true dat. only real gains come when set up right. is from a 3,5 or 7 element beam. PERIOD. other than that like they have allways said. a 5/8 isa 5/8.
-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
Jo-Gunn: Son of a Gunn
- Thread starter Master Chief
- Start date
I certainly have no idea where freecell is coming from. Bad day at the truck stop?
I was pretty clear that Marconi (not Bob) should go and test his theory, contrary to what freecell said in his post. I also said NOT to take MY word for it and NOT to confuse his experiences with my beliefs.
I know we don't agree on the Sigma IV and I'm OK with that. Had I not talked directly to two of Avanti's engineers who both said it was basically a half wave antenna, I'd be more inclined to think the way you do. Imaginary feedpoint? Please clarify. The feedpoint of any antenna is where the feedline meets the antenna. What am I imagining. As far as "authoritative evidence", we have only heard your opinions and the text from the patent. Got any test results from an "authoritative" source to back up your theory?
An I-10K front man; I'm honored. Too bad we find you on the wrong side of the truth once again. How many times do I have to tell you that I paid for everyone of my antennas just like anyone else? Your opinions are nothing more than that; OPINIONS. Wrong ones at that. But nice try.
Flamebait? Who brought the Sigma IV discussion up again? ME?
If anyone feels robbed, then they haven't been reading my posts. I'm the first person to say, "check it out for yourself and come back here and tell us what you learned."
Thanks for peeking your head in and adding exactly NOTHING to the discussion yet again. Still a jerk I see......
"Any fool can criticize, condemn, and complain - and most fools do." Dale Carnegie
I was pretty clear that Marconi (not Bob) should go and test his theory, contrary to what freecell said in his post. I also said NOT to take MY word for it and NOT to confuse his experiences with my beliefs.
I know we don't agree on the Sigma IV and I'm OK with that. Had I not talked directly to two of Avanti's engineers who both said it was basically a half wave antenna, I'd be more inclined to think the way you do. Imaginary feedpoint? Please clarify. The feedpoint of any antenna is where the feedline meets the antenna. What am I imagining. As far as "authoritative evidence", we have only heard your opinions and the text from the patent. Got any test results from an "authoritative" source to back up your theory?
An I-10K front man; I'm honored. Too bad we find you on the wrong side of the truth once again. How many times do I have to tell you that I paid for everyone of my antennas just like anyone else? Your opinions are nothing more than that; OPINIONS. Wrong ones at that. But nice try.
Flamebait? Who brought the Sigma IV discussion up again? ME?
If anyone feels robbed, then they haven't been reading my posts. I'm the first person to say, "check it out for yourself and come back here and tell us what you learned."
Thanks for peeking your head in and adding exactly NOTHING to the discussion yet again. Still a jerk I see......
"Any fool can criticize, condemn, and complain - and most fools do." Dale Carnegie
"Who brought the Sigma IV discussion up again? ME?"
it sure as hell wasn't me. maybe you need to reread the thread.
you and your fictitious avanti engineers. why don't you have them explain to us why the patent is wrong. why don't you have them explain just exactly why the SignaIV "is basically a 1/2 wave antenna". (that's all we get for an explanation from a couple of engineers?) you can't seriously expect anyone to accept that brief, uninformative statement as refuting anything outlined in such precision detail as is the information contained in the patent, much less my past contributions and those of others to the many discussions and the lengthy electrical details outlining just exactly why it is a 3/4 wave antenna and not "basically a 1/2 wave antenna".
if it was a half wave antenna the feedpont impedance would be on the order of 2000 - 5000 ohms and since the driven element is gamma (low impedance) matched there's no chance in hell that it's a half wave antenna. i don't see any parallel resonant matching network at the bottom end of a 1/2 wave element there and neither does anyone else. just give it up. an end fed 1/2 wave is voltage fed (high impedance) and any end fed antenna any number of odd 1/4 waves (including a half wave dipole) is current fed. (low impedance) and there are plenty here who know the difference. this single paragraph alone destroys any credibility to the argument that the Sigma IV is a 1/2 wave antenna. it isn't. it never has been, it isn't now and it never will be, neither it or any knockoff design that builds on it. it's over.
