Study of biasing effects on coupled microstrip lines characteristics

An accurate method for evaluating the effects of biasing potential on the quasi-static even and odd mode propagation characteristics of coupled microstrip lines is given. In this method, the equivalent circuit theory simulates the quasi-static theory for the coupled microstrip lines. The depletion layer capacitance is determined using parallel plate waveguide model. The techniques used here are constructed from the standard transmission line model voltage and current as well as field lines distribution. The elements of the series branch impedance of the equivalent circuit can be found by solving for the current distribution on the conductor given the magnetic potential. The shunt admittance components are determined by using conformal transformation formulas. It is found that the bias potential has great effects on the propagation characteristics of coupled microstrip lines as well as the phase angle of microstrip phase shifter.