Larger diameter, skin effect, affects impedance, resistance and bandwidth, but will you hear it with a too short antenna and 100 mW on AM radio? I don't know? One has to try it. With out analytical data it's just opinion. I looked at 1-1/4" copper pipe. At $9/foot I stopped looking at it. I don't think a radio-shack CB whip vs. 1/2 copper will make it sound fatter. I could be wrong. It might make a difference only measured with a spectrum analyzer.
The transmitter/audio source it self makes most of the difference in fat sound IMHO. Second is the AM radio receiver, which may be kind of crippled audio wise; some are just better than others.
The SStran base loaded antenna design (free on their site) is pretty good, its all spec'ed out, parts instructions. Folks get pretty good results with that. I am going with a mid loaded antenna because I know what Freq I want. If I want to change Freq more than the small about of tuning built-in gives, I have to trade out the loading coil.
1/2 inch copper pipe does quite well, sturdy enough to handle 40+ mph winds, and enough surface area to give a very rich and clean sound.
For those with a Rangemaster, experiment with a 1/2 inch copper pipe fitted with a nut at the bottom to fit the threading on the attachment base and see just how much drastic improvement to that Rangemaster's already great sound you will get!
RFB
Well, it's interesting to talk about.
Mr. Gmcjetpilot - you obviously have a lot
of knowlege.
RFB's aluminum Christmas tree is sure a kick.
If I had my way, I would make an antenna that
is smaller on the bottom and wider on the top.
It is my (possibly correct) understanding that
this set-up would help pull antenna current up
to the top, like a top hat would do. The idea that
a wider top is better was mentioned not too long
ago. I really DON'T know the physics of it.
Because I am not an engineer, I very well may be
out of the ballpark. I just like thinking of different
possibilities. Sometimes I get around to trying them.
Thanks again,
Bruce, MICRO1690/1700
NANO90.9
QUANTUM13.560
Yes. This is why capacitor hats are used to uniform the RF on the vertical evenly. The aluminum Christmas tree antenna does this extremely well.
Imagine an hourglass with only one side with a wide container, the other just a narrow tube. Does not work very well does it.
RFB
For starters, you've missed the whole point of my comment.
RFB: "You're precisely right! The FCC doesn't care if you modify a certified unit"
"NO, the FCC DOES care about modifying kits"
"Oh, that's not what I meant, you were perfectly fine to modify those kits"
"you misunderstood what I meant. Your modification did NOT change it so radically "
"Modifying a kit using components of the same type... again is different"
"With me so far?"
What a jumble of double-speak. You are quick to shoot down others opinions while back-tracking a lot of your own. Nothing is preventing me from expressing concerns over opinions here, obviously, I'm very concerned about the sarcastic nature of yours.
Yes, I would take your Field Inspector buddy's "opinion" because just like the Cop that writes you a traffic ticket, the Field Inspector makes the initial judgment based on his knowledge. Someone at the FCC should be able to define what is and what isn't part of the 3 meter antenna. Why not start with the guy that's going to make that initial judgment. He may not be an attorney but he starts the ball rolling. And if he can't answer the question he damn well better ask his boss.
I'm not the one that said there is something wrong with opinions here or at other forums. You sir, insinuated if the opinion was not based upon your experience it is not valid. Rather it is just hear-say.
I would not say the top hat is a mute (sic) topic as people are asking questions about it. How can you state the majority veere(sic) away from using a top hat? Sounds like an opinion based upon a handful of us questioning the technical aspects of it. There is a very large group of Part 15 users that utilize the top hat. They may not be on the BCB but they have antenna length restrictions just the same. That's not an opinion.
I generally don't argue over opinions. I consider the source and simply choose to accept or disregard them. But you sir, have been very arrogant regarding others.
Tell me something friend...have you ever heard of lessons learned and move on to the next subject of a discussion or do you always bring up past matters that are now days old...for what purpose too I might add.
This is like all the 911 rehashing....instead of putting out the fire, it keeps being fed.
Moveon.org.
And let me say this sir..no one..especially me, has put a gun to your head and insisted you abide by my opinions or interpretations only or anyone elses. Only you do that yourself...as we can clearly see right here. Seems to me that you want us, or me in particular, to set aside what I think and not express that here while everyone else can, or particularly you.
I find that rather disturbing..and a potential personal issue that needs to be worked on...sir.
I'm not the one that said there is something wrong with opinions here or at other forums. You sir, insinuated if the opinion was not based upon your experience it is not valid. Rather it is just hear-say.
No you dont say it at all, you imply it with these days later reviews of old news. I suppose its a matter of interpretation then isn't it. Now if every single post I have put in here preceded with "THIS IS HOW IT IS PERIOD", then perhaps your statement might have some validity. But since that has never happened, then it is a matter of interpretation on your part.
Can we move on now?
RFB
Earlier in this thread, I think it was RF who said..
