Radio frequency antenna with current controlled sensitivity

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.
S.
Patent Laws "to promote the progress of science and useful arts" (Article 1, Section 8).
According to an aspect of this invention, a radio frequency antenna circuit comprises: an antenna constructed and arranged to transfer electromagnetic waves, the electromagnetic waves corresponding to a signal carried by the antenna and generated from a signal source; a Schottky diode electrically coupled in serial relation with the antenna, in operation the signal being applied serially across the antenna and the diode in direct relation with electromagnetic waves transferred by the antenna; and a bias current supply electrically coupled to the Schottky diode and configurable to deliver a desired bias current across the Schottky diode, the Schottky diode responsive to the bias current to realize a desired impedance across the Schottky diode such that a desired impedance match is provided between impedance of the Schottky diode and impedance of the antenna when the signal is applied across the antenna circuit, which selectively tunes the antenna circuit by imparting a desired power transfer therein.
According to another aspect of this invention, a microprocessor controlled tag apparatus comprises: a package; a monolithic semiconductor integrated circuit supported by the package and having a microprocessor and integrated circuitry fabricated therein; and a transponder electrically connected to the integrated circuitry of the semiconductor integrated circuit, the transponder including an antenna circuit having an antenna, a Schottky diode serially connected to the antenna, a power supply applied serially across the antenna and the Schottky diode for respectively imparting an impedance across the antenna and the Schottky diode, and a bias current applied across the Schottky diode to realize a desired impedance of the Schottky diode in relation to impedance of the antenna with the resulting antenna circuit realizing a desired power transfer dependent upon the relative impedances of the antenna and the Schottky diode; and the transponder being selectively tunable within a range of detuned and fully tuned states by way of configuring the bias current across the Schottky diode to realize a desired power transfer for the antenna circuit which imparts a desired signal sensitivity to the transponder