High-frequency excitation of a microstrip line by a probe

The excitation of an infinite microstrip line by a vertical probe is examined in detail. This canonical problem is the basis for many practical via connections and feeds that arise in microwave integrated circuits. A semi-analytical method is used here to study the discrete and continuous spectrum currents excited on the microstrip line when it is fed by a vertical probe. In particular, the high-frequency behavior of the current excited on the strip conductor is studied and compared with that produced by a simpler feed, the delta-gap voltage source.