i had anything but a bad day and i don't work at a truck stop. i'm just really tired of guys like you who think they know what they're talking about (as in this particular instance in regard to the SigmaIV) trying to tell guys like me that i don't know what i'm talking about. it gets old.
just ask your engineer buddies where the high impedance matching network is that's feeding power to the bottom end of that "basically 1/2 wave antenna" and get back to me. right after they explain what that current fed (low impedance) gamma matching network is doing there.
it sure as hell wasn't me. maybe you need to reread the thread.
you and your fictitious avanti engineers. why don't you have them explain to us why the patent is wrong. why don't you have them explain just exactly why the SignaIV "is basically a 1/2 wave antenna". (that's all we get for an explanation from a couple of engineers?) you can't seriously expect anyone to accept that brief, uninformative statement as refuting anything outlined in such precision detail as is the information contained in the patent, much less my past contributions and those of others to the many discussions and the lengthy electrical details outlining just exactly why it is a 3/4 wave antenna and not "basically a 1/2 wave antenna".
if it was a half wave antenna the feedpont impedance would be on the order of 2000 - 5000 ohms and since the driven element is gamma (low impedance) matched there's no chance in hell that it's a half wave antenna. i don't see any parallel resonant matching network at the bottom end of a 1/2 wave element there and neither does anyone else. just give it up. an end fed 1/2 wave is voltage fed (high impedance) and any end fed antenna any number of odd 1/4 waves (including a half wave dipole) is current fed. (low impedance) and there are plenty here who know the difference. this single paragraph alone destroys any credibility to the argument that the Sigma IV is a 1/2 wave antenna. it isn't. it never has been, it isn't now and it never will be, neither it or any knockoff design that builds on it. it's over.
i had anything but a bad day and i don't work at a truck stop. i'm just really tired of guys like you who think they know what they're talking about (as in this particular instance in regard to the SigmaIV) trying to tell guys like me that i don't know what i'm talking about. it gets old.
just ask your engineer buddies where the high impedance matching network is that's feeding power to the bottom end of that "basically 1/2 wave antenna" and get back to me. right after they explain what that current fed (low impedance) gamma matching network is doing there.
:lol :lol :lol
Man are you in a bad mood! Here you popped out of nowhere and the attacks begin yet again.
I'm still looking for the part where I said you were wrong. I'm OK with you having your opinions; it's too bad you are not OK with me having mine. You have a reasonable argument and it has merit. So do mine.
The discussion was about the Son-of-a-Gun antenna and the similarities to the Sigma IV (length, feed, etc). I've decided not to argue about the Sigma IV with anyone out here. Even Bob and I can joke about our theories.
You should back off on the "fictitious engineer" thing though, you are way off base with that. Stick to what you know.
I'll stay with the "basically a half wave theory" based on the input I've had and my own personal experiences. You go with the 3/4 wave thing. Fair enough?
Here is a copy of an e-mail exchange between me and my fictitious engineer from 2000:
Here are his answers:
And here is from a later discussion on the antenna.
There. Happy yet? Its basically a half wave. Some day I'll model it. In the mean time, feel free to model it yourself and by all means share the file and your results. We'll do a test in the desert someday and take real world readings. Until then, it remains theory and interpretation.
I contacted Herb directly. That took some doing. We talked for almost an hour. He asked that I not give his contact details out because he is not interested in answering questions about "old CB antennas." I haven't spoken to him since.
This should close the door on the fictitious engineers and where I was educated on the design of the Sigma IV.
Man are you in a bad mood! Here you popped out of nowhere and the attacks begin yet again.
I'm still looking for the part where I said you were wrong. I'm OK with you having your opinions; it's too bad you are not OK with me having mine. You have a reasonable argument and it has merit. So do mine.
The discussion was about the Son-of-a-Gun antenna and the similarities to the Sigma IV (length, feed, etc). I've decided not to argue about the Sigma IV with anyone out here. Even Bob and I can joke about our theories.
You should back off on the "fictitious engineer" thing though, you are way off base with that. Stick to what you know.
I'll stay with the "basically a half wave theory" based on the input I've had and my own personal experiences. You go with the 3/4 wave thing. Fair enough?
