A piezo-electric tag in the form of a card has a first dipole antenna, a first
rectification circuit, a piezo-electric transformer, a second rectification circuit,
and a transponder circuit. In operation, the antenna receives incoming radiation
and generates a corresponding signal which propagates to the first circuit which
demodulates and filters it to generate a signal which is applied to the transformer
to excite it. The transformer increases the voltage amplitude of the signal by
generating a relatively higher voltage amplitude signal which is used in the tag
to generate a signal for supplying power to the transponder. The transformer provides
voltage magnitude enhancement to generate potentials suitable for operating active
electronic circuits incorporated into the tag. The tag can be personnel wearable
and even adapted for permanent inclusion into biological systems.
