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Caged Di-Pole
Hello,
My attention has been caught by the abilities of a "Fat Conductor" for an antenna. I understand that this has been achieved by using what is (little known about) a Caged Di-Pole. I have seen them before in older photographs, mostly draped over an old steamship, stem to stern. The Caged Di-Pole is supposed to be very well suited for weak signal reception. I know that a Yagi can do very well in this regard, but its the art of it that I'm interested in, and as far as I can see, it's almost an lost aspect of HAM radio nowadays. Does anybody remember these things? 73's Rob |
Caged Di-Pole
Hi Joe..
The main advantage of cage dipole it is its wider bandwidth. It is a nice antenna with a great "vintage" look. Apart from this, its performance is that of a standard dipole... Best regards Miguel Ghezzi (LU 6ETJ) |
Caged Di-Pole
On Wed, 16 Aug 2006 14:06:06 -0700, Joe Bloe
wrote: The Caged Di-Pole is supposed to be very well suited for weak signal reception. Hi Rob, "Supposed to be" is how fairy tales end; they start with "Once upon a time." I know that a Yagi can do very well in this regard, but its the art of it that I'm interested in, and as far as I can see, it's almost an lost aspect of HAM radio nowadays. Does anybody remember these things? More than those who can explain why, when push comes to shove. Hence your complete introduction should have read: Once upon a time the Caged Di-Pole was supposed to be very well suited for weak signal reception. The only attribute of a (uncommon) cage structure is wider bandwidth than a (common) thin wire antenna. This is not the same as bringing more sensitivity. The exertion of building one, and then erecting it probably induces a wishful sense of dream fulfillment. 73's Richard Clark, KB7QHC |
Caged Di-Pole
"Joe Bloe" wrote in message ... Hello, My attention has been caught by the abilities of a "Fat Conductor" for an antenna. I understand that this has been achieved by using what is (little known about) a Caged Di-Pole. I have seen them before in older photographs, mostly draped over an old steamship, stem to stern. The Caged Di-Pole is supposed to be very well suited for weak signal reception. I know that a Yagi can do very well in this regard, but its the art of it that I'm interested in, and as far as I can see, it's almost an lost aspect of HAM radio nowadays. Does anybody remember these things? 73's Rob ====================================== Rob, Photographs of a cage of wires slung between a ship's masts could have been T-antennas in the good old days of LF spark transmitters. The fat conductors increased the capacitance to ground so drawing a greater current into the antenna. For the electrical characteristics of a caged dipole at HF, download program DIPCAGE2 from website below. Yes, the only advantage of a caged dipole is a moderate increase in bandwidth. Its resonant length is slightly less than that of a thin wire. Its appearance has the disadvantage of upsetting residential associations. A few amateurs, without near neighbours, for seventy-mental reasons still swear by it! ---- Reg, G4FGQ. |
Caged Di-Pole
Not that it is too relevant to your original post....
Cebik (http://www.cebik.com) talks about using multi conductor elements in wire quad design to "fatten" the conductor. He mentions that thin wire designs tend to be somewhat lossy (lower fwd gain and narrower b/w etc) and the thicker elements make up for this. Cheers Bob VK2YQA Joe Bloe wrote: Hello, My attention has been caught by the abilities of a "Fat Conductor" |
Caged Di-Pole
Reg Edwards wrote: A few amateurs, without near neighbours, for seventy-mental reasons still swear by it! ---- Reg, G4FGQ. Hey Reg, It was good enough for Marconi.... I wonder what the locals thought.. denny |
Wow. . .
Gee. . . You're sure a cheery fellow.
I was mostly interested in the Historic Art of the darn thing. I well know it's majorly "Out Dated", but if one does things for the pure enjoyment of it, then I guess it's not the issue of performance, but art, which is also defined by retrieving a wonderful time from out of our past. I'm just a stupid romantic at heat. . . And I enjoy being so. Thanks for the info though. I guess some how I got the information backwards, but then again, I also see a great many views on the subject of a fat conductor. . . Me thinks the subject still isn't closed due to that simple fact that nobody really yet knows for sure. 73's Rob On Wed, 16 Aug 2006 15:11:10 -0700, Richard Clark wrote: On Wed, 16 Aug 2006 14:06:06 -0700, Joe Bloe wrote: The Caged Di-Pole is supposed to be very well suited for weak signal reception. Hi Rob, "Supposed to be" is how fairy tales end; they start with "Once upon a time." I know that a Yagi can do very well in this regard, but its the art of it that I'm interested in, and as far as I can see, it's almost an lost aspect of HAM radio nowadays. Does anybody remember these things? More than those who can explain why, when push comes to shove. Hence your complete introduction should have read: Once upon a time the Caged Di-Pole was supposed to be very well suited for weak signal reception. The only attribute of a (uncommon) cage structure is wider bandwidth than a (common) thin wire antenna. This is not the same as bringing more sensitivity. The exertion of building one, and then erecting it probably induces a wishful sense of dream fulfillment. 73's Richard Clark, KB7QHC |
Caged Di-Pole
Gee, Wow...
