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Why do truckers tilt their antennas forward about 20 degrees?
Seen this a lot lately on the road..
-- A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing on usenet? |
It cuts them some slack when they back up to something that
hits it/them. "Dave VanHorn" wrote: Seen this a lot lately on the road.. -- A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing on usenet? |
Also when they drive down the road going real fast, The antennas move up a
little and keep a good groundplane instead of folding back and loosing it. "Steveo" wrote in message ... It cuts them some slack when they back up to something that hits it/them. "Dave VanHorn" wrote: Seen this a lot lately on the road.. -- A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing on usenet? |
In , "Dave VanHorn"
wrote: Seen this a lot lately on the road.. Beats me why they do that, but it's possible the reason is founded somewhere deep in CB mythology. -- A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing on usenet? I think it's a Carnac thing..... A: Shish-Poom-Pah Q: What does it sound like when a sheep explodes? -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
On Tue, 23 Mar 2004 23:11:43 -0500, "Dave VanHorn"
wrote: Seen this a lot lately on the road.. I have heard 2 reasons, some of them have got the idea that it "points" their signal down the road, and that they want to keep them away from their trailer. |
"Juafi" wrote in message link.net... Also when they drive down the road going real fast, The antennas move up a little and keep a good groundplane instead of folding back and loosing it. ??? "keep a good groundplane" ??? This technique must be geared twoard running at about 300 MPH then, at 70+ they are still tilted way forward. |
"Frank Gilliland" wrote in message ... In , "Dave VanHorn" wrote: Seen this a lot lately on the road.. Beats me why they do that, but it's possible the reason is founded somewhere deep in CB mythology. That's a subject that almost deserves a book. The "ground plane" gadgets that extend about 3" from the base of the antenna are pretty good, along with the "5kW" antenna I saw packaged with a mount that had non-removeable RG-58 coax. |
the so-called ground plane that attaches to the base of the antenna IS NOT a
ground-plane because it's mounted above the insulator. inexperienced truckers who buy them know absolutely nothing about Rf. they are simply wasting their money on doo-dads that they think are going to make their radio get out farther. anything that is added to the the antenna above the fiber washer simply increases the electrical length of the antenna. Capacitance hats do not add length but they must be mounted above the loading coil. as far as tilting the antennas forward are concerned, there are sevewral possible scenarios involved. (1) the antenna is taller than 13'6" when mounted veertical and hits the low bridge when passing under therefore a forward tilt is mandatory. (2)they no absolutely nothing about RF radiation or take-off angle and tilt them forward 45 degrees to look cool. (3)tilting the the antenna forward about 15-20 degrees can increase the forward range of the signal by angling the signal closer to the horizon because antennas that are mounted closer to earth ground than 1 wavelength have a higher take-off angle than those that are mounted at or above 1 wavelength. A truckers CB is his/her pride and joy and the ultimate tool we use to communicate with each other over long distances. money is not a object when it comes to building a nice rig for talking on because we spend hours and hours communicating with each other on long trips cross-country -- Mad Dog aka 714 Sandpile aka KG4LBD 2002 KW T2000 "Dave VanHorn" wrote in message ... "Frank Gilliland" wrote in message ... In , "Dave VanHorn" wrote: Seen this a lot lately on the road.. Beats me why they do that, but it's possible the reason is founded somewhere deep in CB mythology. That's a subject that almost deserves a book. The "ground plane" gadgets that extend about 3" from the base of the antenna are pretty good, along with the "5kW" antenna I saw packaged with a mount that had non-removeable RG-58 coax. |
The reality is this - if a vertical is tilted 45 degrees, then you
experience a 3 dB signal loss off to the sides to a vertical that is truely vertical. A horizontal antenna can loose over 20 dB when communicating to a vertical antenna via direct line of site. With skip, it doesn't much matter as the signals will get twisted around a bit, but for local communication, figure the cosine of the angle difference. Cosine of 45 degrees is .707. The cosine of 90 degrees is zero (but there will be some reflected signals and you will usually get a 20 dB attenuation - a 100 times loss of signal *both* on transmit and receive). 3 dB isn't huge, but why have a loss both ways on a circuit? 73 from Rochester, NY Jim --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.639 / Virus Database: 408 - Release Date: 3/22/04 |
On Wed, 24 Mar 2004 04:37:08 -0800, Frank Gilliland
wrote: In , "Dave VanHorn" wrote: Seen this a lot lately on the road.. There could be a logical reason for this. Since an antenna is bent back when moving forward, by tilting it forward, it will compensate for the "bend", and end up straight when moving. Of course, some people exaggerate the effect for reasons which, as of yet, are not known. Dave "Sandbagger" http://home.ptd.net/~n3cvj |
"Mad Dog" wrote in message ... the so-called ground plane that attaches to the base of the antenna IS NOT a ground-plane because it's mounted above the insulator. inexperienced truckers who buy them know absolutely nothing about Rf. they are simply wasting their money on doo-dads that they think are going to make their radio get out farther. Therein lies the humor :) The first one that really made me laugh was the "Zing Ring". A circular gizmo that you were supposed to clamp around the bottom of the loading coil on a base-load antenna. anything that is added to the the antenna above the fiber washer simply increases the electrical length of the antenna. Capacitance hats do not add length but they must be mounted above the loading coil. Years ago, I ran a firestick (5' or so) with a cap hat that I built for it. Worked pretty well, in comparison with base stations in the same general area. I had an above-average ground plane though, on my chrysler imperial. as far as tilting the antennas forward are concerned, there are