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SIRIO SD-27 Dipole

haha - That is funny, and this thread is too. Check this out from:

End-fed Vertical and J-pole

You need to go there to see the pics. Seems the modeling software no likey the Imax.

I-Max 2000 Solarcon A-99 Antenna

The following model is an I-Max 2000 5/8th wave vertical with a vertical feedline or mast connected to the antenna base, and no radials. In this case I picked the worse case multiple of feedline or mast length:

Feedline current is 100% of antenna current. This illustrates why so many people complain about SWR problems and RF in the shack with end-fed verticals like the I-MAX 2000! Other people do not complain and seem to love the antenna. This is because some people pick a lucky mast height or feedline length, while others are not so lucky. They chose a mast height, feedline length, or grounding system length that enhances common mode.

Here is the pattern of an antenna that copies the I-MAX dimensions and feed system:

This is a NEGATIVE gain antenna at low angles. A 1/4wl groundplane would seriously out-talk the I-MAX 2000 or any other 1/2 or 5/8th wl antenna that does not have a large groundplane.

Even if we use the optimum feedline and mast length, here is the very best the end-fed antenna will do:

In this case we now have 2.67 dBi, which is actually a little less than a 1/4wl groundplane will do! The severe common-mode mast and feedline currents make "no-radial" verticals extremely sensitive to mounting height, mounting structure, feedline length, and grounding. This is NOT normal for antennas, it is a sign of a design problem.

Lazybones, this article claims a worse case use for the Imax noted in the image shown. The author does not tell us what that height is, but can we tell anything from that picture that suggest approximately what the height might be?

 
Amazing. RF is an alternating current (AC) feeding the negative and postive sections of an antenna. A dipole is the perfect balanced receptor for a balanced AC waveform. However, an antenna without a radial section is declared the cats meow, while a perfectly balanced dipole is "foo pawed" as being nothing more than a scanner antenna.

I guess coax is better than ladder line too - right?

I don't know if I should laugh or cry.
 
Here is one for you Robb, thought it appropriate. :)

from : Antenna Myths

The DX Myth

No doubt, the single, most often used reference (past the point of triteness) is the number of DX stations said antenna installation garnered. How or why this practice got started is an unsolvable mystery. As condescending as it may sound, amateurs who use their DX contacts as a reference, typically have the poorest of installations, and the worst of operating skills. If your intent is to be a LID (very poor operator), then visit this web page.

Just for the record, the number of DX stations worked has no correlation to any antenna parameter.


Just for fun:

How to sound like a LID
Whatever.
What I put down is the truth. If those people that are willing to throw around unfounded allegations to the contrary, fine. This antenna has done all that I said it did. Solid contacts as well. The antenna works. Some Hams like to put down CB usage for stupid reasons. I can say that, as I am a Ham. You'd be surprised how well it works on 10 meters too, just got a couple of QSL cards today. Some Hams use it on 12 meters with fair results.
 
Whatever.
What I put down is the truth. If those people that are willing to throw around unfounded allegations to the contrary, fine. This antenna has done all that I said it did. Solid contacts as well. The antenna works. Hams like to put down CB usage for stupid reasons. I can say that, as I am a Ham. You'd be surprised how well it works on 10 meters too, just got a couple of QSL cards today. Some Hams use it on 12 meters with fair results.

i'm not sure if i should respond to lazy, or the afore-quoted post. and i WILL go as far as saying....i just don't think 'robb' gets it. i've been '20 over 9' on the proverbial coat-hanger a thousand miles off into skipland. what exactly does that have to do with REAL performance of said coat-hanger? absolutely NOTHING. that coat hanger may NEVER 'get out' again. or, it may every time the planets align correctly & the moon is right. as for 'straight trip' local contacts-my next door neighbor SHOULD hear me every time, but that coat hanger AIN'T NEVER comparing to a wire dipole strung vertically between 2 birds nests. THAT is why SKIP cannot be used as a performance measurement.
anywho, as was not-completely-noted, but 'meant', on another forum, the a99/imax 2000 COULD be a better choice due to MOUNTING differences. those 2 radial-less 'things' could be correctly mounted ABOVE any performance-skewing objects, as well as not having to worry about side-interaction from any metallic mounting objects.
just WHAT exactly the a99/imax 2000 are, is open to speculation. a REAL groundplane, 1/2 wave, 5/8, .64 or whatever, using radials is, generally speaking 'full-length'. even if the antron antennas are 'considered' full-length, WHY, when you unravel the fiberglas, is there a WIRE coiled around the inner support???
 
i'm not sure if i should respond to lazy, or the afore-quoted post. and i WILL go as far as saying....i just don't think 'robb' gets it. i've been '20 over 9' on the proverbial coat-hanger a thousand miles off into skipland. what exactly does that have to do with REAL performance of said coat-hanger? absolutely NOTHING. that coat hanger may NEVER 'get out' again. or, it may every time the planets align correctly & the moon is right. as for 'straight trip' local contacts-my next door neighbor SHOULD hear me every time, but that coat hanger AIN'T NEVER comparing to a wire dipole strung vertically between 2 birds nests. THAT is why SKIP cannot be used as a performance measurement.
anywho, as was not-completely-noted, but 'meant', on another forum, the a99/imax 2000 COULD be a better choice due to MOUNTING differences. those 2 radial-less 'things' could be correctly mounted ABOVE any performance-skewing objects, as well as not having to worry about side-interaction from any metallic mounting objects.
just WHAT exactly the a99/imax 2000 are, is open to speculation. a REAL groundplane, 1/2 wave, 5/8, .64 or whatever, using radials is, generally speaking 'full-length'. even if the antron antennas are 'considered' full-length, WHY, when you unravel the fiberglas, is there a WIRE coiled around the inner support???
Oh I get it just fine. Maybe those that don't get it don't also understand that I do this every day skip is in. Including today.
http://www.video-observer.com/imax/imax2000.htm
http://www.eham.net/reviews/detail/1376


