JPH0983422A - Microwave repeater and radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a repeater not losing beautiful appearance at a low cost by using transmission and reception antennas for the repeater in common so as to reduce the number of antennas in use. SOLUTION: A repeater 10 is used for interconnecting radio terminal equipments A, B, C,.... A low gain antenna 11 is installed to the repeater 10 toward the radio terminal equipments A, B, C,... and a reflection termination 12 is connected to a feeding point of the antenna 11. An incoming radio wave from an optional terminal equipment A is relayed and emitted again to all the radio terminal equipments A, B, C,... in the service area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave (millimeter wave) repeater and a wireless communication system using the repeater, including indoor wireless communication, microwave (millimeter wave) wireless LAN,
It is applicable to wireless high-speed data communication and the like.

[0002]

2. Description of the Related Art In recent years, research and development of wireless LANs have been actively conducted with the remarkable spread of LANs. With the increase in the transmission speed of the wired LAN, 100 will be used in the future wireless LAN.
Since a transmission speed of Mbps or higher is required, a wireless LAN using microwaves or millimeter waves is considered promising. In addition to the advantages of a wide band and miniaturization of the antenna, the characteristics of such short-wave radio waves are high in straightness, easy to be shielded by obstacles, large in transmission loss, and short in transmission distance. Can be given as. When using microwaves and millimeter waves for indoor wireless LAN, it is necessary to successfully compensate for this drawback.

As a method of compensating for this drawback, use of a repeater can be mentioned. As an example, in Japanese Unexamined Patent Publication No. 2-171676, “Communication distance extension device for mobile object identification device”, FIG.
As shown in FIG. 2, a microwave repeater 10 in which feeding points of two microwave antennas are connected to each other is an interrogator 1 and a responder 2.
Installed between to extend the communication distance.

[0004]

However, when the repeater is used indoors, a plurality of wireless terminals are usually on a desk or the like, and the repeater is often installed on the ceiling. is assumed. In this configuration, since the wireless terminals are all located in the same half space as viewed from the repeater, it is necessary to direct a plurality of relay antennas in substantially the same direction. for that reason,
Multiple antennas with the same function will be lined up on the ceiling, which is uneconomical and spoils the aesthetics of the office.

The present invention has been made in view of the above-mentioned circumstances. By sharing the transmitting and receiving antennas of the repeater, the number of antennas can be reduced, the repeater can be downsized, and the repeater can be manufactured at a low cost without impairing the appearance. And a wireless communication system using the repeater.

[0006]

According to a first aspect of the present invention, in a microwave repeater used for interconnecting a plurality of wireless terminals, a low gain antenna is installed at a relay position toward a terminal group, and a feeding point of the antenna is provided. It is characterized by connecting a reflection terminal to and re-radiating the incoming radio wave from any terminal to all terminals within the service area as it is, thus enabling relay between multiple wireless terminals with one antenna The aim is to reduce the size and cost of the repeater and improve the aesthetics of the office.

According to a second aspect of the present invention, in a microwave repeater used for interconnection of a plurality of wireless terminals, a low gain antenna is installed at a relay position toward a terminal group, and a 3-port circulator is provided at a feeding point of the antenna. One of the features is that one port is connected, and an amplifier is connected between the remaining two ports in the direction in which the signal from the antenna is amplified and returns to the antenna again. Therefore, the signal from the wireless terminal is amplified to the other terminal. It re-radiates and requires a power source, but the distance between the terminal and the repeater can be extended and the service area can be expanded.

According to a third aspect of the present invention, in a microwave repeater used for interconnecting a plurality of wireless terminals, a low gain antenna is installed at a relay position toward a terminal group, and a 3-port circulator is provided at a feeding point of the antenna. One of the features is that one port is connected, a frequency converter consisting of a local oscillator and a multiplier is connected between the remaining two ports, and a bandpass filter and an amplifier are further inserted, if necessary. The gain can be made higher than that of the invention of claim 2, the distance between the terminal and the repeater can be further extended, and the service area can be further extended.

According to a fourth aspect of the present invention, in a microwave repeater used for interconnecting a plurality of wireless terminals, a low-gain dual-polarization antenna (shared left / right circular polarization or horizontal) is directed toward a terminal group at a relay position. (Commonly used for vertical polarization) is installed, and an amplifier or a frequency conversion unit is provided between two feeding points of the dual polarization antenna. Therefore, by using a low gain dual polarization antenna, a circulator is provided. Is unnecessary, and the size and cost can be further reduced accordingly.

