Which of the following devices can be used for impedance matching at radio frequencies?
A transformer
A Pi-network
A length of transmission line
All these choices are correct✓الإجابة الصحيحة
الشرح
Impedance transformation can be done by a transformer through its turns ratio, by a Pi-network through its reactive elements, and by a section of transmission line through its transforming property, so all three work at radio frequencies.