JP2784147B2 - Antenna shared circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna sharing circuit for sharing a transmitting antenna and a receiving antenna with a plurality of transceivers. The present invention is suitably applied to a command station, a control station, a base station, and the like of a communication system operated simultaneously.

[0002]

2. Description of the Related Art An antenna No. is assigned to two radios 100 and 101 installed at the same place and operated simultaneously.
1, Antenna No. FIG. 4 (a) shows an example in which 2 is installed. In this configuration, when the operating frequencies of the two radios 100 and 101 are close to each other, the reception is performed by a high-level transmission wave emitted from the radio in a transmission state or noise remaining near the transmission frequency. This causes a problem such as suppression of the sensitivity of the other wireless device in the state or generation of cross modulation. As means for solving this obstacle, the antenna No. 1 and antenna No. It is conceivable that the antennas 2 are physically separated from each other to increase the distance between the antennas so as not to affect each other.

[0003] Usually, in mobile communications and the like that service a certain area, an antenna is installed vertically and an antenna having a wide directivity (omni-directional) is used in a horizontal plane. Therefore, two antennas are used. If you install them vertically at a distance in the vertical direction, as the number of radios increases, the height of the tower where you install the antenna will increase, and the antenna arranged at the top and the antenna arranged at the bottom will not A large difference occurs in the radio wave propagation distance. In addition, if a plurality of antennas are installed at a distance in the horizontal direction, a large antenna distance is required compared to the case of vertical installation because it has directivity on the horizontal plane,
This would result in large tower equipment. For this reason, the configuration shown in FIG. 4A is limited to the case where strict communication quality is not required or the operation of several wireless devices.

In addition, two radios No. 1 installed at the same place and operated simultaneously. 1, No. 2 are parabolic antennas No. 2 respectively. 1, parabola antenna No. FIG. 4 (b) shows an example in which the antenna 2 is installed.
Since the back ratio (F / B ratio) characteristics are excellent, the transmission wave transmitted from one parabolic antenna and the reception wave received by the other parabolic antenna are completely separated to prevent mutual interference. Can be. However, in mobile communication and the like that services within the area, an omnidirectional antenna in the horizontal plane is generally required, but since the parabolic antenna has a sharp directivity, the above-described configuration is used for communication between fixed points. It is not suitable.

[0005] As described above, there is a problem in installing the antennas. Therefore, the antennas are commonly shared, and a configuration example of the shared circuit is shown in FIG.
FIG. 5A shows a configuration in which the antenna 131 is shared by a duplexer composed of a bandpass filter (BPF) 130 and a bandpass filter (BPF) 131. The operation of this duplexer is temporarily determined by the wireless device No. 1, the transmission power is transmitted from the wireless device No. 1. The power is supplied to the antenna 131 via the BPF 130 that passes only the frequency assigned to 1 and the transmission power is transmitted from the antenna 131. On the other hand, the reception signal received by the antenna 131 is
For example, the wireless device No. 2 through the BPF 131 that passes only the reception frequency assigned to the wireless device No. 2. 2 is supplied.

In this case, the wireless device No. Radio N from 1 side
o. The component that leaks to the second side or vice versa is BP
Since it is determined by the cutoff characteristics of F130 and F131, it is necessary to increase the frequency interval assigned to each in order to reduce the leakage component. Also, FIG.
Shows an example in which the divider / combiner 140 is used as a duplexer. Since the inter-terminal attenuation of the divider / combiner 140 is usually about 20 to 30 dB, the wireless device No. 1 and the wireless device No. 2 is 2
Coupling occurs with an attenuation of about 0 to 30 dB. For this reason, this configuration is a configuration that can be applied only to a small power wireless device or the like, and it is difficult to apply this configuration to a communication system having a large transmission power.

FIG. 6 shows a shared circuit having another configuration. This shared circuit is applied to a base station for an automobile telephone or a portable telephone, and the transmission frequency group and the reception frequency group have different frequencies. It is assumed that the communication system is far away. In this figure, the transmitter Nos. Constituting the transmitter group. 1 to the transmitter No. 4 is supplied to the isolators 110 to 113, respectively, and supplied to the band-pass filters (BPF) 114 to 117 via the isolators 110 to 113, respectively. After being limited to predetermined bands by the BPFs 114 to 117, the transmission band-pass filter 118 uses the frequency band allocated for transmission as a pass band.
Via the antenna 119.

