Importance

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Abstract

A radio frequency identification tag (100) in accordance with the present invention includes a first antenna element (112), a second antenna element (114) and a radio frequency identification circuit (116). The first antenna element (112) is electrically isolated from the second antenna element (114). The radio frequency identification circuit has a first pad (230) and a second pad (232). The first and second pads of the radio frequency identification circuit are coupled, respectively, to the first and second antenna elements. The radio frequency identification circuit includes a load modulation circuit (222) coupled to at least one of the first or second pads to produce a load modulated signal on at least one of the first or second pads that varies from a first amplitude to a second amplitude. The load modulation circuit has a modulation impedance and a predetermined voltage threshold that an input signal must exceed before the modulated signal is produced. The first and second pads of the integrated circuit have an input capacitance as measured between them. The modulation impedance, voltage threshold, and pad capacitance are optimized for electrostatic radio frequency identification applications. Alternatively, a modulation circuit is not coupled to the first and second antenna elements and is instead coupled through a third pad with a third electrostatic antenna element for data transmission. Also, electronic article surveillance (EAS) is alternatively provided with the radio frequency identification circuit and is alternatively, selectively defeated.

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First Claim