JPH09284169A - Antenna switching circuit - Google Patents

Abstract

(57) Abstract: An object is to provide a simple and inexpensive antenna switching circuit that does not require a control system. SOLUTION: A circulator 10 having three or more terminals is provided, and a power feeding system 11 and a main antenna 1 are sequentially provided to the terminals viewed in the circulation direction of the circulator 10.
5a and the spare antenna 15b are connected. This is a case where the antenna switching circuit is applied to a transmitting antenna system, and due to the characteristics of the circulator 10, when the main antenna 15a is damaged and the impedance of the terminal becomes infinite, the circulator 10 circulates in the circulating direction. As seen, the connected terminal of the feeding system 11 is coupled to the next terminal on the downstream side, and the feeding is switched to the spare antenna 15b connected thereto.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna switching circuit used for effectively switching a connection from one main antenna to another spare antenna among a plurality of antennas including a spare antenna.

[0002]

2. Description of the Related Art Generally, an antenna of a relay station on a mountain or an antenna of a cellular base station is considered to be damaged by lightning, animals or birds. For outdoor antennas installed under such a fragile condition, a spare antenna should be installed in order to continue communication service even if the main antenna in use is damaged. Is needed.

Conventionally, as a method of monitoring the state of such a main antenna and switching the power feeding path to the spare antenna side when the main antenna is damaged, a TV camera is installed to monitor the main antenna, or as shown in FIG. It has been practiced to provide such an electric antenna switching control system.

That is, FIG. 8 shows an antenna switching circuit in which two receiving antennas can be switched between the main antenna 1 and the spare antenna 2 by an electric control system, and the directions provided in the main antenna 1 and the spare antenna 2 respectively. An antenna breakage detection device is configured by the directional couplers 3 and 4 and the comparator 5 that receives the signals picked up by these directional couplers 3 and 4 and compares the magnitude of the received power energy. The control device 6 receiving the output of the device switches the antenna changeover switch 7 to the antenna side having the larger received power energy.

According to the antenna switching circuit based on such an electric control system, according to the magnitude relation of the received power energy input to the comparator 5, the one with the larger received power energy, that is, the antenna operates normally as an antenna. The antenna can always be automatically switched to the person who is wearing it.

[0006]

However, the antenna switching circuit based on the electric control system as described above is provided with a dedicated electric control system only for the purpose of countermeasures against the risk of antenna damage. There is a problem that it costs a lot to build. Especially,
If a plurality of spare antennas, such as two or three, are provided and the spare antennas are switched, the device becomes more expensive. Therefore, an object of the present invention is to provide an antenna switching circuit having a simple and inexpensive structure that can monitor and switch the antenna without requiring a control system.

[0007]

In order to solve the above problems, an antenna switching circuit according to the present invention has the following (1) to (1).
It is configured as in (4).

(1) An antenna switching circuit according to a first aspect of the invention is an outdoor antenna system including a main antenna and n (n is an integer of 1 or more) spare antennas, and a circulator having n + 2 terminals. Is provided
The power supply system, the main antenna, and the spare antenna are connected in sequence to the terminals of this circulator seen in the circulation direction.

This is a case where the antenna switching circuit is applied to a transmitting antenna system. For example, when the number of spare antennas is one (n = 1), the configuration of FIG. 1 is used and the number of spare antennas is two (n = 2). In this case, the form is shown in FIG. Due to the characteristics of the circulator, when the main antenna is damaged and its terminal impedance becomes infinite, the terminal connected to the power supply system is connected to the next terminal downstream of the circulator in the circulating direction. The feed is switched to the spare antenna which is coupled and connected to the next terminal on the downstream side. Further, when the spare antenna is damaged, it is switched to the next spare antenna on the downstream side in the same manner. In the same manner, the normal antennas connected in the circulation direction of the circulator are sequentially switched. Therefore, the antenna can be automatically switched.