Here is a copy of an e-mail exchange between me and my fictitious engineer from 2000:
Here are his answers:
And here is from a later discussion on the antenna.
There. Happy yet? Its basically a half wave. Some day I'll model it. In the mean time, feel free to model it yourself and by all means share the file and your results. We'll do a test in the desert someday and take real world readings. Until then, it remains theory and interpretation.
I contacted Herb directly. That took some doing. We talked for almost an hour. He asked that I not give his contact details out because he is not interested in answering questions about "old CB antennas." I haven't spoken to him since.
This should close the door on the fictitious engineers and where I was educated on the design of the Sigma IV.
well the 1/4 wave matching stub theory doesn't wash. the opposite end of either an end fed quarter wave or the ends of a half wave dipole represent the same high impedance as does the feedpoint of an end fed 1/2 wave antenna so there is no need for any impedance transformation at the junction where the bottom of the end fed 1/2 wave and the top of the end fed 1/4 wave come together. furthermore any 1/4 wave matching stub would have to be of the open variety (not shorted) to provide a match to a high impedance feedpoint input. feel free to point out the open 1/4 wave (matching section) stub, i don't see one.
the patent also acknowledges that a conventional 3/4 wave antenna exhibits less gain (no argument there) than a 1/2 wave dipole reference (2.15 dbi.) but then again the SigmaIV is not a conventional 3/4 wave antenna and as such exhibits anywhere from 2.2 - 2.8 db. of gain over a 1/2 wave dipole for a total gain of anywhere from 4.35 - 4.95 dbi., still outperforming a 5/8 wave antenna by 1.0 - 1.6 db.. the gamma match primarily matches loads that are <50 ohms to 50 ohm feedline and that's all that's going on there.
the patent also acknowledges that a conventional 3/4 wave antenna exhibits less gain (no argument there) than a 1/2 wave dipole reference (2.15 dbi.) but then again the SigmaIV is not a conventional 3/4 wave antenna and as such exhibits anywhere from 2.2 - 2.8 db. of gain over a 1/2 wave dipole for a total gain of anywhere from 4.35 - 4.95 dbi., still outperforming a 5/8 wave antenna by 1.0 - 1.6 db.. the gamma match primarily matches loads that are <50 ohms to 50 ohm feedline and that's all that's going on there.
and BTW, while graphite has much better thermal conductivity than c o p p e r due to the method by which its wave lattice structure transfers heat at the atomic level it is not better than c o p p e r in the electrical conductivity department, even though when heated or doped with other metals (like c o p p e r) its electrical conductivity can be improved. graphite is only a fair conductor in its unaltered form. it's closest atomic relative is the diamond and it is labelled as an insulator even though both elements contain carbon atoms containing six protons, six neutrons and six electrons each with the only difference between the two being that the graphite molecules are flat groupings of carbon atoms while the same carbon atoms in the diamond molecules are grouped tetrahedrally.
and while i'm at it:
"well documented that a signal wavelength above 5/8 is (for lack of a better word) distorted."
the problem with a "conventional" 3/4 wave (or longer) radiator is that it develops major secondary lobes at higher angles thus reducing the amount of energy in the lower angled lobes, the ones providing the most benefit for long distance direct, ground wave and skywave communications. it has nothing to do with any type of "distortion". that's why there is a reduction in gain.
and while i'm at it:
"well documented that a signal wavelength above 5/8 is (for lack of a better word) distorted."
the problem with a "conventional" 3/4 wave (or longer) radiator is that it develops major secondary lobes at higher angles thus reducing the amount of energy in the lower angled lobes, the ones providing the most benefit for long distance direct, ground wave and skywave communications. it has nothing to do with any type of "distortion". that's why there is a reduction in gain.
Simple, when one element is out of phase. But that would be an oversimplified explanation. Look at the simple J-Pole and you will see that the lower 1/4 wave does not radiate. But you first must have radiation in order to have an out of phase signal to cancel it. So we can argue that there is radiation, but does it add to the signal or propagate? What would you call it?FL Native said:
Nice info freecell. Thank you. I learned something new about graphite, but I hope there won't be a pop-quiz.
