Acoustic surface wave device comprising arrays of parallel metallic strips

An acoustic surface wave device comprising:

• a substrate made of a material able to propagate surface acoustic waves;
• at least two paths at the surface of said substrate, for propagation of surface acoustic waves, the material assuming said propagation along each one of said two paths being the same for said two paths;
• at least one input transducer disposed on said substrate for converting high frequency electrical waves applied thereto into acoustic waves propagating along a first one of said two paths;
• at least one output transducer disposed on said substrate for converting surface acoustic waves propagating along the second one of said two paths into electrical waves;
• and an acoustic surface wave coupler disposed on said substrate for providing a coupling between said first and second paths, said coupler comprising a first array of N parallel conductive strips having a width a.sub.1, a periodicity p.sub.1 and a length l.sub.1, disposed on said substrate across said first path and a second array of N parallel conductive strips having a width a.sub.2, a periodicity p.sub.2, and length l.sub.2 disposed on said substrate across said second path, said strips being in each path disposed perpendicularly to the direction of propagation of acoustic waves when propagating along said paths and said two arrays being interconnected by a connecting array of N conductive strips;
• said strips of said first and second arrays having on the one hand for each one of said two arrays, the same width and the same periodicity and having on the other hand at least one of said two geometrical parameters:
• width, and periodicity, which is different in said two arrays.