Passive transponder for locating avalanche victims

• US 4,656,478 A
• Filed: 07/23/1985
• Issued: 04/07/1987
• Est. Priority Date: 07/30/1984
• Status: Expired due to Term

• Current Assignee: Magnus Granhed
• Original Assignee: Asulab SA (The Swatch Group AG)
• Inventors: Leuenberger, Claude-Eric
• Primary Examiner(s): TUBBESING, THEODORE
• Application Number:
  US06/757,990
• Time in Patent Office: 623 Days
• Field of Search: 343/6.8 R, 343/6.5 R, 343/5 NA, 342/51, 342/193
• US Class Current: 342/51
• CPC Class Codes: A63B 29/021 Means for indicating the location of accidentally buried, e.g. snow-buried, persons
• CPC Class Codes: G01S 13/753 using frequency selective elements, e.g. resonator
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: G06K 19/07762 the adhering arrangement making the record carrier wearable, e.g. having the form of a ring, watch, glove or bracelet record carriers for insertion in the human body for medical purposes A61B90/00; record carriers adapted for attachment to animals A01K11/00
• CPC Class Codes: G06K 19/07786 the antenna being of the HF type, such as a dipole

Abstract

This transponder includes a dielectric support, an antenna and a covering layer. The central portion of the antenna forms a self induction loop which, together with the junction capacity of a non-linear component serving to close the loop, provides a circuit resonating at the frequency at which the transponder receives its energy. The antenna radiates energy at double this frequency which energy may be detected by a receiver.

Claims

1. A passive transponder for seeking out persons by means of a combined transmitter-receiver capable of transmitting at a first frequency and receiving at a second frequency which is a harmonic of said first frequency, comprising:

a dielectric support (11), an antenna formed from a thin conductive sheet (12) fixed to said support and including a non-linear passive component (19) and a conductive portion (16) electrically parallel to said passive component to establish a direct current bias thereof, said antenna sheet defining a cutout portion (15) having an edge (17) which defines a conductive path closed by the passive component to form a self-inductive loop, said loop, together with the capacity of the passive component, providing a circuit resonating at said first frequency, wherein the antenna sheet is linearly elongate, and the cutout portion is disposed proximate a central portion of said elongate antenna sheet intermediate opposite ends thereof.

2. A passive transponder as set forth in claim 1 in which said antenna comprises radiating elements (14a, b) extending from both sides of said self-inductive loop and formed from the same thin sheet.

3. A passive transponder as set forth in claim 2 wherein the distance over which the radiating elements extend from said self-inductive loop is substantially equal to or less than a quarter of the wave length of said first frequency.

4. A passive transponder as set forth in claim 1 in which point shaped portions (18) are provided at the connection points of said non-linear component with said self inductive loop.

7. A passive transponder as set forth in claim 1 wherein the non-linear component is oriented across the bracelet.

5. A passive transponder for seeking out persons by means of a combined transmitter-receiver capable of transmitting at a first frequency and receiving at a second frequency which is a harmonic of said first frequency, comprising:

a dielectric support (11), an antenna formed from a thin conductive sheet (12) fixed to said support and including a non-linear passive component (19) and a conductive portion (16) electrically parallel to said passive component to establish a direct current bias thereof, said antenna sheet defining a cutout portion (15) having an edge (17) which defines a conductive path closed by the passive component to form a self-inductive loop, said loop, together with the capacity of the passive component, providing a circuit resonating at said first frequency, wherein the dielectric support comprises a watch bracelet (21).

6. A passive transponder as set forth in claim 5 wherein the antenna is moulded into said bracelet.

8. A passive transponder as set forth in claim 5 in which said antenna comprises radiating elements (14a, b) extending from both sides of said self-inductive loop and formed from the same thin sheet.

9. A passive transponder as set forth in claim 8 wherein the distance over which the radiating elements extend from said self-inductive loop is substantially equal to or less than a quarter of the wave length of said first frequency.

10. A passive transponder as set forth in claim 5 in which point shaped portions (18) are provided at the connection points of said non-linear component with said self-inductive loop.

11. A passive transponder for seeking out persons by means of a combined transmitter-receiver capable of transmitting at a first frequency and receiving at a second frequency which is a harmonic of said first frequency, comprising:

a dielectric support (11), an antenna formed from a thin conductive sheet (12) fixed to said support and including a non-linear passive component (19) and a conductive portion (16) electrically parallel to said passive component to establish a direct current bias thereof, said antenna sheet defining a cutout portion (15) having an edge (17) which defines a conductive path closed by the passive component to form a self-inductive loop, said loop, together with the capacity of the passive component, providing a circuit resonating at said first frequency, wherein the dielectric support comprises a watch dial.

12. A passive transponder as set forth in claim 11 in which said antenna comprises radiating elements (14a, b) extending from both sides of said self-inductive loop and formed from the same thin sheet.

13. A passive transponder as set forth in claim 12 wherein the distance over which the radiating elements extend from said self-inductive loop is substantially equal to or less than a quarter of the wave length of said first frequency.

14. A passive transponder as set forth in claim 11 in which point shaped portions (18) are provided at the connection points of said non-linear component with said self-inductive loop.

15. A passive transponder for seeking out persons by means of a combined transmitter-receiver capable of transmitting at a first frequency and receiving at a second frequency which is a harmonic of said first frequency, comprising:

a dielectric support (11), an antenna formed from a thin conductive sheet (12) fixed to said support and including a non-linear passive component (19) and a conductive portion (16) electrically parallel to said passive component to establish a direct current bias thereof, said antenna sheet defining a cutout portion (15) having an edge (17) which defines a conductive path closed by the passive component to form a self-inductive loop, said loop, together with the capacity of the passive component, providing a circuit resonating at said first frequency, wherein said antenna comprises radiating elements (14a, b) extending from both sides of said self-inductive loop and formed from the same thin sheet, and wherein notches (22) are provided at junctions between the self-inductive loop and said radiating elements to partially limit an outer contour of said loop.

16. A passive transponder as set forth in claim 15 wherein the distance over which the radiating elements extend from said self-inductive loop is substantially equal to or less than a quarter of the wave length of said first frequency.

17. A passive transponder as set forth in claim 15 in which point shaped portions (18) are provided at the connection points of said non-linear component with said self-inductive loop.

18. A passive transponder for seeking out persons by means of a combined transmitter-receiver capable of transmitting a signal at a first discrete frequency and receiving a return signal at a second discrete frequency which is a harmonic of said first frequency, comprising:

exclusively, a dielectric support (11), and an antenna formed from a thin conductive sheet (12) fixed to said support and including a non-linear passive component (19) and a conductive portion (16) electrically parallel to said passive component to establish a direct current bias thereof, said antenna sheet defining a cutout portion (15) having an edge (17) which defines a conductive path including said conductive portion and closed by the passive component to form a self-inductive loop, said loop, together with the capacity of the passive component, providing a circuit resonating exclusively at said first frequency and radiating a return signal exclusively at said second, harmonic frequency.

19. A passive transponder as set forth in claim 18 in which said antenna comprises radiating elements (14a, b) extending from both sides of said self-inductive loop and formed from the same thin sheet.

20. A passive transponder as set forth in claim 19 wherein the distance over which the radiating elements extend from said self-inductive loop is substantially equal to or less than a quarter of the wave length of said first frequency.

21. A passive transponder as set forth in claim 18 in which point shaped portions (18) are provided at the connection points of said non-linear component with said self-inductive loop.