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Discussion in 'CB Antennas' started by nosepc, Oct 6, 2013.
http://www.hyelectronics.com/NEW-Astro-Plane-ALPHA-Base-Antenna/productinfo/LW-101/ (try this link for astro plane)
Firstly I am a firm believer the Sigma 4 / Vector 4000 is The second best cb vertical ever made for performance, only surpassed by the no longer made Ham International Big Mac.
All 3 are notoriously fragile with the Avanti the strongest.
How anyone can't see in the CST animation that the basket radiates in phase with the radiator mesmerises me.
LB Cebic claimed a non apparent colinear. CST confirms that.
My opinion of free space modelling is its a lot of pish even if it is all the fcc accepts. Bear in mind SHIODA tore them a new asshole in court and most are biased amateurs that have contempt for cb at best, just like the Ofcom RIS here in the UK where now thanks to European harmonisation Cb'ers for the first time have legal AM/FM/SSB with more legal power than foundation hams on SSB.
I see time and again the Av174 and Vector 4K outgun everything vertical on long distance line of sight comms and have done for nearly 3 decades, since big mac production stopped.
To accurately model any antenna mast and coax, including choke if added must also be modelled. Since skyhooks haven't been invented and only isotropic sources I have ever witnessed are our sun and other stars I wouldn't be classing that as an accurate reference source as not only are they hot as fuck but also unstable as fuck too.
So all that we truly have as a reference point is the humble dipole.
I also feel that any mounting height that is not a .5 wave multiple will add out of phase ground cancellation to varying degrees depending on phase of relected signal.
All i see with NEC and its higher cost relations is a seriously flawed software which might explain Marconi's difficulty with getting intetaction with the software's inventor. It's not good business accumen anouncing your product is flawed.
Before anyone asks no I haven't used it and never will after all the drivel I have seen on here, I think its fair to say most people have at best a vague idea on using it and guy who invented it admitted it was flawed for these types of antennas.
So we are left with real world tests where everyone using a sigma 4 or vector 4k see's similar results in the field that prove it is not a J pole.
I had an original sigma 4 and sold it. It outperformed the antenna I replaced it with, and in a lower mounting position, but not by a huge amount, the reason I sold it was I wanted to mount a 3 ele yagi on chimney and put a vertical on top so chose an A/S Mighty Magnum 3 as its far stronger and on a chimney mounted 10' mast and rotator then a 6' mast with yagi halfway and Magnum on top to give me best of both worlds was a much safer and much envied solution in my city.
I was 16 and working parts of the world many adults around me dreamed of with ease.
Now it strikes me as strange that no one except Bob Jeff and Donald seem to accept it is either a .5 wave over a .25 wave non apparent colinear in the case of sigma and new vector or .625 over a .25 in the case of the old vector.
CST proves that as basket radiation is in phase with top .5 wave of radiator whilst at the same time cancelling radiation of out of phase bottom .25 wave of radiator.
Hence Mr Cebik's claim it was a NON APPARENT colinear. This is a man respected the world over and people doubt him chiefly on the grounds of the guys who built it admit they had no idea why it worked and some bullshitters claim its a j pole.
Yet none can replicate a j pole model of it, never ceases to amaze me how bullshit propagates further than those spouting it signal does.
I guess it goes back to the infamous hitler quote the bigger and more repeated the lie the more people will believe it.
It isn't outwith reality that 1 man can be right when all others are wrong. History more than proves that.
Remember this at one time the whole world thought the planet was flat and you would drop of the end. One man proved the whole world wrong.
Donald has supplied the most accurate military standard animation of how it works yet people still doubt.
Want solid proof how much the current in the basket radiates and if it is enough to produce the results replicated in different geographical locations ?
I am surprised no-one has considered this simple test. We can see from CST the basket prevents radiation of bottom .25 wave, sadly i no longer have either antenna to do it, but one for all you experimenters with broken ones or modelling software.
Remove top .5 or .625 top section and see if basket and bottom .25 together radiate and how much,
Something to consider ?
