microstrip balun design

Hi all,

I need to design a balun and I read the tutorial from

http://www.odyseus.nildram.co.uk/RFM...n%20Design.pdf

On the last page, an improved microstrip version (Figure 10) is given but no explaination.

Can anyone tell me why the value of L1 is different from L2? And where can I find the ralated paper? The circuit really confused me.

Thanks.

I believe the value of L1 and L2 at the design frequency will be the same. The choice of a thin trace and thick trace is to provide a tighter layout. C1 open stub and C1 lumped element must be the same also. I don't think this is improved, just distributed (i.e. cheap).

Correct