"Distortion" was not a good word for sure, but all I had at that moment, as I said. I agree with your description.
"fell free to point out the open 1/4 wave stub, i don't see one."
Just as the J-pole does, it is shorted at the bottom and open at the top although the Sigma IV uses three elements which terminate with a loop. I won't argue that it electrically adds to the length of the three elements, but the loop is more about the mechanical support of said elements.
If we got rid of the loop, made the three elements longer to make up for it, and began to droop the elements down, it would be interesting to see how that would change the feed point impedance and resonant frequency of the main radiator.
"Distortion" was not a good word for sure, but all I had at that moment, as I said. I agree with your description.
"fell free to point out the open 1/4 wave stub, i don't see one."
Just as the J-pole does, it is shorted at the bottom and open at the top although the Sigma IV uses three elements which terminate with a loop. I won't argue that it electrically adds to the length of the three elements, but the loop is more about the mechanical support of said elements.
If we got rid of the loop, made the three elements longer to make up for it, and began to droop the elements down, it would be interesting to see how that would change the feed point impedance and resonant frequency of the main radiator.
not to worry. the feedpoint impedance and the frequency at resonance are both still well within the adjustment range of the overall length of the main radiator, gamma rod, the dogbone, (gamma stub) and the gamma match.
and here's why the patent made such important reading. if you remove the ring and pull the radials back down into their "conventional" position and (or not) re-lengthen them to full 1/4 wavelength the higher angle lobes re-appear and the gain at the lower angles drops like a rock. Herb was the inventor of record for the SigmaIV but it appears as though he has forgotten much of the design particulars. the loop around the radials (once again) serves only to extend the physical length of the radials from 89" to the normal 1/4 wavelength required for resonance.
to re-iterate what i said previoulsy in a slightly different manner, if you have a 1/2 wave vertical radiator which you intend to feed from the bottom end the range of possible impedance can be anywhere from 1 or 2 - 5000 ohms. the impedance at the far end of an end fed 1/4 wave vertical radiator also presents the same 1 or 2 - 5000 ohms as the feedpoint of the end fed 1/2 wave radiator so there is no need for any intermediate matching.
i've been modelling and reverse engineering this antenna for the last six months and i'm surprised that no one has ever thought to restore the radials to their "conventional" horizontal position to see what happens. those radials were swept up not only to eliminate coupling to surrounding objects in the near field but this same modification is exactly what was required to restore the energy previously lost in the higher angle lobes to the lower angles.
the four criteria that are critical for any antenna design are: balance, impedance, resonance and pattern. any time we add to or remove anything from the aperture of an antenna all four of these parameters are bound to change, sometimes for the worse and then again sometimes for the better. you've been reading my findings resulting from my months of testing right here in this thread.
and here's why the patent made such important reading. if you remove the ring and pull the radials back down into their "conventional" position and (or not) re-lengthen them to full 1/4 wavelength the higher angle lobes re-appear and the gain at the lower angles drops like a rock. Herb was the inventor of record for the SigmaIV but it appears as though he has forgotten much of the design particulars. the loop around the radials (once again) serves only to extend the physical length of the radials from 89" to the normal 1/4 wavelength required for resonance.
to re-iterate what i said previoulsy in a slightly different manner, if you have a 1/2 wave vertical radiator which you intend to feed from the bottom end the range of possible impedance can be anywhere from 1 or 2 - 5000 ohms. the impedance at the far end of an end fed 1/4 wave vertical radiator also presents the same 1 or 2 - 5000 ohms as the feedpoint of the end fed 1/2 wave radiator so there is no need for any intermediate matching.
i've been modelling and reverse engineering this antenna for the last six months and i'm surprised that no one has ever thought to restore the radials to their "conventional" horizontal position to see what happens. those radials were swept up not only to eliminate coupling to surrounding objects in the near field but this same modification is exactly what was required to restore the energy previously lost in the higher angle lobes to the lower angles.
the four criteria that are critical for any antenna design are: balance, impedance, resonance and pattern. any time we add to or remove anything from the aperture of an antenna all four of these parameters are bound to change, sometimes for the worse and then again sometimes for the better. you've been reading my findings resulting from my months of testing right here in this thread.
