Abstract: This invention relates to apparatus and a method of controlling the amount of delay or phase-shift which is applied to a signal received at or transmitted from each transducer in a multi-transducer antenna to produce a beam directed at a specific target point. For each transducer a first look-up table is used for storing first digital words representative of the included angle between the lines joining the target to a reference point, and the same reference point to a transducer. A second look-up table is associated with the first look-up table for each transducer, and stores second digital words representing delay or phase-shift control signals corresponding to ranges of the target relative to the reference point for each of said first digital words. Each first look-up table is addressed with an address signal representing the direction of the line from the reference point to the target, to obtain a corresponding first digital word.