37results about How to "Uniform excitation" patented technology

A pentagonal antenna array having a high aperture efficiency and a suitably high overall gain and low antenna noise temperature. The high aperture efficiency of this antenna system provides an overall system capacity suitable for broadband communication services. The antenna array consists of five antenna elements each located at a separate vertex of a pentagon. The antenna elements are helical antennas to provide a narrow antenna beam width. The antenna array itself is supported on a base platter which may be steered to point at a satellite using conventional gimbal ring apparatus. The base platter is a planar reflector to reflect the antenna element radiation in the rear direction and thereby reduce the antenna backlobe levels. The input power and the signal transmitted are fed through a phasing / combining network. The phasing / combining network appropriately divides the signal and the input power and phases the signal, prior to feeding the signal to each of the five antenna elements.

A coil for magnetic resonance imaging operates in a transmit mode with multiple loops locked together in a phase relationship like a birdcage coil to provide a uniform transmission field, but in a receive mode like a phased array coil, each coil operating independently to produce a separate signal for reception by the MRI machine. Phasing of the coil during transmit mode is provided by a ring resonator controllably coupled to the loops. Controllable coupling is provided by a series of current limiting elements interposed between the resonant ring and the loops of the coil.

A method and apparatus are described that couples a plurality of electromagnetic sources to a material for the purpose of either processing the material or promoting a chemical reaction. The apparatus couples various electromagnetic sources of various frequencies, including provision for static magnetic fields, radio frequency fields, and microwave fields, with the possibility of applying them all simultaneously or in any combination.

A magnetic resonance imaging apparatus capable of receiving magnetic resonance signals with a plurality of coils while uniformly exciting such signals is to be provided. An RF coil of the magnetic resonance imaging apparatus is provided with an original loop unit, and a conductor which is so connected to the original loop unit as to split the original loop unit into split loop units. A control unit applies a high frequency magnetic field with the original loop unit and receives magnetic resonance signals with the split loop units.

This invention relates to LED field, which discloses a white light LED and its packaging method. The white light LED includes chip, frame, silicon glue, fluorescence power film and periphery parts (such as lens). Difference between the packaging structures is that the space between the fluorescence power and chip is isolated by some materials such as silicon glue, which makes the heat of the fluorescence power and chip isolate; and the fluorescence power film brim contacts with the substrate, which makes the fluorescence power's heat conduct to the exterior to avoid the gather of fluorescence power heat. The chip is fixed on the frame, the silicon glue covers on the chip directly, the designed and prepared fluorescence power film cover on the silicon glue, and the fluorescence power film contact with the cup bowl. This method improves the light producing efficiency, and improves the stability of the light color greatly, and lowers the light decline. And the packaging method is simple, which is fit for industrial production in large scale.

In a method for non-selective excitation of nuclear spin signals in an examination subject with a magnetic resonance system, RF excitation pulses are radiated to excite nuclear spin signals in the examination subject with simultaneous switching of gradients for spatial coding of the excited nuclear spin signals, wherein the RF excitation pulses are designed such that the base frequency of a radiated RF excitation pulse is adapted to the simultaneously switched gradient. By the dynamic adaptation of the radiated RF excitation pulses to the respective simultaneously switched gradients, artifacts due to insufficiently excited nuclear spins in an examination region to be examined (in particular even in examination regions that are arranged off-center) are avoided.

The invention relates to a device and method for testing medium material radiation induction conductivity for a satellite, and belongs to the field of testing. The device and method for testing the medium material radiation induction conductivity for the satellite is applicable to a test on thicker medium material radiation induction conductivity in an electrification effect evaluation inside the satellite. The device comprises a shielding box body, a 60Co irradiation source, a vacuum-pumping system, an upper electrode plate, a lower electrode plate, a sample table, an electrometer, a stabilized voltage source, a titanium window and a vacuum box. The method comprises the steps of utilizing the 60Co irradiation source to generate gamma ray irradiation medium materials, meanwhile utilizing the stabilized voltage source to exert voltage on electrodes on the medium materials, testing a leakage current of the lower electrode plate through the electrometer, obtaining a voltage value V and a current value I of the surface of the medium materials, and further calculating to obtain radiation induction conductivity of the medium materials. The device and method for testing the medium material radiation induction conductivity for the satellite is applicable to the test on the thicker medium material radiation induction conductivity in the electrification effect evaluation inside the satellite.

The invention relates to a preparation method of a standard spectrum sample of Fe-based nanocrystalline. The method comprises the following steps: a chemical formula of a standard sample ratio is selected, and a raw material adding ratio is calculated; raw materials are added in a vacuum induction furnace according to the ratio, and the vacuum induction furnace is adopted to smelt the raw materials into molten steel; the molten steel is poured in a cylindrical graphite mold for heat treatment and forms steel samples; the steel samples are subjected to linear cutting, grinding and polishing treatment, and qualified steel samples are selected according to microscopic examination and ultrasonic nondestructive inspection; the qualified steel samples are subjected to uniformity analysis; a detection result is analyzed, and an average value is taken as an fixed value of the elements; and the standard sample is formed. The invention provides one preparation method of the standard spectrum sample of the Fe-based nanocrystalline by starting from chemical component design, a smelting process and a final sample processing process, a prepared product can be excited effectively and uniformly by a spectrometer, so that more accurate data are obtained, and guarantee is provided for development and production of a Fe-based nanocrystalline material.