I got a little bit of info, enough to find that what I was told wasn't quite right after all. Being that I'm a bit new to the antenna aspect of things, I don't find this surprising at all. However, I did get a two bits of good information, a closer explanation of the effect of a fat conductor antenna, and a web-site with a calculator for just such a thing. Thanks folks, this query has been a total success due to those who care. . . You all! 73's Rob |
Caged Di-Pole
Joe Bloe wrote:
However, I did get a two bits of good information, a closer explanation of the effect of a fat conductor antenna, and a web-site with a calculator for just such a thing. You can probably arrive at the same correct technical conclusions by downloading the free demo version of EZNEC and selecting the diameter of the conductor. -- 73, Cecil http://www.qsl.net/w5dxp |
Caged Di-Pole
Cecil Moore wrote:
Joe Bloe wrote: However, I did get a two bits of good information, a closer explanation of the effect of a fat conductor antenna, and a web-site with a calculator for just such a thing. You can probably arrive at the same correct technical conclusions by downloading the free demo version of EZNEC and selecting the diameter of the conductor. No doubt, Cecil. Of course this wasn't where the conversation started at. I haven't tried EZNEC to model a cage antenna, will it do it? Or do you just make the wires really thick? And how does really thick wire compare to a cage of the same relative diameter? - 73 de Mike KB3EIA - |
Caged Di-Pole
On Thu, 17 Aug 2006 21:33:17 -0400, Mike Coslo
wrote: how does really thick wire compare to a cage of the same relative diameter? Hi Mike, Close, but no cigar. Actually, the degree of closeness depends on how well the cage represents the solid. That degree is a function of the number of wires that form the skeletal shape. Four is pretty lousy, 120 would be outstanding. Then there is something in the middle: http://home.comcast.net/~kb7qhc/ante.../Cage/cage.htm offers an example that may be suitable. This is a 4 meter tall antenna that tunes all frequencies from 20M through 10M. 73's Richard Clark, KB7QHC |
Wow. . .
On Thu, 17 Aug 2006 17:14:21 -0700, Joe Bloe
wrote: Gee. . . You're sure a cheery fellow. I was mostly interested in the Historic Art of the darn thing. I well know it's majorly "Out Dated", but if one does things for the pure enjoyment of it, then I guess it's not the issue of performance, but art, which is also defined by retrieving a wonderful time from out of our past. I'm just a stupid romantic at heat. . . And I enjoy being so. Hi Rob, One does not have to be: 1. Stupid; 2. Romantic; or 3. Out Dated to use a cage properly. Me thinks the subject still isn't closed due to that simple fact that nobody really yet knows for sure. Visit: http://home.comcast.net/~kb7qhc/ante.../Cage/cage.htm to see just how much work you have to go to (the picture explains that easily enough), to know for sure (it isn't really all that mysterious), and to get it right (not hard in the least). 73's Richard Clark, KB7QHC |
Caged Di-Pole
Mike Coslo wrote:
Cecil Moore wrote: You can probably arrive at the same correct technical conclusions by downloading the free demo version of EZNEC and selecting the diameter of the conductor. No doubt, Cecil. Of course this wasn't where the conversation started at. I haven't tried EZNEC to model a cage antenna, will it do it? Or do you just make the wires really thick? And how does really thick wire compare to a cage of the same relative diameter? You can use the free demo version to model a large diameter radiator with up to 20 segments. For the actual multi-wire cage antenna, one would need to spring for the non-free version which is, IMO, the best bargain in ham radio antenna simulation software. Why ask questions here when the answer is available to any individual who springs for EZNEC? -- 73, Cecil http://www.qsl.net/w5dxp |
Caged Di-Pole
http://home.comcast.net/~kb7qhc/ante.../Cage/cage.htm offers an example that may be suitable. This is a 4 meter tall antenna that tunes all frequencies from 20M through 10M. 73's Richard Clark, KB7QHC What is the diameter of the antenna design? buck n4pgw -- 73 for now Buck N4PGW |
Caged Di-Pole
On Fri, 18 Aug 2006 03:07:06 -0400, Buck wrote:
http://home.comcast.net/~kb7qhc/ante.../Cage/cage.htm offers an example that may be suitable. This is a 4 meter tall antenna that tunes all frequencies from 20M through 10M. What is the diameter of the antenna design? Hi Buck, Download the EZNEC file for a specific answer, by dead reckoning (look at the picture) it is around 2 meters in diameter. Plus or minus. ....pretty thick wire. 73's Richard Clark, KB7QHC |
Caged Di-Pole
Richard Clark wrote:
