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Newbie antenna help
New to ham radio. Interested in building an antenna for a base station.
I dont have anything yet, just in the planning stage. Thought about buying a handheld and using that as part of my "base station" one maybe capable of 2 440 and 6. These seem cheaper used than the home units. My question is, is there information out there on how to build one? I have a radio shack book at home that has a plan for a 440. It uses aluminum ground wire. What I find when working with this stuff is it is impossible to make it perfectlyu straight. Doesn't that effect the performance? I mean it comes coiled and when I cut it to length I cant get it perfectly straight. Also, it is posisble to have good performance with one antenna for all the bands? Or is it absolutely necessary to have one antenna for each band? I have limited room. I appreciate your help! |
wrote in message ups.com... New to ham radio. Interested in building an antenna for a base station. I dont have anything yet, just in the planning stage. Thought about buying a handheld and using that as part of my "base station" one maybe capable of 2 440 and 6. These seem cheaper used than the home units. Yes the handhelds are cheaper but they have a lot less power. However if your antenna is high enough, you can do amazing things with it. My question is, is there information out there on how to build one? I have a radio shack book at home that has a plan for a 440. It uses aluminum ground wire. What I find when working with this stuff is it is impossible to make it perfectlyu straight. Doesn't that effect the performance? I mean it comes coiled and when I cut it to length I cant get it perfectly straight. It doesn't have to be perfectly straight. You won't notice any difference unless you have loops coiled in it. Also, it is posisble to have good performance with one antenna for all the bands? Or is it absolutely necessary to have one antenna for each band? I have limited room. Yes there are multiband antennas. Basically, they use some type of coil or trap to subdivide the antenna. The full length of the antenna is used for the lowest frequency, etc. Dee D. Flint, N8UZE |
Dee Flint wrote: wrote in message ups.com... New to ham radio. Interested in building an antenna for a base station. I dont have anything yet, just in the planning stage. Thought about buying a handheld and using that as part of my "base station" one maybe capable of 2 440 and 6. These seem cheaper used than the home units. Yes the handhelds are cheaper but they have a lot less power. However if your antenna is high enough, you can do amazing things with it. My question is, is there information out there on how to build one? I have a radio shack book at home that has a plan for a 440. It uses aluminum ground wire. What I find when working with this stuff is it is impossible to make it perfectlyu straight. Doesn't that effect the performance? I mean it comes coiled and when I cut it to length I cant get it perfectly straight. It doesn't have to be perfectly straight. You won't notice any difference unless you have loops coiled in it. Also, it is posisble to have good performance with one antenna for all the bands? Or is it absolutely necessary to have one antenna for each band? I have limited room. Yes there are multiband antennas. Basically, they use some type of coil or trap to subdivide the antenna. The full length of the antenna is used for the lowest frequency, etc. Dee D. Flint, N8UZE What would you recommend? Building a beam for two meter? If I did that would it work ok on 440 too? Also, I have seen beams mounted bothe on it's side and upright like an outside tv antenna. Which way is better? |
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Here is some antenna theory to read to answer your questions
URL: http://k9erg.tripod.com/theory.htm -- Caveat Lecter |
"Caveat Lector" wrote Here is some antenna theory to read to answer your questions URL: http://k9erg.tripod.com/theory.htm Nice site. Except for the inaccurate advice warning of disastrous effects from operating a J-Pole w/o a BalUn. I use neither a BalUn nor any coiled-feedline as a choke. If my feedline is radiating, it's the most efficient feedline radiator ever made, getting loud and clear 100 mile coverage on VHF Marine between other high sites, and surface contacts between 20-30 nautical miles depending on height of vessels antenna. Another misconception about J-Poles is from at least one web-site offering plans, in which the offerer warned against grounding the antenna. Dangerous and wrong of course, as the antenna and its mast should be grounded and performs very well as such. The stub-capped tops of a copper-pipe J-Pole antenna at the highest point of a structure will indeed be an air terminal for lightning that was going to strike that immediate area anyway. Maybe my lightning down conductors heading 180 degrees from the J-Pole to series of ground rods are the SECRET G. -- Users considering a static and lightning-grounded (and un-choked) J-Pole should make sure the British did not already invent/patent this form of improvement to the J-Pole radiation pattern. ;-) -- 73, Jack |
