Abstract: A radio frequency module includes a multi-chip substrate divided into separate substrates. An antenna block, a duplexer block, a transmitter block, a receiver block, and an oscillator block are formed on the separate substrates. Connection resonators, which are connected to transmission lines, are formed at edges of the separate substrates. The connection resonators on adjacent ones of the separate substrates are arranged close to each other such that the two adjacent resonators are electromagnetically coupled to each other. Thus, the transmission lines on the separate substrates are interconnected, and a signal can be propagated among the blocks.

Abstract: The optical transmission system in accordance with the present invention is an optical transmission system in which an optical fiber transmission line is laid between a transmitting station and a receiving station, first and second optical couplers are provided on the optical fiber transmission line, a first Raman amplification pumping light source is connected to the first optical coupler, a second Raman amplification pumping light source is connected to the second optical coupler, the optical fiber transmission line Raman-amplifies signal light in S band when Raman amplification pumping light is supplied thereto while transmitting the signal light, and the optical fiber transmission line has a zero-dispersion wavelength of 1350 nm to 1440 nm and a cable cutoff wavelength of less than 1368 nm.

Abstract: An optical transmission line having reduced flunctions in transmission quality is formed with a structure in which first and second waveguides whose transmission characteristics at a predetermined wavelength in a wavelength band in use are set opposite to each other and are arranged alternately. The chromatic dispersion of the first and second waveguides are set so as to have signs opposite to each other, and the dispersion slope of the first and second waveguides are set so as to have signs opposite to each other. Embodiments include setting the absolute value of chromatic dispersion in each first waveguide to 1 ps/nm/km or more but 10 ps/nm/km or less, and the absolute value of chromatic dispersion in each second waveguide is set to 1 ps/nm/km or more but 10 ps/nm/km or less.

Abstract: A radar system includes a detection-control circuit for transmitting and receiving the beam of a millimeter-wave signal for detecting a relative position and a relative speed to a target, and a scanning unit for scanning the direction of the beam over a predetermined range. The state of the scanning unit can be switched between a resting state wherein scanning is stopped and the beam is directed towards the center of the scanning range while the detection-control circuit continues detection control, and a scanning state wherein the direction of the beam is scanned over a predetermined range.

Abstract: The present invention relates to an optical fiber having a large positive dispersion in a wavelength band of 1.55 &mgr;m in order to compensate for a negative dispersion inherent in an NZ-DSF in the wavelength band of 1.55 &mgr;m. This optical fiber comprises a depressed cladding structure constituted by a core region; an inner cladding, disposed at the outer periphery of the core region, having a lower refractive index; and an outer cladding having a higher refractive index. In this optical fiber, the relative refractive index difference of the core region with respect to the outer cladding is at least 0.30% but not greater than 0.50%, and the relative refractive index difference of the inner cladding with respect to the outer cladding is at least −0.50% but not greater than −0.02%. Also, the optical fiber has a dispersion greater than 18 ps/nm/km at a wavelength of 1.55 &mgr;m, and an effective cross-sectional area Aeff of at least 70 &mgr;m2 at the wavelength of 1.55 &mgr;m.

Abstract: A radio-frequency amplifier comprises slot lines formed in a top electrode which are bent to define matching segments that are perpendicular to transmitting segments. The matching segments have a length corresponding to one-quarter of the wavelength of a signal to be amplified and are at least partially perpendicular to the transmitting segments. A DC-cut circuit comprising slot lines is connected to the matching segments, an FET is connected to the transmitting segments and the matching segments, and respective matching circuits serve as an input unit and an output unit of the FET. Source terminals of the FET are connected to parts of a top electrode that do not lie between the segments. A drain terminal and a gate terminal are connected, to be electrically separated from each other, to parts of the top electrode, which are electrically separated from the source terminals by the DC-cut circuit, the transmitting segments, and the matching segments.