If I am right I would expect it to be pretty substantial as Donalds CST animation shows. If the j pole camp are right I would expect very little or absolutely no radiation.
I think LB Cebic said it was non apparent to others, but it was very apparent to him and CST.
As for the Astroplane which i have a bnib one lying here, took me 3 decades to find but i found an original, i would doubt very much it is anything other than a starduster variation .25 wave ground plane with a reduced radiator to comply with fcc regulations. Like the Sigma i doubt very much the guys who invented it understood it and probably stumbled on a design that worked. Mounted at same height as an m400 i very much doubt anyone could tell the difference.
heyup m8, there is a bloke near me has some nos mighty magnum 3's and thunderpole 2's, i was looking at them the other day when i picked up my nos uniden.
what size is the box for that astroplane?
im making space and need to know the dimensions lol.
Jazz, you might be right about the Big Mack. My Eznec model of the BM shows it to produce a better gain than either of my S4/NV4K, but the BM also suggest by the currents indicated in Eznec to be producing some real collinear gain.
I figure that is a result of the antenna actually having the physical delay coil to do the work. However, I will admit that my model might be off a bit...as I had to guess at some the dimensions, and the coil designs are totally trial and error guesses.
Henry told us that he got a NOIB Big Mack. I asked him if he would provide me the detailed dimensions, but I think he said he did not want to open the box.
I don't think I've ever disputed Cebik's claim, but I modeled these antennas using Eznec...and I find he may be technically right about the bottom cone constructively adding to the gain...but I see very little gain advantage from the cone after I consider the cancellation effects noted to be in that area of the antenna. My Eznec model is replete with transmission line currents in the cone area to the extent of almost being totally balanced…leaving very little antenna currents to flow into the far field.
Your misunderstanding here is due to a lack of what a free space model is supposed to indicate in a technical sense. It simply has to do with removing Earth effects from the model. Both methods of modeling, real Earth and Free Space report results in DBi.
In my testing I typically see far less of a difference than you claim here, but location and conditions do have their effects and it is not always easy to determine the real cause. How do you determine if a signal is arriving at your antenna via line of sight or via sky waves?
Jazz, you may be right that we need to model the mast, feed line, and the choke if used, but I think this is primarily true only for models over real Earth...as when we compare antenna models or to a center fed dipole.
Shockwave swears that the CST model he posted is a Free Space model. If I make a model using Eznec over real Earth, and I include a mast, Eznec will automatically remove the mast connection to the ground when I change the settings to Free Space. This is done to remove those ground effects on the antenna as a result of being connected to the Earth.
FYI, the FS model will still show the results of the attached mast...unless we physically remove it from the FS model. This is not so good for results if we fail to remove the mast and you often see a very skewed pattern.
Again, Donald makes the claim that this animated image of NV4K pattern is a Free Space model. He does that simply because my Eznec FS models do not indicate the higher gain of 4.15 dbi as noted by Sirio's specs in their ad department's promotional material. So, in my thinking he uses this material to support his claim that Eznec is in error…simply because my FS models do not show the reported gain noted by Sirio specs. I of course disagree with Donald on this issue and think Sirios specs are over real Earth. Just look at Sirios specs for their beams and compare their gain results with those of other folks that make similar beams.
I also wrote Sirio an email asking this very question, and they did not respond.
Jazz, take another honest look at Sirio’s animated CST model image for their NV4K that Donald posted. Tell me if you see an attached mast included in that image...much less a feed line or choke attached to the model. You also don't see any model information for name, gain, angle, etc included in the Sirio pattern image either.
Jazz, what happened in that case might be expected from Roy based on the request I made. He is not in the business of tutoring using his products, and that is what he told me straight out.
Jazz can you post a link where Roy Lewallen claimed his Eznec will not model these type of antennas? Unless I'm wrong...I think Bob told us that Mr. Cebik suggested it would be difficult, but I don't recall Bob saying why.
I may have asked before, but Bob do you know why LB made that statement?
I use to agree that our doing real World testing was best to consider when comparing antennas. I also think doing some effective RW testing is require when using modeling for antenna designs.
