Computer-Aided Design Models for Millimeter-Wave Finlines and Suspended-Substrate Microstrip Lines

This paper presents closed-form expressions that model the electrical characteristics of finlines and suspended-substrate microstrip fines over a wide range of structural parameters for millimeter-wave applications. The expressions for finlines are within +-0.8 percent for the cutoff wavelength and within +-2 percent for the phase constant and the characteristic impedance (based on the power-voltage definition for a small slot (d/b <= 0.2)) of spectral-domain results. The expressions for suspended and inverted microstrips me within +-1 percent. The equations are vital to CAD of millimeter-wave planar circuits using these media.