Abstract: An optical fiber suitable for use in optical communications systems capable of transmitting and receiving a large volume of information. The optical fiber has a chromatic dispersion of at least 4 ps/nm/km and at most 15 ps/nm/km at a wavelength of 1,550 nm and a transmission loss of at most 0.190 dB/km at a wavelength of 1,530 to 1,570 nm. The optical fiber comprises an inner core (refractive index: n1) including the optical central axis, an outer core (refractive index: n2) encircling the inner core, and a cladding (refractive index: n3) encircling the outer core. The relationship between the refractive indexes is expressed as n1>n2>n3. The inner core is made of practically pure silica glass undoped with GeO2. The outer core and the cladding are doped with a refractive-index-reducing dopant such as fluorine. An optical transmission line and an optical communications system are structured by using the foregoing optical fiber.

Abstract: A random seed scramble for preventing the deterioration of a medium is applied to the next generation optical disk. A seed is stored to a BIS area. ID or an EDC is checked to hold interchangeability before and after scramble release. When no error is generated in data before the scramble release, it is recognized as an unscrambled disk. In contrast to this, when no error is generated in data after the scramble release, it is recognized as a scrambled disk. An information storing area showing an area to be rewritten by performing the scramble and an area to be rewritten without performing the scramble is arranged.

Abstract: An optical fiber that can sufficiently suppress the generation of four-wave mixing and that can widen the bandwidth of wavelength of signal light. The optical fiber of the present invention has (a) a chromatic dispersion whose absolute value is not less than 8 ps·nm−1·km−1 and not more than 15 ps·nm−1·km−1 at a wavelength of 1.55 &mgr;m and (b) a dispersion slope whose absolute value is not more than 0.05 ps·nm−2·km−1 at a wavelength of 1.55 &mgr;m. It is more desirable that the optical fiber have (a) a chromatic dispersion whose absolute value is not less than 8 ps·nm−1·km−1 and not more than 12 ps·nm−1·km−1 at a wavelength of 1.55 &mgr;m, (b) a dispersion slope whose absolute value is not more than 0.03 ps·nm−2·km−1 at a wavelength of 1.

Abstract: A radio frequency module includes a multi-chip substrate divided into separate substrates. An antenna block, a duplexer block, a transmitter block, a receiver block, and an oscillator block are formed on the separate substrates. Connection resonators, which are connected to transmission lines, are formed at edges of the separate substrates. The connection resonators on adjacent ones of the separate substrates are arranged close to each other such that the two adjacent resonators are electromagnetically coupled to each other. Thus, the transmission lines on the separate substrates are interconnected, and a signal can be propagated among the blocks.

Abstract: This invention relates to an optical fiber having a structure suitable for long-haul transmission of optical signals having wavelengths different from each other in a wavelength band of 1530 to 1620 nm, and an optical transmission line including the same. The optical transmission line of the present invention includes one or more first optical fibers and one or more second optical fibers. Each of the first optical fibers has a dispersion of +1.0 to +8.0 ps/nm/km in the wavelength band of 1530 to 1620 nm, and a difference between a maximum value and a minimum value of the dispersion thereof is 3.0 ps/nm/km or less. Each of the second optical fibers has a dispersion of −1.0 to −8.0 ps/nm/km in the wavelength band of 1530 to 1620 nm, and a difference between a maximum value and a minimum value of the dispersion thereof is 3.0 ps/nm/km or less.

Abstract: The present invention relates to an optical fiber which enables favorable optical communications in 1.3-&mgr;m and 1.55-&mgr;m wavelength bands, and an optical transmission system including the same. The optical fiber according to the present invention has only one zero-dispersion wavelength within a wavelength range of 1.20 &mgr;m to 1.60 &mgr;m, the zero-dispersion wavelength existing within a wavelength range of 1.37 &mgr;m to 1.50 &mgr;m, and has a positive dispersion slope at the zero-dispersion wavelength, thereby enabling favorable optical communications utilizing each signal light in the 1.3-&mgr;m and 1.55-&mgr;m wavelength bands sandwiching the zero-dispersion wavelength.

