KR19990069498A - Antenna line matching detection circuit of radar transceiver - Google Patents

Abstract

According to the present invention, in order to prevent damage to a circuit element of a receiver due to reflected power due to mismatch of an antenna and a transmission line in a radar, matching of an antenna line that interrupts the radar transmission function if the reflected power of a predetermined reference or more is continuously detected. It relates to a detection circuit. According to the present invention, the transmission signal is received and output to the antenna side, and is electromagnetically coupled to the transmission signal to detect the transmission signal, and electromagnetically coupled to the reflection signal from the antenna side to output the reflection signal, A bidirectional coupler making a second output; A transmission signal detector for detecting a current transmission signal by the bidirectional coupler to produce a first output that is a comparison reference value; A high frequency switch unit receiving the first output and the second output detected by the transmission signal detection unit and time-dividing the outputs alternately at predetermined time intervals; And a discriminating unit detecting the time division signal of the high frequency output from the high frequency switching unit and comparing the first output with the second output to determine the degree of matching between the antenna and the transmission line. According to the present invention, by detecting the level of the reflected power generated by the mismatched state of the transmission line or the antenna unit, if the predetermined level or more, the transmission function is cut off, thereby preventing the damage of expensive circuit elements.

Description

Antenna line matching detection circuit of radar transceiver

The present invention relates to a matching circuit detecting circuit of an antenna line in a radar, and more particularly, in order to prevent damage to a circuit element of a receiving unit due to reflected power caused by mismatching of an antenna and a transmission line, the reflected power of a predetermined reference or more continues. The present invention relates to an antenna line matching degree detection circuit that blocks the radar transmission function if detected.

1 is a block diagram of a general radar system.

In general, as shown in the drawing, the radar system includes a waveform generator 12 for generating a transmission signal, a transmitter 10 for modulating, amplifying and transmitting a signal generated by the waveform generator 12, and a transmitter 10. The receiving unit 16 and the receiving unit 16 for detecting and amplifying the weak reception signal received through the antenna unit 13, the antenna unit 13 for radiating the signal output from the free space And a system controller 20 for converting the digital signal into an appropriate process and providing various control signals, timing signals, and the like necessary for the transmission and reception operation.

The transmitter 10 modulates the signal generated by the waveform generator 12 to a radio frequency (hereinafter referred to as RF) suitable for transmission. After that, the modulated RF signal is amplified by the amplifier to the required size and radiated to the free space through the antenna through the transmission and reception front end 15.

Transmitting and receiving front end portion 15 transmits the transmission output only to the antenna 14 at the time of transmission, and serves to protect the receiver 16 from some leakage power. In addition, the transmission and reception front end 15 is also responsible for amplifying the RF signal received via the antenna 14 in a very short time.

The antenna unit 13 propagates the RF signal output from the transmitter 10 to free space, and also transmits the signal reflected from the target to the receiver 16.

The receiver 16 removes the RF component of the signal received from the antenna 14 through the transmission and reception front end 15 to lower the intermediate frequency, and is configured to maximize the signal-to-noise ratio.

The present invention relates to a detection circuit capable of always monitoring the matching state caused by the performance of the transmission line from the front-receiver 15 to the antenna 14 and the antenna itself in the radar transceiver. The matched state indicates how efficiently power transmission is performed between two adjacent circuits. This mismatch between circuits results from the difference in inherent impedance of two adjacent circuits. Thus, to match two circuits, the unique impedances of each circuit must be made equal.

When the transmission and reception front end 15 and the antenna 14 are in a mismatched state, a part of the transmission output transmitted to the antenna 14 is reflected toward the transmission and reception front end 14. Due to the reflection phenomenon, standing waves are generated in the transmission line connecting the transmitting and receiving front end portion 15 and the antenna 14, and when the standing waves are excessively generated, damaging various circuit elements constituting the receiving portion 16. Problems occur. As such, the magnitude of the standing wave indicating the degree of mismatch is expressed as a standing wave ratio (hereinafter referred to as SWR). In other words, SWR refers to the ratio of the current or voltage measured at the nodes or times of standing waves in the transmission line. In other words, the amplitude ratio between the peak (maximum amplitude) and valley (minimum amplitude) portions of the standing wave.

One way to find SWR is to express SWR using the reflection coefficient | ρ | of the surface where mismatch occurs.

SWR = (1 + │ρ│) / (1-│ρ│)

In other words, when SWR is 1 (the reflection coefficient is 0), it means a completely matched state. That is, it means that the input power is delivered to the output side as it is 100%. On the contrary, when SWR is ∞, most of the input power (100%) is reflected to the input side. Therefore, it is preferable to configure the line and the transmission line between adjacent circuits so that the SWR value is close to one.

