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CB antenna/antennas on a pickup truck
Hi all,
I've got an aluminum tool box in the back of my pickup truck. It's the usual type that spans the bed right behind the cab. I'm thinking that it might make a good antenna mounting point. I don't want to drill into the body of the truck, but I wouldn't mind putting a couple holes in the toolbox. I have two questions. The first is: If I mount brackets to the tool box, will I need some sort of ground strap to connect it to the frame of the truck to give me a good ground? The second is: Will I see any real world improvement in performance by using dual antennas? I like the look of the trucks that I see with antennas on each side of the bed box. It's nice for a balanced appearance. I also understand that it's a bit trickier to adjust SWR with dual antennas. I wouldn't be against using one as an antenna and simply using the other one to balance out the look of the truck (although, I guess some folks might think that's silly). Thanks! -NW |
"NetWeasel" wrote:
Hi all, I've got an aluminum tool box in the back of my pickup truck. It's the usual type that spans the bed right behind the cab. I'm thinking that it might make a good antenna mounting point. I don't want to drill into the body of the truck, but I wouldn't mind putting a couple holes in the toolbox. I have two questions. The first is: If I mount brackets to the tool box, will I need some sort of ground strap to connect it to the frame of the truck to give me a good ground? Yes..I'd drill the box into the truck frame, that way it won't come loose in a traffic accident, and it will give you a good ground. Ground strap would be my last resort.. The second is: Will I see any real world improvement in performance by using dual antennas? Not unless you're in Texas and have bull-horns on your hood. Twin antennas suck..they are too close to each other. Use one antenna. -- http://www.allpar.com/mopar.html |
"NetWeasel" wrote in message ... Hi all, I've got an aluminum tool box in the back of my pickup truck. It's the usual type that spans the bed right behind the cab. I'm thinking that it might make a good antenna mounting point. I don't want to drill into the body of the truck, but I wouldn't mind putting a couple holes in the toolbox. Understandable. I have two questions. The first is: If I mount brackets to the tool box, will I need some sort of ground strap to connect it to the frame of the truck to give me a good ground? Yes. For a quarter wave antenna the ground plane needs to be at least a quarter wavelength in size too for the antenna to function correctly. The truck body forms part of the ground plane while the capacitance of the truck body to earth ground forming the rest of the ground plane in simple terms. The second is: Will I see any real world improvement in performance by using dual antennas? That all depends on your goals. The typical dual antenna setup, when done right, generates maximum signal strength to the front and to the rear. The signal strength to the left and right is considerably reduced. The same applies to your receive signal strength as well. Long hual truckers normaly are concerned with communicating with other truckers on the road. Those truckers are going to be either in front or behind them on the highway. Thus it makes sense to maximize the signal in those directions, and thus the popularity of the setup. If your more interested in general communications in any direction then you really don't want a dual antenna setup. What you want is an antenna location near the center of the truck, which will as nearly as possible, give you a uniform signal in all directions. The site you picked, on the tool box, would be a good one. I like the look of the trucks that I see with antennas on each side of the bed box. It's nice for a balanced appearance. You have to make up your mind, good looks, or good performance. Your typical passenger truck is not wide enough, you need 9 feet, to properly setup a dual antenna system. I also understand that it's a bit trickier to adjust SWR with dual antennas. It can be. I wouldn't be against using one as an antenna and simply using the other one to balance out the look of the truck (although, I guess some folks might think that's silly). Your truck. You have to drive it. Good Luck. -- Leland C. Scott KC8LDO Wireless Network Mobile computing on the go brought to you by Micro$oft |
"Leland C. Scott" wrote in message ... "NetWeasel" wrote in message ... Hi all, I've got an aluminum tool box in the back of my pickup truck. It's the usual type that spans the bed right behind the cab. I'm thinking that it might make a good antenna mounting point. I don't want to drill into the body of the truck, but I wouldn't mind putting a couple holes in the toolbox. Understandable. I have two questions. The first is: If I mount brackets to the tool box, will I need some sort of ground strap to connect it to the frame of the truck to give me a good ground? Yes. For a quarter wave antenna the ground plane needs to be at least a quarter wavelength in size too for the antenna to function correctly. The truck body forms part of the ground plane while the capacitance of the truck body to earth ground forming the rest of the ground plane in simple terms. The second is: Will I see any real world improvement in performance by using dual antennas? That all depends on your goals. The typical dual antenna setup, when done right, generates maximum signal strength to the front and to the rear. The signal strength to the left and right is considerably reduced. The same applies to your receive signal strength as well. Um, sorry wrong Leland, it makes the signal more omnidirectional. Long hual truckers normaly are concerned with communicating with other truckers on the road. Those truckers are going to be either in front or behind them on the highway. Thus it makes sense to maximize the signal in those directions, and thus the popularity of the setup. If your more interested in general communications in any direction then you really don't want a dual antenna setup. What you want is an antenna location near the center of the truck, which will as nearly as possible, give you a uniform signal in all directions. The site you picked, on the tool box, would be a good one. Again, wrong Leland. I like the look of the trucks that I see with antennas on each side of the