ASTROPLANE best vertical antenna ever?

[Hairball]

I'm really torn on taking everything down and going backwards on performance.

 

[Marconi]

After reading this thread completely I am still not sure of which antenna to run. I currently have a Gainmaster up at about 40ft at the coil. Works great, no issues except at some times of the day a higher static/white noise issue. I live in a highly industrialized area. Other than that I'm very satisfied. I have a brand new Targa BT-101 assembled in the garage ready to go up. I will be able to add some mast to have the top of the Targa/Astroplane at the same tip height as the Gainmaster. I know you will ask why chage it if it not broke? I guess just want to try it as I had an Astroplane in the 70s. I was hoping after reading this thread I would really know if it's worth the hassle to swap them out or not. I only operate on 11 meters so the broadbandedness of the Gainmaster does not affect my opinion and I only have room to run one antenna. Thanks to you all for all of you that posted information.

Thanks,

Harry

Hello Harry,

I can only tell you my experiences with noise, and over a long time on the CB, I see exactly what you describe hearing noise on your GM, it varies from time to time. Alexis tells us, he is in the same boat.

I really appreciate folks that try and mitigate noise, and I hear some really good ideas that are reported producing good results.

IMO, my Gain Master showed me the best example of mitigating common model currents using a choke, bar none, even though I have little experience in noise suppression management.

My antenna modeling has demonstrated Common Mode Currents to me over and over. So, I don't think you can buy, out of the box, a better example of a very good CMC choking setup, than the Gain Master. Plus it always worked exceptionally good for me.

Now, I have also done some old corny videos comparing some of my antennas...as I was comparing the signals only. But I can still look back at these old videos (see link to my Youtube folder in my signature below) and sometimes see that I had other antennas I was comparing to the GM, that showed <>1 Sunit less noise...when no signals were were being transmitted in my area at the time.

So, I've also seen the opposite results at times, so IMP this experience was not always consistent over time for me.

IMO, overall I think the Gain Master was the best all around antenna I ever bought...right out of the box.

BTW, going backwards in performance is not always the worst thing to consider, I think giving up a little gain to get an improvement in receiving can be a big plus.

 

[Hairball]

Marconi,

Thank you for the info. Is there any truth that aluminum/metal antennas have less "white noise" than fiberglass antennas? I run a Yaesu that is very good on receive and I can filter down the static but I just hate to not give the new Targa/Astroplane a try for old time sake.

 

[Marconi]

Marconi,

Thank you for the info. Is there any truth that aluminum/metal antennas have less "white noise" than fiberglass antennas? I run a Yaesu that is very good on receive and I can filter down the static but I just hate to not give the new Targa/Astroplane a try for old time sake.

Good question:

The only experience I remember is getting a mild shock in the winter time, mostly as I walked across a synthetic fiber rug in my bare feet and got a spark on touching the metal door knob.

So Harry, if that qualifies as a reliable source of info...maybe static on a fiberglass tubes, supporting a wire radiator inside, is possibly some reliable information. Probably has been used to support the countless stories we've hear about FG antennas being a notorious static and TVI problem, and worse being described as a bad dummy load.

My circle of old radio buddies use to refer to noise on their receivers as "bad conditions," and that is a pretty broad description. Signals going up and down in strength and volume, were said to be the "the band is stretching or stretching-out."

I don't know the science, but I'm sure someone will have the answer soon. I've heard what is sometimes referred to as white noise, but I'm not sure I know what causes it, but again...I'm sure somebody will have and answer shortly.

I tended to believe much of this type of wisdom until I got my Gain Master.

 

[Hairball]

Well if I pull the trigger before winter and swap antennas I will report with an honest assessment of my experiences between the two antennas. Thanks again for the info.

 

[Marconi]

Good luck Harry and keep us posted.

 

[Hairball]

One more question on the A/P. Has it been figured out what wave it is? 1/4, 1/2 or 5/8? Not that it matters just as long as it works.

 

[dave457]

Avanti sold them as a 5/8 wave antenna

 

[Marconi]

IMO, the AstroPlane produces a pattern very similar to a center fed 1/2 wave dipole, and the currents on my models shows a pattern like a 1/2 wave, but some call is a 5/8 wave antenna and the box is said to have 5/8 wave on the shipping container...so it's whatever.

