ASTROPLANE best vertical antenna ever?

[bob85]

Good video, that fixes the coax most of the time ,

its also important remember that conductive masts or ground wires are EXACTLY the same as your coax outer braid,

they can share the same current, they can radiate unwanted rf & they can pick up the same noise as your coax braid,

and while doing it they can spoil your radiation pattern & cause vswr to change with changes in length just like your coax braid.

 

[Marconi]

Sounds like a good plan to me Bob.

With my recent sense of appreciating a vertical monopole, where the antenna works generally with a much lower "noise floor," (an S-Meter reading when no RF signals are to be noted on the meter)...I think much of what you are describing above will surely help your RX receive pleasure in operations of you station.

I just found one of my old videos that clearly shows a difference in the "noise floor" signal while comparing my GainMaster to my Sirio New Top One. The incident is starting at about 7:14 o'clock on this old corny video I did.



The signal conditions were somewhat quiet but the band was acting strange, I didn't sense any DX at the time, and the guy I was talking to (DJ) was about 60 miles to the West of me...and he used a vertical M103C Maco beam up about 40' feet. The signals were fading up and down at times. That said, this clearly shows my NTO floor noise was 1 Sunit less than my Gain Master.

This video is the only chance I would ever have to go back and see this happen while I was comparing signals.

Again, I never considered tracking these responses, but now I appreciate the difference, and likely it is more important than any gain differences I was testing to see.

Below is the Signal Report where I recapped the info from watching this video which I posted on YouTube. The PDF file allows one to Zoom-In for a closer look at the old pencil notes I made on the report.

 

[bob85]

Eddie,
round here most locals not only know noise is a problem some comment that i can hear EVERYTHING & talk to people they can't hear when they are closer,

i don't see any difference in noise between astroplane and gain-master in the same place but my antenna is 120ft+ from houses & well isolated with chokes at both ends of the coax like the video you posted,

i can't compare signals because the base of the gain-master is about the same height as the tip of the astrplane was,

& we don't get the same weather as you guys in sunny Texas charging our fiberglass antennas up so that could be playing a part.

 

[Marconi]

& we don't get the same weather as you guys in sunny Texas charging our fiberglass antennas up so that could be playing a part.

Well Bob, maybe you're right.

There are so many variables to consider in antenna performance, that IMO your idea here, makes such comparisons unlikely in providing any good information for evaluation.

Honestly, I never consider the charging effects, of Sun and Fiberglass, either.

i don't see any difference in noise between astroplane and gain-master in the same place but my antenna is 120ft+ from houses & well isolated with chokes at both ends of the coax like the video you posted,

Bob to be clear, in this video I was comparing my Sirio New Top One to my Gain Master, and and the Signal Report shows the heights at the tips of the antennas.

I think my NTO always typically showed a bit lower noise level than my other antennas during my comparison work. Even when I compared the NTO to my Old Top One I think this also showed the NTO tended to be quieter.

I've never owned an Avanti AstroPlane, but my models show the NTO with a bit more gain, a better match, and a better pattern with better symmetry.

I will make a post below that has a link to an old post I made that tells an old story about a lossey feed line on my Old Starduster. IMO, this is another factor that in the right circumstance can produce a very quiet operating antenna system...and I personally experienced this incident among a few local CB buddies that brought my low signal to my attention.

 

[Marconi]

Here is the link: I've told this story several times, so the content here might not be about quiet operations of an antenna system, but the details in the story should be similar.

SWR HAPPENINGS ?

 

[bob85]

I have no doubt that lossy coax reduces noise and signals Eddie,

I once used close to 200ft of rg58 as a put me on to get the antenna away from the house,
if I remember correctly 100w at the radio gave me 42w at the antenna,
receive was obviously attenuated the same including the noise,

comparing noise between antennas depends on what noise you are talking about,

if its band noise then having two antennas up in different places using equal lengths of the same coax won't make much if any difference with that type of noise,

But if its local noise from electrical goods that nowadays tends to be the noise received for many people then antenna position & where you run your coax can make a huge difference in noise received,

radio signal strength vs distance has an inverse square law,
so half the distance from noise source to antenna or coax causes much more than double the noise to be received,

I have no doubt the NTO has better symmetry than the astroplane and easier to model,
its a gamma fed hat loaded dipole with a fat lower half,
the only transmission-line in its construction is within the gamma section,

The astroplane is a different animal, its mostly radiating transmission-lines,
theres nothing else remotely like in in cb antennas other than the astroplane clones.

