Surface-acoustic-wave unidirectional transducers using anodic oxidation technology and low-loss filters

A new surface-acoustic-wave interdigital transducer (IDT) and unidirectional transducer (UDT) are described. Using a lift-off anodic oxidation method, controllable gaps between electrodes with good insulation can be obtained. Experimental results show good characteristics at 2nd-harmonic operation for a new floating electrode type unidirectional transducer (NG-FEUDT). Also, a low-loss filter of 3.46 dB with side-lobe suppression of 40 dB at 893 MHz is obtained using the above techniques.