wrote in message oups.com... Dee Flint wrote: wrote in message ups.com... New to ham radio. Interested in building an antenna for a base station. I dont have anything yet, just in the planning stage. Thought about buying a handheld and using that as part of my "base station" one maybe capable of 2 440 and 6. These seem cheaper used than the home units. Yes the handhelds are cheaper but they have a lot less power. However if your antenna is high enough, you can do amazing things with it. My question is, is there information out there on how to build one? I have a radio shack book at home that has a plan for a 440. It uses aluminum ground wire. What I find when working with this stuff is it is impossible to make it perfectlyu straight. Doesn't that effect the performance? I mean it comes coiled and when I cut it to length I cant get it perfectly straight. It doesn't have to be perfectly straight. You won't notice any difference unless you have loops coiled in it. Also, it is posisble to have good performance with one antenna for all the bands? Or is it absolutely necessary to have one antenna for each band? I have limited room. Yes there are multiband antennas. Basically, they use some type of coil or trap to subdivide the antenna. The full length of the antenna is used for the lowest frequency, etc. Dee D. Flint, N8UZE What would you recommend? Building a beam for two meter? If I did that would it work ok on 440 too? I'm not into a lot of VHF/UHF work personally however my OM likes loop antennas. However loops don't have any significant gain unless you stack them. Many people do like beams and some build their own. There are MANY good antenna books available from the ARRL. Start with The ARRL Antenna Book. As for working on more than one band, only those designed with that in mind will work adequately on two bands. If it is designed for only one band, it will be very bad on the other. Also, I have seen beams mounted bothe on it's side and upright like an outside tv antenna. Which way is better? Vertical elements on beams will yield vertical polarization and are thus suitable for repeater work and a lot of FM simplex. Horizontal elements will yield horizontal polarization and are thus suitable for weak signal work such as working distant SSB stations (horizontal is the custom on SSB). You really need to get and read a good antenna book. A newsgroup cannot give you enough detail. Dee D. Flint, N8UZE |
Jack Painter wrote:
Nice site. Except for the inaccurate advice warning of disastrous effects from operating a J-Pole w/o a BalUn. I use neither a BalUn nor any coiled-feedline as a choke. If my feedline is radiating, it's the most efficient feedline radiator ever made, getting loud and clear 100 mile coverage on VHF Marine between other high sites, and surface contacts between 20-30 nautical miles depending on height of vessels antenna. . . The problem is that without the balun, the feedline is part of the antenna. So anyone trying to get the same results as you do has to use the same length of feedline, position it the same, and maybe even ground his rig the same way you do. (That is, have the same path from the rig to the Earth through the power wiring.) If he does it differently and happens to not be as lucky as you, he could take a bit of a beating in field strength. And both of you could be running the risk of causing RFI if you're running significant power and your feedline runs close to house or telephone wiring. If a balun is used (actually, two are likely necessary, spaced about a quarter wavelength apart), only the J-Pole will radiate, and the user won't have to worry about lucking out and having just the right feedline and orientation. I think the reason some people love J-Poles and some hate them is that some, like you, have been lucky with feedline length and placement and some haven't. I prefer to depend on design rather than luck to make my antennas work, but lots of folks are perfectly happy to just roll the dice. Roy Lewallen, W7EL |
For two meters and 440 I would suggest a J-pole. If you look on the arrow
