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Avanti Sigma4: An alternative view point
- Thread starter bob85
- Start date
'Doc, what you say is true. But, according to Shockwave's Website he is already in the Patent process. IMO, having a Patent does not stop those that Donald might be concerned about, and for sure if all the details for his antenna are published all over the Internet.
See his comments above the Specifications.
If you have a published Patent you still have to pay to sue.
FMBroadcastAntenna.com | FM Broadcast Antenna's
THE BEST ANTENNA I EVER OWNED
I replaced my first antenna (radio shack 3 element) with a fiber glass bigstick in 80. I'm not sure what year I replaced the bigstick with the first sigma with that distinctive loop. It may have been 82-84. I do remember the day I installed it. I noticed a tremendous impovment in my recive and found myself speaking to and reciving people whom I'd never heard on my 2340 before. I was in bk ny and had no problem being heard Trenton nj. When my parents sold the house I sold the 2340 to a kid who wanted the radio for years. I told him he could take the sigma too but he would have to take it the day I was to move out. He showed up two days late and the Chinese people who bought the house had no idea what he was talking about. That was in 97. When I pass the old house on 68st, I'm amazed when I see the 30 something year old sigma still standing on top of a two story home and on top of A25ft mast. I'm totally impressed. Wish I was using it right now. Best antenna I ever owned.
I replaced my first antenna (radio shack 3 element) with a fiber glass bigstick in 80. I'm not sure what year I replaced the bigstick with the first sigma with that distinctive loop. It may have been 82-84. I do remember the day I installed it. I noticed a tremendous impovment in my recive and found myself speaking to and reciving people whom I'd never heard on my 2340 before. I was in bk ny and had no problem being heard Trenton nj. When my parents sold the house I sold the 2340 to a kid who wanted the radio for years. I told him he could take the sigma too but he would have to take it the day I was to move out. He showed up two days late and the Chinese people who bought the house had no idea what he was talking about. That was in 97. When I pass the old house on 68st, I'm amazed when I see the 30 something year old sigma still standing on top of a two story home and on top of A25ft mast. I'm totally impressed. Wish I was using it right now. Best antenna I ever owned.
This topic always seems to stir things up. I sense some disappointment in my reluctance to share every detail but I assure you it's unfounded. As Marconi suggests everything that can be learned about this antenna is accessible with the Vector design. Even I don't feel there is any significant differences in performance between the antenna Sirio custom manufactures for me and the Vector they sell directly. If you need to confirm this then simply extend the .75 wave Vector to .82 wavelength and you got what I got but for your band.
Any of the tubing diameters can be altered by at least 25% before it makes any noticeable difference in the electrical wavelength or bandwidth. I'm using the same diameter tubing as the Vector which proves to be very robust since only the first 9 feet of this tubing is needed. With respect to the angle of the cone, if the radials and loop are made with 1/4 wavelength conductors it's only possible for the structure to form one angle when assembled.
Today, most patents are best at making lawyers money. Indeed they give you legal rights to your product but they do nothing to stop others from stealing or copying. The US government can't stop China from stealing their secrets and property off the internet so none of us has a chance in hell of protecting anything when their government sponsors and supports theft. China lies and says we're exaggerating and since China owns us, the problem only progresses.
The "selected / elected" here have such little nads left they can't even slap Chinas hand anymore much less take action (did I say that?). We already can't stop China from stealing, poisoning our kids with lead toys, killing 1300 dogs with poisoned treats (they got the cats last year), contaminating our food and collapsing our economy by making everything we buy so every dollar we spend goes there. Now if we need to do something like take action, we will quickly have nothing. Could you imagine a Chinese embargo? LOL, that's why we can't make a move....daah.
Any of the tubing diameters can be altered by at least 25% before it makes any noticeable difference in the electrical wavelength or bandwidth. I'm using the same diameter tubing as the Vector which proves to be very robust since only the first 9 feet of this tubing is needed. With respect to the angle of the cone, if the radials and loop are made with 1/4 wavelength conductors it's only possible for the structure to form one angle when assembled.
