Abstract: A preamplifier arrangement for an MRI system includes a preamplifier coupled to a loop of a multi-channel coil array of the MRI system, wherein the preamplifier and the loop are subject to potentially form an unstable system with oscillation at one or more peak frequencies. The preamplifier arrangement also includes an impedance matching network disposed between and coupled to the preamplifier and the loop. The impedance matching network is configured to generate a high blocking impedance. The preamplifier arrangement further includes an input network disposed between and coupled to the preamplifier and the loop. The input network is configured to provide an input to suppress gain at the one or more peak frequencies.

Abstract: Various systems and methods are provided for radio frequency coil assemblies for a magnetic resonance imaging system. In one example, a method comprises: flowing air through a plurality of airflow passages formed in a radio frequency (RF) coil assembly for a magnetic resonance imaging (MRI) system; and receiving magnetic resonance (MR) signals from an RF coil array of the RF coil assembly, wherein the RF coil array comprises a plurality of RF coil elements, each RF coil element having a loop portion which comprises two distributed capacitance wire conductors encapsulated and separated by a dielectric material.

Abstract: A magnetic resonance imaging system includes a bore, a table configured to support a patient being imaged and movable to move the patient in and out of the bore, a motion sensor, a controller configured to detect patient motion based on changes in an RF signal from the motion sensor. The motion sensor includes a self-resonant spiral (SRS) coil excited by a drive signal to radiate a magnetic field having a predefined resonant frequency and a driver-receiver coupled to the SRS coil and configured to generate the drive signal to excite the SRS coil and to receive the RF signal from the SRS coil. The motion sensor is located such that a portion of the patient is within the magnetic field while the patient is being imaged in the bore.

Abstract: A table for an MRI system includes a top surface for supporting a patient being imaged and a motion sensor for sensing motion of the patient. The motion sensor is located below the top surface and includes a self-resonant spiral (SRS) coil and a coupling loop. The coupling loop generates a drive RF signal to excite the SRS coil to radiate a magnetic field having a predefined resonant frequency. The coupling loop also receives a reflection RF signal from the SRS coil. The motion sensor is located such that at least a portion of a torso of the patient being imaged is within the magnetic field. A controller is configured to detect patient motion based on the reflection RF signal.

Abstract: A table for an MRI system includes a top surface for supporting a patient being imaged and a motion sensor for sensing motion of the patient. The motion sensor is located below the top surface and includes a self-resonant spiral (SRS) coil and a coupling loop. The coupling loop generates a drive RF signal to excite the SRS coil to radiate a magnetic field having a predefined resonant frequency. The coupling loop also receives a reflection RF signal from the SRS coil. The motion sensor is located such that at least a portion of a torso of the patient being imaged is within the magnetic field. A controller is configured to detect patient motion based on the reflection RF signal.

Abstract: Various systems and methods are provided for radio frequency coil assemblies for a magnetic resonance imaging system. In one example, a method comprises: flowing air through a plurality of airflow passages formed in a radio frequency (RF) coil assembly for a magnetic resonance imaging (MRI) system; and receiving magnetic resonance (MR) signals from an RF coil array of the RF coil assembly, wherein the RF coil array comprises a plurality of RF coil elements, each RF coil element having a loop portion which comprises two distributed capacitance wire conductors encapsulated and separated by a dielectric material.

Abstract: Various methods and systems are provided for a common mode trap for a magnetic resonance imaging (MRI) apparatus. In one embodiment, a common mode trap comprises: a first conductor and a second conductor counterwound around a length of a central conductor, the first and the second conductors radially spaced a distance from the central conductor, the first and second conductors fixed to a first side of the central conductor; and a third conductor and a fourth conductor counterwound around the length of the central conductor, the third and fourth conductors are radially spaced the distance from the central conductor, the third and fourth conductors fixed to a second side of the central conductor opposite the first side. In this way, the density of common mode trap conductors in a common mode trap may be increased, thereby increasing the mutual inductance between the common mode trap and the central conductor.

