Abstract: Existing modems of time division duplex (TDD) type can be utilized without modification to perform a high speed wireless communication with stable communication quality in other frequency bands such as quasi-millimeter to millimeter wave bands. There are included a circulator (11) connected to TDD modems (1, 2) and receives signals transmitted thereby to output those signals from a first connection terminal (p1) and outputs signals received at a second connection terminal (p2) to the TDD modems (1, 2), and a frequency converter (2a) that raise the frequency of the signals from the circulator (11) by a predetermined frequency width and lowers the frequency of signals from a receive antenna (32) by a predetermined frequency width.

Abstract: In a frequency converter, a phase-locked loop generates a local-oscillation signal having a low frequency, of a plurality of local-oscillation signals having different frequencies, based on an intermediate frequency beacon signal that results from mixing a predetermined beacon signal with the local-oscillation frequency signal. Even if the phase-locked loop is used to generate the low frequency local-oscillation signal only, a frequency offset and a phase noise taking place in remaining high frequency local-oscillation signals are compensated for or canceled out. The frequency converter thus results in a high frequency accuracy. This arrangement reduces the number of bulky, costly and power-consuming phase-locked oscillators, typically used in the quasi millimeter band or the millimeter band. A simplified, compact frequency converter is thus provided, reducing both installation and operating costs.

Abstract: There is provided a fuse block 3 having an insertion port 7 into which a dark current fuse 11 is inserted and adapted to hold the dark current fuse 11 in a mount position, and the fuse block includes a guide surface 8 which is formed within the insertion port 7 in such a manner as to continue from the mount position for the dark current fuse 11 for contact with the dark current fuse 11 and arms formed at positions lying at lateral sides of the dark current fuse 11 in such a manner as to face the insertion port 7 so as to be able to hold the dark current fuse 11 therein when the dark current fuse 11 is in contact with the guide surface 8.

Abstract: In a frequency converter, a phase-locked loop generates a local-oscillation signal having a low frequency, of a plurality of local-oscillation signals having different frequencies, based on an intermediate frequency beacon signal that results from mixing a predetermined beacon signal with the local-oscillation frequency signal. Even if the phase-locked loop is used to generate the low frequency local-oscillation signal only, a frequency offset and a phase noise taking place in remaining high frequency local-oscillation signals are compensated for or canceled out. The frequency converter thus results in a high frequency accuracy. This arrangement reduces the number of bulky, costly and power-consuming phase-locked oscillators, typically used in the quasi millimeter band or the millimeter band. A simplified, compact frequency converter is thus provided, reducing both installation and operating costs.

Abstract: In a frequency converter, a phase-locked loop generates a local-oscillation signal having a low frequency, of a plurality of local-oscillation signals having different frequencies, based on an intermediate frequency beacon signal that results from mixing a predetermined beacon signal with the local-oscillation frequency signal. Even if the phase-locked loop is used to generate the low frequency local-oscillation signal only, a frequency offset and a phase noise taking place in remaining high frequency local-oscillation signals are compensated for or canceled out. The frequency converter thus results in a high frequency accuracy. This arrangement reduces the number of bulky, costly and power-consuming phase-locked oscillators, typically used in the quasi millimeter band or the millimeter band. A simplified, compact frequency converter is thus provided, reducing both installation and operating costs.

Abstract: A plastic pipe (10) includes a pipe body (12), and, at an end of the pipe body (12), there is formed a socket which is provided in the inner surface or in the vicinity of the inner surface thereof with a heat generating unit (18). In coupling, an outer peripheral surface of an end of a pipe (28) to be coupled is scraped by a scraper or the like, and the end is inserted into the socket. Then, an electric current is supplied to the heat generating unit (18) such that a heat is generated by the same. Then, synthetic resin of the coupling surfaces of the pipe (28) and the socket and synthetic resin disposed thereabout are fused, so that the both members are fusion-coupled to each other.

Abstract: An electro-fusion fitting includes a body which is provided with a heater including a magnetic alloy unit having a predetermined Curie temperature in the vicinity of a joint surface thereof in a manner that a surface of the heater is exposed on the joint surface. The joint surface of the body is brought into contact with a joint surface of a member to be coupled and, if a high-frequency current is applied to the magnetic alloy unit by electromagnetic induction, the magnetic alloy unit generates heat, and a temperature of the magnetic alloy unit is kept at the predetermined Curie temperature due to a temperature self-control function thereof. Therefore, if the Curie temperature is set at a fusion temperature, the joint surfaces of the body and the member to be coupled are coupled to each other.