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Old February 11th 11, 05:41 AM posted to rec.radio.amateur.antenna
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Default Loop fed yagi

Has anyone used or tried an antenna like this ?

http://www.g0ksc.co.uk/intro-lfa.html

Called a loop fed yagi. It is mostly a VHF beam where the driven element is
a loop. The loop is flat with the boom so it looks similar to an extra
element with the ends joined.

There is an example of a 5 element 50 mhz beam. It takes about the same
ammount of aluminum to make a 6 element beam. Would this antenna be more of
an advantage over a 6 element beam of say the K1FO type ?




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Old February 11th 11, 07:58 AM posted to rec.radio.amateur.antenna
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Default Loop fed yagi

Has anyone used or tried an antenna like this ?

http://www.g0ksc.co.uk/intro-lfa.html

Called a loop fed yagi. It is mostly a VHF beam where the driven element is
a loop. The loop is flat with the boom so it looks similar to an extra
element with the ends joined.


Hmmm. It's somewhat similar in philosophy to the "quagi" (Yagi-type
directors, with a quad-loop driver and reflector, but I think it's
even closer to being a Yagi with a folded-dipole driven element (you
can think of a folded-dipole DE as being a very-wide-and-shallow
loop).

You can follow a progression of these designs, from a Quagi (which
uses a square loop DE), to this "loop-fed Yagi", to a standard Yagi
fed with a folded dipole driven element, and then to the WA5VJB "Cheap
Yagi" with its half-folded dipole driven element. All of these use
the folding or looping of the driven element to raise the feedpoint
impedance, which would otherwise usually be well below 50 ohms. The
shape of the driven element controls the type of impedance
transformation you get.

--
Dave Platt AE6EO
Friends of 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 February 12th 11, 02:41 PM
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Default

Quote:
Originally Posted by Dave Platt View Post
Has anyone used or tried an antenna like this ?

http://www.g0ksc.co.uk/intro-lfa.html

Called a loop fed yagi. It is mostly a VHF beam where the driven element is
a loop. The loop is flat with the boom so it looks similar to an extra
element with the ends joined.


Hmmm. It's somewhat similar in philosophy to the "quagi" (Yagi-type
directors, with a quad-loop driver and reflector, but I think it's
even closer to being a Yagi with a folded-dipole driven element (you
can think of a folded-dipole DE as being a very-wide-and-shallow
loop).

You can follow a progression of these designs, from a Quagi (which
uses a square loop DE), to this "loop-fed Yagi", to a standard Yagi
fed with a folded dipole driven element, and then to the WA5VJB "Cheap
Yagi" with its half-folded dipole driven element. All of these use
the folding or looping of the driven element to raise the feedpoint
impedance, which would otherwise usually be well below 50 ohms. The
shape of the driven element controls the type of impedance
transformation you get.

--
Dave Platt AE6EO
Friends of 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!
That new antenna company Innova is making them
__________________
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http://www.saferoofcleaning.com
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Old February 13th 11, 12:41 AM posted to rec.radio.amateur.antenna
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Default Loop fed yagi

On Feb 11, 1:58*am, (Dave Platt) wrote:
Has anyone used or tried an antenna like this ?


http://www.g0ksc.co.uk/intro-lfa.html


Called a loop fed yagi. *It is mostly a VHF beam where the driven element is
a loop. *The loop is flat with the boom so it looks similar to an extra
element with the ends joined.


Hmmm. *It's somewhat similar in philosophy to the "quagi" (Yagi-type
directors, with a quad-loop driver and reflector, but I think it's
even closer to being a Yagi with a folded-dipole driven element (you
can think of a folded-dipole DE as being a very-wide-and-shallow
loop).

You can follow a progression of these designs, from a Quagi (which
uses a square loop DE), to this "loop-fed Yagi", to a standard Yagi
fed with a folded dipole driven element, and then to the WA5VJB "Cheap
Yagi" with its half-folded dipole driven element. *All of these use
the folding or looping of the driven element to raise the feedpoint
impedance, which would otherwise usually be well below 50 ohms. *The
shape of the driven element controls the type of impedance
transformation you get.

--
Dave Platt * * * * * * * * * * * * * * * * * AE6EO
Friends of 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!


Dave I agree with you on the evolution from a folded dipole. Wonder
what this design does for gain and F/B. How do check an N connector to
see if you put it together right? Draw any blood lately?

Jimmie


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