Binary encoded multiple frequency rf indentification tag

Claim 1

A tag for identifying an associated or attached item comprising: an inductance; and a capacitance connected in parallel with the inductance, the capacitance comprising a plurality of individual capacitors, the individual capacitors being connected to establish with the inductance a first resonant circuit having a first predetermined resonant frequency, each of the individual capacitors having a different value, at least one of the individual capacitors including shorting means for causing said at least one capacitor to become short circuited when the first resonant circuit is exposed to electromagnetic energy at the first resonant frequency at a predetermined power level to establish a second resonant circuit having a second resonant frequency said second resonant frequency being dependent upon the particular individual capacitor which is short circuited; wherein each capacitor is capable of being in an active state or a shorted state, the different values determining the bit positions of a binary number uniquely associated with the tag, and the combination of capacitors having active and shorted states establishing the binary number.

Claim 7

A method of identifying an item associated with a tag comprised of an inductance connected in parallel with a capacitance, the capacitance comprising a plurality of individual capacitors each of a predetermined different capacitance, the individual capacitors being connected to establish with the inductance a resonant circuit having a predetermined resonant frequency, selected one or more of the capacitors including shorting means for short circuiting the selected capacitor when the resonant circuit is exposed to electromagnetic energy at the resonant frequency at a predetermined minimum power level, the method comprising the steps of: (a) exposing the resonant circuit to electromagnetic energy at the resonant frequency at a predetermined minimum power level, to cause one of said selected capacitors to short circuit thereby changing the resonant frequency of the resonant circuit; (b) exposing the resonant circuit to electromagnetic energy at varying frequencies to determine the resonant frequency of the resonant circuit; (c) identifying, based upon the resonant frequency, which one of the selected capacitors was short circuited; (d) repeating steps (a) through (c) until all of the selected capacitors have been short circuited and each of the short circuited capacitors have been identified; and (e) establishing a code based upon a combination of the short circuited and non-shorted circuited capacitors to identify the item associated with the tag.

Claim 8

A method of identifying an item associated with a tag comprised of an inductance connected in parallel with a capacitance, the capacitance comprising a plurality of individual capacitors each of a predetermined different capacitance, the individual capacitors being connected to establish with the inductance a resonant circuit having a predetermined resonant frequency, selected one or more of the capacitors including shorting means for short circuiting the selected capacitor when the resonant circuit is exposed to electromagnetic energy at the resonant frequency at a predetermined minimum power level, the method comprising the steps of: (a) exposing the resonant circuit to electromagnetic energy at the resonant frequency at a predetermined minimum power level, to cause one of said selected capacitors to short circuit thereby changing the resonant frequency of the resonant circuit; (b) exposing the resonant circuit to electromagnetic energy at varying frequencies to determine the resonant frequency of the resonant circuit; (c) identifying, based upon the resonant frequency, which one of the selected capacitors was short circuited; (d) repeating steps (a) through (c) until all of the selected capacitors have been short circuited and each of the short circuited capacitors have been identified; and (e) establishing a code based upon a combination of the short circuited and non-shorted circuited capacitors to identify the item associated with the tag.