ABSTRACT
This chapter discusses the transmission of ultrasonic plane waves through a layer with plane-parallel boundaries. It explores the conditions under which ultrasonic waves can propagate in homogeneous layers from the viewpoint of the possible frequencies and the structure of the field. The method of electroacoustical analogies is based on the fact that the characteristics of an acoustic oscillatory system can be compared to well-defined “equivalent” parameters of an oscillatory electric circuit, and the well-known equations and results from electrodynamics can be used to solve problems in ultrasonics. This method greatly simplifies, for example, the analysis of free and forced acoustic oscillations of a layer (plate) when it radiates ultrasound into an adjacent medium with a finite characteristic impedance. The chapter describes the oscillations of real systems in the presence of losses and talks about ideal plane waves excited by harmonic oscillations of an infinite flat surface.