Abstract: Various methods and systems are provided for a common mode trap for a magnetic resonance imaging (MRI) apparatus. In one embodiment, a common mode trap comprises: a first conductor and a second conductor counterwound around a length of a central conductor, the first and the second conductors radially spaced a distance from the central conductor, the first and second conductors fixed to a first side of the central conductor; and a third conductor and a fourth conductor counterwound around the length of the central conductor, the third and fourth conductors are radially spaced the distance from the central conductor, the third and fourth conductors fixed to a second side of the central conductor opposite the first side. In this way, the density of common mode trap conductors in a common mode trap may be increased, thereby increasing the mutual inductance between the common mode trap and the central conductor.

Abstract: When an input digital signal, having a portion with an associated control value, is connected to a digital filter with adaptive compensation, the digital filter with adaptive compensation selects one of a plurality of coefficient scalers (9501, 9601) as directed by a control bus (990). As the input digital signal propagates through the filter, one of a plurality of next coefficient scalers (9502,9602) are selected by the control bus (990). The digital filter with adaptive compensation interleaves in time the coefficients of multiple conventional filters in order to filter each portion of the digital signal according to its associated control value.

Abstract: A difference drive diversity antenna structure (200) and method for a portable wireless communication device (230) aligns a first linear antenna (240) parallel to a major axis (245) of the communication device and drives dual radiators (252, 254) of a second antenna (250) at equal magnitudes but with a 180 degree phase difference. A difference drive diversity antenna structure implemented in a portable wireless communication device maintains significant decorrelation between the first antenna (240) and the second antenna (250) over the common frequency ranges of the dual radiators (252, 254). Also, antenna currents on the body of the communication device are minimized and the effects of a hand or body near the communication device are reduced.

Abstract: An electronic device includes an electrical circuitry interface (112) adapted for coupling with an energy source (106), a comparator (138), and a DC-DC converter circuitry (134) having a switch circuit (161) and an energy storage circuit (132). The switch circuit (161) is coupled to the electrical circuitry interface (112) and to the energy storage circuit (132), and is controlled to charge the energy storage circuit (132). A first input (166) of the comparator (138) is coupled to a voltage that varies with a nominal supply voltage of the energy source (106). A second input (168) of the comparator (138) is coupled to a threshold voltage. A comparator output (160) of the comparator (138) is coupled to the switch circuit (161). In operation, the DC-DC converter circuitry (134) charges the energy storage circuit (132) for a certain time period or until the stored voltage is greater then a desired voltage.

Abstract: The multi-band slot antenna structure and method uses a single antenna to cover at least two distinct reception frequency bands using only one excitation port. In a first type of configuration, dual resonant slots (320, 325) are placed in close proximity and driven using a single differential excitation port having a positive node (370) and a negative node (375). In a second type of configuration, a half wavelength conductor (560, 660, 760) is layered over a quarter wavelength slot (520, 720) or half wavelength slot (620), and when the conductor is heavily magnetically coupled to the slot, a virtual electric short is achieved across the slot. In a third type of configuration, a quarter wavelength conductor (1060, 1160) is layered over a quarter wavelength slot (1020) or half wavelength slot (1120), and the conductor is used to capacitively or inductively load the slot (1120) at frequencies other than the natural resonant frequency of the slot (1120).

Abstract: A difference drive diversity antenna structure (200) and method for a portable wireless communication device (230) aligns a first linear antenna (240) parallel to a major axis (245) of the communication device and drives dual radiators (252, 254) of a second antenna (250) at equal magnitudes but with a 180 degree phase difference. A difference drive diversity antenna structure implemented in a portable wireless communication device maintains significant decorrelation between the first antenna (240) and the second antenna (250) over the common frequency ranges of the dual radiators (252, 254). Also, antenna currents on the body of the communication device are minimized and the effects of a hand or body near the communication device are reduced.