Conventionally, in order to know the matching state of a transmission line, the method of inserting the SWR measuring apparatus which can measure SWR in the middle of a transmission line was used. However, this conventional method has a problem that the performance of the overall radar transceiver is degraded due to the power loss caused by the insertion of the SWR measuring device.

In addition, in the conventional method, due to the insertion of the SWR measuring apparatus, there is a problem that it is impossible to measure the exact matching state due to the increase in standing waves due to the inherent impedance of the SWR measuring apparatus in addition to the inherent matching degree of the radar transceiver.

The present invention is to solve the above problems, in the radar transceiver, an antenna that detects the reflected power level caused by the mismatch between the antenna and the transmission line to block the transmission output of the transmitter when a predetermined reference level or more An object of the present invention is to provide a matching detection circuit for a transmission line.

1 is a block diagram of a general radar system.

2 is a block diagram illustrating an antenna line matching degree detection circuit of a radar transceiver according to the present invention.

* Explanation of symbols for the main parts of the drawings *

CR1: Circulator CPL: Bidirectional Coupler

ATT1: Attenuator PD1: Reversing Power Divider

RF SW: High Frequency Control Switch DET1: Detector

AR1: Amplifier

The present invention for achieving the above object, receives the transmission signal and outputs to the antenna side, and is coupled electromagnetically to the transmission signal to detect the transmission signal, and electromagnetically coupled to the reflected signal from the antenna side A bidirectional coupler making an output of the reflected signal, a second output; A transmission signal detector for detecting a current transmission signal by the bidirectional coupler to produce a first output that is a comparison reference value; A high frequency switch unit receiving the first output and the second output detected by the transmission signal detection unit and time-dividing the outputs alternately at predetermined time intervals; And a discriminating unit detecting the time division signal of the high frequency output from the high frequency switching unit and comparing the first output with the second output to determine the degree of matching between the antenna and the transmission line.

Preferably, the transmission signal detection unit includes an attenuator for attenuating the detected transmission signal to a predetermined level; And a reverse force divider for outputting the first output to the transmission output detection stage and the high frequency switch unit, respectively, by dividing the output so that the user can check the state of the transmission signal passing through the attenuator.

Through the above-described configuration, the present invention has a configuration having a function of monitoring the power of the reflected signal generated due to mismatch between the antenna and the transmission line in the radar transceiver.

According to a preferred embodiment, the discrimination unit is a detector for detecting a high frequency time division signal output from the high frequency switch unit (RF SW), an amplifier for amplifying a predetermined amount of signals corresponding to the detected first output and the second output. (A) and an A / D converter for A / D converting signals corresponding to the amplified first and second outputs, and input signals corresponding to the A / D converted second output and the second output. It includes a microprocessor for receiving and comparing with each other.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

2 is a block diagram illustrating the operation of the antenna line matching detection circuit according to the present invention.

The transmission signal output from the transmitter of the radar transceiver is output to the antenna 14 through the circulator CR1 and the bidirectional coupler CPL. On the contrary, the received signal received from the outside through the antenna 14 is transmitted to the receiver 16 of the radar transceiver through the bidirectional coupler CPL and the circulator CR1.

The circulator CR1 is a circuit element that performs an input / output operation only in a predetermined rotation direction, and determines a transmission direction of a transmission signal or a reception signal according to a transmission / reception function in the transceiver of the radar. That is, when the transmission output is input to the number 1 of the circulator CR1, the output signal is output to the number 2 of the circulator CR1, and the received signal received from the antenna 14 side is input to the number 2 of the circulator CR1 and the circulator CR1. It is output to the receiving unit 16 side which is 3 times.

When the transmission signal is input through the circulator CR1, the bidirectional coupler CPL outputs the transmission signal to the antenna 14 side, and the user can confirm the output state of the transmission signal output to the antenna 14 side. It is electromagnetically coupled (coupled) with the transmission signal to output a first output P0 proportional to the transmission signal. On the contrary, when the reflection signal is input from the antenna 14 side, the bidirectional coupler CPL is electromagnetically coupled to the reflection signal and outputs a second output P2 proportional to the reflection signal. Therefore, the output value of the second output P2 changes according to the magnitude of the standing wave existing in the antenna and the transmission line, and is input to the high frequency switch unit RF SW which is a component of the present invention.

