93results about How to "Reduce SAR" patented technology

A mobile phone capable of reducing an electromagnetic SAR in human bodies includes a base and a cover disposed on the base. The base includes an antenna for transmitting and receiving electromagnetic waves. The cover includes a screen and buttons. Electromagnetic absorbing materials having electric or magnetic loss are applied on the cover to mitigate electromagnetic waves radiating from the antenna into the user. Moreover, a meandered planar inverted-F antenna is attached to the back of the circuit board near the bottom of the base, which can generate a lower near field at the user's side than those in other directions, thereby reducing the electromagnetic specific absorption rate of the mobile phone in human bodies.

An inverted F antenna (IFA) which reduces specific absorption rate (SAR) includes a ground; an auxiliary radiator which is attached to one end of the ground and disposed along a plane direction of the ground; a radiator which lies at an interval from the auxiliary radiator in parallel and radiates electromagnetic waves; a feed which supplies current to the radiator; and a short which interconnects the radiator with the ground and discharges the current to the ground. Accordingly, the SAR can be decreased and the antenna size can be miniaturized.

A radio antenna apparatus is provided with an antenna connected with a radio communication circuit that transmits and receives a radio signal. A load impedance element is connected between a parasitic element of an electrical conductor plate and a ground of a housing of a radio communication apparatus including the radio communication circuit. A controller controls an element value of the load impedance element so as to set a current flowing on the housing to be equal to or smaller than a predetermined value when the radio communication apparatus transmits the radio signal, thereby controlling a specific absorption rate (SAR) to be equal to or smaller than a predetermined value.

A radiation shield (36) includes a virtual magnetic wall (VMW), which is adapted to be placed between a radiating antenna (34) and an object (30) so as to reflect electromagnetic radiation emitted from the antenna in a given frequency band and having an electric field with a given polarization, away from the object. The electric field of the radiation reflected by the VMW is substantially in phase with the electric field of the emitted radiation incident on the VMW.

An antenna assembly (30) for a communication device (20) includes a feed structure (25), which has front and rear sides (26, 27), and which is coupled to be driven by the device so as to radiate an electromagnetic field in a given frequency band. An electrically reactive surface (28) is positioned adjacent to the rear side of the feed structure so as to define a cavity (35) between the feed structure and the reactive surface, thereby substantially nulling the electromagnetic field on the rear side of the feed structure.

Systems and methods for the selection of and application of RF power to a plurality of transmit and/or transmit/receive coil elements to decrease patient SAR and to limit the potential for artifact problems. Without any change to the hardware or software of an MR scanner, the present local coil system provides system logic and coil design flexibility such that only transmit coil elements that are required for a particular portion of an MR scan will be utilized at that time. The local coil system may include any combination of transmit-only, receive-only and transmit/receive coil elements as part of the coil system (array of coil elements). The logic controller of the local coil system gathers input data from the MR scanner, from the attached coil elements and optionally from one or more sensors attached to the coil system itself.

A mobile wireless communications device may include a housing having an upper portion and a lower portion, a dielectric substrate carried by the housing, circuitry carried by the dielectric substrate, and an audio output transducer carried by the upper portion of the housing and connected to the circuitry. The device may further include a user input interface carried by the housing and connected to the circuitry, and at least one auxiliary input/output device carried by the upper portion of the housing and connected to the circuitry. An antenna may also be carried within the lower portion of the housing comprising a pattern of conductive traces on the dielectric substrate.

A wireless communication device includes an antenna configured with two conductive elements separated by an insulating medium providing a separation distance. One conductive element is a ground plane and the other is a microstrip line. The microstrip line and the ground plane exhibit a characteristic impedance that may vary along the length of the microstrip line. The separation distance of the microstrip line from the ground plane is changed to reduce the resonant frequency of the microstrip line. A second microstrip line with an open end and another end shorted to the ground plane is operative to prevent RF current from flowing on the backside of the ground plane. A backside of the ground plane and the second microstrip line may be covered with a lossy magnetic medium to reduce the near field in the space above the backside of the ground plane.

The present invention relates to a method for reducing SAR, a mobile terminal, and a computer readable storage medium. The mobile terminal comprises a first antenna, a second antenna, a first distancemeasuring device, and a second distance measuring device, wherein the first distance measuring device is disposed on a first side of the mobile terminal, and the second distance measuring device is disposed on a second side of the mobile terminal opposite to the first side; the first distance measuring device is used for detecting a distance between the head of a user and the mobile terminal, andreducing the transmission power of the first working antenna according to a head back-off parameter when the distance between the head of the user and the mobile terminal is less than or equal to a preset head distance threshold; the second distance measuring device is used for detecting a distance between the body of the user and the mobile terminal, and reducing the transmission power of the second working antenna according to a body back-off parameter when the distance between the body of the user and the mobile terminal is smaller than or equal to a preset body distance threshold. Therefore, the SAR value of the mobile terminal can be effectively reduced by the first distance measuring device and the second distance measuring device without affecting the OTA performance of the mobileterminal.

A method and apparatus for controlling a SAR (Specific Absorption Rate) in a mobile communication terminal. The SAR is controlled by adjusting a transmission power of a mobile communication terminal. The method for controlling the SAR in a mobile terminal includes the steps of checking a user-selected SAR control mode of the mobile terminal, setting a code value corresponding to a transmission power of the RF signal to a gain of the amplifier, wherein the code value is set to a first code value when the SAR control mode is a safe mode, or is set to a second code value when the SAR control mode is a normal mode, and amplifying the RF signal according to the gain of the amplifier, such that it controls a transmission power of an RF (Radio Frequency) signal by controlling a gain of an amplifier amplifying the RF signal.