bed box. It's nice for a balanced appearance. If looks is what he wants, fine but I think he wants some sort of performance. You have to make up your mind, good looks, or good performance. Your typical passenger truck is not wide enough, you need 9 feet, to properly setup a dual antenna system. I also understand that it's a bit trickier to adjust SWR with dual antennas. Correct, it's a bitch. It can be. I wouldn't be against using one as an antenna and simply using the other one to balance out the look of the truck (although, I guess some folks might think that's silly). You said it, not I. Your truck. You have to drive it. Good Luck. He'll need it. -- Leland C. Scott KC8LDO If you have stake bed holes, go to your local muffler shop, have them bend a sort of "roll bar" for the antenna. Make a mount in the center of the bar for the antenna. Then mount it in the stake bed holes, drilling through the inner bed, into the antenna bar for bolting it up. Here's a pretty good link on how antenna's work. http://www.signalengineering.com/ult..._antennas.html Landshark -- Treat people as if they were what they ought to be and you will help them become what they are capable of becoming. |
"Landshark" wrote in message m... That all depends on your goals. The typical dual antenna setup, when done right, generates maximum signal strength to the front and to the rear. The signal strength to the left and right is considerably reduced. The same applies to your receive signal strength as well. Um, sorry wrong Leland, it makes the signal more omnidirectional. If done correctly, spaced - phased - good ground plane, it works as I described. http://www.bellscb.com/cb_radio_hobb.../antarray.html Long hual truckers normaly are concerned with communicating with other truckers on the road. Those truckers are going to be either in front or behind them on the highway. Thus it makes sense to maximize the signal in those directions, and thus the popularity of the setup. If your more interested in general communications in any direction then you really don't want a dual antenna setup. What you want is an antenna location near the center of the truck, which will as nearly as possible, give you a uniform signal in all directions. The site you picked, on the tool box, would be a good one. Again, wrong Leland. No. The site above has not only a discussion about antenna patterns, but the antenna field pattern plots to prove it. I can supply some EZNEC 4.0 simulation files to prove same if you want. -- Leland C. Scott KC8LDO Wireless Network Mobile computing on the go brought to you by Micro$oft |
"Leland C. Scott" wrote in message ... "Landshark" wrote in message m... That all depends on your goals. The typical dual antenna setup, when done right, generates maximum signal strength to the front and to the rear. The signal strength to the left and right is considerably reduced. The same applies to your receive signal strength as well. Um, sorry wrong Leland, it makes the signal more omnidirectional. If done correctly, spaced - phased - good ground plane, it works as I described. http://www.bellscb.com/cb_radio_hobb.../antarray.html Long hual truckers normaly are concerned with communicating with other truckers on the road. Those truckers are going to be either in front or behind them on the highway. Thus it makes sense to maximize the signal in those directions, and thus the popularity of the setup. If your more interested in general communications in any direction then you really don't want a dual antenna setup. What you want is an antenna location near the center of the truck, which will as nearly as possible, give you a uniform signal in all directions. The site you picked, on the tool box, would be a good one. Again, wrong Leland. No. The site above has not only a discussion about antenna patterns, but the antenna field pattern plots to prove it. I can supply some EZNEC 4.0 simulation files to prove same if you want. -- Leland C. Scott KC8LDO Feel free, but I guess Signal Engineering doesn't know anything, right? Landshark -- That does suck..sometimes you're the windshield..sometimes you're the bug. |
In , "Leland C. Scott"
wrote: "Landshark" wrote in message om... That all depends on your goals. The typical dual antenna setup, when done right, generates maximum signal strength to the front and to the rear. The signal strength to the left and right is considerably reduced. The same applies to your receive signal strength as well. Um, sorry wrong Leland, it makes the signal more omnidirectional. If done correctly, spaced - phased - good ground plane, it works as I described. http://www.bellscb.com/cb_radio_hobb.../antarray.html Long hual truckers normaly are concerned with communicating with other truckers on the road. Those truckers are going to be either in front or behind them on the highway. Thus it makes sense to maximize the signal in those directions, and thus the popularity of the setup. If your more interested in general communications in any direction then you really don't want a dual antenna setup. What you want is an antenna location near the center of the truck, which will as nearly as possible, give you a uniform signal in all directions. The site you picked, on the tool box, would be a good one. Again, wrong Leland. No. The site above has not only a discussion about antenna patterns, but the antenna field pattern plots to prove it. I can supply some EZNEC 4.0 simulation files to prove same if you want. Everyone will think I'm insane for saying this, but Landshark has it right. In order for co-phased antennas to achieve that ideal figure-8 pattern they must be nearly ideal antennas, which CB antennas are not. Landshark's link explains why this happens. I wouldn't expect any significant improvement in the omnidirectional characteristics of dualies (as the site claims), but I do know they don't provide any noticable directional gain. -----= 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! =----- |
I agree as well, a properly engineered single 102"
