229 results about "Radiofrequency field" patented technology

A magnetic resonance system obtaining magnetic resonance exposures of an examination subject, has an examination tunnel, a whole-body antenna with two connection terminals. The whole-body antenna cylindrically extends around the examination tunnel along a longitudinal axis. The system has a radio-frequency supply device in order to respectively supply the whole-body antenna with radio-frequency signals for emission of a radio-frequency field in the examination tunnel. The radio-frequency supply device has a radio-frequency generator for generation of a radio-frequency signal, a signal splitter that divides a radio-frequency signal coming from the radio-frequency generator into two partial signals that are phase-shifted by 90° relative to one another. Two radio-frequency feed lines are connected with the two connection terminals of the whole-body antenna. Via these radio-frequency feed lines, the two partial signals are fed into the whole-body antenna. The whole-body antenna has an intrinsic transmission characteristic such that a radio-frequency field is emitted that is elliptically polarized in a defined manner in a plane lying perpendicular to the longitudinal axis (at least in the unloaded state of the examination tunnel).

The ion acceleration system or complex (T) for medical and / or other applications is composed in essence by an ion source (1), a pre-accelerator (3) and one or more linear accelerators or linacs (6, 8, 10, 13), at least one of which is mounted on a rotating mechanical gantry-like structure (17). The isocentrical gantry (17) is equipped with a beam delivery system, which can be either ‘active’ or ‘passive’, for medical and / or other applications. The ion source (1) and the pre-accelerator (3) can be either installed on the floor, which is connected with the gantry basement, or mounted, fully or partially, on the rotating mechanical structure (17). The output beam can vary in energy and intensity pulse-by-pulse by adjusting the radio-frequency field in the accelerating modules of the linac(s) and the beam parameters at the input of the linear accelerators.

An imbalanced radio frequency (RF) field creates a retarding barrier near the exit aperture of a multipole ion guide, in combination with the extracting DC field such that the barrier provides an m / z dependent cut of ion sampling. Contrary to the prior art, the mass dependent sampling provides a well-conditioned ion beam suitable for other mass spectrometric devices. The mass selective sampling is suggested for improving duty cycle of o-TOF MS, for injecting ions into a multi-reflecting TOF MS in a zoom mode, for parallel MS-MS analysis in a trap-TOF MS, as well as for moderate mass filtering in fragmentation cells and ion reactors. With the aid of resonant excitation, the mass selective ion sampling is suggested for mass analysis.

A combination of specific antenna type(s), with a system of specific antenna Rf field deployment, combined with the intelligent sensing of differing micro processor control of a digital antenna attenuator that controls disproportional attenuation (either synchronously or independently) of the transmission and reception areas of the antenna(e), of electronically paired devices, together with conditional time delays, is used to securely determine the ID and intent of an Rf access system user. A multifunctional remote device (condition unit) is carried by a carrier, the remote device transmits a short range radio frequency (Rf) signal which, when within range, is received by a stationary control unit. A second multifunctional remote device (cluster unit) is carried by the operator of the carrier and must be in secure communication with the condition unit to enable secure transmission between the control and the control unit. The operation of both said multifunctional remote units changes significantly with application in differing fields of use. By intelligently varying the interactive antenna Tx and Rx area, the proximity and therefore position of the remote (condition) unit to the base (control) unit can be deduced, outwardly appearing as a decoding of the intent of the carrier. This system can be implemented as a secure card-less RFID entry system for vehicle, building, border entry and mass transit systems.

A system for controlling an implantable medical device (e.g., a drug delivery device) susceptible to malfunctioning during exposure to a magnetic field and / or Radio Frequency field (e.g., during a magnetic resonance imaging procedure) and a method for operating the same. Exposure of the implantable device to the magnetic field and / or the Radio Frequency field is detected using the sensing device. When the detected magnetic field and / or Radio Frequency field exceeds a corresponding predetermined threshold level, an input signal is generated at the microcontroller. In response to the generated input signal, the microcontroller automatically triggers (i) a safety mode enabling a predetermined safety mode operation that alters some operation, without ceasing all operation, of the implantable medical device and / or (ii) after expiration of a predetermined safety mode time interval when the at least one field being detected falls below its corresponding predetermined threshold level or a predetermined period of time elapses, a self testing mode enabling a predetermined self testing operation to verify proper operation of the implantable medical device. Preferably, both the safety and self testing modes are automatically triggered.

