SPUDT cell with one-wavelength period and quarter-wavelength electrodes

A 2D-periodic unidirectional transducer for surface acoustic wave (SAW) devices is presented. This transducer consists of periodic cells containing only two electrodes and two gaps with quarter period width in each of the multiple tracks. So the structure has maximal possible dimensions of its elements for a cell period equal to one wavelength. In spite of current technological limitations this permits to implement unidirectional transducers in GHz range. In contrast to known multi-track structures with active tracks only, the structure contains alternating both, active transducer tracks and passive reflector tracks with different apertures comparable to SAW wavelength. The structure has a distinct 2D-periodic electrode configuration and exhibit the natural generalization of the well studied and widely used 1D-periodic SAW device functional principle. The tracks strongly interact due to diffraction of waves excited by such electrode structure on a piezoelectric substrate. A structure analysis by means of finite element method shows that complete unidirectionality can be reached. First experimental results are given.