JP2004200800A - Transmission antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission antenna having a function for protecting internal apparatus against reflected powers from antenna elements without providing any isolator. <P>SOLUTION: A CPU 30 in an automatic level control circuit 8 has a VSWR abnormality deciding function. Data detected by a traveling wave power detector circuit 4 and a reflected wave power detector circuit 5 are inputted to the control data input unit 31 of the CPU 30 to compare and decide the data with predetermined thresholds, and, if the VSWR is decided to be abnormal, it opens the input of an amplifier circuit 1 and terminates a connected signal transmission line. It further maximizes the attenuation of a variable attenuator 2 and operates a power switch 37 to turn off the power of the amplifier circuit. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a transmission antenna, and more particularly, to a technique for protecting a device connected to a transmission antenna when a VSWR of the transmission antenna is deteriorated.
[0002]
[Prior art]
2. Description of the Related Art Satellite broadcasting systems using satellites are widely used because they can provide broadcasting over a wide area without having to construct a large-scale infrastructure on the ground. However, when such a system is to be applied to broadcasting for mobiles, such a satellite broadcasting system uses a high frequency such as the S band (2.6 to 4 GHz). It has the property that radio waves become extremely weak in the shadows of the mountains and buildings. Therefore, such a satellite broadcasting system cannot be directly applied to a mobile object. Therefore, development is underway in which a satellite broadcasting system is applied to mobile objects by providing a gap filler device that locally re-radiates radio waves in areas where radio waves are weak.
The gap filler device includes a satellite receiving antenna and a transmitting antenna that locally radiates a signal received by the satellite receiving antenna (for example, see Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2001-230718
[Problems to be solved by the invention]
However, the transmitting antenna device used in the gap filler device must have a radio field intensity that covers the area where satellite radio waves are blocked, but increase the intensity more than necessary so as not to affect surrounding radio wave facilities. Therefore, internal circuits such as an amplifier circuit and a gain adjustment circuit are built in and are controlled so that the output is always constant. As described above, since the transmission antenna has a complicated structure, there has been a problem that when an abnormality occurs in the antenna element or the like and the VSWR is deteriorated, the internal device breaks down.
For this reason, it is conceivable to provide an isolator between the amplifier circuit and the antenna element to protect the circuit device from the reflected power that increases when the VSWR deteriorates. However, a small transmission antenna is desired, and a relatively large transmission antenna is desired. Isolators requiring a volume were not suitable for the transmitting antenna of the gap filler device.
[0005]
In view of the above problems, an object of the present invention is to provide a transmitting antenna having a function of protecting an internal circuit against reflected power from an antenna element without providing an isolator.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 is a transmission antenna provided with an amplifier circuit for amplifying a signal radiated from an antenna element, comprising: a traveling wave power detection unit and a reflected wave power detection unit; Calculating means for calculating a VSWR based on the wave power and the reflected wave power and comparing a preset threshold value with the VSWR calculation value to determine a VSWR abnormality; switch means for releasing an input section of the amplifier circuit; And a circuit protection function for releasing the input section of the amplifier circuit by operating the switch means when the arithmetic means determines that a VSWR abnormality has occurred.
[0007]
A second aspect of the present invention is characterized in that, in the first aspect of the present invention, the arithmetic means turns off the power supply of the amplifier circuit when it is determined that the VSWR abnormality has occurred.
According to a third aspect of the present invention, in the first or second aspect, the switch means includes a terminating resistor, and a signal transmission path for sending a signal to the amplifying circuit at the same time as releasing the input portion of the amplifying circuit, is connected to the terminating resistor. It is characterized by doing.
[0008]
According to a fourth aspect of the present invention, in any one of the first to third aspects, a variable attenuator is provided at an input stage of the amplifier circuit, and the variable attenuator is controlled by an automatic level control circuit provided with a CPU, and the output of the amplifier circuit is controlled. , The arithmetic means for determining a VSWR abnormality is the CPU.
The invention of claim 5 is characterized in that, in the invention of claim 4, when the VSWR abnormality occurs, the CPU operates the amount of attenuation of the variable attenuator to maximize the amount of attenuation.
[0009]
According to a sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, there is provided a notifying means for notifying that the operation of the amplifier circuit has been stopped when the switch means performs the releasing operation.
