace (Wire) on Glass}
have a great sectional width {less likely to break}
and go around and/or across the Window.
At least that is how the one we have in the rear
side window of the Ford Windstar Van is laid-out
it come in {starts} from a single contact point and
goes almost all the way around the rear-side
Window with a 1/2" gap between the far-ends;
plus there is an extra leg starting in one corner
of the Window that goes across the Window at
a Diagonal Angle; and yet another extra leg
starting at the opposite corner of the Window that
goes across the Window at a Horizontal Angle.

* Sort of a bent & folded Window Windom Antenni

FWIW the Ford Windstar Van's Rear-Side Window
Antenna seams to work very well down in the SF
Bay Area but poorly up here in the mountains :
While the Solid Metal Whips and the Wire Wrapped
Whip Antennas seam to do as well in the SFBA
and much better up here in the Sierras. This may
be due to the fact that the Whips actually project
out away from the Body {counterpoise} of the Car
and are physically by-design a better EMF "Probe"
then the Foil-on-a-Window Antennas.

and that's how i hear it on the radio ~ RHF

On Jun 12, 5:59�am, RHF wrote:
On Jun 10, 1:01�pm, bpnjensen wrote:





On Jun 10, 12:55�pm, Twitchell wrote:

I've seen some car radio whip antennas that look like they have a wire wrapped
around them. �The wraps are not close but lazily spiral down the length of the
antenna.

Does this help reception? �Is the coil attached somehow to the car or just the
antenna itself?

twitch

My antenna on my minivan is like that.

I think the supporting whip is fiberglas/or some insulating material,
and the wire is the actual electrical element; and in the interest of
saving length and providing strength, they wrap the wire around the
slightly shorter antenna pole. �The wire is then connected to the lead
of the antenna. �It works fine, about as good as a metal whip of
similar length. �Antennas for cars are pretty uncomplicated
critters... :-)

Auto makers went from Telescoping Whip Antennas
to Solid One-Piece Stainless Steel Antennas because
of lower Cost and greater Durability.

The Fiberglass Rod with Wrapped Wire Whip Antennas
were done for the same reason : lower Cost and greater
Durability; over the life of the Car/Truck.

idtars ~ RHF
�.- Hide quoted text -

- Show quoted text -

I spent 33 years at General Motors Product Service Engineering and I
can tell you that on General Motors vehicles the wire wrapping on the
antenna is there to break up the air stream around the mast so it
doesn't whistle in the wind stream.

Brenda Ann wrote:
wrote in message
. ..
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?

Mine are crossed active loops at MF frequencies. Folded dipole at FM
freqs.

The old window antennas weren't dipoles at all. Both "elements" were
connected to the center of the lead-in. The only reason for the dipole
appearance was symmetry, which helped to make them less of a distraction to
the driver.


Some were top loaded short vertcals as you describe, but not all.

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

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;
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

"bpnjensen" wrote in message
...


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;
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


1) Those were not dipoles. The use of two wires was for symmetry purposes
only. They were not directional at all.

2) The only AM car radios that ever used a loop or loopstick antenna were
the "pull-out" portables. Almost every car radio ever made (up until
digital readout synthesized units) used variable inductors for tuning, but
for tuning only, because they were more stable than variable capacitors.
The antenna was and has always been that whip on the fender/cowl/windshield.
These are far more effective than a loop or loopstick in an automobile,
since those type antennas do not work at all well inside a steel structure.
I guarantee you that if you unplug that whip from your car radio, it will go
silent (unless you are sitting next to the transmitter site.)

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

On Jun 13, 4:46*pm, dave wrote:
bpnjensen wrote:

OK OK! I get it :-) *That's what I get for not paying attention in car
radio class :-)

You're not going to like my post either then.

I use mobile 3G/4G for my in-town listening (sorry 'Dwardo) and Sirius
when I'm away from civilization. *Still listen to the AM at night.
Always will.

Oh, I don't mind :-) Just wrote a reception report for REE via Costa
Rica, so I'm happy.

bpnjensen wrote:
On Jun 13, 7:22 am, 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;
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

Since dirt until very recently AM car antennas have been active whips.
Note the very tiny center conductor in a car antenna co-ax; because the
impedance is so high at 1 MHz. The 31" whip, plus the lead, is your AM
antenna. Same as an MFJ or Stoner Dymek active. No difference. Short
whip into an FET. The old radios had slug-tuned PTOs. Maybe that's
what you're thinking of.