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Old April 12th 05, 02:02 AM
Fred W4JLE
 
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Default MRA Antenna

Has anyone taken a look at this antenna? I heard the designer on 75 last
night working a CT0, he says his is 18 foot in diameter. His buddy was
running a 6 foot version and 200 watts and worked the DX as well. He claims
that it is a "minium reactance antenna" thus the name.

http://www.smeter.net/wb4ene/mra-antenna.php




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Old April 12th 05, 02:52 AM
John Smith
 
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I am only guessing, but there isn't a backpack/portable version of that
antenna available, is there?
And, I just looked at my car, where would I mount that?
Or, is that the kids playhouse, and it obscures the view of the antenna?
grin

Regards,
John

--
I would like to point out, I do appreciate the "Been there--done that!"
posts. Indeed, now your observations, comments and discourse should be
filled with wisdom--I am listening!!!
"Fred W4JLE" wrote in message
...
Has anyone taken a look at this antenna? I heard the designer on 75 last
night working a CT0, he says his is 18 foot in diameter. His buddy was
running a 6 foot version and 200 watts and worked the DX as well. He
claims
that it is a "minium reactance antenna" thus the name.

http://www.smeter.net/wb4ene/mra-antenna.php






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Old April 13th 05, 02:35 PM
'Doc
 
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Fred,
I seem to recall a simular antenna made by 'MFJ' or 'Hygain',
maybe? No idea how 'well' it worked.
'Doc
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Old April 13th 05, 04:59 PM
Wes Stewart
 
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On Wed, 13 Apr 2005 13:35:42 GMT, 'Doc wrote:

Fred,
I seem to recall a simular antenna made by 'MFJ' or 'Hygain',
maybe? No idea how 'well' it worked.
'Doc


I'm having a hard time seeing the "minimal reactance" part of this
design. Looking at the plot of S11 it looks pretty much like any
other antenna with a single resonance.

It has "minimal" reactance at resonance and is highly reactive
elsewhere.


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Old April 13th 05, 08:04 PM
Dave Platt
 
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I'm having a hard time seeing the "minimal reactance" part of this
design. Looking at the plot of S11 it looks pretty much like any
other antenna with a single resonance.

It has "minimal" reactance at resonance and is highly reactive
elsewhere.


It looks to me as if this is a member of the "Super C" antenna...
short, relatively low radiation resistance, and a lot of top-loading
capacitance.

There's an article or two in one of the early ARRL Antenna Compendium
collections (#1 or #2) which analyzes the "Super C" approach, compared
to a short vertical with a more traditional capacity hat made of
straight wires. The analysis seemed to add up to "Probably not worth
the trouble and money", as a similar efficiency can be achieved more
easily and less expensively with the traditional approach. There's a
*lot* of metal in the MRA, and at the price of aluminum this month I
doubt it's a project I'd start.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!


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Old April 13th 05, 08:29 PM
Jim Kelley
 
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Dave Platt wrote:

I'm having a hard time seeing the "minimal reactance" part of this
design. Looking at the plot of S11 it looks pretty much like any
other antenna with a single resonance.

It has "minimal" reactance at resonance and is highly reactive
elsewhere.



It looks to me as if this is a member of the "Super C" antenna...
short, relatively low radiation resistance, and a lot of top-loading
capacitance.

There's an article or two in one of the early ARRL Antenna Compendium
collections (#1 or #2) which analyzes the "Super C" approach, compared
to a short vertical with a more traditional capacity hat made of
straight wires. The analysis seemed to add up to "Probably not worth
the trouble and money", as a similar efficiency can be achieved more
easily and less expensively with the traditional approach. There's a
*lot* of metal in the MRA, and at the price of aluminum this month I
doubt it's a project I'd start.


Yea, but put in on a rotator and add some horses and it could double as
a merry-go-round. :-)

ac6xg


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Old April 13th 05, 09:45 PM
Dave Platt
 
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In article ,
Jim Kelley wrote:

Yea, but put in on a rotator and add some horses and it could double as
a merry-go-round. :-)


Y'know, I had *started* to add a paragraph to my posting suggesting
that this antenna could be disconnected from its feedline and used as
a jungle gym, but decided that it was a trifle irresponsible to do so.
Too much potentially-sharp metal edges to have around the kiddies, and
there's always that chance that Dad might accidentally key up QRO at
the wrong moment. "Honey, I smoked the kids!"

:-)

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
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Old April 13th 05, 09:54 PM
Fred W4JLE
 
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He was saying that his patent was about to be issued, he also mentioned
something about a fractal top. At that point I QSYed.

"Dave Platt" wrote in message
...
I'm having a hard time seeing the "minimal reactance" part of this
design. Looking at the plot of S11 it looks pretty much like any
other antenna with a single resonance.

It has "minimal" reactance at resonance and is highly reactive
elsewhere.


It looks to me as if this is a member of the "Super C" antenna...
short, relatively low radiation resistance, and a lot of top-loading
capacitance.

There's an article or two in one of the early ARRL Antenna Compendium
collections (#1 or #2) which analyzes the "Super C" approach, compared
to a short vertical with a more traditional capacity hat made of
straight wires. The analysis seemed to add up to "Probably not worth
the trouble and money", as a similar efficiency can be achieved more
easily and less expensively with the traditional approach. There's a
*lot* of metal in the MRA, and at the price of aluminum this month I
doubt it's a project I'd start.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!



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Old April 13th 05, 10:11 PM
Cecil Moore
 
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Fred W4JLE wrote:
He was saying that his patent was about to be issued, he also mentioned
something about a fractal top.


A balanced fractal top hat cannot be beat!!! :-)
That's one of the things that fractals are good at.
--
73, Cecil http://www.qsl.net/w5dxp


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Old April 13th 05, 04:36 PM
Richard Clark
 
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On Mon, 11 Apr 2005 21:02:01 -0400, "Fred W4JLE"
wrote:
He claims that it is a "minium reactance antenna" thus the name.
http://www.smeter.net/wb4ene/mra-antenna.php


Hi Fred,

A simple glance at the SWR chart reveals it is in fact a Maximally
Reactive Antenna - at least the initials are preserved.

73's
Richard Clark, KB7QHC


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