According to a seventh aspect of the present invention, in any one of the first to sixth aspects of the present invention, the arithmetic unit issues a return signal after a predetermined time elapses after determining that the VSWR abnormality has occurred, and switches the switch unit in accordance with the return signal. , The amplifier circuit performs a return operation.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an example of a transmission antenna according to the present invention, wherein 1 is an amplifier circuit for amplifying a signal, 2 is a variable attenuator for controlling the magnitude of an input signal of an amplifier circuit 1, 3 is a band-pass filter, 4 is a traveling-wave power detection circuit, 5 is a reflected-wave power detection circuit, 6 is a high-frequency switch as switch means for opening the input unit of the amplifier circuit 1, 7 is a control unit of a transmitting antenna, and this control unit 7 is an automatic control unit. A level control circuit (hereinafter, referred to as an ALC circuit) 8 (shown in FIG. 3) is provided, and the ALC circuit 8 has a circuit protection function described later.
[0011]
10 is an antenna element, 11 is a control unit power supply line for supplying power to the control unit, 12 is an amplifier circuit power line for supplying power to the amplifier circuit 1, 13 and 14 are attenuators, and 15a is a control line for the variable attenuator 2. , 15b denote control lines of the high-frequency switch 6, and the traveling wave power detection circuit 4 and the reflected wave power detection circuit 5 are connected via attenuators 13 and 14, respectively, to form a coupler 16, and are connected to an output signal line. ing.
Further, reference numeral 17 denotes a low-pass filter for separating a signal from a DC power supply, and reference numeral 18 denotes a terminating resistor of, for example, 50Ω, which is connected when the high-frequency switch 6 is operated and the input section of the amplifier circuit 1 is opened. It is provided to terminate the signal transmission line 19 and maintain the characteristics of the preceding circuit. Reference numerals 4a and 5a denote output lines of the traveling wave power detection circuit 4 and the reflected wave power detection circuit 5, respectively, which are both input to the ALC circuit 8.
[0012]
FIG. 2 is a block diagram of a gap filler device provided with the transmitting antenna, and 21 is the transmitting antenna. The transmitting antenna 21 has a distributor 23 connected to the input terminal 22, and is connected to the satellite receiving antenna 25 via the distributor 23 and the signal processor 24. Here, a gap filler device capable of connecting three transmitting antennas 21 to one satellite receiving antenna 25 is shown. Reference numeral 26 denotes communication means for notifying the operating state of the distributor 23, the signal processor 24, the transmitting antenna 21 and the like to a monitoring center located at a remote place.
[0013]
Next, the ALC circuit 8 will be described. The ALC circuit 8 provided in the control unit 7 is configured as shown in the block diagram of FIG. 3, reference numeral 30 denotes a CPU, 31 denotes a control data input unit, 32 denotes an A / D conversion circuit (ADC), and 33 denotes a multiplexer. The multiplexer 33 includes a traveling wave power detection circuit 4 and a reflected wave power detection circuit 5. Output lines 4a and 5a are connected. The multiplexer 33 sequentially selects the output signals and sends the detected values to the ADC 32, which performs A / D conversion and inputs data to the CPU 30.
Reference numeral 34 denotes a gain control signal output unit for controlling the variable attenuator 2, which is output to the control line 15a via a D / A conversion circuit (DAC) 35 and controls the variable attenuator 2. Reference numeral 36 denotes a circuit protection signal output unit, which is connected to the control line 15b to control the high frequency switch 6, and 37a denotes an amplifier circuit control output unit, which controls the power switch 37 of the amplifier circuit 1.
[0014]
Further, 39 is an LED for displaying the state of the transmission antenna 21, 40 is an operation unit for performing operations such as output level setting and flash memory initialization, and 41 is connected to a personal computer or the like to perform program writing and circuit protection functions. This is a serial communication port used to display the operation status.
Reference numeral 42 denotes a flash memory for storing various parameters; 43, a program flash memory for storing a CPU program; and 44, an SRAM used during execution of the program.
[0015]
The ALC circuit 8 configured as described above attenuates the variable attenuator 2 based on the data detected by the traveling wave power detection circuit 4 so that the traveling wave power, that is, the output of the radiated radio wave from the antenna element 10 falls within a predetermined range. In addition to controlling the amount, a circuit protection operation is performed according to the flowchart shown in FIG.
Hereinafter, the flow of the circuit protection operation will be described with reference to FIG. First, initialization processing is performed in S1, serial communication, setting of various registers such as the ADC 32 and the DAC 35, clearing of memory, and the like are performed, and the amount of attenuation of the variable attenuator 2 and the high frequency switch 6 are transmitted from the antenna element 10 to transmit radio waves. Set to standard state. Then, the process proceeds to S2, where monitoring data such as power data of the traveling wave and the reflected wave is obtained, the VSWR is calculated from the monitoring data obtained in S3, and the calculated value is compared with a preset threshold value. For example, if the threshold value is set to 6, if it is less than 6, it is determined that it is normal, if it is 6 or more, it is determined that it is an abnormal value. If it is normal, it proceeds to S12, and if it indicates an abnormal value, it proceeds to S4.
