Characteristics of leaky SAWs on 36-LiTaO3 in periodic structures of heavy electrodes

Experimental data is presented on leaky surface wave propagation on 36-LiTaO₃ with gold and platinum electrodes having a thickness up to 0.04λ. Such heavy electrodes induce a very strong mechanical perturbation of the surface such that very large reflection coefficients are obtained. Reflection coefficients greater than 50% per wavelength (that is per 2 electrodes) and corresponding stopbands (up to 17% relative width) have been observed. The leaky wave attenuation due to the presence of these heavy electrodes is surprisingly low. At 250 MHz, the attenuation is only 2 to 3 higher than when using aluminum electrodes of similar thickness. These COM model parameters are determined using a new technique based on admittance measurements of a one port synchronous resonator