This paper distinguishes between the active and passive states of an a
way element and advances the thesis that models defined in the passive
state maintain their validity in the active state. The influence of r
eactance at the base of an array element is demonstrated and analytica
l expressions are suggested to laid in quantifying these base reactanc
es. A model architecture is proposed together with methods for determi
ning the model parameters. Examples of both analysis and design are in
cluded and the results are compared to measured data.