(2) In the antenna switching circuit according to a second aspect of the present invention, a plurality of circulators having m (m is an integer of 3 or more) terminals are connected in cascade through the terminals, and the circulation of the first circulator is performed. Connect the feeding system to the first terminal seen in the direction, connect the antenna to the remaining terminals of the first circulator and the remaining terminals of the other circulators, and in the circulation direction of the first circulator of these antennas. The antenna connected to the terminal next to the first terminal seen above is treated as a main antenna, and the other antennas are treated as spare antennas.

This is also the case where the antenna switching circuit is applied to the transmission antenna system, as in the above (1).
For example, when two circulators having three (m = 3) terminals are cascade-connected, the configuration shown in FIG. 3 is obtained. Due to the characteristics of the circulator, when the main antenna is damaged and its terminal impedance becomes infinite, it is coupled to the second circulator and switched to the spare antenna connected thereto. Furthermore, when this spare antenna is damaged, in the same way as in claim 1,
Switch to the next spare antenna. Therefore, the antenna can be automatically switched.

(3) An antenna switching circuit according to a third aspect of the present invention is an outdoor antenna system including a main antenna and n (n is an integer of 1 or more) spare antennas, and a circulator having n + 2 terminals. Is provided
The circulator has a terminal viewed in the opposite direction to the circulation direction, with the power supply system, main antenna, and spare antenna connected in sequence. This is the case where the antenna switching circuit is applied to the receiving antenna system. For example, in the case of one spare antenna (n = 1), the configuration of FIG. 5 is used, and in the case of two spare antennas (n = 2), 7 forms.

(4) In the antenna switching circuit according to a fourth aspect of the present invention, a plurality of circulators having m (m is an integer of 3 or more) terminals are cascade-connected through the terminals, and the circulation of the first circulator. The feed system is connected to the first terminal seen in the opposite direction, and the antenna is connected to the remaining terminals of the first circulator and the remaining terminals of the other circulators, and the antenna of the first circulator of these antennas is connected. The antenna connected to the terminal next to the first terminal viewed in the direction opposite to the circulation direction is treated as a main antenna, and the other antennas are treated as spare antennas. This is also the case where the antenna switching circuit is applied to the receiving antenna system, as in the case of (3) above. For example, three (m = 3)
When two circulators having the above-mentioned terminal are connected in cascade, the configuration shown in FIG. 6 is obtained.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 and 3 are diagrams showing antenna switching circuits according to the first and second embodiments of the present invention, in which n (n is an integer of 1 or more) spare antennas 15b, 15c are provided. Spare antenna 15b,
This is a form in which a normal antenna can be automatically selected only by using the same number of circulators 10 and 20 as 15c.

First, the circulator will be described.
As the circulator, for example, a three-terminal circulator which is a microwave element using ferrite is generally used. This three-terminal circulator is a circuit in which the coupling between input and output and the direction of electromagnetic wave flow are cyclically determined between the three terminals.

For example, as shown in FIG. 2, when there are three terminals (ports) indicated by the symbol, around a cylindrical ferrite 17, the terminals ,,, follow the arrows, →, →, → in sequence. As an alternative, it is a circuit that circulates and couples them so that electromagnetic waves flow between them, and does not couple with other terminals in principle.

That is, between the terminal and the terminal, the electromagnetic wave entering from the terminal flows and appears only in the terminal, and the electromagnetic wave does not flow in the terminal. In addition, between the terminal and the terminal, the electromagnetic wave entering from the terminal flows and appears only in the terminal, and the electromagnetic wave does not flow in the terminal. Further, between the terminal and the terminal, the electromagnetic wave entering from the terminal flows and appears only in the terminal, and the electromagnetic wave does not flow in the terminal.

However, when the impedance matching (Z ₀ ) between the circuit and the circulator is realized, the above-mentioned relationship in which the coupling between the input and the output between the terminals and the flowing direction of the electromagnetic wave are realized is When the impedance is 0 (short) or ∞ (open) at a certain terminal, it is reflected by the general characteristics of microwaves without being output to that terminal, and electromagnetic waves flow to the next terminal downstream in the circulation direction.

