Microstrip phase shifter

Hello,

I found some simple examples of the microstripe phase shifters at the CST and IE3D examples see attach. Please could you know, where was this structures publicated or where can I find some information about this microwave circuit ? Somethink like basic princip or How-to design and calculation ?

Thanks for information

For what I see seems that you could apply the same techniques used to for impedance matching in transmission lines with parallel stubs.
Theory is widely explained in the classical text book "Foundation of MW engineering" by Collins.


Regards
Mowgli