On Thu, 17 Aug 2006 21:33:17 -0400, Mike Coslo wrote: how does really thick wire compare to a cage of the same relative diameter? Hi Mike, Close, but no cigar. Actually, the degree of closeness depends on how well the cage represents the solid. That degree is a function of the number of wires that form the skeletal shape. Four is pretty lousy, 120 would be outstanding. Then there is something in the middle: http://home.comcast.net/~kb7qhc/ante.../Cage/cage.htm offers an example that may be suitable. This is a 4 meter tall antenna that tunes all frequencies from 20M through 10M. A single fat wire can be a reasonable approximation to a cage provided that the diameter is very small compared to a wavelength. (The NEC recommendation is around 0.02 wavelength maximum diameter, which you can find in the EZNEC manual in the Building The Model/Modeling The Antenna Structure/About Wires topic.) For a cage of only a few parallel wires, you can use an equivalent diameter as follows, where d = the wire diameter and s = ctr-ctr wire spacing, everything in the same units: 2 wires - Equiv. dia. = 1.414 * sqrt(d * s) 3 wires in a triangle - Equiv. dia. = 1.587 * cube root(d * s^2) 4 wires in a square - Equiv. dia. = 1.834 * fourth root(d * s^3) N wires equally spaced on a circle with radius r - Equiv. dia. = 2 * r * Nth root((N * d) / (2 * r)) -- derived from equations in Fundamentals of Coupled Lines and Multiwire Antennas, by Hidenari Uchida (Sasaki, 1967). I've made myself a note to include this in a future EZNEC manual update. For cages larger than about 0.02 wavelength diameter, you should model the individual wires. Roy Lewallen, W7EL |
Caged Di-Pole
Cecil Moore wrote:
Mike Coslo wrote: Cecil Moore wrote: You can probably arrive at the same correct technical conclusions by downloading the free demo version of EZNEC and selecting the diameter of the conductor. No doubt, Cecil. Of course this wasn't where the conversation started at. I haven't tried EZNEC to model a cage antenna, will it do it? Or do you just make the wires really thick? And how does really thick wire compare to a cage of the same relative diameter? You can use the free demo version to model a large diameter radiator with up to 20 segments. For the actual multi-wire cage antenna, one would need to spring for the non-free version which is, IMO, the best bargain in ham radio antenna simulation software. No doubt, it is great software. Why ask questions here when the answer is available to any individual who springs for EZNEC? First thing is that Mr Bloe didn't start the thread off as what the bandwidth of a cage dipole was. The bandwidth question came later. So while it is good advice to send someone to EZNEC, it is kind of presuming the person already knows the answer to their question when you expect them to *not ask the question* in the first place. I find the topic interesting, and certainly the feedback I've gotten from Richard and Roy have been very illuminating. So I encourage more on the topic. Sure beats those 2000 post threads we seem to get in here! I'd sooner see topics such as this than you and W8JI sharpening your claws on each other......hehe - 73 de Mike KB3EIA - |
Caged Di-Pole
On Fri, 18 Aug 2006 11:43:34 -0400, Michael Coslo
wrote: I find the topic interesting, and certainly the feedback I've gotten from Richard and Roy have been very illuminating. So I encourage more on the topic. Hi Mike, Going further, as you encouraged, you can observe the caged concept applied to the Discone antenna at: http://www.qsl.net/kb7qhc/antenna/Discone/discone.htm This also shows how well 16 wires approximate a solid, and further, it also shows how the geometry of the apex angle affects the matching characteristics. This is shown in 7 Smith charts where that angle varies from 20° to 90°. Upon close examination, it appears I report the wrong interval of frequency sweep as every 0.5 MHz. Certainly the range covers 1 to 30 MHz for them all, but it would appear that I shift to every 0.25 MHz for 50° through 90°. 73's Richard Clark, KB7QHC |
Caged Di-Pole
Since it appears that the benefit of the cage is bandwidth I ran a few
scenario's with EZNEC and a 40 Meter vertical that is 33 feet tall. note that I did not correct for resonance shifting and that I am assuming that whatever the mesh is, it will not beat a solid. http://www.dixienc.us/28FtVert/BandwithVsDia.htm Given that most of us agree that trying to better a 2:1 SWR is into diminishing returns I believe this illustrates the cage's loss of popularity. Defiantly an appealing sight though... de W8CCW John On Wed, 16 Aug 2006 14:06:06 -0700, Joe Bloe wrote: Hello, My attention has been caught by the abilities of a "Fat Conductor" for an antenna. I understand that this has been achieved by using what is (little known about) a Caged Di-Pole. I have seen them before in older photographs, mostly draped over an old steamship, stem to stern. The Caged Di-Pole is supposed to be very well suited for weak signal reception. I know that a Yagi can do very well in this regard, but its the art of it that I'm interested in, and as far as I can see, it's almost an lost aspect of HAM radio nowadays. Does anybody remember these things? 73's Rob John Ferrell W8CCW |