FIG. 1 shows a first embodiment of an antenna switching circuit applied to a transmitting antenna system. In the antenna switching circuit of the same figure, the feeding system 11 is provided at the first terminal, the main antenna 15a is provided at the second terminal, and the spare antenna 15b is provided at the third terminal when viewed in the circulation direction of the three-terminal circulator 10. It is configured by connecting with a waveguide. In the normal case, the power feeding system 1
The electromagnetic waves from 1 are coupled so that the electromagnetic waves flow from terminal to terminal, and the signal is transmitted to the main antenna 15a.

Now, assuming that the main antenna 15a is damaged, the impedance matching (Z
₀ ) cannot be maintained. A situation that is normally considered to appear due to damage is an open state due to the disappearance of the antenna, and the impedance of the terminal to which the main antenna 15a is connected is ∞ when viewed from the circulator 10 side.
Looks (open). Then, the signal entering the circulator 10 from the terminal cannot be output to the terminal, is reflected, and an electromagnetic wave appears at the next terminal on the downstream side in the circulation direction,
Electromagnetic waves are supplied to the spare antenna 15b connected to this terminal.

In this way, when the main antenna 15a is damaged, the circulator 10 automatically switches to the spare antenna 15b. Moreover, the main / spare antenna 15a is operated only by the operation of the circulator 10.
It is possible to provide a low-cost antenna switching circuit that does not require much power consumption as well as a conventional control system is not required because it is possible to switch between / 15b. Have.
In addition to the damage, the spare antenna 15b may be set to automatically switch to an abnormal antenna impedance variation caused by touching an animal.

The antenna switching circuit of FIG. 3 shows a second embodiment of the present invention, in which the three-terminal circulator 10 is used as a first circulator, and a spare antenna is connected to the third terminal of the circulator 10. , Second
Connect the first terminal of the three-terminal circulator 20 of
The second circulator 20 has a second terminal connected to the first spare antenna 15b and a third terminal connected to the second spare antenna 15c by a waveguide. In a normal case, the electromagnetic waves from the power feeding system 11 are coupled so as to flow from one terminal to another, and the electromagnetic waves are transmitted from the terminals to the main antenna 15a.

However, when the main antenna 15a is damaged, the impedance of the port terminal to which the main antenna 15a is connected becomes ∞ (open) when viewed from the first circulator 10 side, and the first circulator 10 enters from the terminal. The signal cannot be output to the terminal, is reflected, appears at the next terminal, and is connected to this terminal.
Into the terminal of the circulator 20. Therefore, this electromagnetic wave is output to the terminal of the second circulator 20,
It is supplied to the first spare antenna 15b connected to this terminal.

Further, when the first spare antenna 15b is also damaged following the damage of the main antenna 15a, the impedance of the port terminal to which the first spare antenna 15b is connected is viewed from the side of the second circulator 20. Becomes ∞ (open), the signal that has entered the second circulator 20 from the terminal appears at the next terminal without being output to the terminal, and is supplied to the second spare antenna 15c connected to this terminal.

In this way, even when there are a plurality of spare antennas, the number of circulators connected in cascade is increased to the same number as the spare antennas, and the spare antennas are automatically switched to the spare antennas on the downstream side in the circulation direction. A switching circuit can be configured.

FIG. 4 is a diagram showing an antenna switching circuit according to a third embodiment of the present invention. This antenna switching circuit increases the number of circulator terminals instead of increasing the number of circulators. This is a construction of an antenna switching circuit that works. That is, the 4-terminal circulator 30 is used as the circulator, and the feeding system 1 is connected to the first terminal of the 4-terminal circulator 30 in the circulation direction.
1, the main antenna 15a is connected to the second terminal, the first spare antenna 15b is connected to the third terminal, and the second spare antenna 15c is connected to the fourth terminal.

