Large dynamic RCS measurement system and measurement method

Abstract

The invention relates to a large dynamic RCS measuring system and method, and relates to the field of signal measurement, the large dynamic RCS measuring system comprises a signal generating end and a signal receiving end, the signal generating end comprises a signal source, a directional coupler connected with the signal source through a microwave cable, and a transmitting antenna and a reference receiver which are respectively connected with the directional coupler; the signal receiving end comprises a receiving antenna and a shunt connected with the receiving antenna through a microwave cable, the shunt is divided into multiple paths of microwave cables, one path and the first test receiver form a first receiving branch, and the other path, the attenuator and the second test receiver form a second receiving branch; the method has the advantages that the problem of data measurement distortion caused by the fact that signals in individual orientations of the measured target exceed the receiving upper / lower dynamic state of a measurement system due to the fact that the RCS difference of the large full-size measured target in different incidence orientations is huge in the past is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of signal measurement, and in particular to a large dynamic RCS measurement system and a measurement method. Background Art

[0002] When performing RCS testing in a conventional compact microwave anechoic chamber, the high-power signal entering the measurement receiver will saturate the receiver, causing distortion of the system measurement results (such as Figure 1 As shown in the figure, when a signal with too low power enters the measurement receiver, there is not enough signal-to-noise ratio between the signal and the receiver noise floor, which will also cause distortion of the measurement results (such as Figure 2 The typical signal receiver has a noise floor of -114dBm (IFBW = 1KHz) at room temperature. The compression point of the receiver measurement is generally around -10dBm. Considering that there is at least 30dB signal-to-noise ratio, the measurement dynamics of the RCS measurement system is generally only 70dB.

[0003] Such measurement dynamics can cover the measurement needs of most targets. However, with the development of technology, some targets have very low RCS values ​​at most observation angles due to their special design. However, in certain specific observation directions, such targets often have very high RCS values. When measuring the RCS of such targets, due to the limited measurement dynamics (i.e., range) of the system, it is generally impossible to take both high and low values ​​into account. Figure 3 As shown in the figure, taking the RCS of a circular metal plate with a diameter of 150 cm as an example, it can be seen that within the range of ±2.5°, the RCS curve of the circular plate fluctuates violently. The RCS dynamics of this type of target exceeds 100dB, far exceeding the dynamic range of general RCS measurement systems.

[0004] Therefore, in view of the above shortcomings, it is necessary to provide a large dynamic RCS measurement system and measurement method. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] The technical problem to be solved by the present invention is to solve the problem that the traditional RCS measurement system has limited dynamics and cannot take both high and low into account.

[0007] (II) Technical solution

[0008] In order to solve the above technical problems, the present invention provides a large dynamic RCS measurement system, including a signal generating end and a signal receiving end, wherein the signal generating end includes a signal source, a directional coupler connected to the signal source through a microwave cable, and a transmitting antenna and a reference receiver respectively connected to the directional coupler; the signal receiving end includes a receiving antenna, a splitter connected to the receiving antenna through a microwave cable, the splitter divides a plurality of microwave cables, one of which forms a first receiving branch with a first test receiver, and another forms a second receiving branch with an attenuator and a second test receiver, and a calibration object or a target to be measured is placed between the transmitting antenna and the receiving antenna.

[0009] As a further illustration of the present invention, preferably, the signal generating end further comprises a power amplifier, and the power amplifier is connected between the signal source and the directional coupler through a microwave cable to amplify the signal generated by the signal source.

[0010] As a further illustration of the present invention, preferably, a first low noise amplifier is connected between the first test receiver and the splitter via a microwave cable, and a second low noise amplifier is connected between the second test receiver and the attenuator via a microwave cable to amplify the received signal.

[0011] As a further illustration of the present invention, preferably, a first limiter is connected between the first test receiver and the first low noise amplifier via a microwave cable, and a second limiter is connected between the second test receiver and the second low noise amplifier via a microwave cable to protect the test receiver.

