  This paper investigates stable suboptimal H-infinity controllers for a class
of single-input single-output time-delay systems. For a given plant and
weighting functions, the optimal controller minimizing the mixed sensitivity
(and the central suboptimal controller) may be unstable with finitely or
infinitely many poles in complex right half-plane. For each of these cases
search algorithms are proposed to find stable suboptimal H-infinity
controllers. These design methods are illustrated with examples.