Today, most patents are best at making lawyers money. Indeed they give you legal rights to your product but they do nothing to stop others from stealing or copying. The US government can't stop China from stealing their secrets and property off the internet so none of us has a chance in hell of protecting anything when their government sponsors and supports theft. China lies and says we're exaggerating and since China owns us, the problem only progresses.
The "selected / elected" here have such little nads left they can't even slap Chinas hand anymore much less take action (did I say that?). We already can't stop China from stealing, poisoning our kids with lead toys, killing 1300 dogs with poisoned treats (they got the cats last year), contaminating our food and collapsing our economy by making everything we buy so every dollar we spend goes there. Now if we need to do something like take action, we will quickly have nothing. Could you imagine a Chinese embargo? LOL, that's why we can't make a move....daah.
Wow, that was a read.
Any update to this? Any new alternatives to a quality Sigma 4?
My experience with one in the mid 80’s to the late 90’s was there was no better ground plane used in my location. It was in a 70 foot tree in the Great Pacific Northwest and held up well to the windstorms and the one and only severe icing. I wish I had paid someone to remove it when I moved away but at the time wasn’t using it much.
I did purchase a quality 5/8 ground plane with 4 radials that was installed in a 65 foot tree that has held up well. I wish I knew the name of it, met a guy at the truck stop back in roughly 2004. I believe it is 21’?
The tree it’s in needs to be trimmed as the branches are blocking the radials and the SWR which has been almost flat for years is now running about 1.8-2.0
Probably Time for new coax (It was the highest quality back then) and if I’m going to go through the effort of replacing, probably time to expect to replace the antenna.
I don’t mind paying for something real as quality, workability, and longevity are the only considerations. Any recommendations??
Any update to this? Any new alternatives to a quality Sigma 4?
My experience with one in the mid 80’s to the late 90’s was there was no better ground plane used in my location. It was in a 70 foot tree in the Great Pacific Northwest and held up well to the windstorms and the one and only severe icing. I wish I had paid someone to remove it when I moved away but at the time wasn’t using it much.
I did purchase a quality 5/8 ground plane with 4 radials that was installed in a 65 foot tree that has held up well. I wish I knew the name of it, met a guy at the truck stop back in roughly 2004. I believe it is 21’?
The tree it’s in needs to be trimmed as the branches are blocking the radials and the SWR which has been almost flat for years is now running about 1.8-2.0
Probably Time for new coax (It was the highest quality back then) and if I’m going to go through the effort of replacing, probably time to expect to replace the antenna.
I don’t mind paying for something real as quality, workability, and longevity are the only considerations. Any recommendations??
You forgot "ALL Jo Gunns SWR get lower the longer they are run"Hey Marconi, Would you have time to model the JG Pilot :drool: - except not with 1/4λ halves, but with 5/16λ (.3125) halves, both with, and without the upper half insulated from ground (as is the Pistol in factory configuration) ?
- Remember, it's gamma matched. http://www.jogunn.com/index.php?pag...facturer_id=0&option=com_virtuemart&Itemid=26
Then it might be interesting to see what happens when you extend to .32λper half (.64 total).
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JGAR - PISTOL (VERTICAL) ANTENNA
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GAIN: 4.75 DB over pink handlebar tassels
MULTIPLICATION FACTOR: 12,000,000,000³ x Infinity²
AUDIO GAIN - Buy Ear Plugs, Louder Than An F-16
POWER RATING: 2000CW. 4000 PEP
WEIGHT: 8.0 lbs.
LENGTH: 10 feet
MATERIALS: 6063T-6 Aircraft Aluminum Tubing
REQUIRES 1 COAXIAL CABLE FOR HOOK-UP
quoted from the piece of paper that came with a pistol that was recently given to me.
There is only one that I know of and it is brand new and expensive. ZeroFive https://zerofive-antennas.com/ has come out with a new antenna called the Colossal 4K. It isn't even listed on their website yet. Special order 4-6 weeks build time, $400~$500. Built to ZeroFive's build quality.