Also in the case of such an antenna switching circuit, when the main antenna 15a is damaged, it is switched to the connected terminal of the first spare antenna 15b, and when the first spare antenna 15b is also damaged, Second
Switching to the connected terminal of the spare antenna 15c, the signal is supplied to the second spare antenna 15c connected thereto. Therefore, a plurality of spare antennas can be automatically switched with one circulator. In short, even when a plurality of (n) spare antennas are provided, one circulator having (n + 2) terminals can be used for the number of spare antennas.

Although the above embodiment has been described by taking the case of the transmitting antenna system as an example, the main antenna and one or a plurality of spare antennas can be similarly switched in the case of the receiving antenna system. The case of the receiving antenna system will be described below.

FIG. 5 is a diagram showing an antenna switching circuit according to a fourth embodiment of the present invention. Switching of a receiving antenna corresponding to the switching circuit of the transmitting antenna according to the first embodiment of FIG. 1 is performed. It is a figure which shows a circuit. In the figure, when viewed in the direction opposite to the circulation direction of the circulator 50, the terminals ,,
The power feeding system 12, the main antenna 15a, and
The spare antenna 15b is connected.

When the main antenna 15a is normal, the electromagnetic waves received by the main antenna 15a are coupled so as to flow from one terminal to another and are transmitted to the power feeding system 12. However, if the main antenna 15a is damaged, the impedance of the terminal becomes infinite, so that the electromagnetic waves received by the spare antenna 15b are coupled so as to flow from terminal to terminal and are transmitted to the power feeding system 12. Therefore, it is possible to automatically switch from the main antenna 15a to the spare antenna 15b.

FIG. 6 is a diagram showing an antenna switching circuit according to a fifth embodiment of the present invention, which shows a receiving antenna corresponding to the transmitting antenna switching circuit according to the second embodiment of FIG. It is a figure which shows a switching circuit. In the antenna switching circuit shown in the figure, the first terminal of the first circulator 50 and the third terminal of the second circulator 60 are connected to connect them in cascade. The first circulator 50 has terminals, when viewed in the opposite direction to the circulation direction,
To the power supply system 12, the main antenna 15a, and the third terminal of the second circulator 60, and to the second circulator 60, when viewed in the direction opposite to the circulation direction, to the terminal ,. The configuration is such that the first terminal of the first circulator 50, the first spare antenna 15b, and the second spare antenna 15c are connected.

When the main antenna 15a is normal, the electromagnetic wave received by the main antenna 15a is coupled so as to flow from the terminal of the first circulator 50 to the terminal, and is transmitted to the power feeding system 12. However, when the main antenna 15a is damaged, the impedance of the terminal becomes infinite, so that the terminal is coupled to the terminal and the electromagnetic wave received by the first spare antenna 15b flows from the terminal of the second circulator 60 to the terminal. Are coupled together and enter the first circulator 50, and the electromagnetic wave is further absorbed by the first circulator 5
Feeding system 1 connected to flow from 0 terminal to terminal
2 is transmitted.

Further, if the first spare antenna 15b is also damaged after the main antenna 15a is damaged,
The electromagnetic wave received by the second spare antenna 15c is
Circulator 60 is connected so as to flow from the terminal to the terminal, and enters the terminal of the first circulator 50,
Further, the electromagnetic waves are coupled so as to flow from one terminal of the first circulator 50 to the other terminal and are transmitted to the power feeding system 12.
Therefore, the receiving antenna is automatically switched from the main antenna 15a to the spare antenna 15b and further to the spare antenna 15c.

FIG. 7 is a diagram showing an antenna switching circuit according to a sixth embodiment of the present invention, which shows a receiving antenna corresponding to the switching circuit of the transmitting antenna according to the third embodiment of FIG. It is a figure which shows a switching circuit. In the antenna switching circuit shown in the figure, when viewed in the direction opposite to the circulation direction of the four-terminal circulator 70, the power supply system 12, the main antenna 15a, and the first spare antenna 1 are respectively connected to the terminals ,.
5b and the second spare antenna 15c are connected.

