A microstrip line is a transmission line or trace that is used to carry high frequency electromagnetic signals between different components on a printed circuit board (PCB). A conductor is placed on a dielectric material, which is then placed on a ground plane. The dielectric layer is also known as the substrate. The ground plane is usually a PCB board, silicon, or other similar technologies. Since microstrip lines are not enclosed, they have a relatively lower power handling capability and losses compared to waveguides.

The below formula is used to calculate the impedance of this line for two different cases – (1) width is lower than height and (2) width is higher than the height of the line. In each of these cases, the behaviour of the RF signal passing through the line will change due to the differences in impedance and permittivity values.

Where,

‘W’ is the width of the microstrip line

‘H’ is the height of the microstrip line, and

‘ɛ_e’ is the effective dielectric constant of the microstrip line.