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Car Forum / Chevrolet / Chevrolet Trucks / November 2005Why the spiral pattern on Radio Antennae and Grid on Windshield?
1) What is the purpose of the spiral pattern on a car's radio antennae (my guess it prevents ice buildup in winter?) 2) What is the purpose of the grid of black dots on the upper portion of the windshield? If I am not mistaken the wire wrapped around the antenna has somthing to do with the keyless entry system, your remote. And the little black dots in the front windshield are maybe perhaps the instant defogger, if your car is equiped. > 1) What is the purpose of the spiral pattern on a car's radio antennae > (my guess it prevents ice buildup in winter?) > > 2) What is the purpose of the grid of black dots on the upper portion of the > windshield? Heh, the "spiral" you see is used to reduce wind noise and the black dots are part the black band around the perimeter of the windshield to protect the adhesive from the sun. Steve > If I am not mistaken the wire wrapped around the antenna has somthing to do > with the keyless entry system, your remote. [quoted text clipped - 8 lines] > the > > windshield? The spiral on the radio antenna is a wire wound around a fiberglass core so the antenna is longer than if it was just a straight rod. I think (not certain) that the dots are the XM antenna. >Heh, the "spiral" you see is used to reduce wind noise and the black dots >are part the black band around the perimeter of the windshield to protect [quoted text clipped - 33 lines] > > Incorrect statements so far: "The wire is wrapped around to make for a longer antenna." "The dots are the XM radio antenna." "The wire wrapped around is for the RKE." "The black dots are an 'instant defogger.'" Why are people insistant on guessing? Do some research. Like I said: "Heh, the "spiral" you see is used to reduce wind noise and the black dots are part the black band around the perimeter of the windshield to protect the adhesive from the sun." But I will narrow down my statement a little bit. The "sprial" on GM antennae are to reduce wind noise, probably the same for other manufacturers, but can't be sure. Steve Hey I just guessed, never really wondered myself, I know my Jimmy has that on the antenna and on the windshield, but I never gave thought to it that was just the first things that came to mind. > Incorrect statements so far: > "The wire is wrapped around to make for a longer antenna." [quoted text clipped - 14 lines] > > Steve What adhesive? thxs >Incorrect statements so far: >"The wire is wrapped around to make for a longer antenna." [quoted text clipped - 14 lines] > >Steve > What adhesive? The adhesive that holds the windshield on the car. The black dots you see are silkscreened onto the glass and then actually burnt into the glass in a furnace. The main purpose is as stated earlier, to protect the adhesive that sticks the glass in the vehicle. UV light would degrate the adhesive. Also the dots simply make it look better. If you looked at the glass from the outside and the border was not there the adhesive would look terrible. I don't know if it is intentional or not but the border also adds to strength. Although your windshield is not tempered it is heat treated. If you had a single section of your windshield without the safety film in the middle break, the border would actually bond the fragments together to a extent. I worked 9 yrs at a glass factory, spent 4 yrs operating silk screeners and 2 years on a tempering furnace. On the furnace I broke a finished panel every 15 minutes for DOT required testing. Look for DOT 247 on your glass. Under names TGS, Spec-Temp and several other customer names. I might have had something to do with it. >> What adhesive? > > The adhesive that holds the windshield on the car. Spend a little time studying antenna design and you might find that you need to revise your opinion in favor of scientific fact. Read some of the antenna manufacturers literature, or cut an antenna open. The spiral wire is for the AM radio band. OP said "black dots on the upper portion of the windshield", nothing about dots around the perimeter of the glass.. >Incorrect statements so far: >"The wire is wrapped around to make for a longer antenna." [quoted text clipped - 16 lines] > > Its part of the tint. > OP said "black dots on the upper portion of the windshield", nothing about > dots around the perimeter of the glass.. > Spend a little time studying antenna design and you might find that you > need to revise your opinion in favor of scientific fact. Read some of > the antenna manufacturers literature, or cut an antenna open. The > spiral wire is for the AM radio band. You have got to be kidding me. *sigh* THE SPIRAL YOU SEE WRAPPED AROUND YOUR AUTOMOTIVE ANTENNA IS THERE TO REDUCE WIND NOISE. Just confirmed that not only has GM done so, Mitsubishi as well. Here's a quote from Mitshubishi's website: "....identify an aeolian tone noise from the pole antenna. Subsequently, generation of the