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)

On 4/16/2016 1:01 PM, aria rangga 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)


If the impedance of each Yagi is 50 ohms (when in the stacked
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.

On 4/18/2016 10:36 PM, John S wrote:
On 4/16/2016 1:01 PM, aria rangga 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)


If the impedance of each Yagi is 50 ohms (when in the stacked
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.

By the way, if each Yagi is about 25 ohms each when stacked, you can use
50 ohm coax throughout.

On Sat, 16 Apr 2016 11:01:29 -0700 (PDT), aria rangga
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:
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 mo
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
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558