Abstract: An electrodynamic acoustic transducer (1a . . . 1e) is presented, which comprises a housing (2), a membrane (3), a coil arrangement (6, 6a . . . 6h) attached to the membrane (3) and a magnet system (9, 10, 11). The coil arrangement (6, 6a . . . 6h) comprises a plurality of coils (7, 8) each having two terminals (T7a, T7b, T8a, T8b, T9a, T9b) being static in relation to the housing (2). Connecting wires (12a, 12b, 13a, 13b) connect the coils (7, 8) and the terminals (T7a, T7b, T8a, T8b, T9a, T9b, T78b). The connecting points (C7a, C7b, C8a, C8b) between the connecting wires (12a, 12b, 13a, 13b) and the coils (7, 8) are symmetrically arranged on the coil arrangement (6, 6a . . . 6h).

Abstract: A tunable metamaterial has a two dimensional array of resonant annular ring elements; and a plurality of voltage controllable electrical tuning elements disposed in or adjacent openings in each of said ring elements, each of said voltage controllable electrical tuning element ohmically contacting portions of only one of said ring elements. The voltage controllable electrical tuning elements may comprise highly doped semiconductor tunnel diodes, or the charge accumulation layer at the semiconductor/insulator interface of a metal-insulator-semiconductor structure, or nanoelectromechanical (NEMs) capacitors. The tunable metamaterial may be used, for example, in an optical beam steering device using the aforementioned tunable optical metamaterial in which a free-space optical beam is coupled into a receiving portion of a plane of the optical metamaterial and is steered out of a transmitter portion of the plane of the optical metamaterial in controllable azimuthal and elevational directions.

Abstract: This disclosure is related to a magnetron including a cylindrical cathode having a center axis, an anode coaxially arranged with the cathode so as to be separated from the cathode via a predetermined space, and a pair of pole pieces provided to both ends of the cathode in the axial direction so as to oppose to each other and having opposing faces perpendicular to the axial direction. The pole piece has a first ridge of a ring shape that is formed on the opposing face and is coaxial with the cathode.

Abstract: The invention performs uniform chemical reactions with high efficiency by action of microwave onto reaction targets placed within a flow path along a center axis of a waveguide for transmission of microwave. The microwave chemical reaction device includes a circular waveguide for transmission of TM or TE mode microwave or a square waveguide for transmission of TE mode microwave and a flow path shielded from a space within the waveguide by a bulkhead of low microwave loss and coaxially extending along the center axis of the waveguide. Reaction targets to be subjected to chemical reactions are accommodated in the flow path and the microwave acts on the reaction targets within the flow path.

Abstract: A geometrically modifiable resonator is comprised of a resonator disposed on a substrate, and a means for geometrically modifying the resonator. The geometrically modifiable resonator can achieve active optical and/or electronic control of the frequency response in metamaterials and/or frequency selective surfaces, potentially with sub-picosecond response times. Additionally, the methods taught here can be applied to discrete geometrically modifiable circuit components such as inductors and capacitors. Principally, controlled conductivity regions, using either reversible photodoping or voltage induced depletion activation, are used to modify the geometries of circuit components, thus allowing frequency tuning of resonators without otherwise affecting the bulk substrate electrical properties. The concept is valid over any frequency range in which metamaterials are designed to operate.

Abstract: A magnetron has an output comprising a coaxial line 15 which transmits energy from a wanted oscillator mode as a first coaxial waveguide mode and energy from an unwanted oscillator mode as a second cylindrical waveguide mode. Energy in the cylindrical waveguide mode is intercepted by slots 17, 18 in the coaxial line 15 and absorbed by material 19. This enables the modes to be separated. Preferably, the output is taken from the axis of the magnetron and the wanted oscillator mode in the &pgr;-1 mode.

Abstract: A balanced modulator has a pair of diodes, a plurality of line patterns including a balance-to-unbalance converter, the line patterns including lines extending toward and connected to the diodes, respectively, and at least a set of capacitive stubs disposed near the lines and spaced from each other by a distance of .lambda./8 (.lambda. is the wavelength at a frequency used). The capacitive stubs are connectable to the lines by bonding wires for isolation adjustments.

Abstract: The invention relates to an electronic life detection system, in particular for the searching for buried persons and the surveillance of buildings, having a microwave transmitting/receiving device for generating and radiating microwaves into an area to be investigated and for registering the microwave signal reflected from the area under surveillance and modulated with the frequencies corresponding to the life functions of any living beings present in the area, which device has a first signal-conditioning device, and a second signal-conditioning device.

Abstract: The invention relates to a biased electronic circuit in which a voltage-controlled component has a characteristic with a non-linear portion and a substantially linear portion. The circuit is biased by a voltage being applied to one terminal of the component thereby shifting the operation of the component to the linear portion.

Abstract: For realizing a highly sensitive and favorably linear frequency modulator stably operating with a small-sized and readily manufactured arrangement, input and output strip electrodes are disposed in face on both ends of a ferri-magnetic film deposited on a magnetic substrate and applied with a DC magnetic field perpendicular thereto, a high frequency electro-magnetic wave being applied through the input electrode, so as to generate a magneto-static forward volume wave propagating through the magnetic film, the propagation phase of which is modulated in response to the intensity variation of the applied magnetic field modulated by a signal, so as to derive a frequency modulated electro-magnetic wave from the output electrode.