Any Astro Plane Fans ?

[bob85]

NB,

suggesting DB somehow handicapped the I-10k is laughable,
he is not building antennas for profit, nor I'm sure does he have a hard on for astroplanes or p500's with old adverts on his bedroom wall,
so where is his Horse ? How does he benefit from handicapping the 5/8wave ?
This is the kind of attitude that chases the people you could learn from away from this forum,

DB is not brainwashed by old advertising & sentimentality about 5/8waves blocking his ability to learn,

Let me clear something up.
I don't care about how people on forums talk to me so don't think you or anybody else upsets me in that way,

if trying to bust bullshit comes across as me been a bully to some its not meant to,

what irritates me is somebody constantly making up their own laws of physics & disrupting threads with technobull,

Not because they are saying I'm wrong but because it makes it difficult for anybody wishing to learn something to determine who is talking technobull unless they go read articles from respected sources that often are not easy to understand for average Joe,

Its not my fault that you don't understand WHY a 5/8-.64wave is said to have more gain than a 1/2wave or that the advantage more than vanishes once you raise the 1/2wave to the same tip height,
I explained it multiple times in multiple threads,
you won't find anybody that understands antennas arguing with me on this point.

Current distribution on 5/8 dipoles is basic stuff that you really should understand before arguing about it,

inventing voltage chokes that don't exist is basic stuff, chokes resist changes in current,
maybe you mean self resonant chokes but that's not what you are saying,

The astroplane is not basic antenna theory when you add the mast inside the basket.
It may look like a simple dipole but its not,
that does not mean it whoops a dipole at the same feedpoint height or that I ascribe GOD like properties to it,
the advantage the astroplane has is height of current maxima, that's physics, not religion,

I don't expect you to be able to separate Zt from Za or recognise both impedances are there in parallel in the astroplane when you add the conductive mast, I'm trying to learn that stuff myself,its not easy like basic dipoles.

 

[Riverman]

I tested it with an analyzer, then backed it up with my Yaesu ys-60 watt meter. Also the SWR meter on my 1000MP agrees with the results.

Where have you been all this time, Oscar? Your noticeable knowledge and no-nonsense, straightforward answers are going to be a great addition to these forums. There are some sharp guys here. Just don't let their occasional bickering and name-calling drive you away. I said it once and I'll say it again. Welcome!

 

[Oscar Goldman]

Where have you been all this time, Oscar? Your noticeable knowledge and no-nonsense, straightforward answers are going to be a great addition to these forums. There are some sharp guys here. Just don't let their occasional bickering and name-calling drive you away. I said it once and I'll say it again. Welcome!

Thanks Riverman71
I just try to share my findings with antennas to whoever needs some help. What I did notice about the AP is that with my shorter support mast, it seems to work better for DX contacts. This just could be differences in propagation, or who really knows.
Example.. My mast is ground mounted.
When using a 20 foot mast as compared to 25 foot mast, it seems the shorter mast was better for DX.
But the reverse was true for local out to 25 miles.
Also my mast is insulated at the base, but run it with ground strapped across the insulator. I never tried it fully insulated from ground.

 

[Riverman]

Thanks Riverman71
I just try to share my findings with antennas to whoever needs some help. What I did notice about the AP is that with my shorter support mast, it seems to work better for DX contacts. This just could be differences in propagation, or who really knows.
Example.. My mast is ground mounted.
When using a 20 foot mast as compared to 25 foot mast, it seems the shorter mast was better for DX.
But the reverse was true for local out to 25 miles.
Also my mast is insulated at the base, but run it with ground strapped across the insulator. I never tried it fully insulated from ground.

Those are great observations, Oscar. I'm sure everyone will be interested in them. As for me, I'm not one of the sharp guys. Just someone trying to learn.

 

[Troubleshooter]

Those are great observations, Oscar. All are points that have been heavily discussed/debated in this thread. I'm sure everyone will be interested in them. As for me, I'm not one of the sharp guys. Just someone trying to learn.

Oscar has vast knowledge in antenna systems, I am so glad to see him finally join the forum.. He is a good friend of mine and definetly knows his stuff.. Welcome brother..