According to a fifth aspect of the present invention, in a radio communication system using the microwave repeater according to any one of the first to fourth aspects, a high gain antenna is provided in the radio terminal and the radio terminal is kept in a normal reception state. When transmission data is generated, transmission is performed only when there is no reception signal, and it is transmitted to all terminals simultaneously via the repeater.Therefore, by providing a high gain antenna to the wireless terminal, relaying is performed. The signal due to is reduced in the amount of attenuation and the service area is expanded, and communication between terminals is realized by transmitting to all terminals simultaneously via a repeater, and the existing LAN can be easily made wireless. It was done like this.

According to a sixth aspect of the present invention, in a microwave repeater used for interconnecting a plurality of wireless terminals, a plurality of high gain antennas are radially arranged at a relay position and one or a plurality of feeding points of the antennas. By connecting using a power combiner / distributor (or a directional coupler having an equivalent function), the feeding points are combined into one, and a reflection termination (open or short circuit) is connected to this feeding point to select an arbitrary 1 It is characterized in that the input signal to one antenna is reflected at the feeding point of the entire antenna system and re-radiated from all the antennas.
The service area can be widened and the influence of multipath fading can be reduced as compared with the invention of claim 1 because the antenna gain is high.

According to a seventh aspect of the present invention, in a microwave repeater used for interconnecting a plurality of wireless terminals, a plurality of high gain antennas are radially arranged at a relay position, and one or a plurality of antenna feeding points are provided. By connecting using a power combiner / divider (or a directional coupler having the same function), the feeding points are combined into one, and one port of a 3-port circulator is connected to this feeding point, and the remaining two The signal from the antenna is amplified between the ports and characterized by connecting an amplifier in the direction to return to the antenna again, so that the signal from the wireless terminal is amplified and then re-radiated to another terminal. Although a power source is required, the distance between the terminal and the repeater can be extended beyond that of the invention of claim 6 to extend the service area.

In a microwave repeater used for interconnection of a plurality of wireless terminals, a plurality of high gain antennas are radially arranged at a relay position, and one or a plurality of feeding points of the antennas are arranged. By connecting using a power combiner / divider (or a directional coupler having the same function), the feeding points are combined into one, and one port of a 3-port circulator is connected to this feeding point, and the remaining two A frequency converter consisting of a local oscillator and a multiplier was connected between the ports, and a bandpass filter and an amplifier were inserted between the ports if necessary. Therefore, there was a concern about the oscillation of the amplifier due to poor isolation of the circulator. It is possible to increase the gain of the amplifier more than the invention of claim 7 and to further extend the distance between the repeater and the terminal.

According to a ninth aspect of the present invention, in a radio communication system using the microwave repeater according to any one of the sixth to eighth aspects, relaying is performed so that only one radio terminal is included in the communication area of each relay antenna. While increasing the gain of the transmitter antenna, the wireless terminal is provided with a low-gain antenna, and the wireless terminal is normally in a receiving state, and when transmission data occurs, transmission is performed only when there is no received signal, and the repeater The antenna gain of the wireless terminal is increased because the gain of the repeater antenna is increased to the extent that only one wireless terminal can be included in the communication area of each relay antenna at the same time. It can be made smaller by that amount, the fluctuation of the received signal level due to the position and orientation of the terminal is small, and it is possible to avoid having to worry too much about the orientation of the antenna. Realizing communication between terminals by sending simultaneously, in which to be able easily wirelessly the existing LAN.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram for explaining the basic configuration (claims 1 and 5) of a repeater and a wireless communication system according to the present invention, in which 10 is a microwave (millimeter wave) relay. , Are wireless terminals, and the repeater 10 is composed of a low gain antenna 11 and a reflection terminal 12, and is used for interconnection of a plurality of wireless terminals A, B, C. The reflection terminal 12 is connected to the feeding point of the low-gain antenna 11 installed toward the wireless terminals A, B, C ... Group in an open or short-circuited manner, whereby the radio wave transmitted from the wireless terminal A is a repeater. The signal is received by the low-gain antenna 11 of 10 and becomes a high-frequency signal toward the reflection terminal 12. At the reflection terminal 12, the received high-frequency signal is reflected as it is, and heads for the antenna 11 again, and the high-frequency signal is re-radiated from the antenna 11 to all the wireless terminals A, B, C, ... Will be delivered to. This allows relaying between terminals that cannot perform direct wave communication due to obstacles or the like in microwave and millimeter wave communication with one antenna. Therefore, high-speed communication becomes possible even indoors where the propagation environment is bad. The inventions of claims 2 to 9 described below are further improvements of the invention of claim 1 described above.
Since the invention is limited to only passive elements, no electric power is required.

