Abstract: An RF antenna includes an input terminal for receiving an RF signal, a supporting element, an electrically conductive coil on the supporting element and disposed to receive the RF signal from the input terminal, and an RF shield formed of an electrically conductive material and disposed under the coil and further including contacts for connection to a ground electrical potential. The antenna generates a circularly polarized RF field. A method of generating an RF field includes generating an RF signal, providing the RF signal to an electrically conductive coil disposed on a magnet core and separated from the magnet core by a supporting element, shielding the electrically conductive coil using an electrically conductive material, and connecting the RF shield to a ground electrical potential so as to provide a current return for the RF signal through the RF shield.

Abstract: An RF coil for NMR experiments having a conductive path for flowing a field-cancelling current to isolate magnetically the RF coil from its environment. NMR data, particularly MRI data from a human subject, is collected with the receiver coil magnetically shielded to avoid loss of the received signal energy to the environment.

Abstract: Apparatus and methods for monitoring a magnetic field and/or detecting ferromagnetic materials. Two transducers are disposed adjacent one another and arranged to provide signals directly related to magnetic field components in parallel but opposite sensing directions. Signal processing apparatus provides an output related to the difference between these two signals. The transducers may be oriented so that the sensing directions are transverse to the magnetic field and the output signal is substantially zero when the magnetic field is in a rest condition. When the magnetic field is disturbed, as by a ferromagnetic body, the output signal changes.

Abstract: A medical screening method for examining a patient utilizing NMR techniques is disclosed. The method uses an NMR imaging apparatus which has a scanning volume region of a limited size and which is operative to produce, during the course of a single scanning operation, a collection of spatially encoded NMR image data for a set of volume elements defined by the part of the patient positioned in the scanning volume region. A patient is positioned within the NMR apparatus, the NMR apparatus operated to conduct a scanning operation, and the patient then moved so that an additional volume portion of the patient is positioned within the scanning volume region. The NMR apparatus is then operated to conduct a further scanning operation with respect to the additional volume portion. This procedure of moving the patient and conducting additional scanning operations is continued until substantially the entire body of the patient is scanned and NMR image data collected therefor.

Abstract: An apparatus and method for processing a first electrical signal having a frequency interval I containing information, and increasing the signal-to-noise ratio thereof utilizes a mixer for shifting the frequencies of the first signal in the interval I to an interval I.sub.s. A plurality of filters, coupled in parallel, to the mixer pass, respectively, only frequencies in subintervals of I.sub.s, which are mutually disjoint. A second embodiment utilizes a plurality of mixers which shift, respectively, mutually disjoint subintervals of I such that their left end points are substantially equal. A plurality of filters, coupled, respectively, to the mixers, pass, respectively, only those frequencies in the shifted subintervals. Preferably, the frequency intervals passed by the filters in both embodiments are equal in bandwidth, and have no gaps therebetween.