Based on the transfer-matrix method, the general expressions of equivalent four-terminal network parameters of varying section torsional horn are derived, the relations between frequency equation and both the rotational velocity amplification and that of the surface tangential velocity of stepped type torsional ultrasonic horn with transitional section of cosine-like type are obtained. When the front section length is equal to that of the back section, the torsional characteristic of the system is studied. The article provides some theoretical foundation for the similar system.

cosine-like; horn; frequency equation; four-terminal network; amplification factor