Theoretical calculations of Boundary Waves using effective permittivity and harmonic admittance approaches on various combination of materials

A theoretical analysis of Boundary Waves assuming infinitely thin excitation electrodes is presented in this paper. First results are shown using standard crystal cuts often used in acoustic wave devices. A comparison between Boundary Waves and Surface Acoustic Waves (without any mechanical effect of the metal strips) is performed, pointing out completely different acoustic wave properties in terms of reflexion coefficient, attenuation and phase velocity and electromechanical coupling factor. A special configuration [001]Si<110>/175 YX LiNbO ₃ is studied, exhibiting a non-leaky boundary wave with a coupling factor close to 11% and a reflexion coefficient of 1.3%