Caged Di-Pole
It takes a month of Sundays for an expert to enter and interpret the input/output data of a cage dipole using an Eznec-type program. The basic characteristics of a cage dipole can be displayed, in practical terms, in a few seconds by downloading program DIPCAGE2 from website below. Vary length and diameter, number and gauge of wires in cage, etc., and observe how resonant length, bandwidth and SWR change. Program DIPCAGE2. Its about 1/2-way down the list. Been there for years! ---- .................................................. .......... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp .................................................. .......... |
Wow. . .
Joe Bloe wrote:
Gee. . . You're sure a cheery fellow. Hi Rob - Richard has a way with words. Stick with him, and you'll start to enjoy it, once you get used to the prose. I was mostly interested in the Historic Art of the darn thing. I well know it's majorly "Out Dated", but if one does things for the pure enjoyment of it, then I guess it's not the issue of performance, but art, which is also defined by retrieving a wonderful time from out of our past. I'm just a stupid romantic at heat. . . And I enjoy being so. It is a viable antenna, and not outdated. It might help you eke out a bit more bandwidth on 80/75 meters. And as far as I am concerned, it is plenty cool looking too. Okay, so you are a romantic. I have a little bit of that in me too! Try these on for size: Make and use some real open line feeder. This stuff is cool, works really well, and has a real retro look to boot. Most of the time we use plastic spacers these days, but if you want to be authentic, you could use wood dowels soaked in hot paraffin. Of course you'll need a tuner for that setup. How about an "open faced tuner"? Wind the coil on a suitable form, and use clips to attach to it to tune. Make everything pretty, and you'll have a nice nostalgia type station that also works. I'd suggest that the tuner have a plexiglass cover for safety. Old school, You bet. Very very cool though. Thanks for the info though. I guess some how I got the information backwards, but then again, I also see a great many views on the subject of a fat conductor. . . Me thinks the subject still isn't closed due to that simple fact that nobody really yet knows for sure. - 73 de Mike KB3EIA - |
Caged Di-Pole
Richard Clark wrote:
On Fri, 18 Aug 2006 11:43:34 -0400, Michael Coslo wrote: I find the topic interesting, and certainly the feedback I've gotten from Richard and Roy have been very illuminating. So I encourage more on the topic. Hi Mike, Going further, as you encouraged, you can observe the caged concept applied to the Discone antenna at: http://www.qsl.net/kb7qhc/antenna/Discone/discone.htm Fascinating, and thank you! The discone and the Smith charts for it are a great graphic tool. I note that your webpage is also featured in Wikipedia. This also shows how well 16 wires approximate a solid, and further, it also shows how the geometry of the apex angle affects the matching characteristics. This is shown in 7 Smith charts where that angle varies from 20° to 90°. Upon close examination, it appears I report the wrong interval of frequency sweep as every 0.5 MHz. Certainly the range covers 1 to 30 MHz for them all, but it would appear that I shift to every 0.25 MHz for 50° through 90°. - 73 de Mike KB3EIA - |
Caged Di-Pole
This can be done with any EZNEC program type, including the demo:
1. Click Open. 2. Select BYDipole.EZ and click Open in the file selection dialog box. 3. Click SWR. Enter 14 for the start frequency, 15 for the stop frequency, and .05 for the frequency step. Click Run. 4. Using the arrow keys or the mouse, move the cursor in the SWR display to the points where SWR is about 2. These are about 14.1 and 14.75 MHz, indicating a 2:1 SWR bandwidth of about 650 kHz. 5. Click Wires in the main window to open the Wires Window. 6. In the Diameter column, change the Diameter from #12 to 6 to represent a 6 inch diameter cage. (Don't put a "#" in front of the 6.) Press the Enter key to finalize the change. 7. Click SWR. Change the start frequency from 14 to 13 and click Run. 8. In the SWR display, move the cursor as before, and note that the 2:1 SWR bandwidth is now about 1.35 MHz, about twice what it was for the original antenna made from #12 wire. Now you're a Reg-certified expert, even if that took you a month of Sundays to do. You can also get a great deal of additional information from EZNEC, such as the feedpoint impedance and SWR at any frequency, the pattern, and effect of height and ground characteristics. If that took you a month of Sundays, you might think a bit about what's reduced your capabilities to that level. Roy Lewallen, W7EL -- Certified by Reg as both Old Wife and Expert! Reg Edwards wrote: It takes a month of Sundays for an expert to enter and interpret the input/output data of a cage dipole using an Eznec-type program. . . . |
