Saw wave-guides

A SAW wave-guide compressor/expander, wherein said SAW wave-guide compressor comprises a combination of 3 dB MSC and a set of two parallel zebra-wave-guides, wherein the following constructive features take place:

• (a) said 3 dB MSC has fingers aligned with the same line in both SAW tracks, having equal aperture;
• (b) both of said two parallel zebra-wave-guides have the same width equal to said track's aperture;
• (c) both of said two parallel zebra-wave-guides have the same periodicity of finger arrangement;
• (d) both of said two parallel zebra-wave-guides have the same total quantity of fingers;
• and
• (e) said two parallel zebra-wave-guides have different quantities of isolated fingers, wherein said different quantities of isolated fingers provides 90-degree relative phase shift between phases of SAW beams, propagated through said two parallel zebra-wave-guides.

A SAW IDT-wave-guide with an inter-digital transducer having topology comprising:

• (a) at least one inter-finger connector for providing a desired equipotentiality of at least two fingers, i.e. there are fingers connected to one of the opposite bus bars only through said inter-finger connector and another finger, wherein said inter-finger connector, arranged either within and/or outside of said array, has substantially small size in the direction, perpendicular to the direction of SAW beam propagation, wherein said small size is less than three λ, where λ is a SAW wave-length at a desired frequency;
• and
• (b) IDT's free surface space borders arranged between interdigitized electrode fingers array and opposite bus bars, wherein at least one said border comprises a substantially wide free surface space, wherein said wide free surface space is wider than half of said λ,
• wherein said free surface space borders are achieved by omission of direct connectors between interdigitized fingers and said opposite bus bars.

A method for improving an IDT characteristics by deriving a narrow SAW track and constructing a combined-IDT topology comprising:

• (a) calculating an original apodized IDT topology having a lot of small overlaps, in assumption of absence of the diffraction spreading effect;
• (b) deriving a narrow track, having a lot of small overlaps, from said original apodized IDT;
• (c) implementing said derived narrow track as a separate narrow SAW IDT-wave-guide, wherein said IDT-wave-guide has weighted topology that calculated to generate the same contribution to electrical characteristics as said derived narrow track, having a lot of small overlaps, in assumption of absence of the diffraction spreading effect;
• (d) implementing a separated SAW main-IDT as a cannibalized apodized IDT assembled from remainder original IDT after deriving said narrow track, wherein said main-IDT has weighted topology that calculated to generate such a contribution to electrical characteristics that is equal to differ between the contribution of said original apodized IDT and the contribution of said IDT-wave-guide, comprising said derived narrow track;
• and
• (e) connecting said main-IDT and said IDT-wave-guide in parallel, whereby forming said combined-IDT topology.

A one-channel zebra-wave-guide implemented as an array of interdigitized electrode fingers, wherein said array comprises:

• (a) at least one inter-finger connector, providing electrical shorting of interdigitized electrode fingers, wherein said inter-finger connector is arranged either within and/or outside of said array, wherein size of said inter-finger connector is substantially small in direction perpendicular to direction of a SAW beam propagation, wherein said size is less than half a λ, where λ is a SAW wave-length at a desired frequency;
• (b) borders on both sides along direction of said SAW beam propagation, wherein each of said borders comprises a substantially wide free surface, wherein said substantially wide tree surface is wider than half of said λ;
• and
• (c) at least two interdigitized electrode fingers, which are periodically-adapted arranged for providing compensation of partial SAW waves reflected from said at least two interdigitized electrode fingers at said desired frequency.

A multi-track SAW wave coding device topology comprising at least one SAW interdigital transducer overlapping at least two SAW tracks,

• wherein at least one of said at least two SAW tracks comprises:
• a SAW reflector;
• a SAW wave-guide;
• and
• a SAW phase shifter;
• and wherein said reflector represents a SAW zebra wave-guide, having fingers arranged with a periodicity adapted for providing in-phase summing of partial SAW waves reflected from said fingers at a desired frequency,
• and wherein said SAW wave-guide represents a zebra-waveguide, having fingers arranged with a periodicity adapted for providing compensation for SAW wave reflections from said fingers at a desired frequency,whereby the SAW wave propagates along said wave-guide substantially with no diffraction spreading due to a wave-guide effect,
• and wherein said SAW phase shifter, having fingers arranged with a periodicity adapted for providing compensation for SAW wave reflections from said fingers at a desired frequency, provides coding of said at least one of said at least two SAW tracks,
• and wherein said coding comprises changing the resulting phase shifter electrical loading, which provides a delay-defined phase shift of the SAW wave, propagating throughout said at least one of said at least two SAW tracks, such that said at least one of said at least two SAW tracks is coded by the phase shift.