However, there is a lot more to RW testing than most of us are able to accomplish. I use to think what I did comparing signals was producing results that were good enough, but after all the discussions we’ve had here on WWDX...I am no longer as confident as I once was…in that regard.
I read some remarks that Bob's made the other day....saying he was no longer sure about some results for his testing of his Vector Hybrid in the past.
Bob use to tell me about his experiences with making contacts over a long distance with his Vector Hybrid, and I believed him. I’ve had similar experiences with some of my antennas in the past, but I figured conditions were what made the difference with long distance contacts. I’ve had many similar experiences over the years, but I could not duplicate the experiences whenever I wished…and that is a big difference.
Jazz, I’ve had a few thoughts like that before too, but now I realize I was only 16.
Do you recall back in the days when HyGain came out with their CLR2, and they referred to it as a collinear antenna. Does that one make the same difference in performance claim idea as your thinking today? IMO, they did that simply because the radiator manifested two current fields, but they were out of phase. It was no more of a positive collinear effect than with my Starduster. But the sales department didn’t care, it just sounded good. This is all similar to what Solarcon calims about the A99 gain. They used such claims as though they posessed a super advantage to the consumer…when in fact all it did was raise a ½ wave radiating element up higher by a few feet, and in fact it also had the ill-effect of raising the maximum radiation angle up a bit compared to a 1/2 wave element.
I see this in my Eznec model of the Sigma4 as well.
Jazz, I think you have likely taken this information in error. I posted an old CB Magazine article dated August, 1970, pps 12-13, entitled “How to Make an Omni into a Beam!”. The talk was about their not understanding why the Astrobeam, using an A/P as the driven element, produced the additional gain and rejection over a conventional dipole yagi type element in their testing.
It’s funny how CBBS tends to muddle the waters sometimes…even for a knowledgeable fellow like yourself.
If you are suggesting what I think you’re saying…I have a J-pole model that produces a gain and angle that is very close to what my New Vector 4000 model shows and the patterns are very similar. Just a little skewing with the J-Pole is about it.
Correction; It was not Hitler who coined this idea…it was Joseph_Goebbels, his propaganda minister.
Jazz, I only doubt the hyped-up gains at lower angles that some are trying to pass off as facts to this forum. The Sigma4, NV4K, and others like it…are probably all great antennas if installed correctly. But IMO, they are just raised up ½ wave radiators at best. Even though the cone design does provide a bit of non-apparent collinear type advantage…the advantage looks to me to be minimal.
I addressed this ¼ wave idea a long time ago and made a post here on the forum.
First you will see that such a radiator will not radiate, because the load is removed, and the radiator left shows no matching ability that I’ve been able to find. In fact this one shows a loss in gain below ZERO.
Second, this idea provides an almost pure cancellation according to my Eznec models, and this seems to me to again support what my NV4K model shows in the bottom cone area.
This is the very opposite of what you expected.
Jazz, if past is prologue however, I would expect someone to come forward with a test telling us this bottom cone idea alone and without the top radiator will work like a champ.
Jazz, I don’t have a clue what Cebik was thinking in this regard, and I guess Bob didn’t have a chance to follow up. Maybe Mr. Cebik was ill, and didn’t feel like talking.
I have to wonder if Cebik ever really wondered about the Avanti Sigma 4 designed antenna in the first place. If he had, and if its results were as good as Donald claims…then surely Cebik would have realized that and made some report about it in his unbelievable volume of work.
