Indeed, being able to calculate and measure the impedances of antennas, transmission lines, etc is very important within RF design, which are almost always complex numbers. attach an antenna whose impedance matches that of the signal source – this maximizes the transmitting-antenna’s power dissipation (and “reflects” back zero power).

But even with lossless transmission lines, it is important in communications to “match impedances,” i.e. Eventually, the frequency of operation can become so high that the transmission line itself – no longer a simple wire – will exhibit significant signal-loss. However, as one approaches RF frequencies, these real-world effects become much more pronounced in cheap components.

This highly non-ideal behavior occurs because, in reality, no true resistor, capacitor, inductor, or wire exists rather they are all processed and manufactured to operate within a certain frequency range – at frequencies where the real-world effects are quantitatively insignificant. This means a normal resistor can become a capacitor, a capacitor can become an inductor, and a normal wire can become a distributed network of inductors and capacitors. In the world of RF (Radio Frequency) electronics, normal “bench-top” circuit components cease to operate the way they were designed to.

Using smith chart to match impedance