Caged Di-Pole
Dear Roy,
But the subject matter is Cage Dipoles. How many man-hours would it take a novice to enter into Eznec, two, in line with each other, spaced apart, cylindrical cages, 2-feet in diameter consisting of 32, 14-gauge wires, with 4 end rings, with time required to diagnose and eliminate the dozen or more bugs which are sure to be introduced. That is, of course, if the free version will accept such an input. We will forget the 10-day induction course. How long would it take an expert like yourself to enter and fully analyse such a dipole. Bear in mind you would have to enter dipoles consisting of 2, 4, 8, 16, 32 and 64 wires, plus end rings, of say 4 different wire gauges. And obtain the resonant frequencies, input impedances and SWRs of all possible combinations. You will say Eznec is probably more accurate. But DIPCAGE2 will do the same job in a few minutes with an accuracy quite good enough for the intended purpose. CB-ers can use it. With Eznec, before the job was finished I would have forgotten what it was all about, strayed off course and ventured into magloops. To keep you happy, I will repeat what I have said before and say that Eznec does an excellent job in those tasks for which it is primarily intended. What better compliment? I am not in competition with you. ---- Reg, G4FGQ. ======================================= "Roy Lewallen" wrote This can be done with any EZNEC program type, including the demo: 1. Click Open. 2. Select BYDipole.EZ and click Open in the file selection dialog box. 3. Click SWR. Enter 14 for the start frequency, 15 for the stop frequency, and .05 for the frequency step. Click Run. 4. Using the arrow keys or the mouse, move the cursor in the SWR display to the points where SWR is about 2. These are about 14.1 and 14.75 MHz, indicating a 2:1 SWR bandwidth of about 650 kHz. 5. Click Wires in the main window to open the Wires Window. 6. In the Diameter column, change the Diameter from #12 to 6 to represent a 6 inch diameter cage. (Don't put a "#" in front of the 6.) Press the Enter key to finalize the change. 7. Click SWR. Change the start frequency from 14 to 13 and click Run. 8. In the SWR display, move the cursor as before, and note that the 2:1 SWR bandwidth is now about 1.35 MHz, about twice what it was for the original antenna made from #12 wire. Now you're a Reg-certified expert, even if that took you a month of Sundays to do. You can also get a great deal of additional information from EZNEC, such as the feedpoint impedance and SWR at any frequency, the pattern, and effect of height and ground characteristics. If that took you a month of Sundays, you might think a bit about what's reduced your capabilities to that level. Roy Lewallen, W7EL -- Certified by Reg as both Old Wife and Expert! Reg Edwards wrote: It takes a month of Sundays for an expert to enter and interpret the input/output data of a cage dipole using an Eznec-type program. . . . |
Caged Di-Pole
Hi Reg
I sure dont mean to become involved with the discussion on Cage Dipoles, and which method of analyzing them, is better. I do want to give some data concerning the time needed to learn to use EZNEC. It isnt necessary to devote the time of a 10 day course in order to be able to get alot of good/valuable data from EZNEC. At Richard Clark's encouragement, I bought Roy's EZNEC program a couple weeks ago. I was able to get good data from the program that same day, The program is not mysterious. I write this post to make it clear that EZNEC can be learned quickly by anyone who trys, and can be learned in one day. I dont inply that I am a well qualified EZNEC operator, but I have learned so much about the antenna I am investigating that I really treasure this EZNEC program, and recommend it to any HAM who has interest in understanding antennas. Jerry "Reg Edwards" wrote in message ... Dear Roy, But the subject matter is Cage Dipoles. How many man-hours would it take a novice to enter into Eznec, two, in line with each other, spaced apart, cylindrical cages, 2-feet in diameter consisting of 32, 14-gauge wires, with 4 end rings, with time required to diagnose and eliminate the dozen or more