Characteristic impedance for finite length microstrip line

A modified approximate and simple expression for the characteristic impedance of a finite-length microstrip transmission line (MSTL) is introduced. The analysis is based on a quasistatic approach to obtaining the mean potential distribution for evaluating the average characteristic impedance of the line. The dispersion effect is taken into account. Experimental results for lines having different lengths and different w/h showed that the line length should not be neglected in the evaluation of the characteristic impedance that can replace the open-ended capacitance in circuit analysis.<>