antenna site http://www.arrowantennas.com/j-pole.html He gives you the information to build your own. FM by mutual agreement is vertical where sideband is horizontal. This relationship is used on VHF and UHF. On 6 meters a simple dipole will get you started. Use the formula 468/desired frequency in MHz equals the total wire length in feet. Make it a little longer for adjustment purposes then cut it in half. Add a center insulator and end insulators. At low power (=100 watts) use pieces of PVC pipe. Tie the shield of the coax to one side of center and the center conductor to the other. Welcome to amateur radio and if I can help you in any way just e-mail me. 73 Fred wrote in message ups.com... New to ham radio. Interested in building an antenna for a base station. I dont have anything yet, just in the planning stage. Thought about buying a handheld and using that as part of my "base station" one maybe capable of 2 440 and 6. These seem cheaper used than the home units. My question is, is there information out there on how to build one? I have a radio shack book at home that has a plan for a 440. It uses aluminum ground wire. What I find when working with this stuff is it is impossible to make it perfectlyu straight. Doesn't that effect the performance? I mean it comes coiled and when I cut it to length I cant get it perfectly straight. Also, it is posisble to have good performance with one antenna for all the bands? Or is it absolutely necessary to have one antenna for each band? I have limited room. I appreciate your help! |
"Roy Lewallen" wrote Jack Painter wrote: Nice site. Except for the inaccurate advice warning of disastrous effects from operating a J-Pole w/o a BalUn. I use neither a BalUn nor any coiled-feedline as a choke. If my feedline is radiating, it's the most efficient feedline radiator ever made, getting loud and clear 100 mile coverage on VHF Marine between other high sites, and surface contacts between 20-30 nautical miles depending on height of vessels antenna. . . The problem is that without the balun, the feedline is part of the antenna. So anyone trying to get the same results as you do has to use the same length of feedline, position it the same, and maybe even ground his rig the same way you do. (That is, have the same path from the rig to the Earth through the power wiring.) If he does it differently and happens to not be as lucky as you, he could take a bit of a beating in field strength. And both of you could be running the risk of causing RFI if you're running significant power and your feedline runs close to house or telephone wiring. If a balun is used (actually, two are likely necessary, spaced about a quarter wavelength apart), only the J-Pole will radiate, and the user won't have to worry about lucking out and having just the right feedline and orientation. I think the reason some people love J-Poles and some hate them is that some, like you, have been lucky with feedline length and placement and some haven't. I prefer to depend on design rather than luck to make my antennas work, but lots of folks are perfectly happy to just roll the dice. Roy Lewallen, W7EL Hi Roy, thanks for the comments. It certainly may be luck as you say, but if so it is exceptional luck ;-) 25 watt marine transceivers rarely perform as well as mine does in this setup. So well that it is highly unlikely that the sixty odd feet of 9913 feedline radiates much if at all. The original configuration had the horizontal (with later vertical drops to ground rods) lightning down conductors added last year, replacing a simple static ground. Coaxial lightning surge arrestor was also added, with shield-grounding. None of these alterations made any noticeable change in the antenna's long range receive and transmit performance. There never was any connection between the transceiver and AC power, using instead a 12vdc deep cell battery with a 12v charger floating the battery. 73, Jack Painter |
wrote in message ups.com... New to ham radio. Interested in building an antenna for a base station. I dont have anything yet, just in the planning stage. Thought about buying a handheld and using that as part of my "base station" one maybe capable of 2 440 and 6. These seem cheaper used than the home units. My question is, is there information out there on how to build one? I have a radio shack book at home that has a plan for a 440. It uses aluminum ground wire. What I find when working with this stuff is it is impossible to make it perfectlyu straight. Doesn't that effect the performance? I mean it comes coiled and when I cut it to length I cant get it perfectly straight. Also, it is posisble to have good performance with one antenna for all the bands? Or is it absolutely necessary to have one antenna for each band? I have limited room. If you go to the ARRL web page, you can find a very good antenna book. It well worth the price. One of the fun aspects of being a ham is experimenting with and building antennas (or is it antennae) . To enhance your fun with expermenting one of your first purchases (after a radio) might be an antenna analyzer like the MFJ 259 . You'll find yourself experimenting with matching sections and different transmision lines as well. You can be an antenna nerd in no time! --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.818 / Virus Database: 556 - Release Date: 12/18/2004 |
