Method for producing a flat flexible antenna

• US 5,408,243 A
• Filed: 01/14/1993
• Issued: 04/18/1995
• Est. Priority Date: 02/05/1992
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: D'Hont, Loek
• Primary Examiner(s): Hajec, Donald
• Assistant Examiner(s): LE, HOANGANH T
• Application Number:
  US08/004,362
• Time in Patent Office: 824 Days
• Field of Search: 343/718, 343/787, 343/788, 343/795, 29/600, 29/DIG. 31, 29/DIG. 95, 29/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 method for producing a flexible antenna comprising the steps of:

forming a flexible antenna core from a plurality of longitudinally extending chains of magnetic soft material maintained in a fixed relationship with each other, said step of forming a flexible antenna core comprising the steps of;

mixing a powder of small particles of magnetic material with a synthetic resin in a vacuum;

placing said mixture in a static magnetic field to arrange said particles end to end in chains parallel to said field, said chain of particles being electrically insulated from each other by said resin;

curing said mixture to bond and maintain said particles in said chains; and

removing said magnetic field;

and

surrounding said flexible antenna core with electrical windings.

2. The method of claim 1 wherein said mixture of particles and resin is formed in the shape of a block and further comprising the step of cutting said block into thin strips along a longitudinal direction corresponding to the direction of the previously applied magnetic field to form a plurality of flexible magnetic cores.

3. A flexible antenna formed by the process of claim 1.