Abstract: A carbon substrate manufacturing method includes a hot molding step, a burn-carbonizing step, a hot isostatical pressure treatment step, and a mirror polishing step. In the hot molding step, molding is performed while heating thermosetting resin powders to be a hard carbon substrate after burn-carbonizing, where the thermosetting resin powders are of a particle size 150 .mu.m or more, HPF 80-150 mm, a moisture content 1.0-3.0 weight %, Fe, Ni, Si and Ca respectively 5 ppm or less. In the burn-carbonizing process, a disk shaped resin molded body is filled into a graphite cylinder and burn-carbonized by heating from the external while the condition therefor is maintained in that the disk shaped resin molded body is stacked holding therein a graphite spacer at every one sheet basis or at every plurality of sheet basis and is loaded on its top with a tungsten carbide weight, where the graphite spacer has a heat conductivity 100 kcal/m.hr..degree. C. or less, a bulk density 1.70-1.85, and a flatness degree 10 .mu.

Abstract: A resonator element formed of a half or a quarter of dielectric cylinder contacts an electrically conductive plane via the resonator element's radially cut side which includes the axis of the cylinder, accordingly, resonates in TE.sub.01.delta. -mode. On an opposite side of the electrically conductive plane there is provided an unbalanced transmission line, for example, of a strip line type or a coaxial line type. An end of the transmission line is electromagnetically coupled via a dielectric material in the transmission line or directly with the radially cut side of the resonator element through an opening provided on the electrically conductive plane. Coupling circuit according to the present invention allows a compact overall circuit configuration.

Abstract: A radio-frequency identification (RF-ID) system including a master unit and a sub unit connected thereto by radio-communication, and used for identifying a moving article on which the sub unit is mounted. The master unit transmits a circularly polarized wave having two carrier components (CW1, CW2), and the sub unit, which does not include carrier generators and branching filters, is powered by a battery provided therein. The sub unit receives the circularly polarized wave, separates the two carrier components by a hybrid circuit, and transmits another circularly polarized wave base upon the received carrier component. The sub unit may be operated in response to a starting command from the main unit, and the main unit may have first and second detecting units separated by n.multidot..lambda.g/8, n: an odd integer, and .lambda.g: effective wave length, to eliminate the occurrence of null point phenomenon.

Abstract: A modulation device using multi-level digital signals includes: a pair of balanced mixers for carrying out quadrature amplitude modulation to deliver a quadrature amplitude modulated signal; input and output hybrid circuits, connected to carrier input terminals of the pair of balanced mixers, for supplying carrier inputs to the pair of balanced mixers; and a modulation characteristic compensation unit connected with input terminals of the pair of balanced mixers for supplying the pair of balanced mixers with orthogonal baseband input signals.

Abstract: A phase modulation method and apparatus for modulating the phase of a carrier wave in accordance with a binary modulating signal to produce a modulated wave. At least one of the amplitude and the phase of the carrier wave or the modulated wave is corrected by predetermined amounts in response to the value of the binary modulating signal, so that the phase position of the modulated waves becomes equal to one of a number of predetermined positions and so that the amplitudes of the modulated waves coincide.

Abstract: A capacitor for use in microwave transistor, comprises a dielectric material layer and conductive layers covering both sides of the surfaces of the dielectric material layer. A plurality of points on the surface of one of the conductive layers are connected by conduction wires. Each of the conductive wires has a length less than .lambda..sub.0 /2.sqroot..epsilon..sub.r, where .lambda..sub.0 is the minimum wavelength of electric signals applied to the capacitor element, and .epsilon..sub.r is the dielectric constant of the dielectric material layer. The middle portion of each of the conductive lines is separated from the above-mentioned one of the conductive layers. The conductive wires prevent the capacitor element from becoming extremely inductive even when the frequency is high.