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Is the Sigma IV really a J-Pole?
- Thread starter Master Chief
- Start date
As Roger Waters said, "But oh, oh, oh, the tide is turning..."
he also said "we dont need no education" lmao, its been advertised as a concentric and coaxial jaypole for years, avanti called it a coinductive antenna ( "whole antenna radiates" ), thats what it said on the box but wait thats just the marketing gurus at work in both cases right?, i dont know what to call it but i do like how well they work 4 legs at 32 foot that is, if only somebody made a bulletproof version
he also said "we dont need no education" lmao, its been advertised as a concentric and coaxial jaypole for years, avanti called it a coinductive antenna ( "whole antenna radiates" ), thats what it said on the box but wait thats just the marketing gurus at work in both cases right?, i dont know what to call it but i do like how well they work 4 legs at 32 foot that is, if only somebody made a bulletproof version
Hey, teacher, leave those kids alone!
Building a bulletproof Sigma IV is easy! Finding a better way to feed it is another issue.
I'm a believer that a gamma rod exhibits more loss in the feedpoint than possibly a beta match. How to pull it off is another issue.
The specs I'm speaking of is more about the gain figures which CLOSELY ressemble a 1/2 wave antenna.....just like a J-Pole!
OK, I'm done beating this horse.....
yes chief those are thae same specs as on the sirio website, they lowered their crazy gain figures a few years back and now claim 1.5dbd for the 5/8, they used to claim 7db for the vector and even higher for the 5/8 sirio 827, i think what they now claim is more like the truth but i see way more than .5db over the 827 especially over distance, i wonder if anybody will bring a vector to the antenna shootout and hopefully a real 27foot avanti im interested to see if you find the same improvement over the original sigma that me and my buddy see and have a laugh at how the quality has dropped on the modern antennas.
MC does your original Sigma IV have 3 or 4 radials in the cone?
Plus you state:
What is you’re bases for this statement? Have you anything besides the words for you and Jay's on that claim about the losses relative to the use of gammas? I do not know the answer, but I hear you both state that repeatedly. I know that you have a different feeder idea for the I-10K and that is a fine feeder no doubt. You both claim to have done field strength test and I know just how difficult that is to accomplish without some very elaborate testing equipment. I would like to hear just how you did that testing and what you used to do that work of FS testing.
I read the piece by Cebik, where he discusses the issue of feeder losses, but I could not find where he definitively stated one way or the other which is best. If you refer to this piece as your evidence then put me on the exact part where Cebik says that? If it says it at all, I will bet he also claims that the difference is so small a difference as to make no difference.
Have you tried a trombone feeder inside of a mockup sigma design to see if you can find a better way to feed the Sigma design directly? The only problem I have ever heard gamma user’s claim about their feeding method has to do with the construction using “Plumbers Delight,” and arguing that using an insulated driven element with a hairpin, tapped coil, or the trombone device is the inherent weakness with the physical use of the insulator and the material it is made off. Don’t you have about the same problem bring a radiator element to ground via a capacitor (insulator) as does the gamma transferring RF thru a small air gap or thru a thin dielectric medium.
Personally, I believe you and Jay both have a very high regard for the Sigma IV design and that you probably started out trying to redesign with Jay’s new idea as the bases to start with. Problem with that was how to make it different and I believe you ran into problems figuring out how you could do that.
I have no quarrel with the I-10K. It is a find device and is very well engineered, very physically sturdy, and is something for you both to be proud of, but it is not a Sigma IV. Personally, I have never seen another antenna besides the Sigma IV lay down such a big signal in the local area of the antenna. But then again, I don't believe that signal is all that is important in an antenna without consideration of many other things, so the point about signal is mute with me. I have talked to folks on my radio that showed me absoutely no signal at all, and to tell the truth I could tell little difference when through with the conversation how the stations compared, one not signal and one showing me a signal of 30 over S9, cause I heard and spoke to both. Now if I thought they were both neighbors I might wonder a bit.