bugs which are sure to be introduced. That is, of course, if the free version will accept such an input. We will forget the 10-day induction course. How long would it take an expert like yourself to enter and fully analyse such a dipole. Bear in mind you would have to enter dipoles consisting of 2, 4, 8, 16, 32 and 64 wires, plus end rings, of say 4 different wire gauges. And obtain the resonant frequencies, input impedances and SWRs of all possible combinations. You will say Eznec is probably more accurate. But DIPCAGE2 will do the same job in a few minutes with an accuracy quite good enough for the intended purpose. CB-ers can use it. With Eznec, before the job was finished I would have forgotten what it was all about, strayed off course and ventured into magloops. To keep you happy, I will repeat what I have said before and say that Eznec does an excellent job in those tasks for which it is primarily intended. What better compliment? I am not in competition with you. ---- Reg, G4FGQ. ======================================= "Roy Lewallen" wrote This can be done with any EZNEC program type, including the demo: 1. Click Open. 2. Select BYDipole.EZ and click Open in the file selection dialog box. 3. Click SWR. Enter 14 for the start frequency, 15 for the stop frequency, and .05 for the frequency step. Click Run. 4. Using the arrow keys or the mouse, move the cursor in the SWR display to the points where SWR is about 2. These are about 14.1 and 14.75 MHz, indicating a 2:1 SWR bandwidth of about 650 kHz. 5. Click Wires in the main window to open the Wires Window. 6. In the Diameter column, change the Diameter from #12 to 6 to represent a 6 inch diameter cage. (Don't put a "#" in front of the 6.) Press the Enter key to finalize the change. 7. Click SWR. Change the start frequency from 14 to 13 and click Run. 8. In the SWR display, move the cursor as before, and note that the 2:1 SWR bandwidth is now about 1.35 MHz, about twice what it was for the original antenna made from #12 wire. Now you're a Reg-certified expert, even if that took you a month of Sundays to do. You can also get a great deal of additional information from EZNEC, such as the feedpoint impedance and SWR at any frequency, the pattern, and effect of height and ground characteristics. If that took you a month of Sundays, you might think a bit about what's reduced your capabilities to that level. Roy Lewallen, W7EL -- Certified by Reg as both Old Wife and Expert! Reg Edwards wrote: It takes a month of Sundays for an expert to enter and interpret the input/output data of a cage dipole using an Eznec-type program. . . . |
Caged Di-Pole
On Sat, 19 Aug 2006 04:16:53 GMT, "Jerry Martes"
wrote: Hi Reg I sure dont mean to become involved with the discussion on Cage Dipoles, and which method of analyzing them, is better. I do want to give some data concerning the time needed to learn to use EZNEC. It isnt necessary to devote the time of a 10 day course in order to be able to get alot of good/valuable data from EZNEC. At Richard Clark's encouragement, I bought Roy's EZNEC program a couple weeks ago. I was able to get good data from the program that same day, The program is not mysterious. I write this post to make it clear that EZNEC can be learned quickly by anyone who trys, and can be learned in one day. I dont inply that I am a well qualified EZNEC operator, but I have learned so much about the antenna I am investigating that I really treasure this EZNEC program, and recommend it to any HAM who has interest in understanding antennas. Jerry Jerry, The truth probably lies somewhere between your view and Reg's. Whilst you may have been able to construct a simple model in a very short time, being confident that you have a valid model on even modest antennas takes much more experience and knowledge. I think it is another of those cases where the more I learn, the less I know. You may find the same in time. Owen -- |
Caged Di-Pole
"Owen Duffy" wrote in message ... On Sat, 19 Aug 2006 04:16:53 GMT, "Jerry Martes" wrote: Hi Reg I sure dont mean to become involved with the discussion on Cage Dipoles, and which method of analyzing them, is better. I do want to give some data concerning the time needed to learn to use EZNEC. It isnt necessary to devote the time of a 10 day course in order to be able to get alot of good/valuable data from EZNEC. At Richard Clark's encouragement, I bought Roy's EZNEC program a couple weeks ago. I was able to get good data from the program that same day, The program is not mysterious. I write this post to make it clear that EZNEC can be learned quickly by anyone who trys, and can be learned in one day. I dont inply that I am a well qualified EZNEC operator, but I have learned so much about the antenna I am investigating