A SURFACE LEAKY WAVE RESONATOR WITH LOW INSERTION LOSS AND SMALL DIMENSION

A new type of SLW resonator with small dimension and low insertion loss on the surface of 49-rotated Y-cut LiNbO₃ has been designed and fabricated successfully by exciting surface leaky wave which is characterized by high electromechanical coupling and large acoustic impedance change under the shorted metallized strips. These resonators are demonstrated to possess prominent advantages over conventional surface acoustic wave resonator （SAWR）, e.g. the required area of piezoelectric substrate can be reduced to less than 1/5 of SAWR at the same frequency and the insertion loss is only 2-5 dB in 50 system.
The measured values of electromechanical coupling k_s² and acoustic impedance mismatching ratio |ε| are presented and theoretical calculation of the reflective frequency responses are given. The factors resulting in small insertion loss are analysed by utilizing an equivalent circuit model. Some typical experimental results are also shown in this paper.