Abstract: A radio-frequency identification (RFID) transponder (tag) in accordance with the principles of the invention includes a patch antenna. The patch antenna may be co-located with RFID circuitry and an impedance matching circuit on one side of a substrate. A ground plane may be formed on the opposite side of the substrate. A quarter wave transformer may provide an “RF short” to ground to connect the RFID circuitry on one side of the substrate with a ground plane located on the opposite side of the substrate.

Abstract: A magnetic tape information storage media includes a cassette housing having one or more spools for holding a length of magnetic tape and an integral radio frequency identification (RFID) transponder. The RFID transponder may be utilized by an external system to provide functions such as, automated sale, rental, or loan of the media, authentication of the media, indexing of information recorded to the media, enablement/disablement of playback of the media, recording of the number of times the media has been played, inventory, and the like.

Abstract: An impedance matching circuit in accordance with the principles of the present invention employs series-connected transmission lines to match a high reflection coefficient source impedance with a load impedance. The matching circuit is formed on a dielectric substrate material and accommodates the relatively limited capabilities of photo-lithographic circuit production. The new impedance matching circuit may be constructed of three series-connected transmission line sections. A first section, the section that is to be connected to the source, transforms the high source impedance into a relatively low valued impedance that is substantially resistive. The reflection coefficient of the first section is substantially equal to the reflection coefficient of the source. A second may be implemented as a quarter-wave transformer that transforms the low impedance developed by the first section into an intermediate impedance value.

Abstract: An RF/ID transponder comprises an integrated circuit package including at least a memory and an RF modulator. A dipole antenna is coupled to the RF modulator, and has a length greater than one-half wavelength of an electromagnetic wave having a nominal frequency within an operating frequency band of the RF modulator. A base plate provides an electrically conductive ground plane, and a housing is attached to the base plate. The integrated circuit package and the dipole antenna are supported by the housing at a predetermined distance from the conductive ground plane. Thereby, the dipole antenna provides a radiation pattern that includes at least first and second squinted beams extending at respective acute angles relative to a vector defined normal to the conductive ground plane, and at least one center beam extending along the vector defined normal to the conductive ground plane.

Abstract: A radio frequency identification transponder (RFID tag) in accordance with the principles of the present includes a tag antenna having a gain and an input impedance. The tag also includes RFID circuitry, which may be in the form of an RFID tag integrated circuit, the RFID circuitry also being characterized, in part, by an input impedance. According to the principles of the present invention the tag's read distance is maximized by tuning the tag antenna impedance and gain. In general, the imaginary part of the antenna impedance is chosen as the negative of the imaginary part of the RFID circuitry's impedance. Additionally, the real part of the tag antenna's impedance is selected by tuning those geometrical antenna parameters that affect both the antenna's gain and impedance. For RFID tags wherein the geometrical parameters of the tag antenna do not affect the gain G.sub.

Abstract: Processes and apparatus for manufacturing radio frequency transponders having substrates formed from a flexible tape or film are disclosed. The RF transponders are formed on the tape so that their longest dimension (e.g., their length ("L")) is oriented parallel to the length of the tape. This layout places few or no constraints in the transponder's length allowing the length of the transponder's antenna circuit to be adjusted to satisfy the requirements of various applications.

Abstract: A system for controlling assets for inventory, loss-control, or monitoring. The system includes a combination RFID and EAS tag and a reader.

Abstract: A radio frequency identification (RFID) transponder (tag) includes a spiral over ground plane antenna. The RFID tag includes a RFID circuitry that may be implemented as an RFID tag integrated circuit and may be mounted on one surface of a substrate such as a printed circuit board. The RFID tag circuitry may be electrically connected to an impedance matching circuit printed on the same side of printed circuit board. The matching circuit is electrically connected to a spiral antenna that may be mounted on same side of the printed circuit board as the tag circuit and matching circuit. The spiral antenna is held a prescribed distance from the ground plane in order to maximize the gain of the RFID tag and to thereby maximize the range of the RFID tag.

Abstract: The present invention provides a method and apparatus for testing RFID tags using wireless radio frequency (RF) communication. The method and apparatus allow RFID tags to be tested individually or in groups while they are in close proximity to each other (e.g., within the read range of the tag).

Abstract: A radio frequency identification system employing a thin, flexible electronic radio frequency identification (RFID) tag having an overall thickness not exceeding approximately 280 microns and the process for its manufacture is disclosed. The RFID tag includes an insulating, flexible substrate having an aperture formed therein for receiving an RFID circuit chip. An antenna forming an integral part of the substrate is electrically connected to circuit chip. A cured adhesive having a portion substantially parallel with the substrate encapsulates the circuit chip so that the chip is operably retained within the substrate aperture.

Abstract: An antenna, used as a voltage and power source, is designed to operate with an arbitrary load, or front end. One or more stubs are added to one or more of the antenna elements. The stubs act as two conductor transmission line and are terminated either in a short-circuit or open-circuit. Where the transmission line is odd multiples of the guided wavelength in length, the short-circuit stubs act as lumped inductors and the open-circuit stubs act as lumped capacitors. The magnitude of these lumped capacitors and inductors (reactances) is affected by a stub length, a stub conductor width, and a stub spacing. Zero or more short-circuit stubs and zero or more open-circuit stubs are added to one or more of the antenna elements to change the reactive (imaginary) part of the antenna input impedance. In a preferred embodiment, the reactive part is changed to equal the negative magnitude of the reactive part of the front end input impedance.

Abstract: An antenna used as a voltage and power source is designed to operate with arbitrary load, or front end. The antenna has one or more (number of) loading bars that are placed adjacent to the elements of the antenna at a spacing distance. The real part of the antenna input impedance is changed by adjusting the loading bar length, width, and/or spacing distance and/or the number of loading bars. These changes are implemented to reduce the real part of the antenna input impedance to make it small enough to develop an adequate voltage, Vp, to operated the front end and connected circuitry. In a preferred embodiment, the real part of the antenna input impedance is reduced to the point at which Vp no longer increases. One or more stubs is added to one or more of the antenna elements. The stubs act as two-conductor transmission line and is terminated either in a short-circuit or open-circuit. The short-circuit stubs act as a lumped inductor. The open-circuit stub acts as a lumped capacitor.

Abstract: Communication of information between the inside and the outside of an electrically conducting enclosure is performed through the use of a frequency selective surface on the electrically conducting enclosure, which permits passage of electromagnetic waves at particular frequencies, but prohibits waves of other frequencies from penetration. Thus, one or more objects contained within the electrically conducting enclosure, which include radio frequency tags attached to the objects containing information about the objects, may be monitored or interrogated by the transmission of an electromagnetic wave at the permitted frequency through the frequency selective surface. With such a system, control and inventory of enclosed objects may be performed while the EMI shielding function of the electrically conducting enclosure is maintained.