Abstract: An RFID device includes conductive tabs, and a conductive structure, with a dielectric layer between the conductive tabs and the conductive structure. The conductive structure overlaps the conductive tabs and acts as a shield, allowing the device to be at least somewhat insensitive to the surface upon which it is mounted, or to the presence of nearby objects, such as goods in a carton or other container that includes the device. The dielectric layer may be a portion of the container, such as an overlapped portion of the container. Alternatively, the dielectric layer may be a separate layer, which may vary in thickness, allowing one of the conductive tabs to be capacitively coupled to the conductive structure. As another alternative, the dielectric layer may be an expandable substrate that may be expanded after fabrication operations, such as printing.

Abstract: A modulator circuit comprises a negative impedance amplifier (6) which is operable such that a signal applied to the amplifier (6) is reflected and amplified. Switching means (14, 16) are provided for switching the impedance of the amplifier (6) between two reflecting states such that the reflected and amplified signal is phase modulated. The impedances of the negative impedance amplifier are selected such that the phase of the reflected and amplified signal switches by substantially 180 degrees. Preferably the impedances of the negative impedance amplifier in the two reflecting states are selected such that the reflection gain of the amplifier in the two reflecting states is substantially the same such that the reflected and amplified signal is a binary phase shift keyed.

Abstract: An AM receiver incorporates an antenna, a transistor, a current source, and a power supply. The antenna is connected to a gate electrode of the transistor and through a link to a signal earth. In operation, the antenna receives radiation and generates a corresponding input signal which propagates to the gate electrode. The transistor is operable to process the input signal in two steps, namely to reflectively amplify the input signal to generate a correspondingly reflectively amplified input signal at the gate electrode in a first step, and amplitude demodulate the amplified input signal in a second step. The transistor is operable in a non-linear region of its current/voltage characteristic whereas it simultaneously provides reflective amplification and signal demodulation, namely the two steps occur simultaneously.

Abstract: An RFID device includes conductive tabs, and a conductive structure, with a dielectric layer between the conductive tabs and the conductive structure. The conductive structure overlaps the conductive tabs and acts as a shield, allowing the device to be at least somewhat insensitive to the surface upon which it is mounted, or to the presence of nearby objects, such as goods in a carton or other container that includes the device. The dielectric layer may be a portion of the container, such as an overlapped portion of the container. Alternatively, the dielectric layer may be a separate layer, which may vary in thickness, allowing one of the conductive tabs to be capacitively coupled to the conductive structure. As another alternative, the dielectric layer may be an expandable substrate that may be expanded after fabrication operations, such as printing.

Abstract: An RFID device includes an antenna structure that provides good performance throughout a range of different positions relative to nearby materials, such as metallic objects in a carton or other container. The antenna structure has compensation elements that interact with the nearby materials to provide good performance over the range of different positions. The compensation elements include both electrical compensation elements, which interact with the nearby materials primarily using electric fields, and magnetic compensation elements, which interact with the nearby materials primarily using magnetic fields. The electrical compensation elements and the magnetic compensation elements may be selected and may be positioned within the antenna structure such that the performance of the antenna structure is substantially unchanged (or at least acceptable) through the range of different positions.

Abstract: A radio frequency identification (RFID) tag includes an antenna configuration coupled to an RFID chip, such as in an RFID strap. The antenna configuration is mounted on one face (major surface) of a dielectric material, and includes compensation elements to compensate at least to some extent for various types of dielectric material upon which the antenna configuration may be mounted. In addition, a conductive structure, such as a ground plane or other layer of conductive material, may be placed on a second major surface of the dielectric layer, on an opposite side of the dielectric layer from the antenna structure.