On the other hand, the reception signal received by the antenna 119 is amplified to a predetermined level by an amplifier 121 via a BPF 120 having a pass band of a frequency band allocated for reception, and further distributed by a distributor 122. Receiver Nos. Constituting the receiver group 1 to the receiver No.
4 respectively. This shared circuit can share the antenna 119 with a plurality of transmitters and a plurality of receivers. However, in order to prevent the transmission signal from leaking to the receiving side, the transmitting frequency and the receiving frequency are set to BP.
The frequencies must be separated so that F118 and BPF120 can sufficiently attenuate. Further, the transmitter No. 1 to
Transmitter No. Isolation between 4 is isolator 1
Since the BPFs 10 to 113 and the BPFs 114 to 117 are secured, each of the BPFs 114 to 117 needs to have a sharp characteristic that passes only one specific frequency channel. Therefore, the transmitter No. 1 to the transmitter No. 4 are fixed.

[0009]

As described above, in the conventional shared circuit sharing the antenna, the channel frequency assigned to each radio is fixed or the frequency assigned to the transmitting side and the receiving The frequency allocated to the side is far enough to be separated by a band-pass filter. However, in a communication system such as MCA in which a large number of channels are allocated in the same frequency band with a narrow channel separation and the channels are operated by a large number of transceivers equal to or more than the number of channels, transmission and reception are performed at the same channel frequency. The principle is that the transceiver can be used if any channel is available .

[0010] If an antenna shared circuit used in such a communication system is to be configured using a band-pass filter, the filter can cope with it by making the pass band variable for channel selection. Since the channel separation is much narrower than the filter can be separated, it is not practical to select the channel by the filter. Therefore, there is a problem that the conventional shared circuit described above cannot be applied to the communication system.

Accordingly, the present invention provides an antenna shared circuit applicable to a communication system in which a large number of channels having narrow channel separations are allocated in the same frequency band and any one of the channels can be accessed by a transceiver. It is intended to provide.

[0012]

In order to achieve the above object, an antenna shared circuit according to the present invention comprises a plurality of transceiver connection terminals to which a plurality of transceivers are respectively connected, and a transmitter to which a transmission antenna is connected. In a shared antenna circuit including an antenna connection terminal and a reception antenna connection terminal to which a reception antenna is connected, each of the transceiver connection terminals is connected to a first terminal of a plurality of three-terminal circulators, respectively, A second terminal of the circulator is connected to a plurality of input terminals of the power combiner via the first isolator, and an output terminal of the power combiner is
The transmitting antenna connection is connected to the terminal, via a plurality of distribution output terminal is the second isolator respective signal divider the reception antenna connection terminal is connected to the input terminal, the first of said plurality of 3-terminal circulator 3 terminals
Each is connected.

Then, a part of the power supplied to the transmitting antenna is taken out and added to at least the power supplied to the signal distributor received by the receiving antenna via a phase adjustment circuit, thereby obtaining the transmitting antenna. And the receiving antenna are combined to cancel the leaked component .

[0014]

According to the present invention, in an antenna shared circuit applied to a communication system in which a number of channels allocated at close frequencies are simultaneously operated without using a filter such as a band-pass filter, the amount of attenuation between a transmitter and a receiver is reduced. It can be a sufficient amount. Also, a circuit has been added to cancel the amount of leakage due to the coupling between the transmitting antenna and the receiving antenna, so that the distance between the transmitting antenna and the receiving antenna can be made shorter than before, and the radio wave The difference in distance can be reduced, and the configuration of the tower on which the antenna is installed can be simplified.

[0015]

FIG. 1 shows the configuration of a transmitting / receiving station to which the antenna shared circuit of the present invention is applied. However, FIG.
Only the main part of the tenor shared circuit is shown. In this figure, reference numeral 1 denotes an antenna shared circuit that shares a transmitting antenna 6 and a receiving antenna 7 in, for example, four transceivers 2 to 5, and 2 to 5 transmit / receive transceivers (TRX1 to TRX4) that access empty channels searched at the time of access. , 6 are transmission antennas (T · ANT) to which the transmission power from the antenna sharing circuit 1 is supplied, and 7 are reception antennas (R · ANT) for supplying received reception signals to the antenna sharing circuit 1.

