Synthesis of Delay Line Networks

Radar video information may be processed on a continuous-trace (as opposed to range-gated) basis by using delay elements whose delay times are integral multiples of the repetition period τ. Networks consisting of such lines and of linear amplifiers and adders yield periodic pass bands. Their properties may be analyzed most conveniently by the transformation z = eppt, where p is the complex frequency variable. A systematic synthesis procedure is presented which realizes a prescribed delay-line transfer function as a cascade of elementary building blocks. Flow-graph techniques may be used to obtain different embodiments corresponding to the same transfer function. It is shown that the required number of delay elements is equal to the number of poles of the z-transfer-function which are located away from the origin, or to the number of zeros, whichever is larger.