[0012] The present invention also provides a large dynamic RCS measurement method, comprising the following steps:

[0013] Ⅰ. Select the calibration body and place it between the transmitting antenna and the receiving antenna. The signal source generates electromagnetic waves of a specific frequency, which are amplified by the power amplifier and transmitted to the directional coupler. The directional coupler sends the generated first coupled signal to the reference receiver, which is marked as R.

[0014] Ⅱ. The second direct signal generated by the directional coupler is irradiated to the calibration body through the transmitting antenna. The calibration body reflects the signal to the receiving antenna. The signal received by the receiving antenna is divided into multiple paths through the splitter. One path is amplified by the first low-noise amplifier and sent to the first test receiver, marked as B1, and the S1 parameter is obtained after data processing; the other path is attenuated by the attenuator, amplified by the second low-noise amplifier, and sent to the second test receiver, marked as B2, and the S2 parameter is obtained after data processing;

[0015] III. Replace the calibration body with the target to be measured and repeat the above steps to obtain the S1 parameter and S2 parameter of the target to be measured;

[0016] IV. Use the S1 parameter of the calibration object and the S1 parameter of the target to perform calibration processing to obtain the low-level RCS signal σ of the target L ; Use the S2 parameters of the calibration body and the S2 parameters of the target to perform calibration processing to obtain the low-level RCS signal σ of the target H ;

[0017] V. Signal σ L and signal σ H The filtered data are screened and combined to obtain new σ data, which is the RCS value of the target being measured.

[0018] As a further illustration of the present invention, preferably, the measurement dynamic range of the first receiving branch is -60 dBsm to 10 dBsm, and the measurement dynamic range of the second receiving branch is -20 dBsm to 50 dBsm.

[0019] As a further illustration of the present invention, preferably, the S1 parameter is obtained by B1 / R, and the S2 parameter is obtained by B2 / R.

[0020] As a further illustration of the present invention, preferably, σ L Among all the data, the data with RCS value higher than 10dBsm are screened out; H Among all the data, the RCS data above 10dBsm and below 50dBsm are filtered and retained.

[0021] (III) Beneficial effects

[0022] The above technical solution of the present invention has the following advantages:

[0023] The present invention designs a new measurement system and combines the measurement method. For some large dynamic measured targets, the RCS measurement of the target can be completed by placing the target once and performing data collection and processing, thereby effectively improving the dynamics of the RCS measurement system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The existing system dynamics are insufficient to measure high RCS values, resulting in distorted line graphs;

[0025] Figure 2 The existing system dynamics are insufficient to measure low RCS values, resulting in distorted line graphs;

[0026] Figure 3 This is the existing line graph of theoretical RCS values ​​for a circular flat plate with a diameter of 150 cm;

[0027] Figure 4 is a conceptual diagram of the measurement system of the present invention;

[0028] Figure 5 It is a line diagram of the dual receiving branch data component level combined data of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] A large dynamic RCS measurement system, such as Figure 4 As shown, it includes a signal generating end and a signal receiving end, wherein the signal generating end includes a signal source, a power amplifier connected to the signal source via a microwave cable, the power amplifier is connected to a directional coupler via a microwave cable, and a transmitting antenna and a reference receiver are respectively connected to the directional coupler via microwave cables.

[0031] like Figure 4 As shown, the signal receiving end includes a receiving antenna, a splitter connected to the receiving antenna through a microwave cable, the splitter divides multiple microwave cables, one of which is connected to a first low-noise amplifier through a microwave cable, the first low-noise amplifier is connected to a first limiter through a microwave cable, the first limiter is connected to a first test receiver through a microwave cable, and the first low-noise amplifier, the first limiter and the first test receiver form a first receiving branch. Another path is connected to an attenuator through a microwave cable, the attenuator is connected to a second low-noise amplifier through a microwave cable, the second low-noise amplifier is connected to a second limiter through a microwave cable, the second limiter is connected to a second test receiver through a microwave cable, the attenuator, the second low-noise amplifier, the second limiter and the second test receiver form a second receiving branch, and a calibration object or a target to be measured is placed between the transmitting antenna and the receiving antenna.