The antenna sharing circuit 1 has four TRs.
Four transceiver connection terminals J1 to J4 to which X2 to X5 are respectively connected, three-terminal circulators CIR1 to CIR4 provided in the same number as the transceiver connection terminals J1 to J4,
An isolator ISO1 to ISO8 provided four times as many as the circulators CIR1 to CIR4, a power combining circuit COMB for combining transmission outputs from TRX1 to TRX4, and TR
Signal distribution circuit DIST for distributing received signals to X1 to X4
And a transmission antenna terminal J5 from which an output of the power combining circuit COMB is output, and a reception antenna terminal J6 for inputting a reception signal to the signal distribution circuit DIST.

The operation of the antenna sharing circuit 1 will be described. For example, it is assumed that the transmission power is supplied from the TRX1 to the terminal J1. Then, the transmission power supplied to the terminal J1 is
Since the signal is input to the first terminal of the three-terminal circulator CIR1, the signal is output from the second terminal and further propagates through the high-frequency transmission line K1 to be supplied to the two-stage cascaded isolator ISO1. Isolator ISO
The transmission power output from 1 is input to the power combining circuit COMB. A terminating resistor is provided in the power combining circuit COMB, and about 3/4 of the input power is absorbed and the remaining 1 / is absorbed.
4 is output from the terminal J5 and the transmission antenna 6
Sent out. Here, since the circuit after the terminal J1 and the circuit after the terminals J2 to J4 have the same configuration,
Similarly, the transmission power from the TRXs 2 to 4 is supplied to the transmission antenna 6 from the terminal J5.

The received signal received from the receiving antenna 7 is supplied to a terminal J6, is divided into four by a signal distribution circuit DIST, passes through two cascade-connected isolators ISO5 to ISO8, and a three-terminal circulator CI.
The signals are supplied to the third terminals of R1 to CIR4, respectively. The received signal is output from the first terminal of the three-terminal circulators CIR1 to CIR4, and is input to TRX1 to TRX4 via the terminals J1 to J4.

Next, to see how much the transmission power from TRX1 is attenuated and input to TRX2, for example, to see the amount of coupling attenuation between TRX1 and TRX4, the route to TRX1 to TRX2 is as follows. Since there are three paths shown in FIG. Route 1: J1-CIR1-K1-ISO1-COMB-
ISO2-K2-CIR2-J2 Path 2: J1-CIR1-K5-ISO5-DIST-
ISO6-CIR2-J2 pathway 3: J1-CIR1-K1-ISO1-COMB-
T ・ ANT-Space-R ・ ANT-DIST-ISO6-
CIR2-J2

In the path 1, the portion that causes attenuation and the amount of attenuation are shown. The amount of attenuation between the input terminals of the power combining circuit COMB is about 20 dB, the amount of reverse attenuation of the cascade-connected isolator ISO2 is about 40 dB, and the circulator CIR2 Is about 20 dB, and the path 1 has a total attenuation of about 80 dB. In addition, the route 2
In FIG. 7, the portion that causes attenuation and the amount of attenuation are shown, where the leakage attenuation of the circulator CIR1 is about 20 dB,
The reverse attenuation of the cascade-connected isolator ISO5 is about 40 dB, and the attenuation between the output terminals of the signal distribution circuit DIST is about 20 dB. In the path 2, the total attenuation is about 80 dB. Further, in the path 3, a portion that causes attenuation and the amount of attenuation are shown.
B, an insertion loss of about 7 dB, a coupling attenuation between the transmitting antenna T · ANT and the receiving antenna R · ANT of about 65 dB (when the antenna interval is vertically 10 wavelengths or more), and an insertion loss of the signal distribution circuit DIST. 7 dB, and the total amount of attenuation in the path 3 is about 79 dB.

