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Folded Balun-matching problem

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goroks

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Hello!

I am designing a folded balun with a coaxial (inner conductor diameter: 0.51 mm; dielectric: 1.58mm and outer:2.2mm)
the balun is for UHF(300MHz) But can got the right return of loss.
Are the dimensions of the coaxial wrong?

Please help
 

Complete description, please. What are you designing, a λ/2 transformer? Instead of giving the dimensions of an unknown dielectric, tell the coax impedance. Sketch the circuit and specify input/output impedance.
 

50 ohms coaxial and it is a 1/4 lambda.

- - - Updated - - -

One more question^^

Baluns are just feeds (transformers) so they are not supposed to radiate. right?

After design they should be connected to a balanced antenna?
 

Baluns are just feeds (transformers) so they are not supposed to radiate. right?
Click to expand...
Yes, but that's no the case for the λ/4 baluns I know. Please clarify the used configuration.
 

balun.PNG

This is the configuration. Thanks^^
 

Pawsey stub Balun-Matching probel

Hello

i am designing on CST studio a balun but cant get it to work. Return of loss bad.

Please help

this is the configurationbalun.PNG
 

Still not a complete description. What's the antenna load, a (70 ohm) λ/2 dipole?

The simplified picture doesn't indicate if the balun part is modelled appropriately.
 
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    goroks

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I am using a half wavelength dipole as load antenna. balun.PNG
This is the balun (pawsey stub designed using CST Studio)

best,
 

Hello,I don't know the problem has been solved or not but I am designing a folded dipole(53MHz) with a balun..well,as we know its load is 280-300ohm(in my design,it's 300ohm).So,I went for designing a 4:1 coax current balun,which converts 75ohm to 300ohm,but I was unable to design it.
Then I switched for sleeve dipole balun(actually, it's more of a RF-choke than to be a Balun) and it's worked...if anyone interested then let me know,I can discuss about my design.
 

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