Abstract:
A circularly polarizing RF antenna suitable for use in a magnetiic resonance imaging tomography apparatus has four current loops, each formed by two U-shaped conductors with the ends of the lateral legs of the U-shaped conductors disposed opposite to each other in mirror-symmetric fashion, and the ends of the lateral legs being bridged by a resonant capacitor. The current loops are arranged on a carrier which forms a portion of a hollow cylinder, and which is divided in an axial direction between two of the current loops, so that at least one of the current loops is removable without electrical contacts. A divisible RF antenna is thus achieved into which a head or a knee joint can be easily introduced for imaging.
Abstract:
An array device having a plurality of stacked circuit boards, each having a recess in a flat side thereof which extends parallel to a narrow side; the recess containing electronic components. Control lines for the electronic components are arranged on a flat side of the circuit board. Each circuit board has a narrow side which is provided with electrodes which are ordered as a matrix in rows and columns. The electrodes of the circuit boards are each associated with a respective switchable amplifier. The switchable amplifiers are arranged one behind the other in the longitudinal direction of a recess, and are connected by respective conductors having substantially equal lengths for coupling the switchable amplifiers to their respective electrodes. A plurality of main control lines are arranged on the narrow sides of the circuit boards for connecting the control lines of the switchable amplifiers in the same column to one another. Thus, the number of electrodes in each row can be increased without being required to be an integral multiple of the inputs of electronic modules.
Abstract:
A frequency modulator includes a first pair of diodes with two capacity diodes, and a second pair of diodes with two additional capacity diodes. The second pair of diodes is employed in parallel. The frequency modulator also includes a first modulator input for reception of a first modulation signal and a second modulator input for reception of a symmetrical second modulation signal. Both pairs of diodes are coupled to an oscillator unit.
Abstract:
A method for simultaneous transmission of at least two high-frequency transmission signals via a common high-frequency line includes providing at least two input signals at respective inlet ports. The input signals are signals of a same carrier frequency. From the input signals, respective transmission signals are provided with different transmission frequencies from each other and from the carrier frequency by mixing the input signals using one frequency mixer each. The frequency mixers are supplied with respective mixer oscillator signals. The transmission signals are transmitted via the common high-frequency line. The mixer oscillator signals are provided from a same oscillator signal.
Abstract:
A balancing circuit comprises a first conductor path and a second conductor path. The first and second conductor paths are arranged in parallel with one another with respect to a signal flow. The first conductor path and the second conductor path are formed by a first stage and a second stage. The first conductor path has a high-pass member that is assigned to the first stage and a high-pass member that is assigned to the second stage. The second conductor path has a low-pass member that is assigned to the first stage and a low-pass member that is assigned to the second stage. Each high-pass member is designed to shift a signal forward in terms of phase by a predetermined amount, and each low-pass member is designed to shift a signal backward in terms of phase by a predetermined amount, in order to generate a balanced or unbalanced signal.
Abstract:
A method for simultaneous transmission of at least two high-frequency transmission signals via a common high-frequency line includes providing at least two input signals at respective inlet ports. The input signals are signals of a same carrier frequency. From the input signals, respective transmission signals are provided with different transmission frequencies from each other and from the carrier frequency by mixing the input signals using one frequency mixer each. The frequency mixers are supplied with respective mixer oscillator signals. The transmission signals are transmitted via the common high-frequency line. The mixer oscillator signals are provided from a same oscillator signal.
Abstract:
An amplifier circuit has a transistor element that has an input terminal, an output terminal) and a third terminal. An input signal to be amplified is supplied to the input terminal. The amplified input signal is emitted as an output signal at the output terminal. The input terminal is connected with the output terminal via a first reactance. The third terminal is connected via a second reactance with a zero potential. One of the reactances is fashioned as an inductor and the other of the reactances is fashioned as a capacitor. An inductance value of the inductor and a capacitance value of the capacitor are dimensioned such that the quotient of the inductance value of the inductor and the capacitance value of the capacitor is equal to the product of a desired input impedance that is effective at the input terminal and an output impedance associated with the output impedance. Based on this dimensioning, the output impedance associated with the output terminal is mapped to the input terminal at the same level or scaled.
Abstract:
A method is disclosed for determining positron emission measurement information in the context of positron emission tomography. The method includes carrying out a positron emission measurement, in a body area of a subject to be examined, to record positron emission measurement information with point resolution and determining a time frame of the measurement by, at the same time, generating images of the body area to be examined with a relatively higher time resolution and with point-resolved image data, using a second imaging method. Further, a local shift of points of individual images of the second imaging method is determined, caused by movement processes of the subject to be examined, and as a function thereof, of the positron emission measurement information for at least a part of the measurement period and of the body area to be examined. Finally, the positron emission measurement information is adjusted as a function of the determined shift.
Abstract:
An arrangement for transmitting magnetic resonance signals, with a transmission link that connects a local coil with a receiver, has a first channel of the local coil with a first single antenna to acquire a first magnetic resonance signal, as well as a first mixer connected with the first single antenna. The first mixer forms an intermediate-frequency first signal from the supplied first magnetic resonance signal. A second channel of the local coil has a second single antenna to acquire a second magnetic resonance signal, as well as a second mixer connected with the second single antenna. The second mixer forms an intermediate-frequency second signal from the supplied second magnetic resonance signal. The local coil has a device for signal combination that, by frequency multiplexing, that combines the intermediate-frequency first signal of the first channel and the intermediate-frequency second signal of the second channel so that it arrives at the receiver via the transmission path. The receiver has an A/D converter at which one of the transmitted intermediate-frequency signals of an associated channel arrives in order to be sampled with a sampling frequency for digitization. For frequency conversion, a first local oscillator frequency is connected at the first mixer and a second local oscillator frequency is connected at the second mixer. the first and second local oscillator frequencies are selected such that intermediate-frequencies formed by the frequency conversion are mirror-symmetrical relative to the sampling frequency of the A/D converter.
Abstract:
The push-pull amplifier with transformational negative feedback is provided for amplification of variable electrical signals. It includes a signal input and a signal output, a transformational negative feedback connected with the signal input and the signal output and an amplifier circuit. The amplifier circuit includes an input and an output as well as a first transistor and a second transistor. The input of the amplifier circuit is thereby connected with the signal input and the output of the amplifier circuit is thereby connected with the signal output via the transformational negative feedback.