Basics properties of leaky modes in printed-circuit transmission lines

Printed-circuit transmission lines used in microwave and millimeter-wave integrated circuits can exhibit several new propagation phenomena. They have relevance to leaky modes in integrated circuits that leak power in the form of the surface wave and/or the space wave, and they influence significantly the circuit behavior. In this paper, we will explain first why and when these transmission lines can become leaky, and then present some important phenomena discovered recently.