Overall, the 'IMAX Exposed' page answers all previously asked questions.
Buy yer own!
Get it yet?
Interesting point of the Sirio dipole is that it can be flipped from vertical to horizontal.
Versatile; but a little awkward to change over between positions. Especially if it is already high on a mast.
 
i'm not sure if i should respond to lazy, or the afore-quoted post.

Just trying to get along and play well with others dave.....just trying to get along. (secretly I think antennas that violate certain principles are garbage - but don't quote me on that)



BTW - The driven element of a beam is - is - is.....ok I'm gunna say it, A DIPOLE!! Add a reflector and some directors and then you have real gain.

Give me my dipole or give me death!!!! lol
 
Oh I get it just fine. Maybe those that don't get it don't also understand that I do this every day skip is in. Including today.

'NO, i don't think you do'....quoting W6XRL4 in his judge chamberlain haller incarnation. i've done incredible things when 'the skip is in'. do you know the difference between your CA skip going to southern cal. or WA vs going to HI vs going to equi-distant south of the equator vs all the way to the east coast on 11m? nobody ever said your or anybody's imax or antron or angel hair pasta noodle can't talk skip. non-propagation aided, line-of-sight signal on 11m is what lazy is looking for. and, i just happen to think you might be right in that the imax/a99 is a better choice for lazy's intended use then the sirio dipole. maybe better choice is the incorrect terminology as i'm not implying that your antenna IN FREE SPACE is the better choice-though it just may be-but that there SHOULD be a better opportunity to MOUNT your antenna WITHOUT skewing the pattern, then with a VERTICAL CENTER FED DIPOLE.
you need a bit more....training....hands-on....something....if you truly believe that 'No doubt, the single, most often used reference (past the point of triteness) is the number of DX stations said antenna installation garnered', is definitive proof of anything other then the antenna sent a signal off into air. skip has absolutely NOTHING to do with effectiveness of an antenna! i talked to FL from the northeast on a $49, 39" midland 'stealth' base antenna. i talked to GA on a handitalkie, with the telescopic antenna & 5 watts, i talked to IL with the center conductor of a piece of coax stuck to the antenna MAST, with NO antenna on it....all on CB. i talked to the ukraine on 40m....with JUST the matching xformer after the end fed wire got pulled out of it by a tree branch. probably couldn't get an S-3 signal out past a mile locally with those 'loads', yet they ALL talked skip. does that make them as good as your antron? or lazy's sirio for that matter. i doubt it. please, go read a bit of the arrl handbook, or the manual that came with your ham test question & answer memorize-me book. i WILL give you credit for getting your ham license though. just learn a little about what you're talking about, please.

'Just trying to get along and play well with others dave.....just trying to get along. (secretly I think antennas that violate certain principles are garbage - but don't quote me on that)', sorry, lazy, antennas that violate certain principles are liars when they're called something they ain't. if they work, who cares. if they cost too much, they're thieves. as for playing well with others....i do that as well as an MMA person in a girls field hockey game ;-)
 
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hmmmm . . .
ahh, what's for dinner?

I had a pot roast with carrots, onions, potatoes and mushrooms all about. It was fantastic. Now I have gas.

Come on people, all this fuss over a dipole? The vast majority of people I talk to are on dipoles. How can you not love a dipole, they are so cute. And look at the pattern when you stand it on it's end! So cute......

Dipolentstehung.gif
 
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Read the ARRL amateur radio handbook for starters! You'll learn a great deal about how antenna theory works and the practical applications used for ALL types of antennas. Then you'll understand how the "gain factor" works! :thumbup:
n9zas

I think you are the one that needs to read it John. If you had, you would see I have valid points that are being "danced around."
 
I had a pot roast with carrots, onions, potatoes and mushrooms all about. It was fantastic. Now I have gas.

Come on people, all this fuss over a dipole? The vast majority of people I talk to are on dipoles. How can you not love a dipole, they are so cute. And look at the pattern when you stand it on it's end! So cute......

Dipolentstehung.gif

MMM, Umm, delicious.

Today was grilled potatoes, Squash, and onions seasoned with butter, garlic, salt and pepper with a side of grilled beef.

And I like dipoles every which way.
 
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Big brown truck delivered my Imax 2000 Last July 1,Put it up and had excellent reports,About 430 that afternoon a thunderstorm rolled into my Florida Backyard and after a bright flash all that was left of my brand new Imax was the base collar and a 1 inch accumulation of fiberglass dust,Man I had a case of fire in the wire,Got to figure out what to try next that will hold up a bit better to the big spark....Jay on de sandpile.,,,
 
Amazing that it didn't get you or your radio.
Usually does.
No such thing as a lightning-proof antenna; never was - never will.
Florida is the 'lightning capital of the world'...
 
Oh it Did,It also took out everything that was plugged into a power socket,Did not Touch the HVAC, Never Figured that out And the coaxial was even routed within inches of the unit !I was lucky the place did not burn down !!
 

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