FIG. 2 is a block diagram for explaining the invention (repeater) of claim 2, wherein the repeater 10 comprises a low gain antenna 11, a circulator 13, and an amplifier 14.
A 3-port circulator 13 is used instead of the reflection termination 12 shown in FIG. 1, one port of which is connected to the low gain antenna 11, and the antenna 11 is provided between the remaining two ports.
The amplifier 14 is connected in the direction in which the signal from is amplified and returns to the antenna again. The received signal from the antenna 11 is guided to the input end of the amplifier 14 by the circulator 13, and the amplified signal is input to the remaining port of the circulator 13 and returned to the antenna 11. As a result, the received signal from the terminal is amplified once and then re-emitted to all terminals. Since the electric power at the time of re-radiation can be increased, the distance between the repeater and the terminal can be extended as compared with the invention of claim 1.

FIG. 3 is a block diagram for explaining the invention (repeater) of claim 3, in which 11 is a low gain antenna, and 1 is a low gain antenna.
3 is a circulator, 14 is an amplifier, 15 is a local oscillator, 16 is a multiplier, and 18 ₁ and 18 ₂ are band pass filters (B / P / F). The present invention replaces the amplifier 14 of FIG. A frequency conversion unit composed of an oscillator (oscillation frequencies f ₁ and f ₂ ) 15 and a multiplier 16 is connected between two ports of the circulator 13, and further band pass filters 18 ₁ (frequency f ₁ ) and 18 as necessary. ₂ (frequency f ₂ ) and the amplifier 14 are inserted. The input signal from the antenna 11 is guided to the frequency conversion unit through the circulator 13, is frequency-converted, is then amplified by the amplifier 14, and is returned to the antenna 11 through the circulator 13. Since the ascending and descending frequencies are different, there is no fear of oscillation of the amplifier due to poor isolation of the circulator 11 that is assumed in the invention of claim 2. Therefore, claim 2
It is possible to increase the gain of the amplifier more than the invention of
The distance between the repeater and the terminal can be further extended. At this time, all terminals commonly use the radio wave of frequency f ₁ for transmission and the radio wave of frequency f ₂ for reception. Since the frequencies of transmission and reception are different, it is possible to transmit and receive at the same time.

FIG. 4 is a constitution for explaining the invention (repeater) of claim 4, in which 14 is an amplifier and 19 is a low gain antenna for dual polarization. The present invention is shown in FIG. Instead of the circulator 13 and the low-gain antenna 11, a low-gain dual-polarization antenna 19 is used. Since the circulator is not required, the configuration becomes simple, leading to cost reduction. Although FIG. 4 shows an example in which only the amplifier 14 is added to the dual polarization antenna 19, a configuration in which a frequency conversion unit as shown in FIG. 3 is added can be considered in the same manner. Further, in order to use this repeater, it is necessary for the terminal side to have the polarizations of the transmitting antenna and the receiving antenna orthogonal to each other.

A fifth aspect of the present invention is a radio communication system using a repeater as described above, wherein the high gain antenna 3 is provided to the radio terminals A, B, C ... As shown in FIG. In the receiving state, when the transmission data is generated, the transmission is performed only when there is no reception signal, and the transmission is performed simultaneously to all terminals via the repeater. That is,
FIG. 1 shows a basic communication mode when the microwave (millimeter wave) repeater according to any one of claims 1 to 4 is applied to communication between wireless terminals, and the wireless terminal has a high gain antenna 3 Is provided to compensate the attenuation due to the low gain antenna of the repeater and reduce the effect of multipath fading. As for the communication procedure, it is possible to send to all terminals at once via the repeater by keeping the wireless terminal in the normal receiving state and when transmission data is generated, transmitting only when there is no received signal. ing. Therefore, it can be applied to bus sharing type communication such as Ethernet.