Just some of my thoughts on the subject.
i have said several times in the past that cebik said it would be very difficult to get accurate results with that antenna using eznec, he did not say why what magnitude of error or that it was impossible, i went searching for answers and we both very sadly ran out of time,
i included the pertinent stuff he said in the alternative view article,
he stated that he did not want to get into pages of meaningless argument with people he said did not understand how it operated, he was well aware of the controversy such antennas cause, that could be why he never wrote about it,
i have no doubt about my testing or which antenna works best,
unlike you eddie i have not changed my mind half a dozen times over what works best here when mounted on the same mast
1 big-mac ( in low wind )
2 my hybrid
to clarify, what im not sure about is why playing with sleeve length and monopole length causes changes in signal when leaving it alone gives stable signals,
how much radiation from the sleeve would be needed for the vector to outperform a 1/2wave at the same tip height?? that's what id like to know,
as for the astrobeam, post that article id like to read it again im sure others would too,
i may have read it as i wanted it to read,
if all they meant was that they did not understand how it gets extra performance over a 3 ele yagi then i appologise for doing what you have done with my posts and emails multiple times in the past,
its annoying isn't it,
without an astroplane model in cst or similar software i will never know if my idea of how it works has any validity.
if im wrong then its no more interesting than a starduster or sirio top-one to me.
what happend to nosee posting shockwaves post just happend to me posting eddies post without hitting reply,
i think i accidentally went back a page then forward and the document expired, this new forum works differently to the old setup, i don't know why yet.
""he stated that he did not want to get into pages of meaningless argument with people he said did not understand how it operated, he was well aware of the controversy such antennas cause, that could be why he never wrote about it""
After years of debate over this antenna I really do see the wisdom of this statement above. From the view of a long time Admin here I have seen this subject do just what he has described .
Bob, I'm having a bad day, but here is the article from the 1970 CB Magazine.
I posted this before, but it was quite small and hard to read unless you print the image out. I made an attempt to enlarge it this time so as to be more readable, but its format is off a bit. I marked the pertinent text with a (*)
thanks eddie, i have saved that,
i did misread what they actually meant, i likely presumed that if they did not understand how the astrobeam worked they must not understand how the astroplane worked either,
its clear they thought the astroplane has more gain than a dipole, and that the astrobeam has more gain when the astroplane design is used as the driven element of a 3 element beam compared to a 3 element beam with a dipole driven element,
i either have not seen the full report or i just failed to pick up on this part,
"Many times an antenna manufacture will design and test a C.B. antenna on a higher frequency because the antenna is smaller and more convenient to handle. This method has its flaws however, because sometimes the scaling down will have an effect on the testing and an antenna that worked well on about 150 MHz will suffer at 27 MHz ,
wishing to avoid this pitfall. Avanti designed and tested the first ASTROBEAM (as they have named it) at 27 MHz"
the astroplane patent clearly states the numbers were measured on a scale model on vhf,
is that how they get the extra gain over a dipole?
you know as well as i do they don't need to put a whole bunch of bs in a patent to fool cbers into buying something,
did they just make it up to fool the patent office into thinking they invented something different to obtain the patent?
the things they claim in the patent about the uptilt in radiation angle with masts less than about 1/4wave in length below the hoop,
and downtilt below the horizon when the legs are not flared out from the mast indicate they did not think the astroplane acts like a simple dipole or starduster, or am i reading that wrong too?
they talk about the effects of the hat loading on efficiency and bandwidth and what happens when the hat is omitted and a full size 1/4wave is used, < this part sounds like what id expect from doing the same thing with a starduster,
the claims of downtilt and uptilt don't sound normal to me,
why does eznec not show these trends? did avanti make it all up?,
or are the transmission-line mode currents which must be flowing at those spacings simply ignored in eznec when modeling an antenna rather than a transmission-line model as i have read in more than one post on the subjest on ham forums,
i cannot get an answer or a look here this explains it,
hope you feel better soon eddie.
Bob, read the whole article carefully and I think you will likely see there is a whole lot of bloviating (CBBS) going on. IMO the BS is from start to finish in that article.
Maybe the 1970's looked pretty good, but it was terrible time for human development, and will probably go down in history as a tipping point between good and evil in our world.
I still have a high regard for the old Top One, and the New Sirio Top One antennas however. Bob, you may quarrel with me on this one too...for changing my mind about this antenna as well.
I think the failure to understand in context the meaning of the cone's contribution to the radiation in the far field is why some get stuck on this point, esp Eddie.
1. it is a long held understanding that radiators with lengths in excess of .625 wavelength of the operating frequency have a very steep TOA.
