1. Low-loss" concept

Figure 1 shows a "classic" filter structure with two transducers in line, the input transducer transforms electrical energy into acoustic energy and vice versa for the output transducer. The transducers consist of metal electrodes mounted on a piezoelectric crystal, as shown schematically (cross-sectional view) in figure 2 , which is an example of two electrodes per acoustic wavelength λ; a period p being constituted by an electrode of width a and an inter-electrode gap b.

Analysis of the [15] structure shows that it behaves approximately like a Finite Impulse Response...