FIG. 6 is a block diagram for explaining the invention (repeater) of claim 6, in which 12 is a reflection terminal, 20 is a power combining / distributing section, 21 is a high gain antenna, and power combining / dividing is performed. The unit 20 is composed of a large number of power combiner / distributor 20a and a transmission line 20b connecting them, and the repeater has a plurality of high-gain antennas 21 arranged radially at a repeater position as shown in the figure, and By connecting the feeding points to each other by using one or a plurality of power combiner / dividers, the feeding points are integrated into one, and the reflection termination is connected to the feeding point. The power combiner / distributor 20a may be a Wilkinson type power combiner or a directional coupler in which a reflectionless termination is added to one port. It suffices if there is sufficient isolation between the ports on the antenna side.

An input signal to any one antenna is guided to a feeding point of the entire antenna system by a plurality of power combiners and reflected at a reflection terminal. On the contrary, the reflected signal is distributed to all the antenna feeding points by the power distributor and re-radiated from each antenna. As a result, the radio wave from any one terminal is demultiplexed by the repeater and sent to all terminals. Since the antenna of the repeater uses a highly directional antenna, signal attenuation due to the relay can be made smaller than in the case of claim 1. Moreover, since the position of the service range of each antenna can be easily changed by the direction of the antenna, the degree of freedom in the layout of the terminal can be increased.
In addition, the fact that the power combiner and the power distributor are shared also contributes to cost reduction. Moreover, the influence of multipath fading is reduced by the high gain antenna.

FIG. 6 is a block diagram for explaining the invention (repeater) of claim 7, wherein 13 is a circulator and 1 is a circulator.
4 is an amplifier, 20 is a power combiner / distributor, and 24 is a high-gain antenna group. This repeater has a 3-port circulator 1 instead of connecting a reflection terminal to the feeding point of the entire antenna system. One port is connected, and the amplifier 14 is connected between the remaining two ports in the direction in which the signal from the antenna is amplified and returns to the antenna again. The same operation as that of the invention of claim 2 shown in FIG. 2 is performed, in which a received signal from a terminal is amplified once and then re-radiated toward all terminals. The distance between the repeater and the terminal for increasing the power at the time of re-radiation can be extended as compared with the invention of claim 6.

FIG. 7 is a block diagram for explaining the invention (repeater) of claim 8 and this repeater is similar to the repeater shown in FIG. 3 instead of the amplifier of FIG. A frequency converter composed of 15 and a multiplier 16 is connected between the two ports of the circulator 13, and band-pass filters 18 ₁ and 18 ₂ and an amplifier 14 are inserted if necessary. This repeater operates in the same manner as the repeater shown in FIG. 3, and since the ascending and descending frequencies are different, there is no fear of oscillation of the amplifier due to poor isolation of the circulator assumed in the invention of FIG. The gain of the amplifier can be increased more than the invention of FIG. 6, and the distance between the repeater and the terminal can be further extended.

The invention of claim 9 is a basic wireless communication system when the microwave (millimeter wave) repeater according to claims 6 to 8 described above is applied to communication between wireless terminals. As shown in FIG. 5, by increasing the gain of the repeater antenna to the extent that only one wireless terminal can fit in the communication area of each relay antenna, the gain of the antenna 4 on the wireless terminal side A, B, C ... Is lowered. , The fluctuation of the received signal level due to the position and orientation of the terminal is reduced. As the communication procedure, as in the invention of claim 5, the wireless terminal is set to the communication receiving state, and when the transmission data is generated, the transmission is performed only when there is no reception signal, so that all the terminals are simultaneously transmitted through the repeater. Send to. Therefore, it can be applied to bus sharing type communication such as Ethernet.

[0025]

According to the microwave (millimeter wave) repeater of the first aspect of the invention, by connecting the reflection end to the feeding point of the low gain antenna, one antenna can perform relay between a plurality of wireless terminals. As a result, the size and cost of the repeater can be reduced and the aesthetics of the office can be improved. Further, since it is composed of only passive elements, it does not require a power source and is easy to install. All terminals use radio waves of the same frequency for both transmission and reception, so frequency resources can be used effectively.

According to the microwave (millimeter wave) repeater of claim 2, instead of the reflection termination of the microwave (millimeter wave) repeater of claim 1, one port of a three-port circulator is connected and left. Since the signal from the antenna is amplified between the two ports and the amplifier is connected in the direction to return to the antenna again, the signal from the wireless terminal is amplified and then re-radiated to another terminal, so a power supply is required. However, the service area can be expanded by extending the distance between the terminal and the repeater.