will outperform duals anyday. Most truckers don't understand how and why antennas radiate RF energy and they run duals because they give a balanced look, as a bonus co-phased antennas tend to supplement each other on vehicles with plastic or fiberglass bodies. The fact is that the trailer blocks a majority of the RF that co-phased antennas provide to the rear so they end up with a system that transceives mainly to the front. The exception to the rule would be a flatbed trailer. I use a 102" whip on my T2000 which is mounted to a flat bar attached to the frame that extends past the edge of the trailer which allows the antenna to "see" behind the trailer. The antenna is supported roughly 6' above the mounting point using a custom made plexiglass bracket. I have also attached 2 braided steel cables to frame which drag the road during travel and supply a make-shift earth ground when parked. I will be flat honest with you and say that this system gets out farther then i care for sometimes. It also works well for sky-wave propagation when conditions permit. My 4x4 truck uses a pedestal mount 102" whip and a 24" x 24" sheet of stainless, the pedestal is mounted to the floor of the bed 1.5' behind the cab and cut to length with the top of the bed, the stainless heet is sandwiched between the top of the pedestal and the bottom of the antenna. Very powerful system using a highly tuned 25 LTD -- Mad-Dog "Frank Gilliland" wrote in message ... In , "Leland C. Scott" wrote: "Landshark" wrote in message om... That all depends on your goals. The typical dual antenna setup, when done right, generates maximum signal strength to the front and to the rear. The signal strength to the left and right is considerably reduced. The same applies to your receive signal strength as well. Um, sorry wrong Leland, it makes the signal more omnidirectional. If done correctly, spaced - phased - good ground plane, it works as I described. http://www.bellscb.com/cb_radio_hobb.../antarray.html Long hual truckers normaly are concerned with communicating with other truckers on the road. Those truckers are going to be either in front or behind them on the highway. Thus it makes sense to maximize the signal in those directions, and thus the popularity of the setup. If your more interested in general communications in any direction then you really don't want a dual antenna setup. What you want is an antenna location near the center of the truck, which will as nearly as possible, give you a uniform signal in all directions. The site you picked, on the tool box, would be a good one. Again, wrong Leland. No. The site above has not only a discussion about antenna patterns, but the antenna field pattern plots to prove it. I can supply some EZNEC 4.0 simulation files to prove same if you want. Everyone will think I'm insane for saying this, but Landshark has it right. In order for co-phased antennas to achieve that ideal figure-8 pattern they must be nearly ideal antennas, which CB antennas are not. Landshark's link explains why this happens. I wouldn't expect any significant improvement in the omnidirectional characteristics of dualies (as the site claims), but I do know they don't provide any noticable directional gain. -----= 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! =----- |
"Frank Gilliland" wrote in message ... Everyone will think I'm insane for saying this, but Landshark has it right. No he doesn't. In order for co-phased antennas to achieve that ideal figure-8 pattern they must be nearly ideal antennas, which CB antennas are not. They don't nessessarly need be to be ideal, but the do need to be installed the same way. By the way no antenna is ideal, but many people have a lot of success anyway. Landshark's link explains why this happens. I wouldn't expect any significant improvement in the omnidirectional characteristics of dualies (as the site claims), but I do know they don't provide any noticable directional gain. If you check the link I provided you will see there is some gain. The gain does not become noticeable until you have at least a 1/4 wavelength separation, and at that it is around 2 db or so. On the site I posted the link for you will see the figure 8 pattern becomes very noticeable for a half wavelength between antennas. Getting to that degree of separation is much easier to do on a semi because of their size, and the fact the antennas are further apart from being mounted on the side view mirrors. Passenger vehicles just don't have the size needed. -- Leland C. Scott KC8LDO Wireless Network Mobile computing on the go brought to you by Micro$oft |
"Leland C. Scott" wrote in message ... "Frank Gilliland" wrote in message ... Everyone will think I'm insane for saying this, but Landshark has it right. No he doesn't. Of course I do Leland, you just don't want me too :) In order for co-phased antennas to achieve that ideal figure-8 pattern they must be nearly ideal antennas, which CB antennas are not. How would you know Leland? Remember, you don't like CB, let alone talk or use or own one. They don't nessessarly need be to be ideal, but the do need to be installed the same way. By the way no antenna is ideal, but many people have a lot of success anyway. Landshark's link explains why this happens. I wouldn't expect any significant improvement in the omnidirectional characteristics of dualies (as the site claims), but I do know they don't provide any noticable directional gain. If you check the link I provided you will see there is some gain. The gain does not become noticeable until you have at least a 1/4 wavelength separation, and at that it is around 2 db or so. On the site I posted the link for you will see the figure 8 pattern becomes very noticeable for a half wavelength between antennas. The point was that it was a much better omni-directional pattern on Dual antenna's, to which that is achieved. You are saying that Signal Engineering, which soul business is antenna's is wrong, good luck on trying to convince others of that. Getting to that degree of separation is much easier to do on a semi because of their size, and the fact the antennas are further apart from being mounted on the side view mirrors. Passenger vehicles just don't have the size needed. -- Leland C. Scott KC8LDO Landshark -- The world is good-natured to people who are good natured. |
"Leland C. Scott" wrote in message ... "Frank Gilliland" wrote in message ... Everyone will think I'm insane for saying this, but Landshark has it right. No he doesn't. Al Banys says your a cock gobbler. |
