Use of the adjoint for computing exact changes in response of cascaded two-port networks

It is shown that the adjoint network concept can be used to compute exact changes in response due to changed parameters for the class of cascaded two-port networks. Such networks are frequently encountered in linear filters and various microwave designs. Computing the change in response this way is both elegant and computationally efficient. In the limit of small parameter changes, the equations reduce to well-known results for first-order network sensitivities. The fact that an analysis of only the original network and not the adjoint is necessary to compute the sensitivity of a driving-point conjugate input variable is highlighted in this formulation.