Abstract: A quadrature detection MRI radio frequency coil includes plural axially-extending conductive legs. At least two of the legs include breaks in conductivity at their mid-point with circumferentially extending inner-bridge conductors connected thereacross to which RF input/output feed connections are conveniently made so as to achieve a center fed coil structure, open at both ends. Other axially-extending legs may also include conductive breaks with capacitive coupling thereacross and circumferentially extending outer-bridges between the outer or distal ends of the legs may also include breaks in conductivity with capacitive coupling thereacross.

Abstract: A system and method is described for amplifying and transmitting an information signal from a downhole drillstring location. The amplifier shifts the relatively low frequency information signal up to a high frequency level, amplifies the high frequency signal and processes it through an impedance matching transformer, and then demodulates the amplified signal back to the original low frequency for transmission through the earth to the surface, thus enabling the use of a much smaller transformer than when the information signal is processed entirely at the low frequency level. A novel transducer consisting of generally cylindrical conductive sleeves separated by an insulative gap is used to provide structural integrity and to transmit the amplified information signal. The conductive sleeves are heat shrunk onto an insulative sleeve and a central mandrel.

Abstract: Undesirable RF coupling via the outside of an outer coaxial cable conductor to/from RF coils in a magnetic resonance imaging apparatus is minimized by employing a parallel resonance tuned RF choke in the circuit. The choke is realized by forming a short coiled section of the coaxial cable with a lumped fixed capacitance connected in parallel thereacross and a conductive tuning rod positioned within the center of the coiled section so as to trim the parallel resonant frequency to the desired value.

Abstract: In an RF/microwave component such as a resonator, multipacting is eliminated in accordance with the present invention by rectifying a portion of the RF signal present within the component to derive a dc potential. This dc potential is used to bias the component so as to the prevent polarity reversal across the component electrodes, thereby to eliminate multipacting without the use of an external bias supply.

Abstract: An electrode of the self-resonant, single-turn loop type adapted for attachment to a source of radio frequency energy to produce deep-heating by hyperthermia. The electrode is characterized by being a long cylindrical electrode having a small diameter to length radio as, for example, 0.5 to 1. The electrode is in the form of a cylinder having a gap along one side to which a plurality of capacitor plates are electrically connected radially outward and in parallel spaced relationship with a dielectric material disposed therebetween.

Abstract: An electrode for use in the treatment of animal tissue by hyperthermia particularly adapted for use in the neck regions wherein a planar field of energy is required so as to concentrate therapeutic energy in the area of a plane passing through the electrode with very little energy available to affect adjacent areas beyond close proximity to the plane of the electrode. In the preferred embodiment the electrode comprises disk segments of a conductive material disposed in overlapped relationship on either side of dielectric material to form conductive annular disks separated by dielectric material so as to be a single self-resonant loop.

Abstract: A self-resonant single-turn electrode for use in the treatment of animal tissue with hyperthermia by coupling the electrode to a supply of radio frequency energy. The electrode comprises a plurality of planar annular disc members concentrically stacked with dielectric material therebetween. Each disc has a radial slit therethrough to form a gap. The discs are stacked with the gaps of adjacent discs 180.degree. apart. The radio frequency energy may be coupled to the entire stack by connecting to only one disc and the discs are all insulated from each other.

Abstract: A diffusion filter can be formed by sandblasting a transparent plate to produce a pitted surface. A neutral density cement having an index of refraction different from that of the plate is applied to the pitted surface and a second plate is then bonded to the first by the cement. The opposing surface of the second plate may also be pitted to achieve increased diffusion. Light that strikes the filter and passes directly through without entering the pits forms a sharp image, while light that enters the pits is refracted so that it forms a soft image superimposed on the sharp image. Some light that enters the pits and is scattered within the cement is absorbed.

Abstract: The present invention discloses an improved electrode for use with apparatus employing radio frequency energy for deep heating of materials. In particular, it is adapted for the medical treatment of living animal tissue by hyperthermia. The electrode comprises a single loop turn having capacitance associated therewith so as to resonate the electrode for maximum power transfer thereto. The electrode causes a field to be generated within the annular region enclosed by the electrode comprising a plurality of concentric, substantially equally powered lines of force in which the living tissue to be treated is disposed. The electrode finds particular use in the treatment of deep seated cancers in patients.

Abstract: An electrode of the type used in the treatment of animal tissue by hyperthermia wherein a self-resonant single turn loop electrode creates a field of electromagnetic energy. The electrode comprises three plate members forming the sides and bottom of a box-like area in which the patient is positioned. The fourth electrode is vertically disposed above the patient and between the two side members being arcuate in shape on the edge adjacent the patient and normal to the other members. The two side members are disconnectable from the back member so that the back member can be positioned beneath a patient's mattress and the side members and arcuate member then placed over the patient in operable position when desired.

Abstract: A brake assembly for skateboards which allows smooth, safe, trouble-free braking. The assembly includes a pivotal, wheel-engaging brake plate and a depressible foot-operated pedal coupled to the plate for selective shifting of the latter into frictional, braking engagement with the wheel. A pair of debris-clearing brushes are also mounted on the brake assembly and assist in braking when the pedal is depressed. A secondary, stationary brush member is also mounted adjacent the remaining wheel assembly for debris-clearing purposes.

Abstract: The present invention discloses an improved electrode for use with apparatus employing radio frequency energy for deep heating of materials. In particular, it is adapted for the medical treatment of living animal tissue by hyperthermia. The electrode comprises a single loop turn having capacitance associated therewith so as to resonate the electrode for maximum power transfer thereto. The electrode causes a field to be generated within the annular region enclosed by the electrode comprising a plurality of concentric, substantially equally powered lines of force in which the living tissue to be treated is disposed. The electrode finds particular use in the treatment of deep seated cancers in patients.