[0032] A power amplifier is set to amplify the signal generated by the signal source, and a first low noise amplifier and a second low noise amplifier are set to amplify the received signal. A first limiter and a second limiter are set to protect the test receiver to prevent the amplifier output signal from being too high and damaging the receiver. Other methods such as attenuators can also be used to protect the receiver.

[0033] The present invention also provides a large dynamic RCS measurement method, comprising the following steps:

[0034] Ⅰ. Select a calibration body and place it between the transmitting antenna and the receiving antenna. The signal source generates an electromagnetic wave of a specific frequency, which is amplified by the power amplifier and transmitted to the directional coupler. The directional coupler sends the generated first coupled signal to the reference receiver and is marked as R.

[0035] Ⅱ. The second direct signal generated by the directional coupler is irradiated to the calibration body through the transmitting antenna. The calibration body reflects the signal to the receiving antenna. The signal received by the receiving antenna is divided into multiple paths through the splitter. One path is amplified by the first low-noise amplifier and sent to the first test receiver, and is marked as B1. After data processing, the S1 parameter is obtained; the other path is attenuated by the attenuator, and then amplified by the second low-noise amplifier and sent to the second test receiver, and is marked as B2. After data processing, the S2 parameter is obtained.

[0036] According to the physical link, the overall signal gain of the first receiving branch is large, and low-level RCS signals can be measured. Therefore, the S parameter S1 obtained by the link is suitable for the part with lower calibration level. In this application, the dynamic range of S1 is -60dBsm to 10dBsm.

[0037] According to the physical link, since the second receiving branch is connected in series with a large-resistance attenuator (40dB), the overall gain of the second receiving branch is low, and high-level RCS signals can be measured. Therefore, the S parameter S2 obtained by this branch is suitable for calibrating high-level signals. In this application, due to the effect of the attenuator, the overall dynamics of the second receiving branch is 40dB higher than that of the first receiving branch. Therefore, the dynamic range applicable to S2 in this application is -20dBsm to 50dBsm.

[0038] Since the dynamic range applicable to the first receiving branch is -60dBsm to 10dBsm, and the dynamic range applicable to the second receiving branch is -20dBsm to 50dBsm, the calibration body in this embodiment needs to be selected to meet the requirements of both branches. Taking this embodiment as an example, at a frequency of 40GHz, the theoretical RCS value of a metal ball with a diameter of 300mm is -11.5dBsm, which can meet the calibration requirements for both receiving branches.

[0039] In addition, when measuring at different frequencies, the tester needs to calculate and decide to select the appropriate calibration body. If the number of receiving branches increases further, appropriate calibration bodies are added according to the above method. For example, if there are three receiving branches, at least two calibration bodies are required for system calibration.

[0040] III. Replace the calibration body with the target to be measured and repeat the above steps to obtain the S1 and S2 parameters of the target to be measured; the S1 parameters of the calibration body and the target to be measured are both obtained through B1 / R, and the S2 parameters are both obtained through B2 / R.

[0041] IV. Use the S1 parameter of the calibration object and the S1 parameter of the target to perform calibration processing to obtain the low-level RCS signal σ of the target L ; Use the S2 parameters of the calibration body and the S2 parameters of the target to perform calibration processing to obtain the low-level RCS signal σ of the target H ;

[0042] V. Signal σ L and signal σ H Screening is performed, and the screening conditions are: L Among all the data, the data with RCS value higher than 10dBsm are screened out; H Among all the data, the RCS data above 10dBsm and below 50dBsm are screened and retained, and the screened data are combined to obtain new σ data, such as Figure 5 As shown, this group of data is the RCS value of the measured target.

