Some aspects of electrostatic transducers

Usually an electrostatic transducer is represented theoretically as an ideal electromechanical transformer followed by a piston-like diaphragm. This is not exact if a thin diaphragm is used. It is shown that by mathematical treatment of known physical relations the four-pole equations (or matrixes) for the relations between acoustical values and electrical ones may be derived. Further it is shown that it is useful to introduce the term of acoustical impedance of the thin diaphragm as a whole which may be represented by an analogue network, having damped poles and zeros at frequencies of the respective modes. A new analogue network of the complete transducer is then given. Curves are shown of normalized impedances of thin diaphragms as a function of relative frequency for different parameters calculated by a computer.