Fanned multistrip coupler filters

Claim 1

Signal processing apparatus comprising: substrate means for propagating an acoustic wave at a surface thereof, first transducer means for launching an acoustic wave along a first propagation track at said surface in a predetermined direction, second transducer means for converting into an electrical output an acoustic wave propagating along a second propagation track at said surface spaced from said first propagation track, and in said predetermined direction, a first array of substantially geometrically parallel electrically-conducting strips affixed to said surface and disposed across said first propagation track, a second array of substantially geometrically parallel electrically-conducting strips affixed to said surface and disposed across said second propagation track, and a third array of electrically conducting strips in mutually non-contacting relation affixed to said surface for interconnecting respective ones of said electrically-conducting strips of said first array to corresponding ones of said electrically-conducting strips of said second array, said first and second arrays having respective first and second predetermined periodicities, the difference between said periodicities being substantially equal to the predetermined operating wave length of said acoustic surface wave, said first predetermined periodicity being greater than said second predetermined periodicity, a fourth array of substantially geometrically parallel electrically-conducting strips affixed to said surface disposed across said first propagation track in substantially geometrically parallel adjacent relation with said first array, a fifth array of substantially geometrically parallel electrically-conducting strips affixed to said surface and disposed across said second propagation track in substantially geometrically parallel adjacent relation with said second array, and a sixth array of electrically conducting strips in mutually non-contacting relation affixed to said surface for interconnecting respective ones of said electrically conducting strips to said fourth array to corresponding ones of said electrically-conducting strips of said fifth array, the periodicity of said third array being the same as that of said second array, the periodicity of said fourth array being the same as that of said first array, and said third and sixth arrays forming oppositely tapered fan-shaped arrays.