W4JLE wrote: For two meters and 440 I would suggest a J-pole. If you look on the arrow antenna site http://www.arrowantennas.com/j-pole.html He gives you the information to build your own. FM by mutual agreement is vertical where sideband is horizontal. This relationship is used on VHF and UHF. On 6 meters a simple dipole will get you started. Use the formula 468/desired frequency in MHz equals the total wire length in feet. Make it a little longer for adjustment purposes then cut it in half. Add a center insulator and end insulators. At low power (=100 watts) use pieces of PVC pipe. Tie the shield of the coax to one side of center and the center conductor to the other. Welcome to amateur radio and if I can help you in any way just e-mail me. 73 Fred wrote in message ups.com... New to ham radio. Interested in building an antenna for a base station. I dont have anything yet, just in the planning stage. Thought about buying a handheld and using that as part of my "base station" one maybe capable of 2 440 and 6. These seem cheaper used than the home units. My question is, is there information out there on how to build one? I have a radio shack book at home that has a plan for a 440. It uses aluminum ground wire. What I find when working with this stuff is it is impossible to make it perfectlyu straight. Doesn't that effect the performance? I mean it comes coiled and when I cut it to length I cant get it perfectly straight. Also, it is posisble to have good performance with one antenna for all the bands? Or is it absolutely necessary to have one antenna for each band? I have limited room. I appreciate your help! I like the looks of that. I wonder if I could use stainless? Is it necessary to use a balun on that? At the same height, what would the difference be between this one and a 6 element yagi? What are those red things on the top? They look like wire twisters. |
I just realized, on that website it does not say the spacing between
elements, only the length of the elements. How would I find out that? |
wrote I just realized, on that website it does not say the spacing between elements, only the length of the elements. How would I find out that? 22/freq (in Mhz) See: http://www.hamuniverse.com/jpole.html Roy has pointed out that a Balun is a good idea. The above site recommends at least 4 coils of feedline at the feedpoint as an RF choke. I used neither and had phenomenal "luck" with a 60' feedline and later added full lightning protection with no detectable change in the prop. Jack Painter Virginia Beach VA |
What are those red things on the top? They look like wire twisters.
I just realized, on that website it does not say the spacing between elements, only the length of the elements. How would I find out that? The little red things on top are just plastic caps. Element spacing & element size are critical. Check the "Parts Catalog" & the "Instructions" for element spacing. It's all there, even a photo of the bracket. If you change the diameter of the elements, you will need to start over with the spacing to tune the antenna. As for Stainless Steel, don't bother, been there, done that. Tried making some out of Stainless Steel CB Whips. A very noticeable difference in performance. You really want to build your own ? Buy one from Arrow Antenna, copy it, then send it back for a refund. Only cost you for shipping. Got to warn you though, I have not got one back yet. 73 Al Lowe N0IMW A HREF="http://ArrowAntennas.com/"ArrowAntennas.com/A Arrow Antenna |
N0IMW wrote: What are those red things on the top? They look like wire twisters. I just realized, on that website it does not say the spacing between elements, only the length of the elements. How would I find out that? The little red things on top are just plastic caps. Element spacing & element size are critical. Check the "Parts Catalog" & the "Instructions" for element spacing. It's all there, even a photo of the bracket. If you change the diameter of the elements, you will need to start over with the spacing to tune the antenna. As for Stainless Steel, don't bother, been there, done that. Tried making some out of Stainless Steel CB Whips. A very noticeable difference in performance. You really want to build your own ? Buy one from Arrow Antenna, copy it, then send it back for a refund. Only cost you for shipping. Got to warn you though, I have not got one back yet. 73 Al Lowe N0IMW A HREF="http://ArrowAntennas.com/"ArrowAntennas.com/A Arrow Antenna Why would stainless steel provide different performance? Can you use regular mild steel for the angle iron bracket? Maybe paint it so it would not rust? If you do change the element size, how do you determine the proper spacing? I appreciate your help! I like the design of the antenna and its simplicity. |
Just a suggetion -- go to a swap meet and buy your antennas for less than
the materials to build one Or here is the scoop on yagi antenna design including a design program http://www.hamuniverse.com/yagibasics.html -- El Enforcer |
Let me suggest that you order a copy of the ARRL Amateur Radio Handbook.