[0016]
In S12, the VSWR abnormality detection number counter is set to an initial set value, and in S13, the antenna abnormality continuation time number counter is reset. Then, in S14, information such as no abnormality is output to the serial communication port, and the process returns to S2 to continue the VSWR abnormality detection operation.
In S4, the counting of the abnormal continuation time is started or continued, and in S5, it is determined whether the continuation time has reached a specified value. If the specified value is reached, the process proceeds to S6, and if not, the process proceeds to S14 to output information indicating that an abnormality has occurred to the serial communication port 41, and returns to S2 to continue monitoring.
The VSWR abnormality detection number counter is a counter for automatically restarting the amplifier circuit up to a set number of times even if a VSWR abnormality occurs, and is set in advance together with a VSWR abnormality determination threshold and the like.
[0017]
In S6, a signal is output from the circuit protection signal output unit 36, the high frequency switch 6 is turned on, the input of the amplifier circuit 1 is opened, and the signal transmission line 19 is terminated. Further, a signal is transmitted from the gain control signal output unit 34, and the amount of attenuation of the variable attenuator 2 is maximized, that is, the amount of attenuation is maximized. Subsequently, the power supply of the amplifier circuit 1 is turned off in S7, and information of the amplifier circuit off is output to the serial communication port 41 in S8.
Next, in S9, the VSWR abnormality detection counter is decremented. For example, if the number counter is 4, which is the initial setting, it is set to 3, and the process proceeds to S10. In S10, the count value of the counter is determined. If the count value is not 0, the process proceeds to S15, waits for 10 seconds, returns to S1, performs the initialization process, and performs the restart operation of the amplifier circuit. If it is 0, the process proceeds to S11, in which the LED 39 blinks or the like to perform a notification operation of the occurrence of the VSWR abnormality, and the VSWR abnormality detection operation ends without performing the return operation of the amplifier circuit 1.
[0018]
As described above, when the VSWR abnormality occurs, the input section of the amplifier circuit is released by the operation of the high-frequency switch serving as the switch means, so that the internal circuit such as the amplifier circuit and devices such as the distributor connected to the preceding stage thereof are connected to the antenna. VSWR abnormality, and the reliability of the transmitting antenna is improved. Further, since the power supply of the amplifier circuit is stopped at the same time, power consumption can be minimized.
Further, since the switch terminates the signal transmission path opened when the input section of the amplifier circuit is opened, the characteristics of the device connected to the preceding stage of the amplifier circuit are not deteriorated.
Further, in the above embodiment, the automatic level control circuit also serves as the calculating means for determining the VSWR. As described above, the transmitting antenna having the automatic level control circuit does not require any additional operation means, and when the VSWR abnormality occurs, the attenuation amount of the amplifier circuit input section is maximized. Even if the release operation of the switch is insufficient or the isolation of the switch means is insufficient, the amplifier circuit can be reliably protected.
[0019]
In addition, by providing an LED as a notification means, it is possible to recognize at a glance that the cause of the occurrence of the abnormality or the operation stop is due to the VSWR abnormality, and information is output from the serial communication port. The cause can be easily known, which is useful for the recovery operation of the device.
Then, even if the transmission is stopped due to the VSWR abnormality, the transmission operation returns after a certain time (here, after 10 seconds). Therefore, if the VSWR abnormality is temporary due to, for example, maintenance work, the transmission antenna automatically performs the transmission operation. It can be started and the trouble for the user can be minimized. Further, if the gap filler device having the transmission antenna of the present invention is provided with the communication means as described above, the occurrence of the VSWR abnormality can be reported to a monitoring center located at a remote place, and the transmission antenna can be directly investigated. The transmission antenna can be managed in a remote place without any need.
[0020]
In the above embodiment, the recovery operation is performed 10 seconds after the occurrence of the VSWR abnormality, but may be set according to the use environment of the transmitting antenna. Further, the number of times of occurrence of the abnormality is counted, and the setting is made so that the recovery operation is not performed when the abnormality is determined four times, but this setting may be canceled.
Further, the transmission antenna used for the gap filler device having the automatic level control circuit has been described, but the present invention is not limited to the gap filler device, and can be widely applied to a transmission antenna provided with an amplification circuit. Further, the present invention can be implemented by providing, for example, a dedicated microcomputer as an arithmetic means without an automatic level control circuit.