Thus, about 80
Since the attenuation of dB is obtained, the transmission power of TRX1 becomes TRX1.
It does not affect the received signal of X2. Also, TRX
Since the configuration of the antenna sharing circuit 1 for 1 to TRX4 is the same, the attenuation can be obtained in any combination of TRX1 to TRX4. Note that, as seen in the MCA system, the TRX1 to TRX4 are configured to access a channel that is an empty channel among a large number of channels allocated in the same frequency band.
No. 4 is not determined in advance which channel to use.

As for the attenuation of each part, the attenuation between the input terminals of the power combining circuit COMB, the reverse attenuation of the isolator, and the leakage attenuation of the circulator can easily obtain relatively specified attenuation. Antenna T ・ ANT
The amount of coupling attenuation between the antenna and the receiving antenna R / ANT differs greatly depending on the manner in which the antenna is installed. Generally, an antenna used for a base station in the MCA method or the like is of a vertical polarization type that is omnidirectional in a horizontal plane, and has a large coupling attenuation in order to cancel the loss of the power combining circuit COMB and the signal demultiplexing circuit DIST. For this purpose, a high-gain, sharp in-plane directivity antenna is vertically installed. When two antennas are vertically separated from each other at the top and bottom of a tower, theoretically, a coupling attenuation of about 80 dB is obtained when an interval of about 6 wavelengths is used between both antennas. It is said that you can do it.

However, by arranging the transmitting antenna 6 and the receiving antenna 7 vertically apart from each other at the upper and lower portions of the tower, the above-mentioned coupling attenuation between the two antennas 6 and 7 can be obtained by adjusting the frequency used. Since the amount of attenuation fluctuates significantly due to differences and the surrounding environment, it is necessary to make adjustments when installing the antenna to secure the amount of attenuation. However, since this adjustment requires a high level of technology and is complicated, it is necessary to arrange the transmission antenna 6 and the reception antenna 7 apart from each other for 10 or more wavelengths, which are usually used frequencies, without performing any adjustment work. At least to ensure the amount of attenuation. However, although such antennas can provide sufficient attenuation, the antenna installed at the top of the tower and the antenna installed at the bottom can be far apart in the vertical direction, resulting in a large difference in the radio wave propagation distance. Had become.

Therefore, the present invention has a means for solving this problem.
FIG. 2 shows an antenna sharing circuit according to the embodiment . In this figure, reference numeral 1 denotes the antenna shared circuit shown in FIG.
Reference numeral 10 denotes a compensation circuit for compensating the coupling attenuation between the transmitting antenna 6 and the receiving antenna 7. The compensation circuit 10 includes a transmitting side directional coupler 11 connected between the terminal J5 and the transmitting antenna 6, a receiving side directional coupler 15 connected between the receiving antenna 7 and the terminal J6, Directional coupler 1
Terminators 12 and 16 respectively connected to phase difference circuits 1 and 15 and phase adjustment circuit 1 connected between bidirectional couplers 11 and 15
3 and a variable attenuator 14.

In this embodiment, the transmission antenna 6 described above is used.
In addition to the path 3 resulting from the coupling between the antenna and the receiving antenna 7, a path 4 including a transmission-side directional coupler 11, a phase adjustment circuit 13, a variable attenuator 14, and a reception-side directional coupler 15 is provided. The power P1 leaked through the route 3 is canceled by the power P2 leaked through the route 4. That is, the operation of the compensation circuit 10 will be described. The transmission power is partially extracted by the transmission side directional coupler 11, the phase of the extracted transmission power is adjusted by the phase adjustment circuit, and the amplitude is adjusted by the variable attenuator 14. By adjusting, the relative phase between the power P1 and the power P2 input to the receiving side directional coupler 15 is set to about 180 ° at the receiving antenna connection terminal J6, and the power P1 is set so that the amplitudes are substantially equal. And the power P2 are canceled.

For example, when the coupling attenuation of the path 3 is 60 dB, the coupling attenuation of the transmitting directional coupler 11 and the receiving directional coupler 15 is 25 dB, and the attenuation of the variable attenuator 14 is 10 dB. Then, the coupling attenuation amount of the path 4 becomes 60 dB in total, and the coupling amounts of the path 3 and the path 4 match. If the phase adjustment circuit 13 adjusts the phases of the path 3 and the path 4 so that the phases are opposite to each other, the attenuation of about 20 dB can be increased in addition to the coupling attenuation of the path 3 alone. Can be about 80 dB.