A wireless communication device includes an antenna configured with two conductive elements separated by an insulating medium. One conductive element is a ground plane and the other is a microstrip line. The ground plane is formed with a bend proximate an end. The microstrip line and the ground plane exhibit a characteristic impedance that may vary along the length of the microstrip line. The separation distance of the microstrip line from the ground plane is changed to reduce the resonant frequency of the microstrip line. A second microstrip line with an open end and another end shorted to the ground plane is operative to prevent RF current from flowing on the backside of the ground plane. A backside of the ground plane and the second microstrip line may be covered with a lossy magnetic medium to reduce the near field above the backside of the ground plane.

A built-in antenna apparatus for a mobile terminal is provided. The built-in antenna apparatus includes a first planar antenna having a first feeding point for providing a first radiation pattern, a second planar antenna having a second feeding point for providing a second radiation pattern, the second planar antenna being located adjacent to the first planar antenna, and a ground stub having a ground point for providing a ground pattern, the ground stub placed a distance apart from the first and the second planar antennas.

A wireless communication device is configured to provide wireless communication to a host device when disposed in a mated position with the host device such that a housing of the wireless communication device extends a distance Lid from a face of the host device. The wireless communication device includes a transceiver, a controller in communication with the transceiver, and a modem in communication with the controller. The wireless communication device also includes a dipole antenna having a dipole effective current axis Ix for a selected wavelength λ in the mated position that is at a distance from the face of the host device that is in the range of about 0.09λ to about 0.25λ.

A mobile radio apparatus antenna for improving the gain and widening the band is provided. A inverted-L antenna (10) is a feed element with one end thereof electrically connected to one plate surface of a circuit board (12) through a feed point. The circuit board (12) is a circuit board of a mobile radio apparatus, to which the circuit parts including the inverted-L antenna (10) are connected. A planar antenna (14) is provided facing the backside plate surface of the plate surface of the circuit board (12), to which the inverted-L antenna (10) is connected, and is a parasitic element with an electrical length in the length direction set to approximately ½ of the wavelength of radio waves communicated by the mobile radio apparatus. Here, the dimension of the inverted-L antenna (10), the circuit board (12), and the planar antenna (14), and the distance therebetween are adjusted to predetermined values, so as to change the self-impedance of the inverted-L antenna (10), the self-impedance of the planar antenna (14), and the mutual impedance between the inverted-L antenna (10) and the planar antenna (14).

An MRI apparatus comprises a waveform controlling means for calculating a radio frequency pulse and applying the pulse to an irradiating means, and the waveform controlling means reads out a radio frequency pulse waveform vector from a first memory means which memorizes multiple radio frequency pulse waveform vectors, calculates a simulated irradiation pattern, and calculates a radio frequency pulse waveform which gives the minimum value of weighted sum of squares of differences of absolute values and squares of differences of phases for an ideal irradiation pattern and the simulated irradiation pattern. An RF pulse waveform showing superior ideal irradiation pattern reproducibility and providing reduced power of the RF waveform is formed, and safety of MRI subject is improved by performing imaging using such an RF pulse.

In a transmit apparatus, a multi-channel radio frequency transmitter (30, 46) includes a plurality of transmit elements (32) defining at least two independently operable transmit channels. A transmit configuration selector (54) determines a selected transmit configuration (60) specifying amplitude and phase applied to each transmit channel to generate a B1 field in a corresponding selected region (90) of a subject (38) coupled with the radio frequency transmitter. The transmit configuration selector determines the selected transmit configuration based on B1 mapping (58) of the subject and a B1 field quality assessment employing at least two different B1 field quality measures.

The invention discloses a wideband low-specific absorption rate (SAR) wireless terminal antenna system. The wideband low-SAR wireless terminal antenna system comprises a printed circuit board (PCB), an antenna bracket, an antenna and a metal piece, wherein the antenna bracket is arranged on the PCB; the antenna covers the outer surface of the antenna bracket; the metal piece covers the inner surface of the antenna bracket; the antenna comprises a main body and two ends; at least one end of the antenna has a bending structure, and a certain gap is formed between the bending structure and the main body; a projection of the metal piece on the inner surface of the antenna bracket at least covers part of the gap; and the metal piece is used for improving capacitance between the bending structure and the main body, so an electric field of the gap between the bending structure and the main body is reduced, and an SAR value is decreased. Compared with the prior art, the wideband low-SAR wireless terminal antenna system is wide in resonant frequency, low in SAR, simple in structure and easy to implement.

The invention discloses wireless communication equipment. A first antenna and a second antenna are arranged on the wireless communication equipment. The electrical length of the first antenna is N times of that of the second antenna, and N is an integer larger than or equal to one. The first antenna and the second antenna are arranged on a printing circuit board in a common ground connection mode, namely, the first antenna and the second antenna share the same grounding point, so that the input impedance of the grounding point of the first antenna and the grounding point of the second antenna is reduced, and energy fed through the antennas is made to be distributed in a relatively even mode in the horizontal direction and the perpendicular direction of the printing circuit board. Consequently, SAR is reduced on the condition that the communication quality of the wireless communication equipment is not reduced.