sevewral possible scenarios involved. (1) the antenna is taller than 13'6" when mounted veertical and hits the low bridge when passing under therefore a forward tilt is mandatory. Many that I've seen are definitely not in that region. (2)they no absolutely nothing about RF radiation or take-off angle and tilt them forward 45 degrees to look cool. That's what I was mostly thinking. Of course my 2M antenna is tilted forward a bit, but that's because the only good mounting point for it has that tilt built in. No practical way to straighten it out, so I just live with it. (3)tilting the the antenna forward about 15-20 degrees can increase the forward range of the signal by angling the signal closer to the horizon because antennas that are mounted closer to earth ground than 1 wavelength have a higher take-off angle than those that are mounted at or above 1 wavelength. Possible. I'm not sure what it would do to polarization. It would rotate to the sides, but then again, that may not be a bad thing. A trucker would normally want to talk fore and aft, and not so much to the sides. That's why the co-phased verticals always made sense to me, provided they are mounted at the right distance. I see co-phased antennas here locally, mounted within 2' of each other.. :) A truckers CB is his/her pride and joy and the ultimate tool we use to communicate with each other over long distances. money is not a object when it comes to building a nice rig for talking on because we spend hours and hours communicating with each other on long trips cross-country I always wondered why so few truckers are hams. You guys spend as much or more on your rigs, as I do but you get so very much less in the end. Now that you don't need CW, anyone who can qualify for a CDL ought to be able to snag a ham ticket in a week or so of spare time reading. Of course you'd still have to have the CB along to talk to the other fellows. |
There could be a logical reason for this. Since an antenna is bent
back when moving forward, by tilting it forward, it will compensate for the "bend", and end up straight when moving. You could make that case for mine, at about 2-5 degrees, but it was purely accidental. In the photos, you can see that it's perfectly vertical, against the edges of the building in the background. Unfortunately, I'm on a slight up-grade. Oh well, it dosen't seem to do any harm. Of course, some people exaggerate the effect for reasons which, as of yet, are not known. I've seen them as far as 45 degrees, and that's in motion at 70 MPH. I've not yet seen one with a bird skewered on it, but that will probably happen. |
On Wed, 24 Mar 2004 13:21:18 -0500, "Dave VanHorn"
wrote: There could be a logical reason for this. Since an antenna is bent back when moving forward, by tilting it forward, it will compensate for the "bend", and end up straight when moving. You could make that case for mine, at about 2-5 degrees, but it was purely accidental. In the photos, you can see that it's perfectly vertical, against the edges of the building in the background. Unfortunately, I'm on a slight up-grade. Oh well, it dosen't seem to do any harm. What photos? Of course, some people exaggerate the effect for reasons which, as of yet, are not known. I've seen them as far as 45 degrees, and that's in motion at 70 MPH. I've not yet seen one with a bird skewered on it, but that will probably happen. |
"Lancer" wrote in message ... On Wed, 24 Mar 2004 13:21:18 -0500, "Dave VanHorn" wrote: There could be a logical reason for this. Since an antenna is bent back when moving forward, by tilting it forward, it will compensate for the "bend", and end up straight when moving. You could make that case for mine, at about 2-5 degrees, but it was purely accidental. In the photos, you can see that it's perfectly vertical, against the edges of the building in the background. Unfortunately, I'm on a slight up-grade. Oh well, it dosen't seem to do any harm. What photos? http://www.inchase.org/outflow/event...2/f5Mount.html That was before I spent 2 months in the hospital, and another 6 (14 total) weeks on a backpack at home, eating through an I/V line. |
You're all wrong. It makes the rig look like a bull with horns, causing
everyone to think the owner has a large scrotum. "Dave VanHorn" wrote in message ... Seen this a lot lately on the road.. -- A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing on usenet? |
On Wed, 24 Mar 2004 13:21:18 -0500, "Dave VanHorn"
wrote: There could be a logical reason for this. Since an antenna is bent back when moving forward, by tilting it forward, it will compensate for the "bend", and end up straight when moving. You could make that case for mine, at about 2-5 degrees, but it was purely accidental. In the photos, you can see that it's perfectly vertical, against the edges of the building in the background. Unfortunately, I'm on a slight up-grade. Oh well, it dosen't seem to do any harm. Of course, some people exaggerate the effect for reasons which, as of yet, are not known. I've seen them as far as 45 degrees, and that's in motion at 70 MPH. I've not yet seen one with a bird skewered on it, but that will probably happen. I remember just how far back a 102" steel whip would bend back at 65 MPH. I guess a shorter and stiffer fiberglass whip bends much less. I would guess that 45 degrees is a bit extreme to compensate for wind bend. I also have trouble buying the "lowering the total height to avoid hitting bridges" theory as well, since if that were the case, it would make more sense to bend them BACK, not forward, just in case they do graze one. If it's bent back, it will deflect downward slightly. If it's bent forward and it strikes an over head object, it will compress and likely shatter. Dave "Sandbagger" http://home.ptd.net/~n3cvj |
Dave wrote:
I remember just how far back a 102" steel whip would bend back at 65 MPH. I guess a shorter and stiffer fiberglass whip bends much less. I haven't seen any rig with a 9' whip antenna on it. Most seem about half that long. Truckers are smart. Anyone driving for long at all knows that a 9' whip atop a tractor is sure to hit lots of stuff. So the vast majority - if not almost all - of whips I see for sale at truckstops are much shorter. ~~~~~~~~~~~~~~~~~~~~~ BDissident news - plus immigration, gun rights, nationwide weather IA HREF="http://www.alamanceind.com"ALAMANCE INDEPENDENT: official newspaper of the Vast Right Wing Conspiracy/A/b/i |
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