Just like any other hobby, this one has a bible that answers most of the questions that come to mind. You can save yourself the delay of having to ask and wait for a reply. To answer your questions. A J-pole requires a balun to eliminate feed line radiation. The difference between it and a yagi at the same height can be likened to a yard sprinkler vs. a hose nozzle. Same amount of water comes out the hose, the j-pole sprays the signal all around, the yagi is the hose nozzle. Are you trying to get a crowd wet, or a single person? On VHF your more often limited by line of sight distance than signal strength. If your beyond line of sight, a gazillion watts or a 100 element beam won't help. The red things keep you from poking your eyes out. wrote in message oups.com... W4JLE wrote: For two meters and 440 I would suggest a J-pole. If you look on the arrow antenna site http://www.arrowantennas.com/j-pole.html He gives you the information to build your own. FM by mutual agreement is vertical where sideband is horizontal. This relationship is used on VHF and UHF. On 6 meters a simple dipole will get you started. Use the formula 468/desired frequency in MHz equals the total wire length in feet. Make it a little longer for adjustment purposes then cut it in half. Add a center insulator and end insulators. At low power (=100 watts) use pieces of PVC pipe. Tie the shield of the coax to one side of center and the center conductor to the other. Welcome to amateur radio and if I can help you in any way just e-mail me. 73 Fred wrote in message ups.com... New to ham radio. Interested in building an antenna for a base station. I dont have anything yet, just in the planning stage. Thought about buying a handheld and using that as part of my "base station" one maybe capable of 2 440 and 6. These seem cheaper used than the home units. My question is, is there information out there on how to build one? I have a radio shack book at home that has a plan for a 440. It uses aluminum ground wire. What I find when working with this stuff is it is impossible to make it perfectlyu straight. Doesn't that effect the performance? I mean it comes coiled and when I cut it to length I cant get it perfectly straight. Also, it is posisble to have good performance with one antenna for all the bands? Or is it absolutely necessary to have one antenna for each band? I have limited room. I appreciate your help! I like the looks of that. I wonder if I could use stainless? Is it necessary to use a balun on that? At the same height, what would the difference be between this one and a 6 element yagi? What are those red things on the top? They look like wire twisters. |
wrote If you do change the element size, how do you determine the proper spacing? I appreciate your help! I like the design of the antenna and its simplicity. When you earlier asked this question I answered it. The specific dimensions are ALL provided in my previous post/reply to you. Here is is again! wrote I just realized, on that website it does not say the spacing between elements, only the length of the elements. How would I find out that? 22/freq (in Mhz) See: http://www.hamuniverse.com/jpole.html 73, Jack |
Why would stainless steel provide different performance? Can you use
regular mild steel for the angle iron bracket? Maybe paint it so it would not rust? If you do change the element size, how do you determine the proper spacing? I appreciate your help! I like the design of the antenna and its simplicity. At one time I had a chance to acquire a large number of Stainless Steel CB whips, cheaper than the cost of aluminum. I used 8 of them to make a 4 element Yagi just like our regular 146-4S. It works, SWR is low, but it just does not work as well as the aluminum elements. Used a couple to make an OSJ, because of the smaller diameter, the spacing is closer to get it to match But like I said there was a very noticeable drop in performance. I really wanted it to work, would have been a good market for them for mounting on 18 wheelers. (Don't ask, I won't sell ether of them.) As for making the bracket out of steel, Why ? it's harder to drill, harder to tap. The 3/16" stress aluminum angle is a lot stronger than it needs to be. As for determining the proper spacing, if you know the exact impedance of the 1/2 wave, there is a formula for figuring the diameter & spacing. Easier to just adjust the spacing for lowest SWR. Unlike other types of J-Poles the OSJ does Not need a balun or choke. It was designed for direct connect to coax. 73 Al Lowe N0IMW Arrow Antenna |
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