Enhanced through-reflect-line characterization of two-port measuring systems using free-space capacitance calculation

A through-reflect-line (TRL) calibration procedure is presented wherein the free-space capacitance and propagation factor of the line standard are used to determine the complex, frequency-dependent characteristic line impedance. The impedance is used in the conventional TRL, so the method is designated the ETRL (enhanced TRL) method. The method is applied to measurement of a microstrip via. The results show that the PCB via model used needs to be modified at frequencies above 2 GHz.>