Plus you state:
What is you’re bases for this statement? Have you anything besides the words for you and Jay's on that claim about the losses relative to the use of gammas? I do not know the answer, but I hear you both state that repeatedly. I know that you have a different feeder idea for the I-10K and that is a fine feeder no doubt. You both claim to have done field strength test and I know just how difficult that is to accomplish without some very elaborate testing equipment. I would like to hear just how you did that testing and what you used to do that work of FS testing.
I read the piece by Cebik, where he discusses the issue of feeder losses, but I could not find where he definitively stated one way or the other which is best. If you refer to this piece as your evidence then put me on the exact part where Cebik says that? If it says it at all, I will bet he also claims that the difference is so small a difference as to make no difference.
Have you tried a trombone feeder inside of a mockup sigma design to see if you can find a better way to feed the Sigma design directly? The only problem I have ever heard gamma user’s claim about their feeding method has to do with the construction using “Plumbers Delight,” and arguing that using an insulated driven element with a hairpin, tapped coil, or the trombone device is the inherent weakness with the physical use of the insulator and the material it is made off. Don’t you have about the same problem bring a radiator element to ground via a capacitor (insulator) as does the gamma transferring RF thru a small air gap or thru a thin dielectric medium.
Personally, I believe you and Jay both have a very high regard for the Sigma IV design and that you probably started out trying to redesign with Jay’s new idea as the bases to start with. Problem with that was how to make it different and I believe you ran into problems figuring out how you could do that.
I have no quarrel with the I-10K. It is a find device and is very well engineered, very physically sturdy, and is something for you both to be proud of, but it is not a Sigma IV. Personally, I have never seen another antenna besides the Sigma IV lay down such a big signal in the local area of the antenna. But then again, I don't believe that signal is all that is important in an antenna without consideration of many other things, so the point about signal is mute with me. I have talked to folks on my radio that showed me absoutely no signal at all, and to tell the truth I could tell little difference when through with the conversation how the stations compared, one not signal and one showing me a signal of 30 over S9, cause I heard and spoke to both. Now if I thought they were both neighbors I might wonder a bit.
well the ad looks really nice on H&Y's site but the antenna in question is not a 7/8 wave antenna, not physically or electrically.
Agreed.
The original Sigma is physically 3/4 long and electrically a 1/2 wave.
The imports are 7/8 long and has been argued here that it is electrically a 5/8 wave.
HY's antenna, after the conversion from MM to feet, is 31+ feet instead of the original Avanti length of 27+ feet.
The original Sigma is physically 3/4 long and electrically a 1/2 wave.
The imports are 7/8 long and has been argued here that it is electrically a 5/8 wave.
HY's antenna, after the conversion from MM to feet, is 31+ feet instead of the original Avanti length of 27+ feet.
"The original Sigma is physically 3/4 long and electrically a 1/2 wave."
no it isn't
"The imports are 7/8 long and has been argued here that it is electrically a 5/8 wave."
no they're not.
first of all, a quarter wave antenna is RESONANT simply BECAUSE it is the correct PHYSICAL LENGTH to accommodate a complete quarter wave of current and voltage distribution. at either end of a quarter wave the impedance is resistive only. being RESISTIVE implies RESONANCE. any antenna which is 1/4 wavelength or any multiple of 1/4 wavelengths is a RESONANT antenna.
5/8 wavelength IS NOT a RESONANT length
7/8 wavelength IS NOT a RESONANT length
one popular antenna is the 5/8 wave vertical. a 5/8 wave antenna can not be RESONANT since it is not a multiple of a quarter wave. the "whip" part of the antenna is in fact 5/8 wavelength and has a net capacitive reactance. all 5/8 wave antennas have an inductance fitted somewhere along the length of the antenna to cancel out the capacitive reactance and resonate the antenna. so in effect, (electrically) a 5/8 wave antenna is in fact a 3/4 wavelength.
now, in keeping with the specifications presented in the ad on H&Y, (9500 mm) can anyone tell me why the total length of the vertical radiating element is four+ feet longer than the 27' of physical length required for a 3/4 wave?
no it isn't
"The imports are 7/8 long and has been argued here that it is electrically a 5/8 wave."
no they're not.
first of all, a quarter wave antenna is RESONANT simply BECAUSE it is the correct PHYSICAL LENGTH to accommodate a complete quarter wave of current and voltage distribution. at either end of a quarter wave the impedance is resistive only. being RESISTIVE implies RESONANCE. any antenna which is 1/4 wavelength or any multiple of 1/4 wavelengths is a RESONANT antenna.
