The exemplary system and method facilitate excitation of RF magnetic fields in ultra-high field (UHF) magnetic resonance (MRI) systems (e.g., MRI/NMR system) using a slotted waveguide array (SWGA) as an exciter coil. The exemplary exciter coil, in some embodiments, is configurable to provide RF magnetic field B.sub.1.sup.+ with high field-uniformity, with high efficiency, with excellent circular polarization, with negligible axial z-component, with arbitrary large field of view, and with exceptional possibilities for field-optimizations via RF shimming.

Embodiments relate to cylindrical MRI coils with at least one row as a birdcage row in a transmit mode. One example embodiment is a MRI Radio Frequency (RF) coil array comprising two or more rows of four or more RF coil elements each. Each of the RF coil elements can be configured to resonate at a working frequency of the coil array in a receive mode. At least one of the rows can be configured as a birdcage coil in the transmit mode, and the two or more rows can inductively couple together such that all the two or more rows can resonate together in the transmit mode at the working frequency.

A method includes disposing a downhole tool having a magnet assembly into a wellbore. The method includes generating, using the magnet assembly, a magnetic polarization in a volume into a subterranean region about the wellbore. The method also includes emitting an excitation in the magnetic polarization in the volume in the subterranean region. The method includes detecting, by at least one antenna, a nuclear magnetic resonance response to the excitation of the volume in the subterranean region. The method also includes determining a property of the subterranean region based on the nuclear magnetic resonance response.

Systems and methods for simultaneous radio frequency (RF) transmission and reception for nuclear magnetic resonance applications, such as magnetic resonance imaging (MRI) are described. The system includes a simultaneous transmit and receive (STAR) control system that compensates for the effects of load changes in a radio frequency (RF) coil due to the inevitable motion of living subjects (e.g., from subject motion, respiration, swallowing). The system also maintains a high transmit-receive isolation, even when scanning a subject using a continuous RF broad band sweep excitation.

Aspects relate to providing radio frequency components responsive to magnetic resonance signals. According to some aspects, a radio frequency component comprises at least one coil having a conductor arranged in a plurality of turns oriented about a region of interest to respond to corresponding magnetic resonant signal components. According to some aspects, the radio frequency component comprises a plurality of coils oriented to respond to corresponding magnetic resonant signal components. According to some aspects, an optimization is used to determine a configuration for at least one radio frequency coil.

NMR tools are described having unidirectional magnetization throughout the magnet assembly. An antenna assembly is positioned around the magnet assembly in order to excite a volume in the surrounding subterranean formation. A layer of soft magnetic core material is positioned under the antenna assembly in order to shield all or most of the RF field generated by the RF antenna away from the conductive components inside the NMR tool. The conductive components may be conductive structural members or a conductive magnet assembly. The soft magnetic core material also shapes the static magnetic field by smoothing out the longitudinal magnetic field variation.

A radio frequency transmit system (40) for use in magnetic resonance imaging apparatuses, comprising a radio frequency driver unit (42) including at least a first radio frequency power source (44; 82) and a second radio frequency power source (46; 84), a radio frequency coil arrangement (48) for generating an RF magnetic excitation field B.sub.1, and a plurality of switching members (68, 70, 72, 74) electrically connecting the radio frequency power sources (44, 46; 82, 84) to different pairs of drive ports (58, 60, 62, 64) in a first and in at least a second switching status. The first drive port (58) of the first pair of drive ports (58, 60) and the first drive port (62) of the at least second pair of drive ports (62, 64) are arranged spaced by a fixed predetermined angular distance in the azimuthal direction (56) about the center axis (50); and a magnetic resonance imaging system (10) including such radio frequency transmit system (40).

Here we present a solid-state spin sensor with enhanced sensitivity. The enhanced sensitivity is achieved by increasing the T.sub.2* dephasing time of the color center defects within the solid-state spin sensor. The T.sub.2* dephasing time extension is achieved by mitigating dipolar coupling between paramagnetic defects within the solid-state spin sensor. The mitigation of the dipolar coupling is achieved by applying a magic-angle-spinning magnetic field to the color center defects. This field is generated by driving a magnetic field generator (e.g., Helmholtz coils) with phase-shifted sinusoidal waveforms from current source impedance-matched to the magnetic field generator. The waveforms may oscillate (and the field may rotate) at a frequency based on the precession period of the color center defects to reduce color center defect dephasing and further enhance measurement sensitivity.

An end ring port structure of an atypical coil for a magnetic resonance imaging system, has an end ring, provided with multiple end ring capacitance positions for disposing equivalent capacitances, with a portion of the equivalent capacitances being formed by two or more split capacitors. A first port has a first leg and a second leg, which are each connected to the end ring. A second port has a third leg and a fourth leg, which are each connected to the end ring. A first capacitor bank is arranged on the end ring between an end ring connection point of the first leg and an end ring connection point of the second leg. The first capacitor bank has at least two capacitors not all belonging to the same end ring capacitance position. A second capacitor bank is arranged on the end ring between an end ring connection point of the third leg and an end ring connection point of the fourth leg. The second capacitor bank has at least two capacitors not all belonging to the same end ring capacitance position.

A dipole antenna assembly includes at least two dipole antennas mechanically, but not electrically, connected to each other. The at least two dipole antennas cross at an intersection point and form dipole antenna arms starting from the intersection point. The dipole antenna arms are arranged in a half-space.