noise was restricted by using a wire spirally wrapped around the antenna. The diameter of the wire is 0.2 times the diameter of the antenna." Here's a link to the article: http://www.mitsubishi-motors.com/corporate/about_us/technology/review/e/pdf/ 2002/14E_05.pdf Now how about a quote from the SAE website? DaimlerChrysler's Peter Gladysz, a Senior Manager in vehicle development and synthesis says, "Daimler- Chrysler's NVH lab works on all platforms simultaneously, so if anything can be utilized cross-platform - like going to a spiral cut antenna to stop whistle noise - it spreads throughout the product line-up" Here's a link to the article: http://www.sae.org/automag/nvh_challenges/ Now, I say to you: "Spend a little time studying antenna design and you might find that you need to revise your opinion in favor of scientific fact." Steve Steve, on the money. >> Spend a little time studying antenna design and you might find that you >> need to revise your opinion in favor of scientific fact. Read some of [quoted text clipped - 36 lines] > > Steve Correct answer BUT wrong method of repair. The spiral is actually cut into the stainless shaft that the antenna is made from. The end ball and the mounting screw fitting with locktite are then pressed on. Then it goes through a wash and pretreat and then through a powder coat booth. Ford and Chrysler were the first to use the spiral cut to both reduce wind noise and to reduce antenna harmonic motion due to wind drag. GM followed VERY shortly, The only real drawback is the spiral cut antennas are not as strong as the standard shaft units and they make lousy window breakers ( take a course on EMS vehicle extrication for that neat trick ) because of it. Oh and if you own a Ford or Chrysler with a fixed antenna it was probably made in Amsterdam NY by Ward Products. The chrome or black spanner nut securing it was produced by Manth/Brownell near Kirkville NY. It was also painted by either WW Custom Clad or Sumax powder coaters. And at least 30,000 of them were scrapped after WW had a fire that damaged the coating after they were processed.  SignatureSteve > > Spend a little time studying antenna design and you might find that you > > need to revise your opinion in favor of scientific fact. Read some of [quoted text clipped - 15 lines] > > Here's a link to the article: http://www.mitsubishi-motors.com/corporate/about_us/technology/review/e/pdf/ > 2002/14E_05.pdf > [quoted text clipped - 14 lines] > > Steve All this discussion is fine about how the shaft is cut but it doesn't explain the wire wrapped around the outside of the shaft. I stand by my original posting which is based on standard radio science, try you local library for the ARRL Antenna Book, written in plain language and found in many libraries as it has been used by hundreds of ham operators to understand antennas and to build their own. No one has yet to post a better response for the group of dots at the upper center of the windshield, yes there are dots in other places that have other purposes and it is very interesting to know but thats not the topic of this thread. >Correct answer BUT wrong method of repair. >The spiral is actually cut into the stainless shaft that the antenna is [quoted text clipped - 15 lines] > > I posted a couple of quotes on why the wire is there. Written in black and white for you to read without going to a library. We are not talking about ham radios, we are talking about automotive antenna, and THE WIRE IS THERE TO REDUCE WIND NOISE. As for the dots, the OP will have to take a picture and send it through to give an answer. He didn't say "group of dots at the upper center of the windshield," he said "the grid of black dots on the upper portion of the windshield." With that, I can guaruntee that 99.9999999% of black dot patterns on windshields are part of the black band provided to protect the adhesive from the sun. Steve > All this discussion is fine about how the shaft is cut but it doesn't > explain the wire wrapped around the outside of the shaft. I stand by my [quoted text clipped - 25 lines] > >coaters. And at least 30,000 of them were scrapped after WW had a fire > >that damaged the coating after they were processed. There is NO WIRE. The spiral pattern is cut in the steel of the antenna. NO WIRE wrapped around it. As for the dots it depends on which dots and where. There are positioning marks on most windshields for the bots to use when they place the glass in the frame. There are also the ones that are printed to block the adhesive around the edges. Don't need any antenna books. SignatureSteve > All this discussion is fine about how the shaft is cut but it doesn't > explain the wire wrapped around the outside of the shaft. I stand by my [quoted text clipped - 25 lines] > >coaters. And at least 30,000 of them were scrapped after WW had a fire > >that damaged the coating after they were processed. > There is NO WIRE. The spiral pattern is cut in the steel of the antenna. > NO WIRE wrapped around it. Read up on it, some are cut and some are wire wrapped. > > There is NO WIRE. The spiral pattern is cut in the steel of the antenna. > > NO WIRE wrapped around it. > > Read up on it, some are cut and some are wire wrapped. 