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A good matching method for 2 stack yagi 433 Mhz 8 Element ?
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aria rangga
Apr 16, 2016, 2:01:31 PM4/16/16
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I was designed yagi that has lenght of the driven 0.16186 x 2 m and the boom is 1.5 m. I plan to use hair pin match, but i still confused about how we decided the lenght of hairpin and the looped coaxial ? And when we can change the impedance while we use vwr analyser? I have been using gama match and i measured the impadance while i changing the lenght of the capacitor ( gama match)
John S
Apr 18, 2016, 11:35:47 PM4/18/16
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configuration), you can attach a 1/4 electrical wavelength of 70 ohm
coax to each antenna, connect them to a T, and then attach your 50 ohm
main coax to the T. Like this...
75ohm 75ohm
Ant1--------- ----------Ant2
|
| 50 ohm feeder
Again, Ant1 and Ant2 are 50 ohms each.
John S
Apr 18, 2016, 11:55:08 PM4/18/16
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50 ohm coax throughout.
Jeff Liebermann
Apr 19, 2016, 1:57:00 AM4/19/16
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On Sat, 16 Apr 2016 11:01:29 -0700 (PDT), aria rangga
<aria....@gmail.com> wrote:
>I was designed yagi that has lenght of the driven 0.16186 x 2 m and the boom is 1.5 m. I plan to use hair pin match, but i still confused about how we decided the lenght of hairpin and the looped coaxial ? And when we can change the impedance while we use vwr analyser? I have been using gama match and i measured the impadance while i changing the lenght of the capacitor ( gama match)
These might help:
<aria....@gmail.com> wrote:
>I was designed yagi that has lenght of the driven 0.16186 x 2 m and the boom is 1.5 m. I plan to use hair pin match, but i still confused about how we decided the lenght of hairpin and the looped coaxial ? And when we can change the impedance while we use vwr analyser? I have been using gama match and i measured the impadance while i changing the lenght of the capacitor ( gama match)
<http://www.grantronics.com.au/docs/StkYagis.pdf>
<http://www.ifwtech.co.uk/g3sek/stacking/stacking2.htm>
I suggest you model the antenna with 4NEC2 or EZNEC in order to
determine the optimum spacing. Neither program will model coax cable
with dielectrics, so just use a 50 ohm characteristic impedance,
identical phases, with half the power going to each antenna.
The hairpin or beta match is easy. Design your antenna for maximum
gain and ignore VSWR or drive impedance. Either measure with an
antenna analyzer or calculate the feed point impedance. Then
calculate the length of a hairpin match that yields the required
inductance with either a Smith Chart or the following calculator:
<http://www.qsl.net/kd2bd/impedance_matching.html>
A bit more:
<http://everything2.com/title/hairpin+match>
The looped coax is a coax balun. Depending on your design, it can
either be 1:1 (50 ohms to 50 ohms) or 4:1 (200 ohms to 50 ohms).
Good luck.
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
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