Ion manipulation systems include ion repulsion by an RF field penetrating through a mesh. Another comprises trapping ions in a symmetric RF field around a mesh. The system uses macroscopic parts, or readily available fine meshes, or miniaturized devices made by MEMS, or flexible PCB methods. One application is ion transfer from gaseous ion sources with focusing at intermediate and elevated gas pressures. Another application is the formation of pulsed ion packets for TOF MS within trap array. Such trapping is preferably accompanied by pulsed switching of RF field and by gas pulses, preferably formed by pulsed vapor desorption. Ion guidance, ion flow manipulation, trapping, preparation of pulsed ion packets, confining ions during fragmentation or exposure to ion to particle reactions and for mass separation are disclosed. Ion chromatography employs an ion passage within a gas flow and through a set of multiple traps with a mass dependent well depth.

A lifecycle management system for detection and tracking of drillpipes which carry low radio frequency tags that comprise an inductive antenna and transceiver operable at a first radio frequency below 1 megahertz, a transceiver operatively connected to that antenna, an ID data storage device, a microprocessor for handling data from the transceiver and data store, and a tag energization inductive antenna which can receive radio frequency energy from an ambient radio frequency field of a second low radio frequency. The system includes a field communication inductive antenna disposed, preferably at a distance of several feet from each object, that permits effective communication therewith at the aforesaid first radio frequency, a data receiver, transmitter and reader data processor in operative communication with the field communication inductive antenna, and a field energization inductive antenna which can produce the ambient radio frequency field at the tag energization inductive antenna.

A method of and system for acquiring data by a data reader from a transponder in which the data from the transponder does not require a preamble to denote the beginning of the data sequence. A radio frequency signal is continuously transmitted by the card reader to generate a radio frequency field. Once a transponder enters the RF field, then response data is generated by the transponder and received by the card reader. The transmission of the radio frequency signal by the card reader is temporarily stopped on detection of the response data from the transponder, and then reinitiated by the card reader after it stops receiving response data from the transponder in order to regenerate the radio frequency field. The response data subsequently received from the transponder in the radio frequency field is then stored in memory.

A radio frequency transmitter arrangement for a magnetic resonance apparatus has a distribution unit and an antenna unit, wherein the antenna unit, to generate radio frequency fields, is fashioned in at least two orthogonal modes, and the distribution unit is fashioned for the division of an RF transmission signal into at least two mode feed signals. At least one adjustment unit is provided to adjust the amplitude and / or phase of one of the mode feed signals and is connected with the antenna unit such that each of the mode feed signals generates a radio frequency field in one of the modes. A multiple transmitter arrangement has at least two radio frequency transmitter arrangements and at least two 180° hybrids. A method is provided to determine at least one setting parameter of the adjustment unit.

In a method and magnetic resonance apparatus for compensation of contrast inhomogeneities in magnetic resonance images caused by spatial distributions of the radio frequency field associated with the radio frequency pulses that are emitted in order to acquire magnetic resonance (MR) data, multiple individual MR images of a particular region of a subject are recorded with different radio frequency pulse sequences leading to different flip angles. A common contrast-homogenized image for the affected region then is generated based on the different individual images, so that within the contrast-homogenized image, intensity variations due to a distribution of the flip angle are smaller than in the individual images, at least in some areas.

A local coil unit for a magnetic resonance apparatus, which radiates a radio-frequency field into an examination subject, has a housing and at least a part of the housing is formed of an insulating dielectric material that passively compensates for an inhomogeneity in the high-frequency field in the subject. The material has a relative dielectric value εr of greater than 50, preferably greater than 100, and a dielectric loss factor tan δ of less than 2.5×10−2, preferably less than 1×10−3. In the dielectric material displacement currents are generated which create an additional magnetic field that compensates for the minima in the B1 field as a result of the eddy currents arising in the patient due to the radio-frequency radiation.