Abstract: A channel characteristic analyzing apparatus that can ensure modeling of a more adequate propagation path by processing position parameters needed in a two-wave model which is used as a line-of-sight propagation path model in a stochastic manner is provided. The channel characteristic analyzing apparatus for analyzing the propagation channel characteristics of a reception apparatus 11b which has received a radio signal of a millimeter wave band, transmitted from a transmission antenna 13a of a transmission apparatus 11a, via a reception antenna 13b, includes computation means which computes h(t) expressed by the following equation (1) as a channel response to the propagation channel characteristic. h(t)=??(t)??(1) where ? is derived as a result of processing the position parameters needed also in the two-wave model in the stochastic manner.

Abstract: Disclosed is a wireless communication method for executing transmission and reception of a radio signal among communication terminals via a plurality of base stations connected to an IP (Internet Protocol) network. One of the base stations performs AD conversion on a radio signal received via an antenna from one of the communication terminals without demodulation, packetizes the AD-converted radio signal into packet data, and transmits the packet data to another base station over the IP network. The another base station performs DA conversion on the packet data received over the IP network from the one base station, transforms the DA-converted packet data into a radio signal without modulation, and transmits the radio signal to another base station via the antenna.

Abstract: A low-cost, compact circular waveguide array antenna which improves an antenna reflection loss characteristic and enables an improvement in radiation characteristics, particularly radiation gain. The circular waveguide array antenna includes feeding portions which feed electromagnetic waves to one ends of circular waveguides and radiation apertures which radiate the electromagnetic waves at the opposite ends. Each circular waveguide includes a conical horn, with a diameter of a feeding side aperture at the feeding portion end being a, a diameter of the radiation aperture being d, which is larger than the diameter a of the feeding side aperture, and an opening angle being 2?. If a wavelength of a central frequency of an employed frequency band is ?, then a value of ?, which is half of the opening angle 2?, is set between 0.8×Arcsin(0.1349114/(d/?)) and 1.2×Arcsin(0.1349114/(d/?)).

Abstract: A method for generating a carrier residual signal and its device, in which a heterodyne optical signal used in a photometric field or an optical fiber radio communication field can be stably generated with a simplified structure. The device includes an optical modulating unit that includes a light source generating a light wave having a specific wavelength, and an SSB optical modulator. A light wave emitted from the light source enters into the optical modulating unit. A light wave emitted from the optical modulating unit includes a carrier component related to a zero-order Bessel function and a specific signal component related to a specific high-order Bessel function while suppressing signal components other than the specific signal component related to the specific high-order Bessel function, and a ratio of optical intensity between the carrier component and the specific signal component is set substantially to 1.

Abstract: A transmitter shown in FIG. 3 inputs to a mixer 36 an IF band modulation signal generated from transmission data and a frequency hopping signal obtained by a hopping synthesizer 38 controlled by a hopping pattern generator 37, thereby obtaining a frequency hopping radio signal to be transmitted. In a receiver shown in FIG. 4, a received signal is amplified and an unnecessary wave is removed from the signal, and the resultant signal is input to a mixer 44. The mixer 44 receives an output signal of a hopping synthesizer 47 controlled by a signal obtained by adding a fixed frequency offset signal to the hopping pattern generator 45. A signal downconverted to a first IF band without frequency hopping corresponding to the offset signal with a radio frequency band signal maintaining the relative spectrum relationship appears in the output of the mixer 44.

Abstract: A low-cost, compact circular waveguide array antenna which improves an antenna reflection loss characteristic and enables an improvement in radiation characteristics, particularly radiation gain. The circular waveguide array antenna includes feeding portions which feed electromagnetic waves to one ends of circular waveguides and radiation apertures which radiate the electromagnetic waves at the opposite ends. Each circular waveguide includes a conical horn, with a diameter of a feeding side aperture at the feeding portion end being a, a diameter of the radiation aperture being d, which is larger than the diameter a of the feeding side aperture, and an opening angle being 2?. If a wavelength of a central frequency of an employed frequency band is ?, then a value of ?, which is half of the opening angle 2?, is set between 0.8×Arcsin(0.1349114/(d/?)) and 1.2×Arcsin(0.1349114/(d/?)).

Abstract: Disclosed is a wireless communication method for executing transmission and reception of a radio signal among communication terminals via a plurality of base stations connected to an IP (Internet Protocol) network. One of the base stations performs AD conversion on a radio signal received via an antenna from one of the communication terminals without demodulation, packetizes the AD-converted radio signal into packet data, and transmits the packet data to another base station over the IP network. The another base station performs DA conversion on the packet data received over the IP network from the one base station, transforms the DA-converted packet data into a radio signal without modulation, and transmits the radio signal to another base station via the antenna.

