The antenna of a phased array radar (PAR) consists of a number of individual radiating elements and it steeres the antenna beam direction by shifting signal phases of these elements. It should be inspected and maintained at periodic times to hold the required performance of a radar system. However, an antenna can not be maintained so frequently, since frequent replacements involve the downtime of system and degrade the system availability. This paper suggests a maintenance policy for a PAR where a PAR is periodically inspected and its failed elements are replace at the M-th (M = 1, 2, ...) inspection. If the number of failed elements exceeds a prespecified value, they are replaced at the succeeding inspection. When failures of elements occur following a Poisson process, the expected cost per unit of time is derived and an optimal M^* which minimizes it is discussed. Finally, numerical examples are given.

View full abstract