that I really treasure this EZNEC program, and recommend it to any HAM who has interest in understanding antennas. Jerry Jerry, The truth probably lies somewhere between your view and Reg's. Whilst you may have been able to construct a simple model in a very short time, being confident that you have a valid model on even modest antennas takes much more experience and knowledge. I think it is another of those cases where the more I learn, the less I know. You may find the same in time. Owen Hi Owen I am not qualified to comment on Reg's information on either computer programs or antennas in general. I am not far from being a beginer at antenna design by today's standards. But I was able to get decent data on a 4 dipole array circularly polarized array that requires some phasing of the dipoles. By my standards, that isnt a modest antenna. Richard Clark was god enough to give guidance and encouragement via E-mail. That may account for my being to get such good data on the first day of trying EZNEC. But, he didnt actually provide data. I am not qualified to differ with your observations concerning learning to use EZNEC. But, as must be clear by now, I am really impresed with this program and I consider it learnable with a little time and logic. It is my hope that I can encourage anyone who has interest in antenna design and understanding to 'give it a try'. It doesnt demand a formal training course. EZNEC is a nifty tool. Jerry -- |
Caged Di-Pole
I find Reg's collection and EZNEC both valuable tools.
There are elements of EZNEC that I have not learned to use. In Reg's collection each applet has a tight focus. Yet neither can be considered complete solutions. I am not certain that I am using either correctly without committing the calculations to physical models. de W8CCW John On Sat, 19 Aug 2006 03:15:07 +0100, "Reg Edwards" wrote: Dear Roy, But the subject matter is Cage Dipoles. How many man-hours would it take a novice to enter into Eznec, two, in line with each other, spaced apart, cylindrical cages, 2-feet in diameter consisting of 32, 14-gauge wires, with 4 end rings, with time required to diagnose and eliminate the dozen or more bugs which are sure to be introduced. That is, of course, if the free version will accept such an input. We will forget the 10-day induction course. How long would it take an expert like yourself to enter and fully analyse such a dipole. Bear in mind you would have to enter dipoles consisting of 2, 4, 8, 16, 32 and 64 wires, plus end rings, of say 4 different wire gauges. And obtain the resonant frequencies, input impedances and SWRs of all possible combinations. You will say Eznec is probably more accurate. But DIPCAGE2 will do the same job in a few minutes with an accuracy quite good enough for the intended purpose. CB-ers can use it. With Eznec, before the job was finished I would have forgotten what it was all about, strayed off course and ventured into magloops. To keep you happy, I will repeat what I have said before and say that Eznec does an excellent job in those tasks for which it is primarily intended. What better compliment? I am not in competition with you. ---- Reg, G4FGQ. ======================================= "Roy Lewallen" wrote This can be done with any EZNEC program type, including the demo: 1. Click Open. 2. Select BYDipole.EZ and click Open in the file selection dialog box. 3. Click SWR. Enter 14 for the start frequency, 15 for the stop frequency, and .05 for the frequency step. Click Run. 4. Using the arrow keys or the mouse, move the cursor in the SWR display to the points where SWR is about 2. These are about 14.1 and 14.75 MHz, indicating a 2:1 SWR bandwidth of about 650 kHz. 5. Click Wires in the main window to open the Wires Window. 6. In the Diameter column, change the Diameter from #12 to 6 to represent a 6 inch diameter cage. (Don't put a "#" in front of the 6.) Press the Enter key to finalize the change. 7. Click SWR. Change the start frequency from 14 to 13 and click Run. 8. In the SWR display, move the cursor as before, and note that the 2:1 SWR bandwidth is now about 1.35 MHz, about twice what it was for the original antenna made from #12 wire. Now you're a Reg-certified expert, even if that took you a month of Sundays to do. You can also get a great deal of additional information from EZNEC, such as the feedpoint impedance and SWR at any frequency, the pattern, and effect of height and ground characteristics. If that took you a month of Sundays, you might think a bit about what's reduced your capabilities to that level. Roy Lewallen, W7EL -- Certified by Reg as both Old Wife and Expert! Reg Edwards wrote: It takes a month of Sundays for an expert to enter and interpret the input/output data of a cage dipole using an Eznec-type program. . . . John Ferrell W8CCW |