2. it is a long held understanding that the reason these longer radiators have such steep, virtually useless, TOA is because of the out-of-phase currents on the lowest roughly 1/4 wave of the radiator which are affecting the upper portion of the radiator.
3. there seems to be no real discussion of any positive contribution of the out-of-phase lower radiation of these antennas because it is accepted they have no positive contribution to the radiation into the far field.
4. Therefore, the only thing the cone has to do to put the greater radiation of a 3/4 or 7/8 wavelength antenna into the far field at a useful TOA is to nullify the negative contribution of the lower out of phase currents.
The CST model, and field testing shows this is what is done. And as a bonus there is some, if not a great amount, of positive radiation eminating from the cone itself.
The other day I backed out of my steep drive way into the street. The car seemed to be hampered in its motion. Not until I put it into forward gear did it occur to me to release the emergency brake so the car could roll freely. What a difference this made. Of course, the emergency brake added absolutely ZERO horsepower to my drive train, but neither did it prevent the horses available from galloping into the horizon when I disengaged it.
This is why anyone needing accurate data regarding this design has relied on CST Microwave studio. No model done in EZNEC has ever been able to replicate what we see in the field regarding collinear currents, gain and phase of the radiation currents.
This is not what proves every EZNEC model we have seen of the antenna is wrong even though it does prove EZNEC can only see the design as a 1/2 wave. The irrefutable proof that EZNEC misses significant in phase radiation from the cone is the programs requirement that a 180 degree phase delay be used if you stack another collinear 1/2 wave on top when the only possible delay that works in the field is 90 degrees.
Don't be so sure about that mast either. Take a closer look and you'll notice the CST model does not end directly at the base of the cone. Enough mast is shown below the cone that the currents descending on the mast (or coax) can easily be identified as in phase with the rest of the antenna. It would make no sense to attempt to choke off any residual current here.
With respect to the lack of model info, the reason is much more innocent than your assumptions. Remember I requested the CST model of this design for my use and fully disclosed this fact at the time of my request. Wouldn't it make sense they might remove specific brand information in that case? Your question about gain is redundant since they have published the CST results as 2dbd for many years now. You should also recognize the fact 2db over a dipole would be the same 2dbd regardless of if the model was in free space or over real ground.
Marconi, you know that over the years several people have personally pointed out the deficiencies in Roy's program that have prevented EZNEC for modeling the Sigma with the radiation currents that are apparent in the field. You're also aware that Roy wouldn't touch the subject with a 10 foot pole once you provide him with evidence of these errors. It's one design out of thousands where his program fails miserably. It's obviously much easier for him to ignore the problem than to fix it to please the few who know it fails here.
Let's be careful about taking peoples words out of context here. The ONLY thing Bob "questioned" in his recent post was if "electronic beam tilt" was possible between the two elements. That has no impact on his test results regarding impressive gain on the distant horizon.
Why do you assume a "real collinear" must have a phasing coil you can see? Do you know how many collinear antennas are designed with simple transmission line providing the required phase delay? The currents traveling inside the coaxial cone on the Sigma function as a transmission line to the radiator above it. The cone is an electrical 1/4 wavelength and provides the required 90 degree phase shift from the source to the half wave so that it radiates in phase with CMC on the outside of the cone. CMC is totally separate from any current inside the cone and not affected by cancellation or shielding.
you could be right about the article eddie,
first they expected better results using the astro as the driven element then results were unexpected and they had to figure it out,
or do they mean the magnitude of improvement was the surprise?
i never was fortunate enough to own an astrobeam to form an opinion on how well they work, i don't recall ever seeing them for sale over here,
i won't quarrel over the cte or sirio top-one eddie,
i don't dispute they are effective when mounted at the same tip height as other antennas,
they should be as the current maxima is higher above ground/surroundings,
they put more wind load on your mast/chimney than any other vertical mounted at the same tip height, the sirio more so than the cte or astroplane,
you know my thoughts on antennas made from weak materials and the piss poor unreliable construction of the cte astroclone.