Multiresonance design of a Tonpilz transducer using the finite element method

Abstract

The design and characterization of a wide bandwidth Tonpilz transducer is carried out using the finite element method. This wide bandwidth has been achieved by introducing a symmetric flexural resonance (sometimes called a "flapping" resonance) in the head-piece of the Tonpilz transducer. This flexural resonance is exploited by lip-mounting of the transducer as opposed to the more traditional nodal mount. Each transducer is characterized by high-power handling, high-electroacoustic efficiency, broad bandwidth (low-Q), and high-electromechanical coupling. These are characteristics which are usually associated with designs employing more complicated electrical or mechanical matching techniques. An array of these transducers was constructed and displays low-ripple (<3 dB) transmission of one-octave 20-40 kHz signals. A comparison with a recent broad-band design by Inoue et al. [1993] which uses a matching plate is also made to illustrate the inherent simplicity of the flexural resonance approach.