Caged Di-Pole
"John Ferrell" wrote in message ... Since it appears that the benefit of the cage is bandwidth I ran a few scenario's with EZNEC and a 40 Meter vertical that is 33 feet tall. note that I did not correct for resonance shifting and that I am assuming that whatever the mesh is, it will not beat a solid. http://www.dixienc.us/28FtVert/BandwithVsDia.htm Given that most of us agree that trying to better a 2:1 SWR is into diminishing returns I believe this illustrates the cage's loss of popularity. Defiantly an appealing sight though... de W8CCW John On Wed, 16 Aug 2006 14:06:06 -0700, Joe Bloe wrote: Hello, My attention has been caught by the abilities of a "Fat Conductor" for an antenna. I understand that this has been achieved by using what is (little known about) a Caged Di-Pole. I have seen them before in older photographs, mostly draped over an old steamship, stem to stern. The Caged Di-Pole is supposed to be very well suited for weak signal reception. I know that a Yagi can do very well in this regard, but its the art of it that I'm interested in, and as far as I can see, it's almost an lost aspect of HAM radio nowadays. Does anybody remember these things? 73's Rob John Ferrell W8CCW What if all the wires are not the same length. I know my friends were able to cover all of 75/80 without retuning but this may have been because of the losses in the steel wire they were using.. |
Caged Di-Pole
FINALLY!!! Something good comes from being FAT. When does a FAT antenna become
OBESE?? :-) Jimmie D wrote: "John Ferrell" wrote in message ... Since it appears that the benefit of the cage is bandwidth I ran a few scenario's with EZNEC and a 40 Meter vertical that is 33 feet tall. note that I did not correct for resonance shifting and that I am assuming that whatever the mesh is, it will not beat a solid. http://www.dixienc.us/28FtVert/BandwithVsDia.htm Given that most of us agree that trying to better a 2:1 SWR is into diminishing returns I believe this illustrates the cage's loss of popularity. Defiantly an appealing sight though... de W8CCW John On Wed, 16 Aug 2006 14:06:06 -0700, Joe Bloe wrote: Hello, My attention has been caught by the abilities of a "Fat Conductor" for an antenna. I understand that this has been achieved by using what is (little known about) a Caged Di-Pole. I have seen them before in older photographs, mostly draped over an old steamship, stem to stern. The Caged Di-Pole is supposed to be very well suited for weak signal reception. I know that a Yagi can do very well in this regard, but its the art of it that I'm interested in, and as far as I can see, it's almost an lost aspect of HAM radio nowadays. Does anybody remember these things? 73's Rob John Ferrell W8CCW What if all the wires are not the same length. I know my friends were able to cover all of 75/80 without retuning but this may have been because of the losses in the steel wire they were using.. |
Caged Di-Pole
Certainly when it is to fat to maintain its shape!
I started yet another personal diet this past week. Being Fat is a real problem to be taken seriously... de W8CCW John On Wed, 30 Aug 2006 08:27:27 -0400, Dave wrote: FINALLY!!! Something good comes from being FAT. When does a FAT antenna become OBESE?? :-) Jimmie D wrote: "John Ferrell" wrote in message ... Since it appears that the benefit of the cage is bandwidth I ran a few scenario's with EZNEC and a 40 Meter vertical that is 33 feet tall. note that I did not correct for resonance shifting and that I am assuming that whatever the mesh is, it will not beat a solid. http://www.dixienc.us/28FtVert/BandwithVsDia.htm Given that most of us agree that trying to better a 2:1 SWR is into diminishing returns I believe this illustrates the cage's loss of popularity. Defiantly an appealing sight though... de W8CCW John On Wed, 16 Aug 2006 14:06:06 -0700, Joe Bloe wrote: Hello, My attention has been caught by the abilities of a "Fat Conductor" for an antenna. I understand that this has been achieved by using what is (little known about) a Caged Di-Pole. I have seen them before in older photographs, mostly draped over an old steamship, stem to stern. The Caged Di-Pole is supposed to be very well suited for weak signal reception. I know that a Yagi can do very well in this regard, but its the art of it that I'm interested in, and as far as I can see, it's almost an lost aspect of HAM radio nowadays. Does anybody remember these things? 73's Rob John Ferrell W8CCW What if all the wires are not the same length. I know my friends were able to cover all of 75/80 without retuning but this may have been because of the losses in the steel wire they were using.. John Ferrell W8CCW |
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