Flat flexible antenna

• US 5,625,366 A
• Filed: 03/02/1995
• Issued: 04/29/1997
• Est. Priority Date: 02/05/1992
• Status: Expired due to Fees

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: D'Hont, Loek
• Primary Examiner(s): Le, Hoanganh T.
• Application Number:
  US08/398,194
• Time in Patent Office: 789 Days
• Field of Search: 343/718, 343/787, 343/788, 343/795, 26/600, 26/DIG. 31, 26/DIG. 95, 26/DIG. 40
• US Class Current: 343/718
• 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 19/07779 the inductive antenna being a coil
• CPC Class Codes: G06K 19/07781 the coil being fabricated in a winding process
• CPC Class Codes: H01Q 7/06 with core of ferromagnetic material H01Q7/02 takes precedence
• CPC Class Codes: Y10S 29/095 Magnetic or electrostatic
• CPC Class Codes: Y10T 29/49016 Antenna or wave energy "plumbing" making

Abstract

Apparatus and method for producing a flexible antenna suitable to be incorporated in a badge or similar object. The antenna comprises electrical windings (28, 38) surrounding a flexible antenna core (26, 36). The antenna core (26, 36) is of a material having a high quality factor formed of a plurality of mutually insulated, longitudinally extending chains of magnetic soft material of high μ. According to one embodiment, a powder of small particles of a magnetic soft material of high μ is mixed with a synthetic resin so that a high saturation of magnetic material in the mixture is formed in a vacuum. The mixture is cured in a strong magnetic field so that the particles form chains (18A, 18B, 18C) of the particle parallel to the applied magnetic field.

Claims

1. A flexible antenna comprising:

a flexible antenna core including a plurality of stacks of longitudinally extending strip-shaped layers of magnetic soft material maintained in a fixed relationship with each other, said flexible antenna core also including an insulating material for electrically insulating adjacent ones of said strip-shaped layers within each stack from each other and also electrically insulating adjacent ones of said stacks from each other; and

electrical windings surrounding said flexible antenna core.

2. The flexible antenna of claim 1 wherein each of said plurality of longitudinally extending strip-shaped layers of magnetic material comprises an amorphous alloy having a longitudinal direction oriented parallel to a selected magnetic field.

3. The flexible antenna of claim 1 wherein said strip-shaped layers are attached in a middle area so that ends of each of said layers are able to move freely with respect to each other.

4. A flexible antenna comprising:

a flexible antenna core including a plurality of chains of a powder of magnetic material wherein each of said chains maintained in a fixed relationship with each other and electrically insulated from each other by a synthetic resin wherein the powder of magnetic material is bonded and mixed with said synthetic resin to maintain said insulated longitudinal extending chains in a fixed position; and

electrical windings surrounding said flexible antenna core.

5. An antenna comprising:

a first longitudinally extending chain of magnetic material;

a second longitudinally extending chain of magnetic material disposed in an opposed relationship to said first chain of magnetic material, said second chain of magnetic material electrically insulated from said first chain of magnetic material;

a third longitudinally extending chain of magnetic material disposed in an opposed relationship to both said first and said second chains of magnetic material, said third chain of magnetic material electrically insulated from both said first and said second chains of magnetic material; and

electrical windings proximate said first, second and third longitudinally extending chains of magnetic material.

6. The antenna of claim 5 wherein said first, second and third longitudinally extending chains of magnetic material are electrically insulated from each other by a synthetic resin and wherein each of said longitudinally extending chains of magnetic material comprises a powder of magnetic material bonded and mixed with said synthetic resin to maintain said insulated longitudinally extending chains in a fixed position.

7. The antenna of claim 5 wherein said first, second and third longitudinally extending chains of magnetic material comprises thin wires of magnetic soft iron covered with an insulating layer.

8. The antenna of claim 5 wherein said first, second and third longitudinally extending chains of magnetic material each comprise an amorphous alloy having a longitudinally direction oriented parallel to a selected magnetic field.

9. The antenna of claim 5 wherein said electrical windings surround said first, second and third longitudinally extending chains of magnetic material.

10. A flexible antenna comprising:

a flexible antenna core including a plurality of chains of a powder of magnetic material wherein each of said chains maintained in a fixed relationship with each other and electrically insulated from each other by an insulating material; and

electrical windings surrounding said flexible antenna core.

11. The flexible antenna of claim 10 wherein said insulating material comprises a synthetic resin.