When the ratio of the combined power in the case where the power P1 and the power P2 are in the opposite phase with respect to the case where the power P2 is in the same phase is expressed as an attenuation At,

(Equation 1) As shown. Referring to Equation 1, when the power P1 and the power P2 are theoretically equal in amplitude and the phases are opposite to each other, an infinite amount of attenuation occurs, but the amplitude of the power P1 and the power P2 actually increases. Are completely equal to each other and the phases cannot be completely opposite phases. Generally, the attenuation At is about 20 dB.

FIG. 3 shows a modification of the antenna sharing circuit with the compensation circuit 10 shown in FIG. 2. In this example, the variable attenuator 14 is omitted, and the directional couplers 11 and 15 are connected instead. The directional couplers 11 and 15 are of variable quantity type. In this case, when the coupling attenuation amount of the path 3 is set to 60 dB as described above, the coupling amounts of the directional couplers 11 and 15 are adjusted to 30 dB, respectively. 4
And the relative phases of the powers input from the above may be made to be opposite phases.

In the above description, the transmitting and receiving antennas are shared by the four transceivers. However, the present invention is not limited to this. And the receiving antenna can be shared. As explained above,
In the antenna sharing circuit of the present invention, since a transmitting antenna and a receiving antenna can be shared by a large number of transceivers without using a filter, the present invention is applied to a communication system for simultaneous operation within the same frequency band such as the MCA system. Can be possible. In particular, the channel separation between channels within the same frequency band is 25k.
It is a narrow frequency such as 1 Hz or 12.5 kHz, and is a suitable antenna shared circuit in a communication system in which each of the transceivers is accessed in a multi-channel manner.

[0030]

Since the present invention is constructed as described above, a transmitter-receiver which uses any one of a large number of channels allocated in the same band without using a filter such as a band-pass filter can be used. Can be made a sufficient amount of attenuation (isolation). Also,
A compensation circuit has been added to cancel the amount of leakage due to the coupling between the transmitting antenna and the receiving antenna, so that the distance between the transmitting antenna and the receiving antenna can be made shorter than before, and it is installed vertically. The difference between the radio wave propagation distances of the two antennas can be reduced, and the configuration of the tower on which the antennas are installed can be simplified.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a main part of an embodiment of an antenna shared circuit of the present invention.
FIG.

FIG. 2 is an embodiment of an antenna shared circuit with a compensation circuit according to the present invention.
It is a figure showing composition of an example.

FIG. 3 is a modification of the antenna shared circuit with a compensation circuit of the present invention.
It is a figure showing composition of an example.

FIG. 4 is a diagram showing a conventional antenna installation method.

FIG. 5 is a diagram showing a conventional antenna sharing method.

FIG. 6 is a diagram showing a conventional antenna shared circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna shared circuit 2-5 Transceiver (TRX1-TRX4) 6 Transmission antenna (T • ANT) 7 Receiving antenna (R • ANT) 10 Compensation circuit 11,15 Directional coupler 12,16 Terminator 13 Phase adjustment Circuit 14 Variable attenuator

Claims (1)

(57) [Claims] An antenna shared with a plurality of transceiver connection terminals to which a plurality of transceivers are respectively connected, a transmission antenna connection terminal to which a transmission antenna is connected, and a reception antenna connection terminal to which a reception antenna is connected. In the circuit, each of the transceiver connection terminals is respectively connected to a first terminal of a plurality of three-terminal circulators, and a second terminal of each of the plurality of three-terminal circulators is connected to a plurality of inputs of the power combiner via a first isolator. And a plurality of distribution output terminals of a signal distributor in which the output terminal of the power combiner is connected to the transmission antenna connection terminal and the reception antenna connection terminal is connected to the input terminal. through the second isolator are respectively connected to the third terminal of the plurality of three-terminal circulator, the transmitting a Part of the power supplied to the antenna
At least with the receiving antenna via the phase adjustment circuit
Adding to the supplied power supplied to the signal distributor
The transmission antenna and the reception antenna are coupled
An antenna shared circuit characterized by canceling a leaked component by performing the above operation.