Need Help to Design a Microstrip HPF for Complementary Diplexer

Hi, I am trying to design a microstrip complementary HPF (High Pass Filter) for my diplexer design. I have already designed the LPF section for that diplexer in microstrip using Pozar's equations. But, I am getting problem to design HPF. I am using a series capacitor as a first component in my design as I have restriction to use a parallel component first for diplexer design. But, when I am trying to convert this series capacitance into microstrip form it becomes a series open circuit stub. But it is not possible to implement a open circuit stub in a series form. Then I tried to use the Kuroda's identity to overcome that problem but there is no such identity which could convert my series O. C. stub into a parallel O. C. stub. I am really confused with this. If you have any suggestions or solutions regarding to this issue, then please reply me. Thanks in advance.

Nijam