helix antenna matching

Hi All,


I want to design a helix antenna, i got the theoretical value through the website below:

http://jcoppens.com/ant/helix/calc.en.php

So now, I want to build the helix antenna practically for freq 3.55GHz.


I got a copper wire(thickness)1.6mm,
no.of turns =20,
turn spacing =0.1wavelength.

wavelength=83.3mm
Diameter(internal) =29.4mm
1)space winding = 8.3mm,
2) total length = 166.6mm,
3) min.reflector size =52mm,
4)reflector /conductor separation = 0.8mm
5)total length of conductor =1859mm


Theoritical gain=22.02dBi.


I have got a pvc pipe . The diameter of pvc pipe is 27mm so when i wind the copper wire and finally it gives nearly 30mm diameter.


Next, i wind the copper wire according to space winding 8.3mm for each turn.

Now my question is :

a)how much would be the input impedance for the spec above.


b)Should i need to add stub matching such as adding the one end of copper tape to copper wire and the other end of copper tape to the pin of n-type.


Plz reply me.

Thank you.


Regards,
Saran

Hello saran,
good link.

You need to calculate input impedance using network analyzer.
Please also refer this
http://df2ck.de/tech/helix/
(awesome ariticle)

If you still face problem after reading this page tell us.

:)

Added after 2 minutes:

see the image attached too.

BR,
Abhishekabs

Hi Abhishek,

For 3.55GHz,

I found that the input impedance is 155ohms by using this equation below:

Z= 140 x c/lambda , rite?

c stands for circumference where c = pai x diameter( internal)

Can u help me to calculate the input impedance? And tell me whether i need to add stub matching?

Waiting 4 ur reply.


You can refer the parameters from my today's first reply .

Regards,
Saran