Scattering matrix and Hybrid microwave circuits
A microwave circuit ordinarily consists of several microwave devices connected in some way to achieve the desired transmission of a microwave signal. The interconnection of two or more microwave devices may be regarded as a microwave junction. Commonly used microwave junctions include such waveguide tees as the E-plane tee, H -plane tee, magic tee, hybrid ring (rat-race circuit), directional coupler, and the circulator. This section describes these microwave hybrids, which are shown in Figure 1 :
Figure 1 : Microwave hybrids.
A two-port network is shown in Figure 2. From network theory a two-port device can be described by a number of parameter sets, such as the H, Y, Z, and ABCD parameters :
Figure 2 : Two port network
All these network parameters relate total voltages and total currents at each of the two ports. For instance,