According to the microwave (millimeter wave) repeater of claim 3, instead of the amplifier of the microwave (millimeter wave) repeater of claim 2, a frequency converter comprising a local oscillator and a multiplier is used as a circulator. Since it is connected between two ports and, if necessary, a bandpass filter and an amplifier are inserted, the amplification gain can be made higher than in the case of claim 2, and the distance between the terminal and the repeater can be further extended. The service area can be expanded. In addition, since the transmission frequency and the reception frequency can be set to be the same in all wireless terminals, channel control is not required and frequency resources can be effectively used. Furthermore, since the frequency of transmission and reception is different in each terminal, transmission and reception can be performed simultaneously.

According to the microwave (millimeter wave) repeater of claim 4, instead of the circulator and the low gain antenna of the microwave (millimeter wave) repeater according to claims 2 and 3, a low gain dual polarization antenna is used. Since it is used, the size and cost can be further reduced because the circulator is unnecessary. In addition, since the polarized waves of the transmitted and received radio waves are orthogonal to each other in the terminal, the same frequency can be used for transmission and reception while transmitting and receiving at the same time.

According to the wireless communication system of the fifth aspect, by providing the wireless terminal with the high-gain antenna, it is possible to reduce the amount of signal attenuation due to relaying and expand the service area. In addition, as a communication procedure, the wireless terminals are set to the normal reception state, and when transmission data occurs, transmission is performed only when there is no reception signal, and by transmitting to all terminals simultaneously via the relay device, Since the communication is realized, the existing LAN can be easily made wireless by applying the present system instead of the physical layer of the bus sharing type wired LAN such as Ethernet.

According to the microwave (millimeter wave) repeater of the sixth aspect, a plurality of high gain antennas are radially arranged at the relay position, and the feeding points of the antennas are provided with one or a plurality of power combiner / dividers. By connecting, the power supply points are combined into one,
Since the reflection termination is connected to this feeding point, the service area can be widened and the influence of multipath fading can be reduced as compared with the invention of claim 1 because the antenna gain is high. Moreover, since the position of the service range of each antenna can be easily changed depending on the antenna orientation, the degree of freedom in the layout of the terminal can be increased.

According to the microwave (millimeter wave) repeater of claim 7, instead of connecting the reflection terminal to the feeding point of the entire antenna system of the microwave (millimeter wave) repeater of claim 6, a three-port circulator. Connect one port of and leave the other 2
The signal from the antenna is amplified between the two ports and the amplifier is connected in the direction to return to the antenna again, and the signal from the wireless terminal is amplified and then re-radiated to other terminals. The distance between the devices can be extended beyond the invention of claim 6, and the service area can be further expanded.

According to the microwave (millimeter wave) repeater of claim 8, in place of the amplifier of the microwave (millimeter wave) repeater of claim 7, a frequency converter consisting of a local oscillator and a multiplier is used as a circulator. 8. The connection between two ports, and further, if necessary, a bandpass filter and an amplifier are inserted, and the ascending and descending frequencies are different.
Since there is no concern about the oscillation of the amplifier due to the isolation failure of the circulator assumed in the invention of claim 1, it is possible to increase the gain of the amplifier more than that of the invention of claim 7 and further extend the distance between the repeater and the terminal.

According to the wireless communication system of claim 9, the gain of the repeater antenna is increased to the extent that only one wireless terminal can fit in the communication area of each relay antenna.
The antenna gain of the wireless terminal can be reduced by that amount, the fluctuation of the received signal level due to the position and orientation of the terminal is small, and the orientation of the antenna need not be taken into consideration. Also, as a communication procedure, the wireless terminal is kept in a communication receiving state, and when transmission data occurs, transmission is performed only when there is no reception signal,
Since communication between terminals is realized by transmitting to all terminals simultaneously via a repeater, by applying this system instead of the physical layer of a bus sharing wired LAN such as Ethernet, existing Wireless LAN can be easily made.

[Brief description of drawings]

1 is a configuration diagram for explaining a microwave (millimeter wave) repeater according to claim 1 and a wireless communication system according to claim 5 using the repeater according to claims 1 to 4; .

FIG. 2 is a configuration diagram for explaining an example of a microwave (millimeter wave) repeater described in claim 2;

FIG. 3 is a configuration diagram for explaining an example of a microwave (millimeter wave) repeater described in claim 3;

FIG. 4 is a configuration diagram for explaining an example of a microwave (millimeter wave) repeater described in claim 4;

5 is a configuration diagram for explaining a microwave (millimeter wave) repeater according to claim 6 and a wireless communication system according to claim 9 using the repeater according to claims 6 to 8. FIG. .

