Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.
David Pozar, Microwave Engineering is an excellent reference. The book that was recommended earlier is on Microstrip filter design is also very good too.
One thing that these books and alot of literature is lacking is the fact that they never give a closed loop formulation on how the widths and spacings are related to the capacitance and the poles/zeros.