I can turn the Free Space model I use for the A/P upside down and it looks very similar to a 3/4 wave Sirio New Vector 4000, if I extend the mast inside of the bottom radial area to 3/4 instead of a 1/2 wave...so folks in CB call it a lots of things, but in business the advertising descriptions probably rule and puffing is the old name for what they do to promote products.

It is sorta' like you kids...you can name them whatever you like.

Below are some antenna pattern overlays for a little comparison.

 

[Hairball]

This is probably a dumb question. If I put up the AP, the mast will be 37 feet. Does that length affect the performance in anyway?

 

[Marconi]

This is probably a dumb question. If I put up the AP, the mast will be 37 feet. Does that length affect the performance in anyway?

Harry, that is good question.

Here is my suggestion.

I set my models length for the antenna mast at 192" - 197" x 1..50" inches and extend this mast form the mounting hub and down <> 1/4 wavelength below the loop...at the bottom of the antenna.This will get you close to a 1/2 wavelength overall, considering the diameters in play here.

Then at this point I make a 2" inch isolation, a non conductive space in my models. Then I add the supporting mast below this point, down to the Earth with another pipe also at 1.50" inches in diameter.

I then add a choking device or Isolater for the feed line at this same point. The idea here is to isolate the feed line and the supporting mast from the antenna currents, and minimize the currents on the antenna mast inside the radials and below as much as possible. In this case, another good man on this forum The DB as found that making his models with this antenna mast length set at 220" inches long...instead of the 197" inches like I use, lowers the currents on the antenna mast even more, and that is good.

These ideas have, more or less, been proven to benefit this antenna pattern, the gain and angle of the pattern, the match can also be effected. IMO, the main benefit for this setup idea is helping to eliminate antenna noise from getting into your receiver.

Such results may be found to be amazing, when you can hear weak signals as your CB buddies around you are complaining about too much noise and they can only hear the biggest signals on their receiver.

Harry, my stuff above is relative more toward modeling, but Bob85 is the man to ask about more details regarding the real world results.

So, ask away.

 

[Hairball]

Thank you for the in depth information. It's refreshing to exchange questions and ideas on this forum and not get pounded with negative opinions. Thank s again.

 

[Marconi]

Thank you for the in depth information. It's refreshing to exchange questions and ideas on this forum and not get pounded with negative opinions. Thank s again.

Thanks Harry, but what you say is just a sign of the times...and it happens...just like you say.

 

[freecell]

This is my ASTROPLANE copy avanti AV-101, ALL manufactured in IRON.

I get better signal than a dipole, a loop and a slim-jim.







more than 8dbi


woww

Iron is a poor conductor. Conductivity is the ability of a material to propagate (force vectors of dielectric discharge) an electric current. Steel, including the range of grades known as stainless vary between 3% - 15% conductivity when referenced to copper at 100%. Aluminum comes in at 45 - 61%. See the chart posted further down the page.

Iron has extremely poor conductivity.
Ranking Metal % Conductivity*
1 Silver (Pure) 105%
2 Copper 100%
3 Gold (Pure) 70%
4 Aluminum 61%
5 Brass 28%
6 Zinc 27%
7 Nickel 22%
8 Iron (Pure) 17%
9 Tin 15%
10 Phosphor Bronze 15%
11 Steel (Stainless included) 3-15%
12 Lead (Pure) 7%
13 Nickel Aluminum Bronze 7%

 

[freecell]

Modelled using eznec4, with the av101 at a feedpoint height of 36 feet we see the following:

Slice Max Gain: 4.38 dBi @ an Elevation Angle of 31.0 degrees.

This is the highest gain seen from configurations at 18', 27' 32' and 36' feedpoint heights, installed in the usual fashion, on a conducting mast from ground level to the feedpoint. Lowest Elevation Angle occurs @ 18' and is 16.0 degrees with gain @ 2.80 dBi. Beginning at 27' we see a second lobe evolving at higher angles and reduced gain figures. At no height mentioned above do we see anything close to the advertised gain appearing at an elevation (takeoff) angle of 5 degrees as mentioned in the patent and depicted using the polar elevation chart shown in figure 7 of the patent.

In addition, both resonant and non-resonant levels of high and low current, both in phase and out of phase with regard to the antenna are seen flowing in the support structure at all four heights.