"Landshark" wrote in message ... Feel free, but I guess Signal Engineering doesn't know anything, right? They can't seem to get their facts right. For example: " The pattern is "pulled" to areas where there is the most vehicle body. The pattern is the worst in directions where there is no metal body for a radial." This is from their comment about mounting an omnidirectional antenna lifted right off their WEB page. The dual antennas mounted near the mid point of the vehicle should each have a similar pattern distortion due to mounting location, for example to the front and rear with some to the side where the antenna is mounted. Those are the directions where the metal is located, with more to the front and rear than to the side. Now refer to the antenna pattern for the site I mentioned you will see the greater field strength is to the front and rear of the vehicle too for quarter wavelength spaced antennas fed in phase, and is in the same direction. Both effects are adding together in the same general direction. However under their comments about a dual antenna setup they claim just the opposite in a round about manner. -- Leland C. Scott KC8LDO Wireless Network Mobile computing on the go brought to you by Micro$oft |
"Leland C. Scott" wrote in message ... This news group should be named "rec.voodoo.11m.radio" from all of the crap that's passes for fact. Here's a fact................Al Banys says you like men for sex partners....buttboy. |
"Landshark" wrote in message m... "Leland C. Scott" wrote in message ... "Frank Gilliland" wrote in message ... Everyone will think I'm insane for saying this, but Landshark has it right. No he doesn't. Of course I do Leland, you just don't want me too :) Then explain away the the information on the other site. Get a copy of EZNEC and model it yourself. http://www.eznec.com/ And if you're to cheap to buy a copy then try the freebee versions at: http://www.qsl.net/wb6tpu/swindex.html Then you can check at the site below for antenna modeling tips and information about many types of antennas from an expert in the area. http://www.cebik.com/ And another interesting antenna site: http://www.antennex.com/ In order for co-phased antennas to achieve that ideal figure-8 pattern they must be nearly ideal antennas, which CB antennas are not. How would you know Leland? Remember, you don't like CB, let alone talk or use or own one. You have been sleeping at the keyboard. I was on CB back in the late 70's until I got fed up with all of the jerks on the air. Even ran a mobile AM/SSB system. I used a Midland combo base- mobile radio. At that time the rigs were 23 channels. I've been there, done that, and gave away the radio to my nephew some years ago. They don't nessessarly need be to be ideal, but the do need to be installed the same way. By the way no antenna is ideal, but many people have a lot of success anyway. Landshark's link explains why this happens. I wouldn't expect any significant improvement in the omnidirectional characteristics of dualies (as the site claims), but I do know they don't provide any noticable directional gain. If you check the link I provided you will see there is some gain. The gain does not become noticeable until you have at least a 1/4 wavelength separation, and at that it is around 2 db or so. On the site I posted the link for you will see the figure 8 pattern becomes very noticeable for a half wavelength between antennas. The point was that it was a much better omni-directional pattern on Dual antenna's, to which that is achieved. You are saying that Signal Engineering, which soul business is antenna's is wrong, good luck on trying to convince others of that. They also make antennas for money. And when money is involved you have to suspect the claims they make. It won't be the first nor the last time a manufacture stretched the truth, i.e. lied. But then again you guys also believe Class "C" amplifiers are linear, "magic" lenghts of coax to fix antenna SWR etc. This news group should be named "rec.voodoo.11m.radio" from all of the crap that's passes for fact. -- Leland C. Scott KC8LDO Wireless Network Mobile computing on the go brought to you by Micro$oft |
In , "Leland C. Scott"
wrote: "Landshark" wrote in message om... "Leland C. Scott" wrote in message ... "Frank Gilliland" wrote in message ... Everyone will think I'm insane for saying this, but Landshark has it right. No he doesn't. Of course I do Leland, you just don't want me too :) Then explain away the the information on the other site. Get a copy of EZNEC and model it yourself. Forget about all that antenna-modeling software crap and build a simple field-strength meter. Then go measure it yourself because that's how it's done in the real world, and that's how the page at Landshark's link came up with the radiation pattern for the bumper-mount antenna. A similar pattern can be found in almost any radio-communications handbook that covers mobile antennas. -----= 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! =----- |
In , Frank Gilliland
wrote: snip ... A similar pattern can be found in almost any radio-communications handbook that covers mobile antennas. Including Radio Shack's famous tome, "All About CB Two-Way Radio" which, IMO, should be the rrcb FAQ by proxy. -----= 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! =----- |
"Leland C. Scott" wrote in message ... "Frank Gilliland" wrote in message ... Forget about all that antenna-modeling software crap and build a simple field-strength meter. Then go measure it yourself because that's how it's done in the real world, Have you personaly done so for the setup in question? Stick to your 2 meter handheld...gayboy. |
"Frank Gilliland" wrote in message ... Forget about all that antenna-modeling software crap and build a simple field-strength meter. Then go measure it yourself because that's how it's done in the real world, Have you personaly done so for the setup in question? and that's how the page at Landshark's link came up with the radiation pattern for the bumper-mount antenna. A similar pattern can be found in almost any radio-communications handbook that covers mobile antennas. The antenna simulation software shows the same thing as single bumper mount antenna pattern as on the page Landshark posted. That's why I question the omni pattern for a dual antenna setup. In fact Frank you can look up the pattern for such a setup, dual antenna, in a copy of the radio engineer's handbook, and I'm surprised you haven't since you know about it. More than one Ham has modeled some commercially manufactured antennas and discovered they don't perform as the ads suggest. When the manufacture was confronted with the results they modified their claims. The software modeling approach works or people wouldn't waste their time with it. In fact more antenna manufactures are doing it since it saves a lot of screwing around making error prone measurements with a field strength meter, and that's how they are doing it now in the real world. -- Leland C. Scott KC8LDO Wireless Network Mobile computing on the go brought to you by Micro$oft |
