On the choice of reflection coefficient zeros of coupling networks

Abstract

The classical problem of broadband matching was first studied by Bode ( 1) and developed later by Fano ( 2); however, Fano's solution, although very elegant, has a practical limitation. The key idea is to replace the load Z 2(S) by its Darlington equivalent ending in 1 ohm, but the optimum design is, in general, not very simple. Youla ( 3) proposed an alternative method where it is relatively easy to find the optimum network even for the more complex impedance load. The paper shows that maximization of the gainbandwidth product, in the presence of load or source variations, depends on the choice of the reflection coefficient zeros, either in the left half-plane or in the right half-plane.