5/8 wavelength IS NOT a RESONANT length
7/8 wavelength IS NOT a RESONANT length
one popular antenna is the 5/8 wave vertical. a 5/8 wave antenna can not be RESONANT since it is not a multiple of a quarter wave. the "whip" part of the antenna is in fact 5/8 wavelength and has a net capacitive reactance. all 5/8 wave antennas have an inductance fitted somewhere along the length of the antenna to cancel out the capacitive reactance and resonate the antenna. so in effect, (electrically) a 5/8 wave antenna is in fact a 3/4 wavelength.
now, in keeping with the specifications presented in the ad on H&Y, (9500 mm) can anyone tell me why the total length of the vertical radiating element is four+ feet longer than the 27' of physical length required for a 3/4 wave?
the antenna shown on h+y is a 3 legged antenna called a lw150, the cheap crap i have are 4 leggers called a vector 4000, only the vector is listed on sirio's own website, i have only ever seen a lw150 made by CTE, is that just an old pic h+y are usng? and why use the lw150 name when all the other base antennas on there are called what the makers call them :?: on the plus side their price is good so you wont lose so much when it breaks :twisted:
great points bob85.... but how 'bout someone answering my question?
"now, in keeping with the specifications presented in the ad on H&Y, (9500 mm) can anyone tell me why the total length of the vertical radiating element is four+ feet longer than the 27' of physical length required for a 3/4 wave?"
"now, in keeping with the specifications presented in the ad on H&Y, (9500 mm) can anyone tell me why the total length of the vertical radiating element is four+ feet longer than the 27' of physical length required for a 3/4 wave?"
I always thought them boogers that were longer than a 1/2 wavelength were as long as they are because of the way the tuner worked to bring them into resonance, but I am beginning to think it is all smoke and mirrors.
I never went along with this antenna is .625, and this one is .64, and this one is a .75 or a .875 based on the physical length, but I could not argue why I felt that way either. Wish I could help you freecell, good to see you back.
BTW, I never did fully understand that t-connector stub device idea you briefly touched on some time back. Maybe you could send me a better explaination via PM or email if you don't have time for this forum anymore. I always enjoyed your arguments even though I often was left behind in understanding. I know that MC and several others are up on their game in this stuff so maybe they will come forward and answer your question, but I just don't know why the antenna is so long, but I do know it has to be.
BTW, the subject of increased losses using a gamma match to feed this antenna has come up. What are you thoughts on that issue?
Good luck in your quest.
I never went along with this antenna is .625, and this one is .64, and this one is a .75 or a .875 based on the physical length, but I could not argue why I felt that way either. Wish I could help you freecell, good to see you back.
BTW, I never did fully understand that t-connector stub device idea you briefly touched on some time back. Maybe you could send me a better explaination via PM or email if you don't have time for this forum anymore. I always enjoyed your arguments even though I often was left behind in understanding. I know that MC and several others are up on their game in this stuff so maybe they will come forward and answer your question, but I just don't know why the antenna is so long, but I do know it has to be.
BTW, the subject of increased losses using a gamma match to feed this antenna has come up. What are you thoughts on that issue?
Good luck in your quest.
Here we go.....freecell said:
Yes it is.
It wasn't my argument, but I have no reason to doubt the claim.freecell said:
Agreedfreecell said:
Agreedfreecell said:
Sure. It was argued that the longer radiator took the original 1/2 over a 1/4 ( 3/4 ) to a 5/8 over a 1/4 ( 7/8 ). The matching network took care of the mismatch. Whether they tapped the gamma rod or slighly changed the size of the "cage" is unknown to me. Again, it wasn't MY argument, but being unable to disprove it at this time leaves me to accept this argument or at least to say that it has merit.freecell said:
You are not suggesting that a non-resonant length antenna won't work, are you?