Abstract: The present invention relates to a dispersion-managed optical fiber which can be manufactured easily and has a structure which enables the easy connection thereof with other optical fiber and the like. The dispersion-managed optical fiber is a silica-based optical fiber ensuring its single mode at a predetermined wavelength within a signal wavelength band, in which first portions each having a positive chromatic dispersion and second portions each having a negative chromatic dispersion are arranged alternately and adjacent to each other. In the dispersion-managed optical fiber, the dopant concentration is made uniform in the longitudinal direction and, corresponding to the above-mentioned first and second portions, the refractive index of a glass layer not doped with GeO2 as a dopant is adjusted or the residual stresses in glass layers are changed.

Abstract: The present invention relates to an optical fiber comprising a structure which effectively suppresses the occurrence of nonlinear phenomena without increasing transmission loss such as macrobending loss. The optical fiber according to the present invention comprises, radially in succession from the center axis thereof, a center region having a predetermined refractive index, a first annular region having a higher refractive index than the center region, and a second annular region doped with fluorine and having a lower refractive index than the first annular region. In particular, this optical fiber has an effective area of 70 &mgr;m2 or more with respect to light having a wavelength of 1550 nm, whereas the fluorine contents in the second annular region is adjusted such that the refractive index thereof decreases with distance from the center of the optical fiber.

Abstract: A distributed control device in a decentralized supervisory control system comprises an I/O interface, a data storage section for storing PIO data from a controller and additional information such as data obtention time, a time obtention section for adding a time to the data when the data is stored in the data storage section, a data distribution section for distributing the PIO data and other supervisory information, a supervisory control section for carrying out supervisory control using the PIO data from the controller, a network interface for communicating with other distributed control devices and the supervisory device, and a communication section for connecting this distributed control device to the other distributed control devices and the supervisory device.

Abstract: The present invention relates to a dispersion-compensating optical fiber which can transmit, with a low loss, light signals having a high power; and an optical transmission system including the same. This dispersion-compensating optical fiber is insured its single mode at a wavelength of 1.55 &mgr;m, and comprises, about the optical axis, at least a first core having a refractive index n1, a second core having a refractive index n2 (>n1), and a cladding having a refractive index n3 (<n2). Also, this dispersion-compensating optical fiber has a chromatic dispersion of −10 ps/nm/km or less at the wavelength of 1.55 &mgr;m, whereas the ratio 2a/2b of the outside diameter 2a of the first core with respect to the-outside diameter 2b of the second core is 0.05 or more.

Abstract: Electrodes are formed on both top and bottom surfaces of a dielectric plate and grounded coplanar lines, as transmission lines, are formed on the top surface of the dielectric plate. A plurality of micro-strip lines, each composed of high-impedance lines and low-impedance lines alternately connected in series, is arranged at a pitch shorter than the wavelength of a wave traveling along the grounded coplanar lines. A spurious mode propagation blocking circuit thus constructed prevents a spurious mode wave, such as a parallel-plate mode, from traveling.

Abstract: A radar system includes a detection-control circuit for transmitting and receiving the beam of a millimeter-wave signal for detecting a relative position and a relative speed to a target, and a scanning unit for scanning the direction of the beam over a predetermined range. The state of the scanning unit can be switched between a resting state wherein scanning is stopped and the beam is directed towards the center of the scanning range while the detection-control circuit continues detection control, and a scanning state wherein the direction of the beam is scanned over a predetermined range.

Abstract: The present invention relates to a single-mode optical fiber having a configuration which enables lowering of dispersion slope while securing a sufficient MFD. This single-mode optical fiber has a refractive index profile in which an indent with a sufficient width is provided at the center of its core region.

Abstract: This invention relates to an optical transmission line having a structure that reduces dispersion with respect to signal light in a 1.55-&mgr;m band. Each transmission unit includes a dispersion-shifted optical fiber as a transmission medium and a mode removing unit for reducing the optical power of high-order modes excluding a fundamental mode of light signals propagating through the dispersion-shifted optical fiber. The dispersion-shifted optical fiber has an incident terminal on which the light signals are incident and an exit terminal from which the light signals are emitted, and has a cutoff wavelength longer than the wavelength of the light signals at a fiber length of 2 m. The mode removing unit has a structure for reducing the optical power of high-order modes to 1/10 or less, preferably 1/40 or less, of the optical power of the fundamental mode so as to satisfy the single-mode condition in relation to fiber length.