Modeling of shielded, suspended and inverted, microstrip lines

Electromagnetic simulation and modeling of suspended-substrate microstrip lines have an important role in designing microwave and millimeter- wave integrated circuits. Suspended- substrate microstrip lines are sometimes manufactured and placed in a shield to reduce performance degradation from external influences. In this paper, we will illustrate modeling of shielded, suspended-substrate, microstrip lines using the finite element method(FEM). We specifically determine the capacitance per unit length, inductance per unit length, and characteristic impedance of shielded, suspended, microstrip lines. We compared our results with those obtained by other methods and found them to be in agreement. We extended the modeling by designing our own model of shielded, inverted, microstrip lines and compared it with shielded, suspended, microstrip lines. We found them to be very close.