ASTROPLANE best vertical antenna ever?

[Henry HPSD]

Hello Robb,

If i may add..

A j pole doesnt always need RF isolation.
There are those who have can be "dc grounded".

Agreed on the CMC issue, but in all fairness, this could be said for all end fed verticals.
(including the V4K ?)

Yes, in theory (moddeling) you will notice a sligth eleptical pattern.
I doubt if anyone will notice this without measuring equipment.

We allready have quite some J-poles (we sell them) up in the air for CB.
And you know what the strange thing is.
I KNOW the antenna is a halve wave radiator with a 1/4 wave matching stub.

But still all stations claim the antenna is so much better compared to all others.
Think that has to do with "looks" hihi....Now, i could take advantage of it and write on the site "2 s-units independent better than gainmaster etc". But thats not my cup of tea. I Can imagine the antenna outperforming some, due to the additional heigth though.

And there are quite some antenna just rubbish, for which i know they perform less.
What im trying to say...
Im afraid these days i sometimes think:

The costs and effort spend for a new antenna, are responsable for its performance , in a equal way together with the actuall electrical characteristics.

Kind regards,

H.

 

[Shockwave]

Put a J-pole on top of a horizontal Yagi and see how directional its pattern is. On 2 meters you can turn the J-pole and on weak signals it's the difference between white noise and full quieting.

I can say the Vector design only shows evidence of undesirable CMC radiation when the antenna is not tuned to the 50 ohm coax and standing waves are present on the transmission line. When the antenna is properly tuned, no change in length or positioning of the coax will effect the VSWR.

 

[nosepc]

The J-pole does not confine out of phase radiation taking place in the lower 1/4 wave of the vertical radiator. The matching stub on the J-pole skews its radiation pattern. The radiation on the cone of the Vector is omni-directional and nearly equivalent to that of a 1/4 wave monopole. This radiation is in phase with the upper 1/2 wave that extends above the cone.

Anyone who knows a little about antennas, you know that for the next segment of antenna phase radiate in the same direction and phase must be 180 degrees out of phase.

As it does?

Magically gives a flip in the air?

The rest is fantasy, I have not seen a shred of evidence other than a drawing.

 

[bob85]

henry i agree the extra height of current maxima plays a notable part in the better signal performance of a j-pole and vector over shorter antennas on the same mast,
i don't think that is the only reason the vector out performs all other antennas we have tested discounting the big-mac,

i was looking at your j-pole the other day, nice work

cebik in his "some j-poles i have known" tells us wider spaced j's have more pattern distortion due to radiation from the short leg caused by the top of the short leg been out there in fresh air with high impedance while its counterpart is connected to the bottom of the 1/2wave,
causing radiation from the short leg and some asymmetry to the pattern,

your j-pole looks to have a fairly wide spacing, have you done any actual measurements of front to back ratio?

are the gain figures you quote average or peak gain?

im not expecting major asymmetry but it highlights the error in automatic assumptions that the parallel lower 1/4wave has equal phase and current magnitude causing total cancellation of radiating currents in the lower 1/4wave as nosepc claims,

the arrl open sleeve article also claims the 1/4wave sleeve radiates in phase with the upper 1/2wave,
the cst plot again shows some in phase radiation from the sleeve.

 

[W5LZ]

Beside the point, but...
One way of making the radiation pattern (of a 'J'-pole) more symmetrical is by adding a couple more of those 'short legs' around the antenna. If they are added 'symmetrically' the pattern will also become symmetrical. Add enough of those 'short legs' and you got a 'sleeve' antenna, right?
- 'Doc

 

[The DB]

Anyone who knows a little about antennas, you know that for the next segment of antenna phase radiate in the same direction and phase must be 180 degrees out of phase.

As it does?

Magically gives a flip in the air?

The rest is fantasy, I have not seen a shred of evidence other than a drawing.

So your in the "just another j-pole" camp. Its a common camp, but unfortunately it is made up of people that, for the most part, don't completely understand the j-pole to begin with. Almost everyone that I've seen make this claim also claims that a j-pole is just another 1/2 wavelength end fed antenna.

To start lets take a look at the phase of the various parts of a j-pole.

I see part of the matching section is in phase with the top 1/2 wave element of the antenna and part is not. However, it is widely said that the radiation from the matching section of the j-pole cancels. Well lets take a look...

This plot clearly shows different gains on different sides of the the antenna. If the RF from both halves of the matching section perfectly canceled as many people in the j-pole camp maintain the red circle would be centered, but it clearly is not. The only thing that can cause such a difference is the matching section below, part of which is in phase and part of which is out of phase.

Further, for those that think a j-pole is nothing more than a half wavelength antenna...

