Hello all, let me preface my question by asking whoever responds to please keep things light. I understand the math related to impedance but I'd like focus on getting a more intuitive feel for this concept. Now correct me if I'm wrong, but impedance is resistance plus reactance. Reactance is a resistance that changes with frequency, a capacitor for example.
My question is, what exactly causes the 90ohms of impedance in a USB cable? If you take one apart all you have are 4 conductors and a shield, what contributes to the reactance? Furthermore, why is a "homemade" USB cable that does not have a 90ohms impedance unable to reliably transmit data?
My question is, what exactly causes the 90ohms of impedance in a USB cable? If you take one apart all you have are 4 conductors and a shield, what contributes to the reactance? Furthermore, why is a "homemade" USB cable that does not have a 90ohms impedance unable to reliably transmit data?