Conditions (5.44b) are somewhat more complicated to implement than the others, because none of the variables calculated on the boundary can be zeroed out by short- or open-circuiting. From Figure 5.20(b), we can see that in addition to the gyrator coupling between the two meshes that must be maintained, we also must keep the waveguides which lie along the boundary.
In the problem interior, parallel and series junctions in the five-variable mesh are connected, through waveguides, to four neighboring junctions; on the southern boundary, however, each is connected to three--two to the east and west) and one to the north. Due to this asymmetry, we might suspect that it will be necessary to adjust the boundary waveguide impedances away from the values that they would take on the interior (which is ). In fact, it is possible to show that by introducing transformers, with turns ratios of in these waveguides, we indeed have a lossless termination which satisfies conditions (5.44b). We must set the boundary immittances to