Modeling of End Radiation and Leakage in I.H.P. SAW Resonators on Lithium Tantalate with Low Cut Angle

In this article, the leakage from longitudinal ends of finite IDT in I.H.P. SAW resonator is discussed. Firstly, the finite length model, with end leakage mainly, is built up by Hierarchical Cascading Technology. Then, by the tuning of grating length, two factors that influence end leakage are separated. One is the scattering from end of IDT and another one is from end of reflector. Through the indicator, anti-resonant Q, it is found that the scattering from end of IDT is the dominant impact to end leakage. Comparatively, the Q drop caused by reflector can be improved easily when the number of grating is larger than 30-40. At last, a fitting method is given to evaluate quality factor rapidly with different length of grating in 2.5D model.