Directed stick radiator

Abstract

An elongate, acoustic radiator (referred to as a directed stick radiator or stick radiator) consists of an exciter or oscillator emitter (11), that excites or propagates mechanical wave motion directly or by an optional adapter (12) to a mechanical waveguide with stick design. Therefore mechanical waves travel along the waveguide axes with wave velocity cW. The mechanical waves cause local displacements of transformer elements (14) coupled to the waveguide that are transformed into acoustical radiation. The waveguide is terminated with an active or passive impedance termination (15), e.g. a non-reflecting impedance termination. Local sound radiations interfere and directed in-phase radiation follows. The input impedance, the directivity characteristic, the areas of the same phase and the efficiency of the radiation can be adjusted by the points of excitation, the wave velocity of the mechanical waves, the length of the waveguide, the amplitudes of displacement, the properties of the mechanical acoustical transformer and the impedance termination. The volume of the enclosure is adjusted by the properties of the waveguide and the transformer. The directed stick radiator can be used as a warning or signal device, for speech or music transmission, for noise cancellation, and working in reverse operation it can be used as directed microphone.