FIG. 6 is a configuration diagram for explaining an example of a microwave (millimeter wave) repeater according to claim 7;

FIG. 7 is a configuration diagram for explaining an example of a microwave (millimeter wave) repeater according to claim 8;

FIG. 8 is a diagram illustrating an example of a case where a microwave repeater is installed between an interrogator and a responder to extend a communication distance.

[Explanation of symbols]

1 ... Interrogator, 2 ... Responder, 3, 4 ... Antenna, 10 ... Repeater, 11 ... Low gain antenna, 12 ... Reflection termination, 13 ...
Circulator, 14 ... Amplifier, 15 ... Local oscillator, 1
6 ... Multiplier, 18 ₁ , 18 ₂ ... Bandpass filter, 19 ...
Dual-polarization low-gain antenna, 20 ... Power combiner / divider, 20
a ... Power combiner / distributor, 20b ... Transmission line, 21 ... High-gain antenna, 22 ... High-gain antenna group.

Claims (9)

[Claims] 1. In a microwave repeater used for interconnection of a plurality of wireless terminals, a low gain antenna is installed at a relay position toward a terminal group, and a reflection terminal is connected to a feeding point of the antenna to connect an arbitrary terminal. A microwave repeater that re-radiates incoming radio waves from all terminals to all terminals within the service area. 2. In a microwave repeater used for interconnection of a plurality of wireless terminals, a low gain antenna is installed at a relay position toward a terminal group, and one port of a 3-port circulator is connected to a feeding point of the antenna. The microwave repeater is characterized in that a signal from the antenna is amplified between the remaining two ports and the amplifier is connected in the direction of returning to the antenna again. 3. In a microwave repeater used for interconnection of a plurality of wireless terminals, a low gain antenna is installed at a relay position toward a terminal group, and one port of a 3-port circulator is connected to a feeding point of the antenna. A microwave repeater characterized in that a frequency converter composed of a local oscillator and a multiplier is connected between the remaining two ports, and a bandpass filter and an amplifier are further inserted if necessary. 4. A microwave repeater used for interconnection of a plurality of wireless terminals, which has a low gain polarization-sharing antenna (sharing left and right circularly polarized waves or horizontally and vertically polarized waves) toward a terminal group at a relay position. ) Is installed, and an amplifier or a frequency conversion unit is provided between two feeding points of the dual polarization antenna. 5. A radio communication system using the microwave repeater according to claim 1, wherein the radio terminal is provided with a high gain antenna, and the radio terminal is kept in a normal reception state to generate transmission data. If there is no received signal, the wireless communication system performs transmission only when there is no received signal, and transmits to all terminals simultaneously via the repeater. 6. A microwave repeater used for interconnection of a plurality of wireless terminals, wherein a plurality of high gain antennas are radially arranged at a relay position, and the feeding points of the antennas are one or a plurality of power combiner / distributor ( Or, a directional coupler having an equivalent function) is used to connect the feeding points to one, and a reflection termination (open or short circuit) is connected to this feeding point to input to any one antenna. A microwave repeater characterized in that a signal is reflected at a feeding point of the entire antenna system and re-radiated from all antennas. 7. A microwave repeater used for interconnecting a plurality of wireless terminals, wherein a plurality of high gain antennas are radially arranged at a relay position, and the feeding points of the antennas are one or a plurality of power combiner / distributor ( Or, a directional coupler having an equivalent function) is used to connect the feed points to one, connect one port of a 3-port circulator to this feed point, and connect the antenna between the remaining two ports. A microwave repeater in which an amplifier is connected in a direction in which the signal of is amplified and returns to the antenna again. 8. In a microwave repeater used for interconnection of a plurality of wireless terminals, a plurality of high gain antennas are radially arranged at a relay position, and the feeding points of the antennas are one or a plurality of power combiner / distributor ( Or a directional coupler having an equivalent function) to connect the feeding points to one, connect one port of a 3-port circulator to this feeding point, and connect the local oscillator between the remaining two ports. And a frequency converter composed of a multiplier are connected, and a band pass filter and an amplifier are further inserted, if necessary. 9. A wireless communication system using the microwave repeater according to claim 6, wherein the gain of the repeater antenna is set so that only one wireless terminal is included in the communication area of each relay antenna. On the other hand, the wireless terminal is provided with a low gain antenna, and the wireless terminal is kept in a normal receiving state, and when transmission data occurs, transmission is performed only when there is no received signal, and all terminals are transmitted via the repeater. A wireless communication system characterized by simultaneous transmission.