 

[The DB]

Hey guys compare the links below and I think you will see DB and Needle Bender are comparing apples and oranges.

It wasn't an apples and oranges thing, he made a claim that wasn't true and I challenged it. This is the claim.

And as far as the AP exhibiting a 'lower TOA' - well from the many 5/8 & AP models I've seen posted on this forum, it appears the 5/8 have their greatest gain in the 8°- 9° lobe whereas the AP appears to have its highest gain lobe up about 32°

This claim was false, and when I pointed it out he didn't deny it. In fact, this is part of what he had to say about it.

so DB, yes I flew a bit too quickly through the last few pages and mistook Marconi's "Old Top One" models for being anywhere near close to an AP.

On this point their is no longer disagreement between he and I.

Since you did not post an image of your model, only the pattern overlays, I assume your models above are isolated (ISO) at the base of the mast inside the antenna and below the bottom hoop.

Yes, most of them are. Its not like I am tied to it, but I have a note on the optimum mast length, and generally I keep the mast at that length. That being said, perhaps I missed it, but I am not sure about the height of the antennas in said document. I would guess by looking at it that the models are near 36 feet to some part of the antenna, and I am guessing that the part of the antenna in question is the hoop as when I mount the antenna's hoop at 36 feet I get the same low angle for the low angle lobe as you, or within a degree or so. I also get less gain than you overall and a pattern that looks very different from yours. If I am making an incorrect assumption let me know.

EDIT: Come to think of it, perhaps I should model both the mast and the outside of the feed line. The thing that concerns me about the mast only going straight down to the earth is that isn't always the case for people. Take my house for example, if I mounted an antenna mast on the chimney which is in the middle of my roof and ran a ground wire, the wire would not go straight down to the earth, and in fact would end up being longer, which could in and of itself change things.

I know that Avanti published a gain of 4.46 db over an isotropic source and the model in my link above shows a maximum gain close to 4.46 dbi at 32* degrees. IMO this is similar to Bob's ideas that Avanti puffed about their antenna performance just like other manufactures are prone to do.

I found the 4.46 dBi gain point for my model with the mast attached straight down to the earth below. In my case, the feed point is at 45.5 feet off the ground, and the low angle lobe, which is where the gain is, is at 11 degrees off of horizontal.

I cannot explain the difference in antenna gain between our models for the examples above, but I have models that produce similar gains to yours when I use two wires for the hub instead of the 5 wire design I use...that simulates the A/P antenna's hub at 2.50" x 6" inches.

DB, maybe when you get some time we might discuss these gain differences.

This I am curious about, could you explain what you did and why here?


The DB

 

[Oscar Goldman]

It wasn't an apples and oranges thing, he made a claim that wasn't true and I challenged it. This is the claim.



This claim was false, and when I pointed it out he didn't deny it. In fact, this is part of what he had to say about it.



On this point their is no longer disagreement between he and I.



Yes, most of them are. Its not like I am tied to it, but I have a note on the optimum mast length, and generally I keep the mast at that length. That being said, perhaps I missed it, but I am not sure about the height of the antennas in said document. I would guess by looking at it that the models are near 36 feet to some part of the antenna, and I am guessing that the part of the antenna in question is the hoop as when I mount the antenna's hoop at 36 feet I get the same low angle for the low angle lobe as you, or within a degree or so. I also get less gain than you overall and a pattern that looks very different from yours. If I am making an incorrect assumption let me know.

EDIT: Come to think of it, perhaps I should model both the mast and the outside of the feed line. The thing that concerns me about the mast only going straight down to the earth is that isn't always the case for people. Take my house for example, if I mounted an antenna mast on the chimney which is in the middle of my roof and ran a ground wire, the wire would not go straight down to the earth, and in fact would end up being longer, which could in and of itself change things.



I found the 4.46 dBi gain point for my model with the mast attached straight down to the earth below. In my case, the feed point is at 45.5 feet off the ground, and the low angle lobe, which is where the gain is, is at 11 degrees off of horizontal.



This I am curious about, could you explain what you did and why here?


