To design a filter (using stubs), we take the following steps:
(Step 1) Determine the normalized LPF prototype element values from the filter specifications.
(Step 2) Determine the normalized LC values of the prototype LPF.
(Step 3) Convert the L/C values into the impedances of short/open-circuited stubs.
(Step 4) To use Kuroda identity 2 to convert the two SSs (series short-circuited stubs) Z1 and Z3 into POs (parallel open-circuited stubs), we insert UEs between Z1/Z2 and the transmission line, and ...

Section 7.2: Microstrip Filter Implementation
of the book "Electronic Circuits with MATLAB, PSpice, and Smith Chart" (Wiley, 2019)
A bunch of m-files and OrCAD/PSpice files listed in the book can be downloaded at https://wyyang53.wixsite.com/mysite/p....