Like ftg said, in that circuit the length of line between the IC and lumped component is part of an impedance matching circuit. You can use a length of transmission line as an impedance transformer. That microstrip line appears to be 50 ohms. If the impedance at the IC pin isn't 50 ohms, then a length of line will transform it to something else which is a function of the line length. If the impedance at the IC pin is 50 ohms, then the length doesn't matter (expect for resistive and dielectric losses), it will stay 50 ohms independent of line length. Again, like ftg said, you can play with that in QUCS simulation to get a feel for what happens. Find the transmission line component that lets you specify impedance and length. Place a S-parameter source (Power Source), transmission line, and resistor to ground. If the transmission line is 50 ohms and resistor is 50 ohms, then the length won't matter. S11 will be matched always. If the resistor isn't 50 ohms, or the transmission line isn't 50 ohms, S11 will be a function of the line length.