The DB

Thanks Riverman71
I just try to share my findings with antennas to whoever needs some help. What I did notice about the AP is that with my shorter support mast, it seems to work better for DX contacts. This just could be differences in propagation, or who really knows.
Example.. My mast is ground mounted.
When using a 20 foot mast as compared to 25 foot mast, it seems the shorter mast was better for DX.
But the reverse was true for local out to 25 miles.
Also my mast is insulated at the base, but run it with ground strapped across the insulator. I never tried it fully insulated from ground.

I removed the ground strap across the base insulator on my 25 foot mast holding the AP up.
My swr curve shifted up 300khz from the original 26.965 to 27.600 to 27.280 to 28.000. I did notice more local power line noise compared to the mast grounded. The transmitter seems to be operating fine with no RFI from common mode on the feed line.

 

[Oscar Goldman]

Oscar has vast knowledge in antenna systems, I am so glad to see him finally join the forum.. He is a good friend of mine and definetly knows his stuff.. Welcome brother..

Thanks Troubleshooter

 

[The DB]

I removed the ground strap across the base insulator on my 25 foot mast holding the AP up.
My swr curve shifted up 300khz from the original 26.965 to 27.600 to 27.280 to 28.000. I did notice more local power line noise compared to the mast grounded. The transmitter seems to be operating fine with no RFI from common mode on the feed line.

When I model these two situations, namely a grounded and ungrounded version of this antenna mounted with the feed point at 25 feet off the ground, I did notice a slight shift in the SWR curve in the same direction. It wasn't as large as yours, about 200 KHz, but it happened. I also noticed that disconnecting the mast from the earth caused a pretty significant amount of common mode currents to flow in the mast. It was honestly the most I have seen in any of my models of this antenna. I don't know that it would be enough to cause a problem, however, it would make it more sensitive to things like the line noise you mentioned.

*****EDIT*****
I just noticed that their was an observation about the antenna that was disconnected from ground had better DX performance that I missed in my reply. Modeling agrees with that as well.

The red plot and its label including "mcg" means "mast connected to ground"
The blue plot and its label including "mdg" means "mast disconnected from ground"

This model agrees with your observation. The model with the mast not connected to ground actually has more than 10% greater efficiency overall, as well as a slightly wider 3 dB beamwidth as compared to the model that is directly connected to the earth. Both of which will allow for more reliable DX contacts.
*****/EDIT*****

When it comes to the 20 vs 25 foot mounting height, the 20 foot length did have a slightly higher angle of radiation for its low angle lobe, however, its lobe also covered a much larger area of the sky within its 3dB beamwidth than the antenna mounted at 25 feet. It did have 0.38 dB less gain overall, but that isn't a noticeable difference. If skip conditions were very good to the point that the higher angles of radiation could be used, it would have a definite advantage over its counterpart that was mounted higher. And when it comes to local contacts, the higher antenna will always have the advantage over a lower antenna.

An oddity to note, the antenna mounted at 20 feet has a radiation efficiency of 57.24%, while the antenna mounted at 25 feet only has a radiation efficiency of 52.06%. It is unusual, however not unheard of, for an antenna that is mounted lower to report a higher efficiency than the same antenna mounted higher. It is just an interesting detail I noticed with this comparison.


The DB

 

[bob85]

Something i noticed with my astroplane is when i first put it up i was in a rush in the dark & it was starting to rain,

i guessed the mast length, the choke was done slapdash wrapped around an empty lemonade bottle & taped to the isolator,
not scramble wound but far from a neat solenoid 5 turn choke,
i left the bottle in and walked the wet & slippy pole up,

it looked stupid but i was back on the air,

i have a plasma tv pretty close to the radio, every time i turned the tv on the receiver noise floor lifted,
i could hear low level sizzling on weak FM stations,

since i tidied the choke up & set the mast above the isolator the tv noise has gone.

 

[Oscar Goldman]

When I model these two situations, namely a grounded and ungrounded version of this antenna mounted with the feed point at 25 feet off the ground, I did notice a slight shift in the SWR curve in the same direction. It wasn't as large as yours, about 200 KHz, but it happened. I also noticed that disconnecting the mast from the earth caused a pretty significant amount of common mode currents to flow in the mast. It was honestly the most I have seen in any of my models of this antenna. I don't know that it would be enough to cause a problem, however, it would make it more sensitive to things like the line noise you mentioned.

