MOSFET as a variable Capacitor

I want to couple a mosfet to a microstrip line and use it as variable capacitor by varying Vgs.But I don't know how to start with the circuit.Can any body guide me?

why not use varicap diode? why mosfet?
https://en.wikipedia.org/wiki/Varicap

My project advisor insists!

http://micant.hanyang.ac.kr/articles/53.pdf

I do not have that good knowledge of MOS to begin with.Can you tell me where to look for a start.Thanks for the file