Abstract: A channel characteristic analyzing apparatus that can ensure modeling of a more adequate propagation path by processing position parameters needed in a two-wave model which is used as a line-of-sight propagation path model in a stochastic manner is provided. The channel characteristic analyzing apparatus for analyzing the propagation channel characteristics of a reception apparatus 11b which has received a radio signal of a millimeter wave band, transmitted from a transmission antenna 13a of a transmission apparatus 11a, via a reception antenna 13b, includes computation means which computes h(t) expressed by the following equation (1) as a channel response to the propagation channel characteristic. h(t)=??(t)??(1) where ? is derived as a result of processing the position parameters needed also in the two-wave model in the stochastic manner.

Abstract: The present invention provides a radio communication device, a transmitter and a receiver capable of handling a plurality of signal waves. A radio communication device has a millimeter-wave transmitter (15) and a millimeter-wave receiver (29). Millimeter-wave transmitter (15) includes a multiplexing circuit (1), a millimeter-wave up-converter (4) and an antenna (3), and the millimeter-receiver includes an antenna (31), a millimeter-wave down-converter (32) and an output processing circuit (45). The signal waves dedicated to the user are modulated by a modulation circuit (121 to 124) so as to be allocated between the ground broadcast waves and satellite broadcast waves. The frequencies are multiplexed in an intermediate frequency band, after that, the multiplexed frequencies are converted into a millimeter-wave band and the resultant is transmitted. On the reception side, the multiplexed waves are down-converted, separated to signal waves and demodulated.

Abstract: In a radio optical fusion communication system with the integration of an optical fiber transmission path and a radio propagation path, wherein by first and second light sources, an intermediate-frequency signal generating means for generating a modulating signal at an intermediate frequency band, a modulator for modulating an optical signal from the first light source into an SSB modulated optical signal using the intermediate-frequency signal, and an optical mixer for mixing the modulated optical signal with the optical signal from the second light source to obtain an optical transmission signal in a base station, the frequency of either of the optical signals is controlled such that the difference in frequency between the optical signals is a desired frequency of a modulated radio signal, thus switching the frequency channel of the modulated radio signal in the radio propagation path.

Abstract: A receiver receives an RF-band modulated signal transmitted from a transmitter, as well as an un-modulated carrier also transmitted from the transmitter and having a phase noise characteristic coherent with that of the modulated signal, and a product of the two components is generated to thereby restore an IF-band transmission source signal. In the receiver, a small planar antenna having a broad beam characteristic such as a single-element patch antenna is combined with an amplifier and a mixer circuit, which are formed on a micro planar circuit by an MMIC technique, so as to form a unit receiving circuit. A plurality of such unit receiving circuits are disposed on the receiver at intervals smaller than a wavelength corresponding to an IF band, and detection outputs from the unit receiving circuits are power-mixed. Thus, the receiver serves as a high-gain antenna having a detection function, and can realize a broad beam radiation characteristic comparable to that of a single-element antenna.

Abstract: A method for generating a carrier residual signal and its device, in which a heterodyne optical signal used in a photometric field or an optical fiber radio communication field can be stably generated with a simplified structure. The device includes an optical modulating unit that includes a light source generating a light wave having a specific wavelength, and an SSB optical modulator. A light wave emitted from the light source enters into the optical modulating unit. A light wave emitted from the optical modulating unit includes a carrier component related to a zero-order Bessel function and a specific signal component related to a specific high-order Bessel function while suppressing signal components other than the specific signal component related to the specific high-order Bessel function, and a ratio of optical intensity between the carrier component and the specific signal component is set substantially to 1.

Abstract: A reference local oscillation signal transmission station 1 radiates a reference local oscillation signal to a service zone. A portion of the signal received by each radio slave station terminal 2 is branched and fed to an injection locked oscillator 6. As a result, a local oscillation signal which is synchronized with the reference local oscillation signal is obtained. In the slave station terminal 2, the thus-obtained local oscillation signal is fed to a transmission frequency converter (mixer) 7 and a reception frequency converter (mixer) 8. An IF band transmission modulated signal is fed to the mixer 7 for frequency conversion to a radio frequency band, and the thus-obtained radio-frequency modulated signal is transmitted. Meanwhile, a received radio-frequency modulated signal is fed to the mixer 8 for down conversion, and the thus-obtained signal is fed to an IF band demodulator 10 so as to restore an information signal.

