1/6 transformer

I want to design a high power(200w CW) directional coupler as following circuit,It work over the range from (30~80)MHz.

I am going to use a 3:5 voltage ratio transmission-line transformer as a 1:3 impedance ratio transformer.

However I don"t know how to design 1:6 impedance ratio transformer,who can help me?
Thanks.

See attachment below.

You can use a 5/2 four delay line transformer similar to your 5/3 transformer.

Thank VSWR,FVM.
I hope to read the book Transmission Line Transformers,May you email the ebook to me? my email is liok802000@yahoo.com.cn
Thank.

Added after 29 seconds:

Thank VSWR,FVM.
I hope to read the book Transmission Line Transformers,May you email the ebook to me? my email is liok802000@yahoo.com.cn
Thank.

You should be able to locate it at the internet, e.g. among these fileshttp://rapidlibrary.com/index.php?q=...ansformers+pdf