No it wont make the signal stronger, it just makes the signal more clear at its furthest range.
Hmmm.. ok, how is that so different?
If a signal is not clear enough to listen to at a given distance, but then modifications are applied, which result in making that same signal now useable at the distance it previously was not. - well, then in essence what you have is indeed a stronger signal! --No?
For those with a Rangemaster, experiment with a 1/2 inch copper pipe fitted with a nut at the bottom to fit the threading on the attachment base and see just how much drastic improvement to that Rangemaster's already great sound you will get!
I am really considering trying that after the the install with the standard whip at location first - I'd be interested to experiencing the resulting difference.
I recall hearing the same thing about 5 or 6 years ago on the Community Radio USA forum, and again recently here.
Because now there is more surface area for the signal to be evenly distributed OFF that antenna, thus the signal that was noisy at a given point away from it will be a bit clearer. That does not make the signal fed to the antenna stronger, it just makes the signal chew through over the noise. Its the same thing as raising an FM rig up into the air for LOS, but here we are merely making more footprint for the flea signal to fly away from.
Wider is better, and like the improvement of bandwidth on the Rangemaster using a wider element, is the same with adding loops and hats and all the rest to plain ol vertical elements.
RFB
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After reading several posts on the antenna ideas offered here, I thought I would offer a little concrete example of what I think y'all are talking about. Maybe we could call it an "inverted discone" antenna.
See the link for an explanation of this antenna type.
http://en.wikipedia.org/wiki/Discone_antenna
Gee, it keeps getting lower every time!
I have so much going on - I have to check,
I'm seriously not sure if I started this thread.
Anyway, the ideas I had were meant to be
for my SS-Tran.
I would give my left leg for a Rangemaster,
but then I wouldn't be able to walk very well.
Bruce, MICRO1690/1700
The discone is another type of antenna very much worth discussion. My ARRL Handbook shows illustrations of these for HF, which is the most practical application, since the structure increases in size as wavelength gets longer.
Building one of solid metal, as is shown in pictures, would best require a sheet metal worker, but the type shown in your link with just stiff wires could be home built.
The question to be answered probably by trial would be how well it does standing 10-feet high from the ground.
Any experience with a discone in Part 15?
What about discone for FM part 15?
Oh, you know, Bruce MICRO1700 talked about tin foil.... maybe here is where a cardboard form could be wrapped in tinfoil.
I had a discone for the ham radio 2 meter band.
It WAS homemade by a friend - out of harware
cloth or something like that. It was a fantastic
antenna but it was big. The cone section was
about 4 feet tall for 2 meters (144 to 148 MHz.)
So if you extrapolate that down to the AM band,
were talking about something that would be
much much bigger than a house.
A version for FM would probably be 10 feet tall.
(Just a crude estimation.)
The idea for the upside down cone for AM BCB
is a whole different animal. I was just thinking
that more antenna current would get pulled up
to the top. I'm thinking of a top that would only
be a foot or two wide.
If I ever come up with anything ever, you can bet
it will be goofy and weird, just like the rest of my
Part 15 station. But it will also be fun.
Best Wishes,
Bruce, MICRO1690/1700
If I ever come up with anything ever, you can bet
it will be goofy and weird
You would be surprised at how well weird can work better than normal.
The will to be weird means the will to go outside the box and discover new things not found inside the box.
RFB
I'm going to take a 5 foot pole and
put a cone on the top that will be
about 4 feet high and a couple of
feet wide at the top. The top surface
of the cone will be the wide part.
The top surface will not be conductive
so it won't be a top hat. The RF current
will flow on the outside surface of the
cone. I don't know how I'm
going to do it. But they didn't know
how to build the Lunar Lander - they
just figured the design out as they
went along.
Now this is fun again because I'm going
to figure it out. If it doesn't work, who
cares?
Also, the whole thing will have to be
guyed.
Watch for it in the next couple of months.
It will happen.
Best Wishes,
Bruce, MICRO1690/1700
OK. That's it. They didn't know
how to build the Lunar Lander - they
just figured the design out as they
went along.
Now this is fun again because I'm going
to figure it out. If it doesn't work, who
cares?
That's the spirit! Set aside for awhile all that stale pale stiff upper lip legal this-legal that mumbo jumbo. Throw away them piles of paper filled with endless formulas and 8x11 edges of limitation. For the sake of learning and growing and the good ol days of CREATIVITY....by golly take that small step for man and giant leap for mankind....JUMP..YOU CAN MAKE IT!!! YES..YOU CAN!! CHANGE!!
And if it doesn't work..well you found a way how not to do it for the next time. You still discovered a new frontier! To boldly go where no one has gone before!! (music theme from Star Trek here) SWOOSH!!!
Pay no attention to that man behind the curtain wearing the badge! (theme from Star Wars Emperor scene)
RFB