[0043] In summary, the measurement system provided by the present invention uses the same receiving antenna, and a splitter is used at the back end for branching. Each receiving branch matches a different receiver, corresponding to different measurement dynamics. In conjunction with the above-mentioned measurement method, in general, it is only necessary to place the target once for data collection and processing once to complete the RCS measurement of a large dynamic target. The test efficiency is high, and the measurement dynamics of the RCS measurement system can be greatly improved.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A large dynamic RCS measurement system, characterized by: It includes a signal generating end and a signal receiving end, wherein the signal generating end includes a signal source, a directional coupler connected to the signal source through a microwave cable, and a transmitting antenna and a reference receiver respectively connected to the directional coupler; the signal receiving end includes a receiving antenna, a splitter connected to the receiving antenna through a microwave cable, the splitter divides a plurality of microwave cables, one of which forms a first receiving branch with a first test receiver, and another forms a second receiving branch with an attenuator and a second test receiver, and a calibration object or a target to be measured is placed between the transmitting antenna and the receiving antenna.

2. A large dynamic RCS measurement system according to claim 1, characterized in that: The signal generating end also includes a power amplifier, which is connected between the signal source and the directional coupler through a microwave cable to amplify the signal generated by the signal source.

3. A large dynamic RCS measurement system according to claim 2, characterized in that: A first low noise amplifier is connected between the first test receiver and the splitter via a microwave cable, and a second low noise amplifier is connected between the second test receiver and the attenuator via a microwave cable to amplify the received signal.

4. A large dynamic RCS measurement system according to claim 3, characterized in that: A first limiter is connected between the first test receiver and the first low noise amplifier via a microwave cable, and a second limiter is connected between the second test receiver and the second low noise amplifier via a microwave cable to protect the test receiver.

5. A large dynamic RCS measurement method, characterized by: The following steps are included: Ⅰ. Select the calibration body and place it between the transmitting antenna and the receiving antenna. The signal source generates electromagnetic waves of a specific frequency, which are amplified by the power amplifier and transmitted to the directional coupler. The directional coupler sends the generated first coupled signal to the reference receiver, which is marked as R. Ⅱ. The second direct signal generated by the directional coupler is irradiated to the calibration body through the transmitting antenna. The calibration body reflects the signal to the receiving antenna. The signal received by the receiving antenna is divided into multiple paths through the splitter. One path is amplified by the first low-noise amplifier and sent to the first test receiver, marked as B1, and the S1 parameter is obtained after data processing; the other path is attenuated by the attenuator, amplified by the second low-noise amplifier, and sent to the second test receiver, marked as B2, and the S2 parameter is obtained after data processing; III. Replace the calibration body with the target to be measured and repeat the above steps to obtain the S1 parameter and S2 parameter of the target to be measured; IV. Use the S1 parameter of the calibration object and the S1 parameter of the target to perform calibration processing to obtain the low-level RCS signal σ of the target L ; Use the S2 parameters of the calibration body and the S2 parameters of the target to perform calibration processing to obtain the low-level RCS signal σ of the target H ; V. Signal σ L and signal σ H The filtered data are screened and combined to obtain new σ data, which is the RCS value of the target being measured.

6. A large dynamic RCS measurement method according to claim 5, characterized in that: The measurement dynamic range of the first receiving branch is -60dBsm to 10dBsm, and the measurement dynamic range of the second receiving branch is -20dBsm to 50dBsm.

7. A large dynamic RCS measurement method according to claim 5, characterized in that: The S1 parameters are obtained through B1 / R, and the S2 parameters are obtained through B2 / R.

8. A large dynamic RCS measurement method according to claim 5, characterized in that: σ L Among all the data, the data with RCS value higher than 10dBsm are screened out; H Among all the data, the RCS data above 10dBsm and below 50dBsm are filtered and retained.

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