Here is a link about it:
https://simonthewizard.com/2020/08/26/video-zerofive-colossal-4/
Hey Lee.
The video guy says the radiator is 27' from the center. What do you think he means when he says, "...from the center," center of what?
He also claims it is a 7/8 wavelength antenna.
If the radiator is 27' feet above the bottom radial stand-off brackets, then it looks to me like this is a 3/4 wavelength antenna.
The radials look close to 9' feet tall and that is close to the height for the New Vector 4K. My old Sigma 4 had radials 92" inches high and when I stood it up the loop was maybe close to 2 feet above my head.
This Zero Five does look to be much more robust however and that could be a plus in bad weather.
Good report from both you and Simmon. Keep us posted if you hear more on this one.
Thanks,
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Probably the end
Correct
Agreed. I have lost 3 Vector type antennas in the last 35 years to ice loading. I am in the process of putting up a "new Vector 4k" - supposedly more robust. We will see. If it doesn't make it, then I will definitely be looking to get one of these.
Vortex antennas make a superduty version with 3/8wave radials,
they claim the longer radials improve gain & give a big increase in bandwidth.
Marconi did some models that showed there could be some truth in the bandwidth claim.
they claim the longer radials improve gain & give a big increase in bandwidth.
Marconi did some models that showed there could be some truth in the bandwidth claim.
Bob I don't remember this project, but I have 36 iterations for the Vortex M2 or the Mark 2...which might be the same antenna.
Do you have a title for the model you referred to here? It will save me from taking a wild guess at what you're looking at. The model I happened to check was set at 27.205 MHz. It has radials that are 163" inches long, and a radiator 318" inches which is close to 3/8 and 3/4 WLs respectively.
The model also shows a 4.20:1 SWR bandwidth, but the resonance is at 27.5 MHz.
So, this model needs some work and is not a good example, because when I set it in Free Space so I could check the Average Gain for accuracy...the model failed miserably. I have 35 more I could check, so maybe you can help this old man out, and then I will check and report if what was done back then was close to the facts being talked about here.
Do you have a title for the model you referred to here? It will save me from taking a wild guess at what you're looking at. The model I happened to check was set at 27.205 MHz. It has radials that are 163" inches long, and a radiator 318" inches which is close to 3/8 and 3/4 WLs respectively.
The model also shows a 4.20:1 SWR bandwidth, but the resonance is at 27.5 MHz.
So, this model needs some work and is not a good example, because when I set it in Free Space so I could check the Average Gain for accuracy...the model failed miserably. I have 35 more I could check, so maybe you can help this old man out, and then I will check and report if what was done back then was close to the facts being talked about here.
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Bob, see if this thread might be where you think I posted a model showing some good results like you describe above. Post #14 and #19.
https://www.worldwidedx.com/threads/vortex-q82-mk2.221042/
I want to look and see if this guy in the video ever followed-up with his installation and talked about his new antenna.
If Simon is still around, I want to ask him if he has followed up with other operators using this new best thing in CB antennas.
I think you are right Bob, when you tried making your radials longer you saw the gain drop.
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Toll_Free posted:
"The "sigma" design found a novel approach of getting rid of the BIGGEST problem in the antenna industry: Matching a low impedance to a high impedance. The half wave has > 1K ohm of input resistance, coupled with reactance."
the most effective and efficient method for feeding the base (high impedance) of an end fed half wave vertical is from the opposite end (high impedance) of an end fed quarter wave vertical.
"The "sigma" design found a novel approach of getting rid of the BIGGEST problem in the antenna industry: Matching a low impedance to a high impedance. The half wave has > 1K ohm of input resistance, coupled with reactance."
the most effective and efficient method for feeding the base (high impedance) of an end fed half wave vertical is from the opposite end (high impedance) of an end fed quarter wave vertical.