In , "Leland C. Scott"
wrote: "Frank Gilliland" wrote in message .. . Forget about all that antenna-modeling software crap and build a simple field-strength meter. Then go measure it yourself because that's how it's done in the real world, Have you personaly done so for the setup in question? Over the years I have tested many different antenna installations, both on my own vehicles and at customer request. Here are a few that I remember: Just last month I tested a 4' helical mounted on the center of the roof of a pickup. It showed a little gain to the front and rear, kinda like what people are trying to achieve with dualies. Another was a dual-antenna setup on a tractor cab. I don't remember the make but they were short, center-loaded whips on the mirrors. Almost no signal to the rear with or without the trailer, moderate signal to the front and sides. On the same truck (at a later date) was mounted a single 66" whip from RS on the passenger-side mirror. This was goofy: it was generally omni with a little gain to the front-left and right-rear, and there was -no- expected dead-zone to the left-rear (possibly due to the antenna height). Pretty good antenna! As far as I know he still uses it. Tested dual 9' whips on the bumper of a very sweet GMC pickup (1-ton custom job, diesel, fording package....the works!). Pattern was almost perfectly omni. EXCELLENT SIGNAL STRENGTH!!! I also tested my own truck with different antennas. The mount is centered on the roo-guard. It almost always shows a slight gain to the sides, but is generally omni. I have tested more and with different types of radios (lots of VHF), but I can't remember all of them offhand, and I don't feel like typing all day. I should mention that I chose the location for the antenna mount on my truck (on the front at hood level) because it was the location with the best RF ground, as tested with my GDO. This is the case for -my- truck. I wouldn't extrapolate that for any other vehicle. In fact, the other day I was going over the Chevy (S-10) with the GDO looking for a good spot for an antenna mount, and the spot that works so well on the Dodge is -not- a very good RF ground on the Chevy. No antenna modeling software can predict something like that. BTW, the easiest way to do a pattern test is to park the meter with a spotter a couple hundred feet away, drive the test vehicle in a tight circle, stop every ten degrees, key up and transmit the heading. It takes all of ten minutes, give or take, depending on how fast your spotter can read the meter and write down the data. And I still don't understand the desire for front/back gain on a vehicle. Unless you drive most of the time on the long, straight highways of the desert and plains, a directional pattern isn't going to do much good at all, and what little bit gain you can get from a directional pattern won't amount to anything you can hear from the speaker. Oh well, to each his own. As for me, I'm going to try dual 9' whips on the rear bumper of the GMC. and that's how the page at Landshark's link came up with the radiation pattern for the bumper-mount antenna. A similar pattern can be found in almost any radio-communications handbook that covers mobile antennas. The antenna simulation software shows the same thing as single bumper mount antenna pattern as on the page Landshark posted. That's why I question the omni pattern for a dual antenna setup. In fact Frank you can look up the pattern for such a setup, dual antenna, in a copy of the radio engineer's handbook, and I'm surprised you haven't since you know about it. More than one Ham has modeled some commercially manufactured antennas and discovered they don't perform as the ads suggest. When the manufacture was confronted with the results they modified their claims. The software modeling approach works or people wouldn't waste their time with it. In fact more antenna manufactures are doing it since it saves a lot of screwing around making error prone measurements with a field strength meter, and that's how they are doing it now in the real world. Antenna modeling software is a great tool for learning theoretical antenna design. But unless the software was written by a team of grad students at Cal-Tech and runs on Big Blue, it cannot possibly account for all the variables involved. It is not, and should not be used as, a substitute for actual field measurements. -----= 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! =----- |
"Leland C. Scott" wrote in message ... "Frank Gilliland" wrote in message ... Forget about all that antenna-modeling software crap and build a simple field-strength meter. Then go measure it yourself because that's how it's done in the real world, Have you personaly done so for the setup in question? Same question, have you? and that's how the page at Landshark's link came up with the radiation pattern for the bumper-mount antenna. A similar pattern can be found in almost any radio-communications handbook that covers mobile antennas. The antenna simulation software shows the same thing as single bumper mount antenna pattern as on the page Landshark posted. That's why I question the omni pattern for a dual antenna setup. In fact Frank you can look up the pattern for such a setup, dual antenna, in a copy of the radio engineer's handbook, and I'm surprised you haven't since you know about it. More than one Ham has modeled some commercially manufactured antennas and discovered they don't perform as the ads suggest. When the manufacture was confronted with the results they modified their claims. The software modeling approach works or people wouldn't waste their time with it. In fact more antenna manufactures are doing it since it saves a lot of screwing around making error prone measurements with a field strength meter, and that's how they are doing it now in the real world. -- Leland C. Scott KC8LDO I'm sure they have the same software, but yet you don't understand. I'll believe Frank, before I'll believe some sort of software program you recommend. Landshark -- Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen. |
