Recommended reading for designing a cascaded coupler

[Eugen_E]

Hello,

I need to design a cascaded coupler (3 or 5 sections) on microstrip, to get a flat response in the useful bandwidth. Please recommend a book/paper/tutorial useful for designing cascaded couplers.

Edit:
I optimized a 5 section coupler, for flat response and I got a very tight coupling for the central coupler, Z0E=191 Ohm , Z0o=13 Ohm . This values are extreme for implementing in microstrip, resulting in a very tight coupling, very narrow spacing.
Can I implement the central coupler as a Lange or cascaded Lange coupler? This will affect the phase response of the central coupler, and the overall coupler frequency response?

Thanks

 

[kspalla]

These impermanence are reliasable with CPW. Have you tried it?

 

[Eugen_E]

As you can see I don't have enough experience with MW, just starting.
I will try it, though I read CPW is quite difficult to design and simulate, with no equations available...
I was told it is easier to do it in stripline.

Anyway it's just a school project and not an actual design, but I was curious how this could be done.

 

[ge]

A cascaded Lange is difficult to build but works. A great deal depends on what you want to accomplish (frequency, bandwidth, producability, cost). Cascaded Wilkinson is cheaper & easier to build,
(###.microwaves101.com/encyclopedia/couplers.cfm).
Somewhere I've got a book with good information on cascaded Lange couplers.