(2) This transmission line is a stripline structure, designed according to the strip line.Common sense, the transmission delay is about 180ps/in at 50 ohms.Of course, the above derivation result is only an approximation, and the equivalent capacitance of the transmission line per unit length is usually between 3.5 and 3.8 PF.However, in high-speed PCB design, it is often important to remember some common empirical values, sometimes eliminating some cumbersome calculations.