Design of low-frequency constant time delay lines

DELAY lines are used in many applications in both high-frequency and low-frequency fields. In low-frequency applications such lines consist of a cascade connection of inductance-capacitance network sections employing lumped constants. Ideally, the line should have no attenuation; its characteristic impedance should be constant, and the phase shift should be a linear function of frequency. With the latter condition, the time delay is constant and the character of the signal is unchanged in its transmission over the line. In design practice, one attempts to meet as closely as possible these ideal conditions within the limits of cost, space, and practicability.