Importance

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Abstract

An antenna in a transponder receives signals from a reader, modulates them, and reflects them back to a reader to pass the information contained in the transponder to the reader. The system includes a thin planar dielectric material having first and second opposite surfaces, preferably with the approximate dimensions of a credit card. First conductive material is disposed on the first surface of the dielectric member at a first end of the member. Second conductive material on the second opposite surface of the dielectric member at the second end of the member defines a dipole with the first material. The second material, preferably triangular in configuration, extends from the second end to a median position between the opposite ends. An electrical circuitry module on the dielectric member produces reflected signals modulated at a particular frequency from the signal transmitted by the reader to pass information contained in the transponder to the reader. The third conductive material on the second surface of the member is electrically coupled with the second conductive material and extends from the triangular apex toward the first end to enhance an impedance match between the dipole and electrical circuitry. The third material has a first low impedance portion split into two parts connected in parllel to provide an extended effective length in a relatively small distance, and has a second portion, preferably a 'pigtail', of substantially higher impedance than the first portion connected in series with the first portion.

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First Claim