1. A method of modeling a network, comprising the steps of: carrying out a 1 port measurement on the network by inputting an excitation signal at one port of the network and recording the results at the port; generating a 1 port parametric model of the network; optimising the values of the parameters of the 1 port parametric model by reducing the difference between the results of the measurement step and results calculated using the 1-port parametric model and the excitation signal.