Note the horizontal radiation patterns (the red circles) and the gain figures from said circles in the above two plots. If you average the maximum and minimum horizontal gain figures of the j-pole pattern above you get a higher average gain figure than the 1/2 wavelength antenna horizontal gain figure. Even though this overall gain increase is minor, it clearly shows that there is a difference between end fed half wavelength and j-pole antenna designes.

This actually makes sense, as the only way to achieve perfect cancellation between the two halves of the matching section below the j-pole's half wavelength radiator is to put both vertical elements in the same physical space, which is physically impossible. Further, if you use four stubs in the j-pole design where all of the stubs are equally spaced around the central element every stub will be in phase with the top 1/2 wavelength section, and thus the "non-apparent collinear" that L. J. Cebik alluded to. It also looks strikingly similar to another design... Go figure...

So for people like you who claim that this antenna works "just like a j-pole" I agree, mostly. I simply disagree with you on how a j-pole works...

Also when it comes to modeling, I have no reason to not believe Shockwave when he claims the Vector/Sigma models do not simulate reality with programs other than CST. He and several other respected names on this forum have tested and shown real world results that line up with the CST data. Further, he has consistently given reliable information in general on any number of other topics.

Now if only I could afford CST Microwave Studio...

Modeling data:

The j-pole is modeled 5.5 meters or 1/2 wavelength above 4nec2's "Real Ground" on the "average" sub-setting. The feedpoint is also several segments above the base of the antenna to simulate the higher feedpoint of the j-pole in relationship to the base of the antenna. The 1/4 wavelength stub is 0.25 meters in the positive "X" direction on the three dimensional plot.

The 1/2 wavelength model base was mounted 8.25 meters over the same "Real Ground" and "Average" sub-setting to achieve the same tip height. This was to match the half wavelength vertical portions of the two antennas up as much as possible to minimize any discrepancy do to the differing length differences. If the two antennas were mounted at the same base height instead, the half wavelength antenna would have even less gain that it does in the diagram above.


The DB

 

[nosepc]

I find no point of parallelism between an OPEN SLEEVE antenna and Vector 4000.

I would like to know where you come and explain it. <gotproof>

http://www.mydarc.de/dk7zb/Duoband/open-sleeve.htm.



I found a page where irradiation show an animated diagram CST??

Looks perfectly corresponding currents coaxial to a stretch of 1/4 wave

Confined streams are displayed on the cone of the antenna.

+ A half wave.

nothing more.

".. It is a high gain vertically polarized .82 wave( ? ) Coaxial antenna. It is the coaxial cone at the base of this antenna.."

http://fmbroadcastantenna.com/dominator.html

Irradiation is not displayed in the same phase, but with a delay of 180 degrees, which affirms my position.

:sneaky2:

 

[AudioShockwav]

Have you taken the time to read any of the above referenced post`s about this antenna?

There are a few years worth of discussion here on this forum about this antenna.

PLEASE open your mind and invest some time researching the words and experience of other members here on the forum about the design.
You will find answers to some of the questions you have in these other threads.


The Member here, Shockwav has done extensive testing with this style antenna.

Take another look at the CST animation with an open mind and see if you see anything other than a 1/2 wave.


Do you not see the radiation on the outside of the cone in phase with the upper 1/2 wave of the antenna?

Finally, Cebik used the words " non apparent collinear antenna"
There is much information to been seen here.

73
Jeff

 

[Shockwave]

I find no point of parallelism between an OPEN SLEEVE antenna and Vector 4000.

I would like to know where you come and explain it. <gotproof>

http://www.mydarc.de/dk7zb/Duoband/open-sleeve.htm.



I found a page where irradiation show an animated diagram CST??

Looks perfectly corresponding currents coaxial to a stretch of 1/4 wave

Confined streams are displayed on the cone of the antenna.

+ A half wave.

nothing more.

Irradiation is not displayed in the same phase, but with a delay of 180 degrees, which affirms my position.

:sneaky2:

I've seen it so many times now I'm no longer surprised. If you want the Sigma / Vector to be nothing more than a 1/2 wave, apparently you can develop a case of "selective blindness".

This extremely powerful force has successfully blocked several members from seeing the lower 33% of many images posted in the forum. Perhaps the bifocals have failed and only allow them to see the top 66% of images.

This is the only logical explanation. I could understand that the worded description may be difficult to follow in every detail but to not see the cones radiation in the CST model is either blindness or denial. You pick.

If you want to learn, STOP RESISTING and accept the fact you have misunderstood the way this antenna works. Keep going on this track and you will be disregarded and ignored as not having a serious desire to learn.