the radial modification has little to no effect on the resonant length of the main radiator. electrically speaking, there's no such thing as a 5/8 wave antenna. i'll get into this more later on but i'll leave you with this to think about for a while. the first antenna design that was ever officially dubbed as a 5/8 wave antenna was a 1/2 wave center fed dipole with the bottom most end of the dipole elevated 1/8 of a wavelength above ground.
what the engineer meant is that he was well aware that in a conventional 3/4 wave ground plane gain at the lower angles suffers due to the creation of secondary high angle lobes that are not conducive to long distance direct, ground wave and sky wave communications circuits. the upswept radials eliminates the wasted high angle radiation and compresses the pattern and attendant energy back down into the lower angle lobes where it does the most good, creating a 3/4 wave vertical that defies the conventional thought paradigm.
antenna gain is increased by directing radiation in a single direction, while necessarily reducing it in all other directions since power cannot be created by the antenna. thus the higher the gain, the larger the aperture and the narrower the beamwidth. in this particular example the elimination of the secondary high angle lobes and compression of the pattern energy into the lower angle lobe of the elevation plane resulted in the narrower beamwidth, hence the increased gain.
what the engineer meant is that he was well aware that in a conventional 3/4 wave ground plane gain at the lower angles suffers due to the creation of secondary high angle lobes that are not conducive to long distance direct, ground wave and sky wave communications circuits. the upswept radials eliminates the wasted high angle radiation and compresses the pattern and attendant energy back down into the lower angle lobes where it does the most good, creating a 3/4 wave vertical that defies the conventional thought paradigm.
antenna gain is increased by directing radiation in a single direction, while necessarily reducing it in all other directions since power cannot be created by the antenna. thus the higher the gain, the larger the aperture and the narrower the beamwidth. in this particular example the elimination of the secondary high angle lobes and compression of the pattern energy into the lower angle lobe of the elevation plane resulted in the narrower beamwidth, hence the increased gain.
I'd like to see your model. Post what you have to date and PM me the url. I won't share it with anyone. I'm most interested in seeing how you simulated the loop. I also want to see the differences in the radiation patterns. What software program are you using to model it? I have EZNEC, NEC-Win Plus, and just starting to play with MMANA
There is no need for impedance matching at the TOP part of the 1/4 wave element and the BOTTOM of the 1/2 wave element (which is at the same level as the loop) if I understand you correctly, to which I would agree. Is this not exactly like the J-pole? Then you find the 50 ohm tap on the 1/4 wave element and use the gamma to cancel the inductive reactance.
The Sigma IV still smells like a J-pole. Maybe not exactly, but real real close.
My phone conversation with Herb revealed that he is getting up in age and he admitted to not giving CB antennas much thought in the last 30 years. Still, he remembered the design.
"those radials were swept up not only to eliminate coupling to surrounding objects in the near field but this same modification is exactly what was required to restore the energy previously lost in the higher angle lobes to the lower angles."
Is this not similar to this part of the antenna not radiating, but redirecting the energy? What is the angle of the modified major lobe?
There is no need for impedance matching at the TOP part of the 1/4 wave element and the BOTTOM of the 1/2 wave element (which is at the same level as the loop) if I understand you correctly, to which I would agree. Is this not exactly like the J-pole? Then you find the 50 ohm tap on the 1/4 wave element and use the gamma to cancel the inductive reactance.
The Sigma IV still smells like a J-pole. Maybe not exactly, but real real close.
My phone conversation with Herb revealed that he is getting up in age and he admitted to not giving CB antennas much thought in the last 30 years. Still, he remembered the design.
"those radials were swept up not only to eliminate coupling to surrounding objects in the near field but this same modification is exactly what was required to restore the energy previously lost in the higher angle lobes to the lower angles."
Is this not similar to this part of the antenna not radiating, but redirecting the energy? What is the angle of the modified major lobe?
that was a poke. a joke. hahaha...... now can we get back to the original topic.
:shock:
wasn't this thread about a "son of a gun" ???? as usual around here its been hijacked.
:shock:
wasn't this thread about a "son of a gun" ???? as usual around here its been hijacked.