An ultrasonic detection system having an array of ultrasonic transducers that are uniformly closely disposed relative to each other such that the active surfaces for transmission or reception are maintained on a straight or curved line. The transducers form radiation or reception beams in a specific direction. Beam orientation is accomplished by selecting a group of transducers from the array and/or respectively applying appropriate phase-shifts to the signals to be fed to each of the transducers or to the signals produced from each of the transducers. Shields are maintained between two adjacent transducers for suppression of sidelobes.