Abstract: This paper presents the general and concise expressions of spectral-domain electric and magnetic Green's functions for multilayer media derived by using spectral -domain immittance approach-Because the determination of the spectral-domain Green's functions is accomplished by the investigation of voltages and currents on the equivalent circuits, which correspond to electric and magnetic current sources respec-tively, the derivation procedure is easy to follow. Finally, the above Green's functions are applied to millimeter wave multilayer microstrip lines. The dispersion characteristics and the effects of physical parameters on the effective dielectric constant and characteris-tic impedance are investigated.

Key words: spectral-domain immittance approach, green's function, transmission-line theory, multilayer microstrip lines