When it comes to the 20 vs 25 foot mounting height, the 20 foot length did have a slightly higher angle of radiation for its low angle lobe, however, its lobe also covered a much larger area of the sky within its 3dB beamwidth than the antenna mounted at 25 feet. It did have 0.38 dB less gain overall, but that isn't a noticeable difference. If skip conditions were very good to the point that the higher angles of radiation could be used, it would have a definite advantage over its counterpart that was mounted higher. And when it comes to local contacts, the higher antenna will always have the advantage over a lower antenna.

An oddity to note, the antenna mounted at 20 feet has a radiation efficiency of 57.24%, while the antenna mounted at 25 feet only has a radiation efficiency of 52.06%. It is unusual, however not unheard of, for an antenna that is mounted lower to report a higher efficiency than the same antenna mounted higher. It is just an interesting detail I noticed with this comparison.


The DB

Thanks for the input.
I do like the performance better at 20 foot mast height, since I do not local talk that much. I was going to put it on a 30 foot mast, but I do not know how it will affect performance. Maybe this antenna is more ground dependent than I thought. Also the wider lobe will be better for more stations coming in at different arrival angles.

 

[Oscar Goldman]

Something i noticed with my astroplane is when i first put it up i was in a rush in the dark & it was starting to rain,

i guessed the mast length, the choke was done slapdash wrapped around an empty lemonade bottle & taped to the isolator,
not scramble wound but far from a neat solenoid 5 turn choke,
i left the bottle in and walked the wet & slippy pole up,

it looked stupid but i was back on the air,

i have a plasma tv pretty close to the radio, every time i turned the tv on the receiver noise floor lifted,
i could hear low level sizzling on weak FM stations,

since i tidied the choke up & set the mast above the isolator the tv noise has gone.

Very interesting.
I have a plasma in the living room. I can hear it on 40 meters throwing hash all over the band, but not on 10 or 11 meters with the AP.

 

[The DB]

Thanks for the input.
I do like the performance better at 20 foot mast height, since I do not local talk that much. I was going to put it on a 30 foot mast, but I do not know how it will affect performance. Maybe this antenna is more ground dependent than I thought. Also the wider lobe will be better for more stations coming in at different arrival angles.

Here you go, a comparison at 20 and 25 feet like above with 30 feet added in as well.

While, again, it has a higher overall gain and lower angle of radiation than the other antennas, its beamwidth is the same or less than the antenna mounted at 25 feet. It is also less efficient that the other two antennas in this comparison. For your wants being DX, I would not make that change, unless you wanted to compare your situation with this modeling result.

I agree with your statement about the wider lobe and its advantages for DX. Most people blindly aim for as much gain as the lowest angle possible, and flat out ignore everything else. I guess they think that all DX signals come in on that very narrow range of angles or something...


The DB

 

[bob85]

DB
do you know how nec calculates efficiency?
is it height above ground, the mast length or current magnitude on the mast that's changing efficiency,
what else could it be ?

i agree the lowest angle is not always the best for dx,
i have had whoopings in DX from stations that could not reach local stations that i could on the vector,
i had the 5/8 low mounted cloudwarmer that worked 600 miles that my vector never has.

 

[Oscar Goldman]

Here you go, a comparison at 20 and 25 feet like above with 30 feet added in as well.

While, again, it has a higher overall gain and lower angle of radiation than the other antennas, its beamwidth is the same or less than the antenna mounted at 25 feet. It is also less efficient that the other two antennas in this comparison. For your wants being DX, I would not make that change, unless you wanted to compare your situation with this modeling result.

I agree with your statement about the wider lobe and its advantages for DX. Most people blindly aim for as much gain as the lowest angle possible, and flat out ignore everything else. I guess they think that all DX signals come in on that very narrow range of angles or something...


The DB

Nice model
That is what I kind of figured what would happen going higher with it. I also like the antenna better with the straight top section I have on, then with the capacitance hat like the original design.
It just seems to play better.