PHASED ARRAYS

A phased array system comprising a plurality of elements (1) each element being arranged to transmit/receive signals with a predetermined phase and/or amplitude with respect to other elements of the array, whereby a beam steering function is afforded, each element (1) of the array including a transducer, the transducers of the array elements (1) being placed in communication with at least three reference stations (3-5) which are spaced apart in three dimensions such that data communication between each transducer and the reference stations (3-5) can be used to define the position of each element relative to the stations and wherein the phase and/or amplitude of signals transmitted and/or received by the elements is determined in dependence upon the said relative position thus defined, whereby improved beam steering accuracy is afforded.