Reduced passband ladder type SAW impedance element filters on strong piezoelectric substrates

Two ways of reducing coupling coefficient for 36-LiTaO/sub 3/ substrates are discussed: (1) a transducer with dummy electrodes and (2) an SiO/sub 2/ sublayer between the electrodes and the substrate. A theoretical coupling of modes (COM) model is used to find conditions for a twofold decrease of coupling. Experiments are made with test resonator-type structures for extraction of COM parameters and the obtained data are used for SAW duplexer design.