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bob wrote:
"as you sweep the radials up towards the central monopole the resonant frequency of both monopole and radials moves up while transmissionline mode impedance comes down, you end up with element lengths somewhat longer than freespace calculations for a given resonant frequency,"
spot on.
now you need a gamma match. increased capacitance between radials and antenna due to much closer proximity electrically shortens the main radiator. now you need to lengthen the main radiator.
the patent tells us several times that when the acute angle formed between the vertical element and the radials at the base of the antenna is increased to 30 degrees that directivity increases on the order of .5-.6 dB.. as the angle becomes progressively wider the directivity increases still further.
https://pdfpiw.uspto.gov/.piw?Docid=04282531&homeurl=http://patft.uspto.gov\
if we look at the input resistance of a ground mounted 3/4 wave vertical on earth ground fed at its base we see that the nominal impedance is in the neighborhood of 70 ohms. a gamma match is used in specific cases where the input resistance is substantially less than 50 ohms.
i asked my self the question, why is the input resistance so low as to require a gamma match? the close proximity of the radials to the vertical radiator increases the capacitance between the radials and the vertical element, accomplishing several things at once.
first and foremost, it satisfies the inventors goal of "reducing by 50 - 85 % the lateral or radial space required as compared to a 1/4 wl. or 5/8 wl, ground plane antenna (using full size 1/4 wl. radials) while simultaneously providing better gain than a 5/8 wl. antenna."
this is not possible according to the information provided in the patent itself.
fortunately for me, that is not my goal. i know the trade-off is coming next.
moving the radials upward in close proximity to to radiating element compresses the electric and magnetic charge while increasing the capacitance between the radials and the vertical element. this creates additional loss resistance. it drives down input resistance (now you need the gamma match) while also driving the frequency down the band, now requiring the lengthening of the vertical element by +or- 5.5" to bring it back up into the band and with the additional loss the swr bandwidth is wider than it should be. it is not well known that as loss resistance increases in an antenna system that the bandwidth will be widened but for all the wrong reasons. claims of ever increasing swr bandwidths mean more Rloss / loss resistance (bad) and less Rrad / radiation resistance. (bad) altogether it all adds up to reduced antenna radiation efficiency.
moving the radials away from the vertical element raises the impedance, doing away with the need for the gamma match. note: quit using the free space formulas for calculating radiator lengths, none of you are operating these antennas anywhere near "free space." for a 3/4 wl. end fed vertical radiator (not in free space) the formula is: 738 / 27.205 = 27.127 feet or 27 feet, 1.5 inches.
when you are high enough above ground that altering feedpoint elevation has no effect on the antenna whatsoever, then you're in free space. best indications to date tell us that this doesn't begin to happen with regard to ground plane antennas until the feedpoint height above ground approaches 1.5 wavelengths, i.e., where earth ground underneath the antenna has absolutely no effect or influence over the pattern developed by the antenna and that the formation and shape of that pattern is solely dependent on the physical properties and the attendant electrical characteristics of the antenna itself and nothing else.
move the radials away from the vertical element until you see something closer to 50 ohms, at which point you will have eliminated a large amount of "manufactured" ground losses while increasing the directivity and the radiation efficiency of this antenna which was primarily designed to be more convenient for the user by "reducing lateral or "radial" space" while negatively impacting antenna radiation efficiency.
this also bears repetition: you cannot uncouple the antenna current from the feedline (eliminating additional loss resistance) using only 3 or 4 radials, regardless of their physical orientation. no more additional expenses for unnecessary baluns, chokes or isolation schemes, i will no longer spend more money to "fix" poorly designed vertical antennas or to pay for expensive and unnecessary support structures.
when someone makes the statement that the need and requirement for an efficient ground plane is a problem when it comes to 1/4 wl. and 5/8 wl. "ground plane" antennas then you know that you're in the wrong place if you're looking for a high performance antenna system. you'll find this statement in the patent.
if henry and the gang are looking for tips to improve the performance of these antennas, here they are.
these are just a few of the many reasons why i no longer use commercially manufactured antennas.
