Why the spiral pattern on Radio Antennae and Grid on Windshield?

And I believe the ones top-center on the window are there as a sunscreen, since you can't get a visor over there. You don't often need to look through that portion of the window, so they block out the sun.

Reply to
Mike Levy
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Never seen one from the factory. Who made it? GM Ford and Chrysler all use cut stainless for the masts. Then powder coat them black.

Reply to
Steve W.

Mitsubishi is definatly wire wrapped, the rest, except for Chrysler, I can't find any reference to.

Steve

Reply to
Steve Mackie

My 2004 Dodge truck seems to be wound, like with stainless steel foil??

Al

Reply to
Big Al

That's cut

Reply to
Steve Mackie

Mitsu huh. Figures ...

I've got a bunch of the others around here as spares. They are all ground. The easy way to tell is to look at the base area, the grind stops about an inch above the adapter. On average we coated 30,000 a day for each of the big three. Hated the damn things because they were racked 20 per row on a 3 row rack. You had to get between the rows and coat the adapters, then down the shafts, then spin them while coating from the outside. Too much powder and you hid the details and had a "drip" on the end. Not enough and you got textured finish.

Reply to
Steve W.

Mine is also a wire wrap, just went down and looked at it. I took a picture, but my camera sucks so it didn't take well. I can tell it's a wire wrap because it's starting to seperate in one spot and in another there is a kink in the wire. I also looked at the two cars parked next to me, a late model Buick and a late 90's Caravan. The Caravan appeared to be a wire as well and the Buick's was identical to mine. You really can't get much more common than a mid-90's W-Body GM, so it's safe to say there is A LOT of wire wrapped antennas "whipping in the wind."

Steve

Reply to
Steve Mackie

The spiral is to reduce wind noise???? Reducing the smoothness of a wind-exposed surface hardly reduces the wind noise---in fact it would have the opposite effect.

The spiral is indeed for the purpose of increasing the effective length of the antenna. It's a common practice to use a coil to reduce the physical size of an antenna without decreasing its effective length.

As for the dots, I have no idea. My guess would be to act as a sunscreen.

Reply to
Sean Elkins

GULP--the sound of me eating my words. Looks like I was wrong about the wind noise, although in my meager defense that does seem counter-intuitive that roughing up the surface would cut wind noise. I thought the more streamlined an object the less air it would displace?

Reply to
Sean Elkins

From an Engineering stand point.... The Spiral wrap induces Eddy Currents

which reduces the wind drag force on the antenna to minimize vibrational

whipping action.... This and the German periscope spiral function

are notorious educational discussions at Automotive Engr Seminars offered

in Detroit in the fall.

Reply to
Dennis Mayer

this spiral is there to improve gas mileage. Studies indicate a 20% increase in EPA gas mileage rating when a spiral antenna is used.

Reply to
hardworking

How can a little radio antenna improve gas mileage that much? If it has that much effect then how much would you improve the mileage if you removed it all together?

Reply to
<vgatehouse

Reply to
hardworking

Most of the above-mentioned apply, especially the eddy current and vibration, but the primary purpose of the spiral is to prevent/avoid wind resonance (re: Tacoma State Bridge). If you have ever driven in sleet/rain and have the spiral-wound antenna caked in ice, the antenna will vibrate, depending on our speed, initially with one node, then two nodes, then three if you are crazy enough to drive that fast in that weather.

Franko

in oil

Reply to
Franko

If it was that simple to increase gas mileage, why don't cars have several of these. And if a small piece of wire has that much effect on a large vehicle, why are airplane wings so big?

If the vaccuum I could create behind my motorcycle is to be looked at, I would pull a tractor trailer off the road when I passed by.

Sounds like a lot of horse manure to me. An AWFUL LOT of horse manure.

I am sure there is a valid reason for the spiral, but I don't think it has anything to do with gas mileage. If it did, all the manufacturers would be using it. And you would find someone on the tube seling them and making a mint. Have you seen that? I didn't think so!!

Reply to
Yammie

Just think what that antenna, a fuel line magnet, and a tornado would do for your mileage! You would probably have to drain fuel out of your tank to keep it from overflowing.

Reply to
Bill W

Reply to
STOVEBOLT

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