 

[Marconi]

I have no doubt that lossy coax reduces noise and signals Eddie,

I once used close to 200ft of rg58 as a put me on to get the antenna away from the house,
if I remember correctly 100w at the radio gave me 42w at the antenna,
receive was obviously attenuated the same including the noise,

comparing noise between antennas depends on what noise you are talking about,

if its band noise then having two antennas up in different places using equal lengths of the same coax won't make much if any difference with that type of noise,

But if its local noise from electrical goods that nowadays tends to be the noise received for many people then antenna position & where you run your coax can make a huge difference in noise received,

radio signal strength vs distance has an inverse square law,
so half the distance from noise source to antenna or coax causes much more than double the noise to be received,

I have no doubt the NTO has better symmetry than the astroplane and easier to model,
its a gamma fed hat loaded dipole with a fat lower half,
the only transmission-line in its construction is within the gamma section,

The astroplane is a different animal, its mostly radiating transmission-lines,
theres nothing else remotely like in in cb antennas other than the astroplane clones.

Bob, what you say here all seems to make sense too.

Thus, we now have even more complications in evaluating any differences among the CB vertical antennas that others sometimes report-on. Some of the same antennas that I might compare and/or model, and I can't explain why I see such little differences either.

That is unless maybe I compare two antennas, in the real world, at the same height to the feed point. I remember we use to hear this was the only way to test and compare antennas for performance.

It makes me wonder, when we hear and read about other's that claim 1-3 Sunits of differences in signals with their favorite antenna blowing the sock off the antenna they don't like.

And often these same guys can't explain why the differences...no more than I can.

 

[bob85]

I would say that most of the difference people see when both antennas are at he same tip height is not down to the antennas gain or small differences in matching loss between antennas.

other factors like how much current is on the coax braid mast or ground wires matter

its easy to make an antenna look bad,

just bolt it to a metal mast that will carry high common mode without radials & isolation,

or use a coax length that will carry high common mode without radials & isolation & a good choke at the feed-point & you get bitten as well as cause rfi & pick up local noise.

 

[Marconi]

Back in the days when I first got a base antenna and started talking more regular, I think it was back in the late 80's, I recall a couple or three Ham operators would come on channel, and hassle us, making claims about Common Mode Currents and coax issues. And, it wasn't friendly discussions. I didn't know any CB'r, at the time, knew much of anything about those issues...me included.

I can't remember for sure, but I think you might have been the first to start talking about such...in my experience.

Bob, I've tried some CMC mitigation and grounding ideas over time, but I don't recall ever seeing any of those efforts produce a "WOW" moment for me.

Only after a while at modeling, did I start to really realize any significance to mitigation and more recently to noise suppression. And noise suppression is a biggie IMO.

I think I can fairly state that solutions for these type problems, that you've talked to us about repeatedly, could be more important to successful operations...than any difference we might see, simply using a higher gain or the latest whizzbang CB antenna, according to promotions and advertising.

Height makes a difference, and I could always get my Starduster up higher than most any other antenna. It was naturally quiet for me most of the time. I can't say the same for the A99, which I could also get up very high. Now I understand these issues were likely due to much of the problems being discussed here.

Thanks Brother.

 

[bob85]

Nobody on cb here knew anything about the potential effects of mast & coax currents including me Eddie,
i have not come across many hams i know that do either,

some know about rf on the coax when its biting them & some know a choke will reduce it but not what the currents can do to pattern or how it can effect your local noise level,

they all do the typical bolt antenna to metal mast & some run a ground wire to a copper rod, its posted all over the forums as the way to do it ,

just about everybody thinks no radial end-feds are ok even though some hate imax & a99 while others like them,
Nobody questions why that is,

the lovers love them because they withstand bad weather better than cheap aluminium,
& the haters make shit up in their own heads about noisy white dummyloads & rfi monsters ,

most think 1/2wave = crap & 5/8wave = good
when the truth is how you install it can make MUCH more difference that what antenna it is.

Some think having a low vswr stops rf on the coax braid & others just don't think about any of this,

The ones that give any thought at all to coax still think you need 1/2wave multiples to get accurate vswr readings,

only a few of the people i helped fix their issues gives any thought to mast / coax currents & noise,

the rest just sit moaning about the s6 of noise they get or how they can hear F """ all when their neighbor comes home from work,

W4RNL, W2DU, W8JI, changed what i thought i knew,
There is still much to learn .

 

[The DB]

I agree Bob, antenna currents (and even some part of transmission line currents) are largely misunderstood, even by many people who consider themselves knowledgeable.

Its unfortunate, but to truly understand what an antenna is doing, currents really are the key. Either by itself or with some other component RF current literally determine every aspect of an antenna, from its radiation pattern, to its feed point impedance and SWR, to how much noise your antenna picks up when receiving, ect, ect, ect. Pick any aspect of what an antenna is doing, be it as intended or otherwise, its all related to the flow of RF current.


The DB

 

[bob85]

^All 100% true DB

 

[Marconi]

I finally saw the light, and I couldn't agree anymore.

 

[Hairball]

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

 

[Alexis Mercado]

Hairball, I’ll be waiting for your results since I am in the same boat as you.