326 results about "Rf field" patented technology

A RF-ID based wireless terminal has shortened session set-up and user identification time for conducting transactions with interactive service applications. The wireless terminal includes a terminal identification number and a user identification as a RF-ID tag. A RF-ID reader transmits a RF field for detecting the RF-ID tag in the terminal and provides an output signal when the terminal is within the reader field. The output signal establishes a connectionless communication to an access point or other terminal which initiates a wireless paging operation, in lieu of conducting a terminal discovery process, based upon the content of the RF-ID tag. The terminal initiates a wireless session between the terminal and the access point or terminal for conducting transactions with a service application linked to the access point or terminal.

A resonator system for generating a radio frequency (RF) magnetic field in a volume under investigation of a magnetic resonance (MR) arrangement, comprises a number N of individual resonators (2) which surround the volume under investigation and which are each disposed on a flat dielectric substrate (1) around a z-axis, wherein the individual resonators (2) have windows (8) through each of which one individual RF field is generated in the volume under investigation in single operation of the individual resonators (2) and, through cooperation among the individual resonators (2), a useful RF field (7) is generated in the volume under investigation, wherein a remote RF field (6) is asymptotically generated far outside of the resonator system, and the spatial distribution of the useful RF field (7) is substantially mirror-symmetrical relative to a first plane A which contains the z-axis, and that of the asymptotic remote RF field (6) is substantially mirror-symmetrical relative to a second plane B which contains the z-axis, the useful RF field (7) extending substantially parallel to the first plane A in the volume under investigation, wherein the number of individual resonators (2) is N>4 and wherein, during operation of the resonator system at at least one point in time, the substrate plane of at least one individual resonator (2) subtends an angle of more than 40° with respect to the direction of the useful RF field (7) in the volume under investigation, and at least one further individual resonator (2) subtends an angle of less than 40° with respect to the direction of the useful RF field (7) in the volume under investigation, is characterized in that the first plane A is not rotated about the z-axis relative to the second plane B or is rotated by less than 360° / (N+1). The inventive resonator system realizes a resonator system with improved field homogeneity and full quadrature suitability, high quality factor and large efficiency using straightforward constructional measures.

Decoupling circuits are provided which transfer energy induced from an MRI pulsed RF field to an energy dissipating surface. This is accomplished through broadband filtering or by resonant filtering. In a passive component network for an implantable leadwire of an active implantable medical device, a frequency selective energy diversion circuit is provided for diverting high-frequency energy away from a leadwire electrode to a point or an area spaced from the electrode, for dissipation of high-frequency energy.

Apparatus and methods are provided for trapping, manipulation and transferring ions along RF and DC potential surfaces and through RF ion guides. Potential wells are formed near RF-field generating surfaces due to the overlap of the radio-frequency (RF) fields and electrostatic fields created by static potentials applied to surrounding electrodes. Ions can be constrained and accumulated over time in such wells. During confinement, ions may be subjected to various processes, such as accumulation, fragmentation, collisional cooling, focusing, mass-to-charge filtering, spatial separation ion mobility and chemical interactions, leading to improved performance in subsequent processing and analysis steps, such as mass analysis. Alternatively, the motion of ions may be better manipulated during confinement to improve the efficiency of their transport to specific locations, such as an entrance aperture into vacuum from atmospheric pressure or into a subsequent vacuum stage.

A fast data transfer collection system using message authentication and contactless RF proximity card technology in non-contact storage and retrieval applications. The system is generally comprised of Host computers (application computer systems), Target radio frequency (RF) terminals, and a plurality of portable Tags ("smart" or "proximity" cards). A Host provides specific application functionality to a Tag holder, with a high degree of protection from fraudulent use. A Target provides control of the RF antenna and resolves collisions between multiple Tags in the RF field. A Tag provides reliable, high speed, and well authenticated secure exchanges of data / information with the Host resulting from the use of a custom ASIC design incorporating unique analog and digital circuits, nonvolatile memory, and state logic. Each Tag engages in a transaction with the Target in which a sequence of message exchanges allow data to be read(written) from(to) the Tag. These exchanges establish the RF communication link, resolve communication collisions with other Tags, authenticate both parties in the transaction, rapidly and robustly relay information through the link, and ensure the integrity and incorruptibility of the transaction. The system architecture provides capabilities to ensure the integrity of the data transferred thus eliminating the major problem of corrupting data on the card and in the system. The architecture and protocol are designed to allow simple and efficient integration of the transaction product system into data / information processing installations.

An apparatus and method for low frequency asset tracking includes a low frequency transmitter tag associated with a cargo container or other high value commodity, a plurality of receivers that detect low frequency signals, and a microprocessor that uses algorithms and / or data pertaining to the propagation characteristics of the signal to locate the position of the container or high value commodity. The tag may include sensors to monitor container properties or conditions, such as temperature, motion, intrusion, RF fields, or other properties of interest. Sensor data may be modulated on the low frequency transmitter signal.