microstrip design. Microstrip can be used anywhere to design filters, impedance matching device, interdigital capacitor, in amplifier design. every where in rf microwave desgin.
I aggree with Khouly.
The fundamentals must be clear before master.
Read old books written by TERMAN, Ryder etc.
Also Balanis book on antenna if possible.
I don't know what you will to do.but you can read some books adout Rf basic theory.
i introduce some books to u.
<microwave engineering>&<microstrip filter for wireless communication application>
In RF cicruit, youhave to now the basic as my collegues have wrtitten about Scattering parametes and others intersting basic........So there are many books talk about them as vendelin, pozar, gonzalez .......