"Frank Gilliland" wrote in message ... BTW, the easiest way to do a pattern test is to park the meter with a spotter a couple hundred feet away, drive the test vehicle in a tight circle, stop every ten degrees, key up and transmit the heading. It takes all of ten minutes, give or take, depending on how fast your spotter can read the meter and write down the data. My reason for asking is the pattern is of course 3d. Doing an elevation slice through the pattern I have seen extensive variation in the pattern as the elevation slice is moved up and down in the z-axis when multiple elements are involved. Normally the main lobe in the field pattern is not at 90 degrees to the vertical antenna, but tilted up by some number of degrees. Standing at ground level a few hundred feet away doesn't really give you a good idea of the of what the field pattern looks like. And I still don't understand the desire for front/back gain on a vehicle. Unless you drive most of the time on the long, straight highways of the desert and plains, Long haul truckers spend a lot of their time driving over long sections of straight highways. a directional pattern isn't going to do much good at all, and what little bit gain you can get from a directional pattern won't amount to anything you can hear from the speaker. Tell a hard core Dxer that a db or so difference don't matter and see what happens. They will swear up and down it does. Oh well, to each his own. As for me, I'm going to try dual 9' whips on the rear bumper of the GMC. A buddy of mine used a 4-point mag-mount on the roof of his car to hold a 9 foot whip when he was on 11m years ago. He claimed around 100+ miles with a standard radio. Antenna modeling software is a great tool for learning theoretical antenna design. But unless the software was written by a team of grad students at Cal-Tech and runs on Big Blue, it cannot possibly account for all the variables involved. It is not, and should not be used as, a substitute for actual field measurements. I think if you contact Mr. Cebik, W4RNL, you will find he does both, model and test. Seems his models predict real antenna performace rather well. If he didn't then there would be no way to advise others about areas that require care when modeling atennas. Also Roy, W7EL, has a lot of experience too. I worked with Mr. Cebik on a Turnstile matching idea. As he pointed out in an article in QEX the schema has the draw back of producing a gain variation of around 2 db from perfect omnidirectional. While not a big deal it can be improved by a small adjustment to the length of the phasing lines that do the impedance match at the expense of a small increase in SWR. The analytical solution was confirmed by the antenna simulation software, which showed an improvement in pattern circularity and equal currents in the antenna elements. -- Leland C. Scott KC8LDO Wireless Network Mobile computing on the go brought to you by Micro$oft |
Listen I know how you feel. Bought a brand new F150 and didn't want any
holes in it either. after talking in this dopey group i decided to drill the holes. I put in a plastic side mount bracket right next to the F150 marking and used a fiberglass 4' antenna. works better and looks better than any other hook up I have had in the past. Forget about the drilling problem, go for the looks and it will all work out better for you. PS what kind of a truck is it? "NetWeasel" wrote in message ... Hi all, I've got an aluminum tool box in the back of my pickup truck. It's the usual type that spans the bed right behind the cab. I'm thinking that it might make a good antenna mounting point. I don't want to drill into the body of the truck, but I wouldn't mind putting a couple holes in the toolbox. I have two questions. The first is: If I mount brackets to the tool box, will I need some sort of ground strap to connect it to the frame of the truck to give me a good ground? The second is: Will I see any real world improvement in performance by using dual antennas? I like the look of the trucks that I see with antennas on each side of the bed box. It's nice for a balanced appearance. I also understand that it's a bit trickier to adjust SWR with dual antennas. I wouldn't be against using one as an antenna and simply using the other one to balance out the look of the truck (although, I guess some folks might think that's silly). Thanks! -NW |
In , "Leland C. Scott"
wrote: "Frank Gilliland" wrote in message .. . BTW, the easiest way to do a pattern test is to park the meter with a spotter a couple hundred feet away, drive the test vehicle in a tight circle, stop every ten degrees, key up and transmit the heading. It takes all of ten minutes, give or take, depending on how fast your spotter can read the meter and write down the data. My reason for asking is the pattern is of course 3d. Doing an elevation slice through the pattern I have seen extensive variation in the pattern as the elevation slice is moved up and down in the z-axis when multiple elements are involved. Normally the main lobe in the field pattern is not at 90 degrees to the vertical antenna, but tilted up by some number of degrees. Standing at ground level a few hundred feet away doesn't really give you a good idea of the of what the field pattern looks like. It gives a good idea of the field pattern where it matters. How many aeronautical CBers do you talk to in any given year? And I still don't understand the desire for front/back gain on a vehicle. Unless you drive most of the time on the long, straight highways of the desert and plains, Long haul truckers spend a lot of their time driving over long sections of straight highways. I think that's what I just said..... a directional pattern isn't going to do much good at all, and what little bit gain you can get from a directional pattern won't amount to anything you can hear from the speaker. Tell a hard core Dxer that a db or so difference don't matter and see what happens. They will swear up and down it does. And some people still claim to see Elvis at shopping malls. Oh well, to each his own. As for me, I'm going to try dual 9' whips on the rear bumper of the GMC. A buddy of mine used a 4-point mag-mount on the roof of his car to hold a 9 foot whip when he was on 11m years ago. He claimed around 100+ miles with a standard radio. I have pulled in signals