Abstract: A transmitter 1 transmits from a transmission antenna 7 a mixture signal containing a radio-frequency (RF)-band modulated signal, and a portion of power of a local oscillation signal used for frequency conversion. Meanwhile, a receiver 8 detects the transmitted signal by means of a reception antenna-detection section 9. In the reception antenna-detection section 9, a plurality of base unit reception circuits 11 are disposed. Each base unit reception circuit 11 includes a planar printed antenna 12 such as a patch antenna, an amplifier circuit 13 formed on a very small planar circuit by means of an MMIC technique, and a mixer circuit 14 serving as a square-law detector. Respective outputs of the base unit reception circuits 11 are power-mixed and fed to the IF signal demodulation section. The IF signal demodulation section 10 demodulate reception data.

Abstract: A wireless communication system according to the invention is to perform communication with a terminal station at a radio frequency higher than a millimeter wave band. The wireless communication system includes, as transmission devices to the terminal station, a center station device which forms a baseband signal to the terminal station and a plurality of access point devices which receive delivered signals from the center station device and emit radio waves to the terminal station. Cover areas of the access point devices partially overlap to constitute a service area to the terminal station by all the cover areas. In this manner, a frequency higher than a millimeter wave band is applied to wireless communication to the terminal station to make it possible to widen the service area.

Abstract: In a radio optical fusion communication system with the integration of an optical fiber transmission path and a radio propagation path, wherein by first and second light sources, an intermediate-frequency signal generating means for generating a modulating signal at an intermediate frequency band, a modulator for modulating an optical signal from the first light source into an SSB modulated optical signal using the intermediate-frequency signal, and an optical mixer for mixing the modulated optical signal with the optical signal from the second light source to obtain an optical transmission signal in a base station, the frequency of either of the optical signals is controlled such that the difference in frequency between the optical signals is a desired frequency of a modulated radio signal, thus switching the frequency channel of the modulated radio signal in the radio propagation path.

Abstract: This invention includes a wireless transmitter comprising an IF-signal generator that modulates input signals into those of an intermediate frequency band, signal distributors that distribute signals from the IF-signal generator, and a plurality of signal-transmission units that convert the signals distributed by the signal distributors into those of a radio frequency band, and then transmit the converted radio signals. The invention also includes a wireless receiver that receives the radio-frequency-band modulated signals and restores the signals of the intermediate frequency band. In this way, effective diversity is realized and signal interruptions are prevented. In addition, a handy, low-cost wireless communications system is provided.

Abstract: A system shown in the drawing automatically sends information stored in a server to a mobile terminal (MT) that has entered a service area. At least one access point station (AP#1) of access point stations (AP#1 to AP#3) installed in a high place is connected by cable to a contents server or an external network; a service area having a shape of a spot is deployed under the above access point station. Further, the access point station (AP#1) is linked wirelessly ad hoc to another access point station (AP#2, AP#3) by means of wireless P-P (point-to-point) link. Consequently, the another access point station can also deploy an equivalent hotspot service. Accordingly, a millimeter-wave ad hoc communication network spreading two-dimensionally can be realized without constructing a cable network.

Abstract: A wireless communication system according to the invention is to perform communication with a terminal station at a radio frequency higher than a millimeter wave band. The wireless communication system includes, as transmission devices to the terminal station, a center station device which forms a baseband signal to the terminal station and a plurality of access point devices which receive delivered signals from the center station device and emit radio waves to the terminal station. Cover areas of the access point devices partially overlap to constitute a service area to the terminal station by all the cover areas. In this manner, a frequency higher than a millimeter wave band is applied to wireless communication to the terminal station to make it possible to widen the service area.

Abstract: A receiver receives an RF-band modulated signal transmitted from a transmitter, as well as an un-modulated carrier also transmitted from the transmitter and having a phase noise characteristic coherent with that of the modulated signal, and a product of the two components is generated to thereby restore an IF-band transmission source signal. In the receiver, a small planar antenna having a broad beam characteristic such as a single-element patch antenna is combined with an amplifier and a mixer circuit, which are formed on a micro planar circuit by an MMIC technique, so as to form a unit receiving circuit. A plurality of such unit receiving circuits are disposed on the receiver at intervals smaller than a wavelength corresponding to an IF band, and detection outputs from the unit receiving circuits are power-mixed. Thus, the receiver serves as a high-gain antenna having a detection function, and can realize a broad beam radiation characteristic comparable to that of a single-element antenna.