It is unlikely ANY of us has a better understanding of antenna than L. B. Cebik did. If you don't agree with his "non apparent collinear" analysis of the design, you need to adjust your line of thinking to fall inline with the expert who did understand the design.

 

[nosepc]

The absolutely wrong you are.

The animation does not show a phase radiation, but that looks like the current travels 180 °

In the animation the animation erased degrees of phase.

Why? CST modeling shows.

http://fmbroadcastantenna.com/dominator.html

Then make a comparison on anything.

Between a dipole and the "Dominator"

It does not say high, medium, nothing, showing nothing, he may have chosen the diagrams showing a positive and negative hidden.

The animation is clear, there is so blind as those who will not see.

Also not to insist that the antenna is 3/4 radiating wave, if it were good for nothing in CB.

3/4 vertical wave serves to*satellite dish.

 

[Shockwave]

The absolutely wrong you are.

The animation does not show a phase radiation, but that looks like the current travels 180 °

The animation is clear, there is so blind as those who will not see.

Also not to insist that the antenna is 3/4 radiating wave, if it were good for nothing in CB.

3/4 vertical wave serves to*satellite dish.

Now that you obviously see the opposing radiation between the cone and the vertical radiator, you better not tell me you didn't just find your 180 degree phase inversion "flip" you apparently did not see before. Almost like "magic" this antenna has confined the out of phase radiation in the lower section of the vertical.

Now place your eyes on the colors of radiation present around the outside of the cone and notice they perfectly match the phase of the upper 1/2 wave that is allowed to radiate in a constructive phase with the cone. You now have the "non apparent collinear" the genius Cebik described. The more you go against these facts the less genius like you appear.

Your incorrect thoughts that this design is a high angle radiator are based on the fact you keep working with software that has consistently demonstrated NO ability to accurately model this design. It's such a powerful low angle radiator that it's outperforming all other verticals in the VHF FM broadcast band.

It's also interesting to note that most of the time when modeling reveals the majority of energy is contained in the higher angle lobes, it also reveals that out of phase radiation is present on the antenna.

This is the exact effect we should expect with a 3/4 wave IF phase correction has not taken place in the lower 1/4 wave section. The Vector design is a completely different animal. Its cone acts like a collinear by confining out of phase radiation and replacing it with in phase radiation.

 

[Lil'Yeshua]

The absolutely wrong you are.

The animation does not show a phase radiation, but that looks like the current travels 180 °

In the animation the animation erased degrees of phase.

Why? CST modeling shows.

FMBroadcastAntenna.com | FM Broadcast Antenna's

Then make a comparison on anything.

Between a dipole and the "Dominator"

It does not say high, medium, nothing, showing nothing, he may have chosen the diagrams showing a positive and negative hidden.

The animation is clear, there is so blind as those who will not see.

Also not to insist that the antenna is 3/4 radiating wave, if it were good for nothing in CB.

3/4 vertical wave serves to*satellite dish.

The info ised on that link is for. .82/7/8 wave Vector not the new 3/4 wave

 

[Shockwave]

In the animation the animation erased degrees of phase.

Why? CST modeling shows.

FMBroadcastAntenna.com | FM Broadcast Antenna's

Then make a comparison on anything.

Between a dipole and the "Dominator"

It does not say high, medium, nothing, showing nothing, he may have chosen the diagrams showing a positive and negative hidden.

The animation is clear, there is so blind as those who will not see.

Also not to insist that the antenna is 3/4 radiating wave, if it were good for nothing in CB.

3/4 vertical wave serves to*satellite dish.

The phase of the source in the model has been run through one complete 360 degree cycle of drive. The actual phase of the source is also completely irrelevant. The important aspect of phase is that all surfaces of the antenna that are allowed to radiate freely, are also in a constructive phase. Something the CST chart at the top right clearly shows is taking place.

To summarize, field tests, experimentation with phase delays, the most advanced software modeling tool and L. B. Cebik all support the design functions as a "non apparent collinear". That it is definitely a low angle radiator with a complete 270 degrees or 3/4 wavelength of radiation taking place.

 

[nosepc]

"http://fmbroadcastantenna.com/dominator.html"

".. It is a high gain vertically polarized .82 wave( ?? ) Coaxial antenna. It is the coaxial cone at the base of this antenna.. "

What is the coaxial wave???? .82 ??

"..It is the tapered 1/4 wave coaxial cone that sets this antenna apart from others..."


contradictions !!


A phase radiation ONE lobe corresponding to the length of 3/4 wave antenna does not correspond to the frequency of 27MHZ.

ANTENNA LENGTH CAN NOT HAVE IN PHASE 3/4 WAVE

THAT'S IMPOSSIBLE,

 

[The DB]

What was this movie called again?

op:


The DB