from just about every distance between here and Mexico with my homebrew base vertical, but propogation just isn't very reliable beyond 5 or 10 miles. Regardless, I have no intention of mounting an 18' stick on the truck. I think I'll stay with the idea of dual niners on the rear bumper. It should make the most out of the range that's available, and I'll also be able to test some of these dual-antenna theories. Antenna modeling software is a great tool for learning theoretical antenna design. But unless the software was written by a team of grad students at Cal-Tech and runs on Big Blue, it cannot possibly account for all the variables involved. It is not, and should not be used as, a substitute for actual field measurements. I think if you contact Mr. Cebik, W4RNL, you will find he does both, model and test. Seems his models predict real antenna performace rather well. If he didn't then there would be no way to advise others about areas that require care when modeling atennas. Also Roy, W7EL, has a lot of experience too. I am familiar with W4RNL, and he is very good with the software. But if you haven't noticed, he tends to play with software much more than hardware. But if modeling software had the capability to accurately predict the performance of any given antenna then there would be no reason to test them in the field. Yet he -does- test his models, which is indicitive of the fact that the software has not evolved far enough to stand on it's own, and he evidently recognizes this fact. I worked with Mr. Cebik on a Turnstile matching idea. As he pointed out in an article in QEX the schema has the draw back of producing a gain variation of around 2 db from perfect omnidirectional. While not a big deal it can be improved by a small adjustment to the length of the phasing lines that do the impedance match at the expense of a small increase in SWR. The analytical solution was confirmed by the antenna simulation software, which showed an improvement in pattern circularity and equal currents in the antenna elements. Now this is what I'm talking about.... some people just can't sleep at night knowing that their radiation pattern is not a perfect circle (or whatever desired pattern they have drawn in their mind). Smoothing the dimples of a turnstile doesn't add any gain, it just redistributes it at the expense of a little ERP. How (or why) is that even worth the effort for such a cheap and easy antenna? -----= 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! =----- |
Frank Gilliland wrote:
How (or why) is that even worth the effort for such a cheap and easy antenna? Bact to the OP. 9 foot whip on a pick-up truck is best, eh Frank? tree pruning problems considered |
In , Steveo
wrote: Frank Gilliland wrote: How (or why) is that even worth the effort for such a cheap and easy antenna? Bact to the OP. 9 foot whip on a pick-up truck is best, eh Frank? Yep. A non-magnetic whip is best, but even a magnetic steel whip will outperform any other 1/4-wave vertical on the market. That's my story and I'm sticking to it. BTW, I have been considering what it would take to setup a small scale production run of -good- 9-foot fiberglass whips. Any comments and/or suggestions are welcome. tree pruning problems considered I'm not sure but I think the max height for a motor vehicle (without a special permit) is something like 13 feet, which means you should be able to mount the whip up to 4 feet off the ground and have relatively few problems. I'll check on that height limit...... -----= 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! =----- |
Frank Gilliland wrote:
In , Steveo wrote: Frank Gilliland wrote: How (or why) is that even worth the effort for such a cheap and easy antenna? Bact to the OP. 9 foot whip on a pick-up truck is best, eh Frank? Yep. A non-magnetic whip is best, but even a magnetic steel whip will outperform any other 1/4-wave vertical on the market. That's my story and I'm sticking to it. BTW, I have been considering what it would take to setup a small scale production run of -good- 9-foot fiberglass whips. Any comments and/or suggestions are welcome. tree pruning problems considered I'm not sure but I think the max height for a motor vehicle (without a special permit) is something like 13 feet, which means you should be able to mount the whip up to 4 feet off the ground and have relatively few problems. I'll check on that height limit...... You won't have to check..you'll hear it banging pretty strong. g They are great antenna's, but not usually practical..and very odious looking. |
Frank Gilliland wrote:
BTW, I have been considering what it would take to setup a small scale production run of -good- 9-foot fiberglass whips. Any comments and/or suggestions are welcome. Can you make them two piece with an easy dependable connection? That way a guy could unscrew the clearance problem, and then easily re-connect it when needed. |
Steveo wrote:
Frank Gilliland wrote: BTW, I have been considering what it would take to setup a small scale production run of -good- 9-foot fiberglass whips. Any comments and/or suggestions are welcome. Can you make them two piece with an easy dependable connection? That way a guy could unscrew the clearance problem, and then easily re-connect it when needed. ....tunable link, or lock it down with locknuts for the same as last time..hmmm.. |
In , Steveo
wrote: Frank Gilliland wrote: snip I'm not sure but I think the max height for a motor vehicle (without a special permit) is something like 13 feet, which means you should be able to mount the whip up to 4 feet off the ground and have relatively few problems. I'll check on that height limit...... You won't have to check..you'll hear it banging pretty strong. g They are great antenna's, but not usually practical..and very odious looking. In Washington the max vehicle height is 14 feet. That doesn't mean the roads are required to clear a vehicle with that height, but it does mean that any hard obstruction lower than 14 feet must be marked. Maybe adding a small electric winch to pull down the tip of the antenna, activated by a switch on the dash....? -----= 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! =----- |
Steveo wrote:
Frank Gilliland wrote: In , Steveo wrote: Telescopic!! Why didn't I think of that!? It would be multi-banded since you could just extend it more the lower you went in frequency. It's gonna take quite an off-set under the body panel to hold it all. :-) How about a really long door-spring with tubing in the center that is connected to a pump, so the antenna can be softened or stiffened as needed? Just give the pump a few strokes and it rises to it's proper operating length..... How about an auto tune option that would self pump..mo money! sounds like the 11m screwdriver antenna -- KC8TCQ Know thyself. If you need help, call the C.I.A. |
Frank Gilliland wrote:
In , Steveo wrote: Frank Gilliland wrote: snip I'm not sure but I think the max height for a motor vehicle (without a special permit) is something like 13 feet, which means you should be able to mount the whip up to 4 feet off the ground and have relatively few problems. I'll check on that height limit...... You won't have to check..you'll hear it banging pretty strong. g They are great antenna's, but not usually practical..and very odious looking. In Washington the max vehicle height is 14 feet. That doesn't mean the roads are required to clear a vehicle with that height, but it does mean that any hard obstruction lower than 14 feet must be marked. Maybe adding a small electric winch to pull down the tip of the antenna, activated by a switch on the dash....? Telescopic!! Why didn't I think of that!? It would be multi-banded since you could just extend it more the lower you went in frequency. It's gonna take quite an off-set under the body panel to hold it all. :-) |
In , Steveo
wrote: Telescopic!! Why didn't I think of that!? It would be multi-banded since you could just extend it more the lower you went in frequency. It's gonna take quite an off-set under the body panel to hold it all. :-) How about a really long door-spring with tubing in the center that is connected to a pump, so the antenna can be softened or stiffened as needed? Just give the pump a few strokes and it rises to it's proper operating length..... -----= 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! =----- |
Frank Gilliland wrote:
In , Steveo wrote: Telescopic!! Why didn't I think of that!? It would be multi-banded since you could just extend it more the lower you went in frequency. It's gonna take quite an off-set under the body panel to hold it all. :-) How about a really long door-spring with tubing in the center that is connected to a pump, so the antenna can be softened or stiffened as needed? Just give the pump a few strokes and it rises to it's proper operating length..... Think it will float in the competitive CB market? g |
Frank Gilliland wrote:
In , Steveo wrote: Telescopic!! Why didn't I think of that!? It would be multi-banded since you could just extend it more the lower you went in frequency. It's gonna take quite an off-set under the body panel to hold it all. :-) How about a really long door-spring with tubing in the center that is connected to a pump, so the antenna can be softened or stiffened as needed? Just give the pump a few strokes and it rises to it's proper operating length..... How about an auto tune option that would self pump..mo money! |
In , Steveo
wrote: Frank Gilliland wrote: In , Steveo wrote: Telescopic!! Why didn't I think of that!? It would be multi-banded since you could just extend it more the lower you went in frequency. It's gonna take quite an off-set under the body panel to hold it all. :-) How about a really long door-spring with tubing in the center that is connected to a pump, so the antenna can be softened or stiffened as needed? Just give the pump a few strokes and it rises to it's proper operating length..... How about an auto tune option that would self pump..mo money! I think they already have that on the market, but it comes with the warning that if it stays pumped for more than 4 hours you should see your doctor immediately. -----= 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! =----- |
Frank Gilliland wrote:
In , Steveo wrote: Frank Gilliland wrote: In , Steveo wrote: Telescopic!! Why didn't I think of that!? It would be multi-banded since you could just extend it more the lower you went in frequency. It's gonna take quite an off-set under the body panel to hold it all. :-) How about a really long door-spring with tubing in the center that is connected to a pump, so the antenna can be softened or stiffened as needed? Just give the pump a few strokes and it rises to it's proper operating length..... How about an auto tune option that would self pump..mo money! I think they already have that on the market, but it comes with the warning that if it stays pumped for more than 4 hours you should see your doctor immediately. Two slaps with the ruler from sister Mary elephant is the cure..bummer |
Keith Hosman KC8TCQ wrote:
Steveo wrote: Frank Gilliland wrote: In , Steveo wrote: Telescopic!! Why didn't I think of that!? It would be multi-banded since you could just extend it more the lower you went in frequency. It's gonna take quite an off-set under the body panel to hold it all. :-) How about a really long door-spring with tubing in the center that is connected to a pump, so the antenna can be softened or stiffened as needed? Just give the pump a few strokes and it rises to it's proper operating length..... How about an auto tune option that would self pump..mo money! sounds like the 11m screwdriver antenna Did it work for you? |
|
On Mon, 21 Jun 2004 18:30:41 -0700, Frank Gilliland
wrote: In , Steveo wrote: Frank Gilliland wrote: How (or why) is that even worth the effort for such a cheap and easy antenna? Bact to the OP. 9 foot whip on a pick-up truck is best, eh Frank? Yep. A non-magnetic whip is best, but even a magnetic steel whip will outperform any other 1/4-wave vertical on the market. That's my story and I'm sticking to it. Frank; Can you qualify that a little more? A 1/4 wave S/S whip will outperform any other 1/4 wave antenna when mounted in the same location? |
In , Lancer
wrote: On Mon, 21 Jun 2004 18:30:41 -0700, Frank Gilliland wrote: snip Yep. A non-magnetic whip is best, but even a magnetic steel whip will outperform any other 1/4-wave vertical on the market. That's my story and I'm sticking to it. Frank; Can you qualify that a little more? A 1/4 wave S/S whip will outperform any other 1/4 wave antenna when mounted in the same location? Yeah, I probably should clean that up...... http://tinyurl.com/258ny -----= 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! =----- |
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