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. Mitsubishi is definatly wire wrapped, the rest, except for Chrysler, I can't find any reference to. Steve > > > There is NO WIRE. The spiral pattern is cut in the steel of the > antenna. [quoted text clipped - 8 lines] > http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups > ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- > Mitsubishi is definatly wire wrapped, the rest, except for Chrysler, I > can't > find any reference to. > > Steve My 2004 Dodge truck seems to be wound, like with stainless steel foil?? Al That's cut > > Mitsubishi is definatly wire wrapped, the rest, except for Chrysler, I > > can't [quoted text clipped - 5 lines] > > Al this spiral is there to improve gas mileage. Studies indicate a 20% increase in EPA gas mileage rating when a spiral antenna is used. terry > That's cut > [quoted text clipped - 7 lines] >> >> Al 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? > this spiral is there to improve gas mileage. Studies indicate a 20% > increase in EPA gas mileage rating when a spiral antenna is used. [quoted text clipped - 11 lines] >>> >>> Al it is simple.... the antenna spiral creates a vortex in a manner such that it creates a low pressure around the front of the vehicle. this low pressure effect is like the vehicle always driving or being pulled into a vacuum. And this take less gas to move the vehicle along and is similar to a draft when one follows real close behind a big truck on the highway. > 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 [quoted text clipped - 16 lines] >>>> >>>> Al 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!! > it is simple.... > the antenna spiral creates a vortex in a manner such that it creates a [quoted text clipped - 23 lines] >>>>> >>>>> Al 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. > 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 [quoted text clipped - 37 lines] >>>>>> >>>>>> Al The spiral reduces noise created by air rushing across it. If you don't belive it, run a piece of tape lengthwise to the antenna and drive at 65 mph. It will have considerable noise. STOVEBOLT (Nickname for 1930's Chevy) >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 [quoted text clipped - 37 lines] >>>>>> >>>>>> Al 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. SignatureSteve Williams > Mitsubishi is definatly wire wrapped, the rest, except for Chrysler, I can't > find any reference to. > > Steve 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 > Mitsu huh. Figures ... > [quoted text clipped - 19 lines] > http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups > ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- >There is NO WIRE. The spiral pattern is cut in the steel of the antenna. >NO WIRE wrapped around it. [quoted text clipped - 5 lines] > >Don't need any antenna books. 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. > Incorrect statements so far: > "The wire is wrapped around to make for a longer antenna." [quoted text clipped - 14 lines] > > Steve 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. > > Incorrect statements so far: > > "The wire is wrapped around to make for a longer antenna." [quoted text clipped - 24 lines] > > As for the dots, I have no idea. My guess would be to act as a sunscreen. 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? > > > Incorrect statements so far: > > > "The wire is wrapped around to make for a longer antenna." [quoted text clipped - 29 lines] > that roughing up the surface would cut wind noise. I thought the more > streamlined an object the less air it would displace? 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. > The spiral on the radio antenna is a wire wound around a fiberglass core > so the antenna is longer than if it was just a straight rod. I think > (not certain) that the dots are the XM antenna. The spiral wrap on the car antenna is there to reduce wind drag & stop antenna 'whip motion'. The German's used this feature on WW2 submarine periscopes to stabilize 'periscope viewing'. With the spiral wrap, antennas could be made smaller diameter & still resist wind/water force without bending nor vibrating much in the breeze. > >Heh, the "spiral" you see is used to reduce wind noise and the black dots > >are part the black band around the perimeter of the windshield to protect [quoted text clipped - 19 lines] > >> > >>>windshield? > without bending nor vibrating much in the breeze. the same is correct for metal chimneys like the ones they have in oil refineries Andreas 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 > > without bending nor vibrating much in the breeze. > > > the same is correct for metal chimneys like the ones they have in oil > refineries > > Andreas |
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