Abstract: A multi-layered compact slot antenna shortens the physical length of a slot antenna (710) by using more than one conductive layer, separated by a dielectric layer, to create inductor structures (790, 795) within a slot antenna. Adding inductance to a slot antenna allows a physical reduction in slot length without altering the antenna's radiant frequency range. The geometry of the inductor structures can be designed so that the electric current direction seen about the slot and the electric field direction across the slot is maintained, which aids antenna efficiency and allows arrangements of multiple compact slot antennas. Capacitor structures (780, 785) can also be included to balance out the additional stored magnetic energy in the inductor structures (790, 795).

Abstract: In a digital modulator with compensation, a digital bit stream from a microphone (705), a speech coder (706), and a channel encoder (707) is sent to an encoder (720) which translates the bits into I/Q digital pulses with phase shift keying. A symbol correlater (730) notes when predetermined target phase symbol sequences, which contribute to a high peak-to-average power ratio, enter the encoder. If a target symbol sequence is encountered, the correlater directs compensation amplifiers or compensation filters (734, 737) of the I/Q signals. Next, I/Q pulse shaping filters (764, 765) filter the I/Q pulses according to communication system specifications. The filtered I/Q signals are then sent to a quadrature modulator (790) for RF modulation. Compensation of target symbol sequences reduces the negative impact they have on peak-to-average power ratio and increases the efficiency of the power amplifier (795) which extends the battery life of a communication device (700).

Abstract: A modular communication device (102), which provides for radio frequency (RF) communication in a communication system (100), comprises a first modular unit (106) and a second modular unit (108). The first modular unit (106) includes a housing (110); a user interface (113) including a display (114) and keys (116); electrical circuitry (605), including a transceiver (606) coupled to an antenna (610); a battery connection interface (308) for receiving a battery (302); and a connection interface (120). The second modular unit (108) includes a housing (128); a user interface (135) including a speaker (650), a microphone (648), and a keypad (140); a retractable antenna (134); a battery connection interface (402) for receiving a battery (142); and a connection interface (143). When the connection interfaces (143, 120) are connected, the user interface (135), the antenna (134), and the battery connection interface (402) are coupled to the electrical circuitry (602).

Abstract: A balun network is provided having first and second conductor portions symmetric along a center line therebetween. A connecting conductor portion 130 couples ends of the first and second conductor portions with a spacing therebetween. The first and second conductor portions have a like-length of one-quarter wavelength. A balanced port 140 is provided between a first end of the first conductor portion 110 and a first end of the second conductor portion 120. An unbalanced port 150 is provided between a ground reference plane 160 and a first end of the first conductor portion.

Abstract: A half-wave balun network balanced for at least current is provided by a conductor section having contiguous conductor portions 130 and 140. A balanced port 110 is provided between ends of the conductor section. An unbalanced port 120 is provided between one end of the conductor section and a ground plane 107. A difference between impedances of the contiguous conductor portions 130 and 140 of the half-wave balun network provides for a selectable impedance ratio between the port impedances of the balanced and unbalanced ports 110 and 120. In one embodiment the number of different impedance conductor portions approaches infinity, thereby providing a tapered conductor section.

Abstract: A radio communication device a first housing portion (101) and second housing portion (103). The second housing portion is movably supported on the first housing portion to move between an extended position and a collapsed position. The second housing portion projects outwardly from the first housing portion in the open position. An antenna (107) is positioned in the second housing portion, the antenna includes a first component (640, 749, 859, 969) having a first tuning characteristic and a second component (647, 748, 858, 968) having a second tuning characteristic. One of the antenna components is tuned for a preferred characteristic when the radio telephone is collapsed and the other of the antenna components is tuned to the preferred characteristic when the antenna is extended.

Abstract: A radio communication device (50) has a housing having a first housing element (51) and a second housing element (53). The first housing element (51) is movable between an extended and a closed position. The radio communication device has at least two antennas (112, 113). A switch (121) is provided that is operable to switch between a first antenna (112) and a second antenna (113) responsive to position of the first housing element (51). Preferably the first antenna (112) is disposed in the first housing element (51) and the second antenna (113) is disposed in the second housing element (53) or a battery housing (57).