"as you sweep the radials up towards the central monopole the resonant frequency of both monopole and radials moves up while transmissionline mode impedance comes down, you end up with element lengths somewhat longer than freespace calculations for a given resonant frequency,"
spot on.
now you need a gamma match. increased capacitance between radials and antenna due to much closer proximity electrically shortens the main radiator. now you need to lengthen the main radiator.
the patent tells us several times that when the acute angle formed between the vertical element and the radials at the base of the antenna is increased to 30 degrees that directivity increases on the order of .5-.6 dB.. as the angle becomes progressively wider the directivity increases still further.
https://pdfpiw.uspto.gov/.piw?Docid=04282531&homeurl=http://patft.uspto.gov\
if we look at the input resistance of a ground mounted 3/4 wave vertical on earth ground fed at its base we see that the nominal impedance is in the neighborhood of 70 ohms. a gamma match is used in specific cases where the input resistance is substantially less than 50 ohms.
i asked my self the question, why is the input resistance so low as to require a gamma match? the close proximity of the radials to the vertical radiator increases the capacitance between the radials and the vertical element, accomplishing several things at once.
first and foremost, it satisfies the inventors goal of "reducing by 50 - 85 % the lateral or radial space required as compared to a 1/4 wl. or 5/8 wl, ground plane antenna (using full size 1/4 wl. radials) while simultaneously providing better gain than a 5/8 wl. antenna."
this is not possible according to the information provided in the patent itself.
fortunately for me, that is not my goal. i know the trade-off is coming next.
moving the radials upward in close proximity to to radiating element compresses the electric and magnetic charge while increasing the capacitance between the radials and the vertical element. this creates additional loss resistance. it drives down input resistance (now you need the gamma match) while also driving the frequency down the band, now requiring the lengthening of the vertical element by +or- 5.5" to bring it back up into the band and with the additional loss the swr bandwidth is wider than it should be. it is not well known that as loss resistance increases in an antenna system that the bandwidth will be widened but for all the wrong reasons. claims of ever increasing swr bandwidths mean more Rloss / loss resistance (bad) and less Rrad / radiation resistance. (bad) altogether it all adds up to reduced antenna radiation efficiency.
moving the radials away from the vertical element raises the impedance, doing away with the need for the gamma match. note: quit using the free space formulas for calculating radiator lengths, none of you are operating these antennas anywhere near "free space." for a 3/4 wl. end fed vertical radiator (not in free space) the formula is: 738 / 27.205 = 27.127 feet or 27 feet, 1.5 inches.
when you are high enough above ground that altering feedpoint elevation has no effect on the antenna whatsoever, then you're in free space. best indications to date tell us that this doesn't begin to happen with regard to ground plane antennas until the feedpoint height above ground approaches 1.5 wavelengths, i.e., where earth ground underneath the antenna has absolutely no effect or influence over the pattern developed by the antenna and that the formation and shape of that pattern is solely dependent on the physical properties and the attendant electrical characteristics of the antenna itself and nothing else.
move the radials away from the vertical element until you see something closer to 50 ohms, at which point you will have eliminated a large amount of "manufactured" ground losses while increasing the directivity and the radiation efficiency of this antenna which was primarily designed to be more convenient for the user by "reducing lateral or "radial" space" while negatively impacting antenna radiation efficiency.
this also bears repetition: you cannot uncouple the antenna current from the feedline (eliminating additional loss resistance) using only 3 or 4 radials, regardless of their physical orientation. no more additional expenses for unnecessary baluns, chokes or isolation schemes, i will no longer spend more money to "fix" poorly designed vertical antennas or to pay for expensive and unnecessary support structures.
when someone makes the statement that the need and requirement for an efficient ground plane is a problem when it comes to 1/4 wl. and 5/8 wl. "ground plane" antennas then you know that you're in the wrong place if you're looking for a high performance antenna system. you'll find this statement in the patent.
if henry and the gang are looking for tips to improve the performance of these antennas, here they are.
these are just a few of the many reasons why i no longer use commercially manufactured antennas.
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