When the main antenna 15a is normal, the electromagnetic waves received by the main antenna 15a are coupled so as to flow from one terminal to another and are transmitted to the power feeding system 12. However, when the main antenna 15a is damaged, the electromagnetic waves received by the first spare antenna 15b are coupled so as to flow from one terminal to another and are transmitted to the power feeding system 12.

Further, if the first spare antenna 15b is also damaged after the main antenna 15a is damaged, the electromagnetic waves received by the second spare antenna 15c are coupled so as to flow from one terminal to another and are transmitted to the power feeding system 12. .
Therefore, the receiving antenna is automatically switched from the main antenna 15a to the spare antenna 15b and further to the spare antenna 15c.

[0037]

As described above, according to the present invention, the following excellent effects can be obtained. (1) An outdoor antenna installed in a situation where it is easily damaged,
A circuit that automatically switches to the spare antenna even if it is destroyed by a lightning strike, an animal, a bird, etc. can be realized with a very simple configuration of only a circulator. (2) Since a conventional electric switching control system is not required, it is very inexpensive and power consumption is reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a transmission antenna switching circuit according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining the configuration and operation of a circulator.

FIG. 3 is a configuration diagram of a transmission antenna switching circuit showing a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a transmission antenna switching circuit showing a third embodiment of the present invention.

FIG. 5 is a configuration diagram of a receiving antenna switching circuit showing a fourth embodiment of the present invention.

FIG. 6 is a configuration diagram of a receiving antenna switching circuit showing a fifth embodiment of the present invention.

FIG. 7 is a configuration diagram of a receiving antenna switching circuit showing a sixth embodiment of the present invention.

FIG. 8 is a configuration diagram showing an antenna switching circuit using a conventional control system.

[Explanation of symbols]

1 ... Main antenna, 2 ... Spare antenna, 3,4
... Directional coupler, 5 ... Comparator, 6 ... Control device, 10, 50 ... 3-terminal circulator (first circulator), 11, 12 ... Feed system, 15a ... Main antenna, 15b ... ... 1st spare antenna, 15c
...... Second spare antenna, 17 ... Ferrite, 20,
60 ... 3-terminal circulator (second circulator), 30, 70 ... 4-terminal circulator

Claims (4)

[Claims] 1. An outdoor antenna system comprising a main antenna and n (n is an integer of 1 or more) spare antennas, a circulator having n + 2 terminals is provided, and the circulator has terminals viewed in a circulation direction. An antenna switching circuit characterized in that a power feeding system, a main antenna and a spare antenna are connected in sequence. 2. A plurality of circulators having m (m is an integer of 3 or more) terminals are connected in series through the terminals, and a power supply system is connected to the first terminal of the first circulator seen in the circulation direction. , Connecting an antenna to the remaining terminals of the first circulator and to the remaining terminals of the other circulator, and connecting to the next terminal of the first terminal of these antennas seen in the direction of circulation of the first circulator An antenna switching circuit that treats the other antenna as the main antenna and the other antennas as the spare antenna. 3. An outdoor antenna system comprising a main antenna and n (n is an integer of 1 or more) spare antennas, a circulator having n + 2 terminals is provided, and the circulator is viewed in a direction opposite to the circulating direction. An antenna switching circuit characterized in that a power feed system, a main antenna, and a spare antenna are sequentially connected to the terminals. 4. A power supply system is provided by connecting a plurality of circulators having m (m is an integer of 3 or more) terminals in cascade through the terminals, and by observing the first circulator in the direction opposite to the circulation direction. And connect an antenna to the remaining terminals of the first circulator and the remaining terminals of the other circulator, and of the first terminal of these antennas viewed in the direction opposite to the circulation direction of the first circulator. An antenna switching circuit characterized in that the antenna connected to the next terminal is treated as the main antenna and the other antennas are treated as spare antennas.