Surface wave devices with low passband ripple

A SAW (surface wave) device comprising:

• an input IDT (inter-digital transducer), and an output IDT for receiving SAWs from the input IDT, at least one of the input and output IDTs having a slanted finger geometry for SAWs at a plurality of different wavelengths over an aperture of the IDTs;
• and
• a shield electrode between the input IDT and the output IDT;
• wherein at least one edge of the shield electrode is slanted or stepped so that SAW reflections at said edge from different positions across the aperture have substantially 180 degree phase differences between them, whereby said reflections are substantially cancelled at said plurality of different wavelengths, a slant or step size of said edge varying in dependence upon the SAW wavelength across said aperture.

A SAW (surface wave) device comprising:

• an input IDT (inter-digital transducer), and an output IDT for receiving SAWs from the input IDT;
• and
• two shield electrodes arranged successively in a SAW propagation path between the input IDT and the output IDT;
• wherein each of the two shield electrodes is slanted across an aperture of the IDTs, and the two shield electrodes are substantially symmetrical about a central line between them and perpendicular to the SAW propagation path.