The first output P0 of the bidirectional coupler CPL is then attenuated to some extent in the attenuator ATT1, so that it is designed to be equal to the power level of the reflected signal with an acceptable standing wave ratio. In general, when the standing wave ratio of the antenna and the transmission line is 1.5: 1, the loss of the reflected signal is -14dBm. With reference to this, a third output P1 having a signal level of -14 dB is made by using an attenuator ATT1 having a loss of 11 dB, and half the output of the attenuator ATT1 (-3 dB) again in the half power divider PD1. . The third output P1 thus produced is used as a reference value when compared with the output of the reflected signal having the predetermined SWR value, that is, the second output P2.

As described above, the attenuation degree of the attenuator ATT1 is determined by how much the allowable value of the standing wave ratio SWR detected in the antenna and the transmission line is set. Generally, the third output P1 of the half power divider PD1 is The second output P2 of the bidirectional coupler CPL adjusts the attenuator ATT1 value to be the same. In this case, the bidirectional coupler CPL uses the same coupling coupling value for the output P0 and the coupling coupling value for the output P2.

On the other hand, the high frequency switch unit RF SW time-divisions the third output P1 from the half power divider PD1, that is, the SWR value of the antenna and the transmission line and the second output P2 of the bidirectional coupler CPL used as a reference value at predetermined intervals. To the determination unit 40. The high frequency control switch unit RF SW selects one of the two outputs under the control of a microprocessor which is a component in the determination unit 40.

The high frequency signal in which the reference value and the SWR value are output from the high frequency control switch unit RF SW is input to the determination unit 40.

In the discrimination unit 40, the high frequency signal is detected by the detector DET1 and then amplified to a predetermined size through the amplifier AR1, and the signal is converted into a digital signal through an analog-to-digital converter A / D. .

The microprocessor then stores the converted digital signal in memory and compares the reference value stored in the memory by the reference value. The reference value stored in the memory is set to have a level slightly higher than the output value of the amplifier AR1, for example, when the maximum allowable standing wave ratio is 1.5: 1.

Then, when the magnitude of the reflected power as the digital signal is larger than a predetermined reference value, that is, when the SWR value of the antenna and the transmission line is larger than 1.5: 1, the power of the reflected signal returned from the antenna side is excessive and the circuit element of the radar receiver part is excessive. Are broken. Therefore, the microprocessor repeatedly checks the converted digital signal at predetermined time intervals, and issues a command to block the transmission function of the transmitter by outputting a defect signal when the reflected signal is larger than n times the set reference value.

Therefore, by detecting the reflected power of the standing wave generated by the antenna and the transmission line and comparing it with a predetermined reference value, the state of the antenna and the transmission line is always checked. It is possible to prevent them from damage.

As described above, according to the present invention, it is possible to detect the level of the reflected power generated by the mismatched state of the transmission line or the antenna unit and to cut off the transmission function if it is above a certain level, thereby preventing the damage of expensive circuit elements. have.

Claims (4)

It receives a transmission signal and outputs it to the antenna side, and is electromagnetically coupled to the transmission signal to detect the transmission signal, and is electromagnetically coupled to the reflection signal at the antenna side to generate the power and the second output of the reflection signal. Coupler; A transmission signal detector for detecting a current transmission signal by the bidirectional coupler to produce a first output that is a comparison reference value; A high frequency switch unit receiving the first output and the second output detected by the transmission signal detection unit, time division at predetermined time intervals, and outputting them alternately; And And a discriminating unit detecting the time division signal of the high frequency outputted from the high frequency switching unit, comparing the first output with the second output to determine the degree of matching between the antenna and the transmission line, and blocking the transmission function if the reference level is higher than a predetermined reference value. An antenna line matching degree detection circuit of a radar transceiver. The method of claim 1, wherein the transmission signal detection unit An attenuator for attenuating the detected transmission signal to a predetermined level; And Half the output so that the user can check the state of the transmission signal passed through the attenuator, one of which is output to the transmission output detection stage and the other includes a reverse force divider for outputting the first output to the high frequency switch unit An antenna line matching degree detection circuit of a radar transceiver. The method of claim 1, wherein the determining unit A detector for detecting a high frequency time division signal output from the high frequency switch unit; An amplifier for amplifying the signals corresponding to the detected first output and the second output to a certain degree; An A / D converter for A / D converting the amplified signals corresponding to the first output and the second output; And And a microprocessor for receiving and comparing the signals corresponding to the A / D-converted first and second outputs. The method of claim 1, wherein the determining unit Comparing the magnitude of the reflected signal power with a preset value, and detecting the frequency of occurrence of the case where the magnitude of the reflected signal power is larger than a predetermined reference value to determine the matching degree of the antenna line. Line matching detection circuit.