Surface acoustic wave passive transponder having parallel acoustic wave paths

• US 4,620,191 A
• Filed: 06/30/1983
• Issued: 10/28/1986
• Est. Priority Date: 06/30/1983
• Status: Expired due to Term

• Current Assignee: X-Cyte Inc.
• Original Assignee: X-Cyte Inc.
• Inventors: Skeie, Halvor
• Primary Examiner(s): Tubbesing, T. H.
• Assistant Examiner(s): Barron, Jr., Gilberto
• Application Number:
  US06/509,525
• Time in Patent Office: 1,216 Days
• Field of Search: 343/6.5 SS, 343/6.8 R, 343/6.8 LC, 310/313 R, 310/313 B, 310/313 D, 333/150-155, 333/193-196
• US Class Current: 342/51
• CPC Class Codes: G01S 13/343 using sawtooth modulation
• CPC Class Codes: G01S 13/755 using delay lines, e.g. acoustic delay lines
• CPC Class Codes: H03H 9/1455 constituted of N parallel or series transducers

Abstract

A passive transponder for use in an interrogation/transponder system comprises a substrate having a substrate surface defining a path of travel for surface acoustic waves; a launch transducer element arranged on the surface for converting interrogating signals into surface acoustic waves which propagate along the path of travel; a plurality of tap transducer elements arranged on the surface at spaced intervals along the path of travel for converting surface acoustic waves into respective output signals; and a circuit, connected to the tap transducer elements, for combining the output signals of these transducer elements to form reply signals. In order to reduce the effect of spurious signals, the tap transducers are arranged both in series and in parallel with respect to the path of travel.

Claims

1. In a passive transponder adapted for use in an interrogation system for transmitting a reply signal containing coded information in response to the receipt of an interrogating signal, said transponder comprising:

(a) a substrate having a substrate surface defining paths of travel for surface acoustic waves;

(b) at least one launch transducer arranged on said surface for converting said interrogating signal into surface acoustic waves which propagate along said paths of travel;

(c) a plurality of tap transducers arranged on said surface at spaced intervals along said paths of travel for converting said surface acoustic waves into respective output signals; and

(d) circuit means connected to said tap transducers for combining said output signals to form said reply signal;

the improvement wherein said tap transducers are arranged acoustically both in series and in parallel along said paths of travel.

2. The improvement defined in claim 1, wherein said tap transducers are arranged such that said acoustic waves, propagated simultaneously from said at least one launch transducer, arrive at each tap transducer at a different time.

3. The improvement defined in claim 2, wherein said tap transducers are arranged such that said acoustic waves, propagated simultaneously from said at least one launch transducer, arrive at all of the tap transducers arranged in one series path before arriving at the tap transducers arranged in another, parallel path.

4. The improvement defined in claim 1, wherein said at least one launch transducer comprises a plurality of separate transducer elements connected electrically in series.

5. The improvement defined in claim 1, wherein said tap transducers are arranged in parallel rows.

6. The improvement defined in claim 5, wherein said tap transducers are arranged in four parallel rows.

7. The improvement defined in claim 5, wherein said rows are successively further away from said at least one launch transducer, starting with the row on one side.

8. The improvement defined in claim 5, wherein the two side rows are further away from said at least one launch transducer than the center rows.

9. The improvement defined in claim 1, wherein said at least one launch transducer comprises a plurality of separate transducer elements connected electrically in parallel.