How to design RF transformers with coaxial?

RF transformer:
http://www.minicircuits.com/appnote/tran14-2.pdf
How RF Transformers Work:
http://www.minicircuits.com/appnote/howxfmerwork.pdf
Broadband VHF/UHF Amplifier Design Using Coaxial Transformers:
http://www.polyfet.com/HFE0503_Leong.pdf

Regards,
IanP

search for articles by Ruthroff, like this one:

http://www.highfrequencyelectronics....204_Sevick.pdf

Transmission line transformers by jerry sevick, noble publishing is a good reference.