try installing a physical 3/4 wave vertical radiating element over 3 or 4 1/4 wave (or slightly less) radial elements, connect an analyzer or noise bridge at the feedpoint and watch what happens when you sweep the radial elements upward to within 15 degrees of the bottom 1/4 wave section of the vertical element.
what you will see is larger and larger amounts of capacitive reactance in the vertical element as the radials are swept up closer and closer. this has the effect of electrically shortening the antenna (less than 3/4 wl) necessitating the extra 4+ feet in the total length of the vertical element to create the necessary inductive reactance required to cancel the capacitive reactance created as the proximity of the radial elements was drawn closer and closer to the bottom 1/4 wavelength of the vertical element while (electrically) resonating the vertical element at 3/4 wavelength.
what you will see is larger and larger amounts of capacitive reactance in the vertical element as the radials are swept up closer and closer. this has the effect of electrically shortening the antenna (less than 3/4 wl) necessitating the extra 4+ feet in the total length of the vertical element to create the necessary inductive reactance required to cancel the capacitive reactance created as the proximity of the radial elements was drawn closer and closer to the bottom 1/4 wavelength of the vertical element while (electrically) resonating the vertical element at 3/4 wavelength.
Forgot to comment on this one:
My feeling about gamma losses has to do with its capacitive properties and comaprisons to T-match and Beta match schemes. Sure they work, but not as well as other feed methods. I haven't been able to find any info on Cebik's site different than what you have already pointed out. All I can say is its like the "through the glass" antennas as compared to a regular installation. When I come up with the answer to your question, I'll post it. Other than that, I go with my gut, my tests, and Jay's tests which support mine. As far as elaborate test equipment, NOPE; a Bird field strength meter was used.
I don't have a different feeder design for the I-10K. It works perfect just the way it is. I would like to see machined aluminum blocks instead of the stainless steel clamps though. Stainless steel is not as good a conductor as aluminum. I also have an issue with the stainless steel to aluminum reaction caused by dissimilar metals. Stainless steel is great for hardware and tips of Avanti antennas, but I would rather have an all aluminum signal path to the antenna.
I have not tried to modify the Sigma at all. Bringing a tap to ground can be done easily and still be mechanically sound. The antennas that fail are because someone is cutting corners to maximize profits.
I'm unaware of ANY testing Jay has done with the Sigma IV. I know what he thinks about that antenna though. For me, I like the way it looks and nothing more. It certainly didn't perform as well as my Sigma 5/8 and that antenna was soundly beat by the I-10K! Also, Jay and I have never tested antennas together and other than some conversations early in the Mastadon 5000 projct, I've had only minor input.
I was scrolling back and forth while trying to respond to your questions. I hope I answered them all!
I have ORIGINAL Avanti antennas with three legs.Marconi said:
My feeling about gamma losses has to do with its capacitive properties and comaprisons to T-match and Beta match schemes. Sure they work, but not as well as other feed methods. I haven't been able to find any info on Cebik's site different than what you have already pointed out. All I can say is its like the "through the glass" antennas as compared to a regular installation. When I come up with the answer to your question, I'll post it. Other than that, I go with my gut, my tests, and Jay's tests which support mine. As far as elaborate test equipment, NOPE; a Bird field strength meter was used.
I don't have a different feeder design for the I-10K. It works perfect just the way it is. I would like to see machined aluminum blocks instead of the stainless steel clamps though. Stainless steel is not as good a conductor as aluminum. I also have an issue with the stainless steel to aluminum reaction caused by dissimilar metals. Stainless steel is great for hardware and tips of Avanti antennas, but I would rather have an all aluminum signal path to the antenna.
I have not tried to modify the Sigma at all. Bringing a tap to ground can be done easily and still be mechanically sound. The antennas that fail are because someone is cutting corners to maximize profits.
I'm unaware of ANY testing Jay has done with the Sigma IV. I know what he thinks about that antenna though. For me, I like the way it looks and nothing more. It certainly didn't perform as well as my Sigma 5/8 and that antenna was soundly beat by the I-10K! Also, Jay and I have never tested antennas together and other than some conversations early in the Mastadon 5000 projct, I've had only minor input.
I was scrolling back and forth while trying to respond to your questions. I hope I answered them all!