[0021]
【The invention's effect】
As described above in detail, according to the first aspect of the present invention, when a VSWR abnormality occurs, the input section of the amplifier circuit is released by the operation of the switch means, so that the input section is connected to the internal circuit such as the amplifier circuit and the preceding stage. Device can be protected from the VSWR abnormality of the antenna, and the reliability of the transmitting antenna is improved.
[0022]
According to the invention of claim 2, in addition to the effect of claim 1, the power supply of the amplifier circuit is stopped when the VSWR abnormality occurs, so that the power consumption can be minimized.
According to the invention of claim 3, in addition to the effect of claim 1 or 2, the switch means terminates the signal transmission line opened when the input section of the amplifier circuit is opened, so that the amplifier circuit is terminated. It does not degrade the characteristics of the equipment connected in the previous stage.
[0023]
According to the invention of claim 4, in addition to the effect of any one of claims 1 to 3, the automatic level control circuit also serves as the calculating means for determining the VSWR. In this case, there is no need to provide a separate operation means.
According to the fifth aspect of the invention, in addition to the effect of the fourth aspect, when the VSWR abnormality occurs, the amount of attenuation of the input portion of the amplifier circuit becomes maximum, so that the release operation of the switch means is insufficient. However, the amplifier circuit can be reliably protected.
[0024]
According to the invention of claim 6, in addition to the effect of any one of claims 1 to 5, it is possible to recognize at a glance that the cause of the occurrence of the abnormality or the operation stop is the VSWR abnormality by the notifying means, and the information indicates the transmitting antenna. The cause of the operation stoppage can be easily known, which is useful for the operation of restoring the apparatus.
According to the invention of claim 7, in addition to the effect of any one of claims 1 to 6, even if the transmission is stopped due to the VSWR abnormality, the return operation is performed after a predetermined time, so that the VSWR abnormality is caused by, for example, maintenance work. If it is temporary, the transmitting antenna can automatically start the transmitting operation, and the trouble for the user can be minimized.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating an example of a transmission antenna according to the present invention.
FIG. 2 is a block diagram of a gap filler device including the transmission antenna of FIG. 1;
FIG. 3 is a block diagram of an ALC circuit provided in the control unit of FIG. 1;
FIG. 4 is a flowchart showing a flow of a circuit protection operation of the ALC circuit CPU.
[Explanation of symbols]
1 ············································· Automatic control Circuits, 10 antenna elements, 18 terminating resistors, 19 signal transmission paths, 21 transmission antennas, 30 CPU as arithmetic means, 36 circuit protection signal output section, 37 power switch 37a... Amplifier circuit control output unit, 39... LED as notification means, 41... Serial communication port as notification means.

Claims (7)

A transmitting antenna having an amplifier circuit for amplifying a signal radiated from an antenna element, comprising: a traveling wave power detecting unit and a reflected wave power detecting unit; and calculating a VSWR based on the detected traveling wave power and reflected wave power. Calculating means for determining a VSWR abnormality by comparing a preset threshold value with the VSWR calculation value; and switch means for releasing an input portion of the amplifier circuit;
A transmitting antenna, comprising: a circuit protection function that, when the arithmetic means determines that a VSWR abnormality has occurred, activates the switch means to release an input section of the amplifier circuit. 2. The transmitting antenna according to claim 1, wherein the calculating means turns off the power supply of the amplifier circuit when determining that the VSWR abnormality has occurred. 3. The transmitting antenna according to claim 1, wherein the switch means includes a terminating resistor, and connects a signal transmission line for transmitting a signal to the amplifying circuit at the same time as releasing the input portion of the amplifying circuit to the terminating resistor. In a transmitting antenna having a variable attenuator at an input stage of an amplifier circuit and controlling the variable attenuator by an automatic level control circuit having a CPU to keep the output of the amplifier circuit constant, a calculating means for determining VSWR abnormality The transmitting antenna according to claim 1, wherein the transmitting antenna is the CPU. 5. The transmitting antenna according to claim 4, wherein when a VSWR abnormality occurs, the CPU operates the amount of attenuation of the variable attenuator to maximize the amount of attenuation. The transmitting antenna according to any one of claims 1 to 5, further comprising a notifying means for notifying that the operation of the amplifier circuit has been stopped when the switch means performs a releasing operation. The transmitting antenna according to any one of claims 1 to 6, wherein the arithmetic unit issues a return signal after a predetermined time elapses after the occurrence of the VSWR abnormality is determined, and the switch unit and the amplifier circuit perform a return operation by the return signal. .

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