moment method line microstrip -patch -antenna

I am modeling the microstrip line using moment methods and had obtained the impedance matrix. Yet I donot know how to model the source for the microstrip line? Does it use a ribbon of current or some delta source?
btw, RWG basis function is used in my code.

Maybe a good reference is [1] (Zheng, "Electromagnetic Modeling of Microstrip Circuit Discontinuities and. Antennas of Arbitrary Shape," Ph.D thesis,. University of Colorado at Boulder, 1990). However, I cannot get it.

Modeling the microstrip line u can refer to paper by Mirshekhar Syakhal etal
Moreover u can treat the source as ribbon of current and solve for V.

thank you for reply!

if I model the source as a ribbon of current, does it mean that an additional basis function should be added between the line and the ground?
thank you again.