A passive chaff jamming test device and method based on a vector network analyzer

Abstract

A kind of passive chaff jamming test device and method based on vector network analyzer, radar transmitting antenna installed on antenna platform, radar receiving antenna installed on antenna platform;And radar wave-absorbing material between transmitting antenna and receiving antenna, for attenuating the linear transmission of signal from transmitting antenna to receiving antenna, for realizing low-power transmitter connected to transmitting antenna for safe ground test, for producing radar radio frequency signal to the chaff scattering unit dispersed above platform, while also connected network analyzer to receiving antenna, which can measure low-power radio frequency signal reflected by dispersed countermeasure unit;The present application can carry out mid-range ground test of chaff countermeasure unit, including measuring radar cross section.This test makes it possible to manufacture higher quality units and send them to the operators of countermeasure units with greater convenience, safety and lower test cost.

Description

Technical Field

[0001] This invention relates to the field of radar testing, and in particular to a passive chaff interference testing device and method based on a vector network analyzer. Background Technology

[0002] In the field of electronic countermeasures, ensuring the consistency of equipment unit performance is essential. To ensure that the countermeasures manufactured throughout the entire production process remain unchanged, thus guaranteeing performance consistency, we conduct a test called batch acceptance testing (LAT). The principle behind batch acceptance testing is to first test a large number of "good" units, and then use the obtained data to set a benchmark for subsequent production units. The benchmark used for batch acceptance testing should be directly related to the key factors that make electronic countermeasures effective.

[0003] It is important to note that batch acceptance testing does not test the effectiveness of individual countermeasures, but rather uses previously established benchmarks to determine whether the unit is similar to units previously considered "good." Therefore, batch acceptance testing focuses on repeatability between individual tests so that any discrepancies can be entirely attributed to production quality.

[0004] Radar countermeasures, such as chaff, can generate numerous small clouds of metal-coated fiberglass. The metallic coating allows the fibers to act as dipoles that can reflect radar. When reflectivity is combined with widespread dispersion, it creates a large radar cross-section. For example, a large radar cross-section can prevent an enemy's radio frequency seeker from locking onto the user's aircraft.

[0005] Currently, radar countermeasures such as chaff units are primarily tested in two ways. The first is a simple functional test. The second measures the sleeve dimensions, fiber length, and marking appearance. While these tests are necessary, neither directly examines the radar cross section (RCS), a key factor determining the effectiveness of countermeasures units. To ensure test effectiveness, countermeasures such as chaff units are operated on an aircraft while guiding threats are monitored to see if they disengage from the aircraft. This testing method is extremely costly and time-consuming. Furthermore, regulations related to aircraft operation, operational and maintenance threats, and the limited number of units that can be distributed per flight (e.g., 30 units) further increase the complexity of flight testing. Additionally, because chaff is released from a mobile platform, the distance between the release point and the measuring equipment changes with each test run. While this effect is measurable, it must be considered after each test. Moreover, wind factors and turbulence can vary significantly throughout the testing process, affecting the way the chaff is dispersed. Summary of the Invention

[0006] The purpose of this invention is to provide a passive chaff jamming testing device and method based on a vector network analyzer to solve the aforementioned problems. This device and method are capable of performing mid-range ground tests on countermeasures units such as chaff, including measuring radar cross-sections. This testing allows for the manufacture of higher-quality units and their delivery to countermeasures unit operators with greater convenience, security, and lower testing costs.

[0007] The present invention provides a passive chaff interference RCS test device based on a vector network analyzer, wherein an antenna platform is installed on a ground support member, and at least one first radar transmitting antenna is set on the antenna platform;

[0008] At least one first radar receiving antenna is mounted on an antenna platform, and the first radar receiving antenna is configured to transmit in a Ka-band frequency or an X-band frequency.

[0009] A radar absorbing material is disposed on the antenna platform, the radar absorbing material being linearly located between the first radar transmitting antenna and the first radar receiving antenna, for attenuating the linear transmission of the signal between the radar transmitting antenna and the radar receiving antenna;

[0010] The first low-power transmitter is communicatively connected to the radar transmitting antenna and configured to generate radio frequency signals in a predetermined frequency band for the radar transmitting antenna to transmit.

[0011] The first network analyzer is communicatively connected to the radar receiving antenna and configured to determine the received power of the transmitted radio frequency signal reflected from the countermeasures units dispersed above the antenna platform.

[0012] The countermeasure dispersion mechanism disperses the countermeasure elements into a volume at a certain distance above the antenna platform.

[0013] Furthermore, the low-power transmitter is configured to operate within the range of 20-21 dBmw.

[0014] Furthermore, the radar absorbing material includes one or more of the following: foam absorber, polyurethane foam, Holland shield, rubber foam, ferrite material, semiconductor, graphite, carbon nanotubes, iron ball coating, or carbon nanotube-based coating, wherein the polyurethane foam is carbon loaded with conductive carbon black and / or crystalline graphite particles, and the rubber foam is impregnated with carbon and iron.

[0015] Furthermore, the counter-dispersion mechanism is located within a range of 4.5-15M above the antenna platform, and includes an airflow unit configured to control the airflow passing through the counter-dispersion unit during testing to achieve consistent dispersion.

[0016] Furthermore, at least one second radar transmitting antenna and a second radar receiving antenna are provided on the antenna platform; a second low-power transmitter is communicatively connected to the second radar transmitting antenna and configured to generate a second radio frequency signal in a second frequency band for transmission with the second radar transmitting antenna; a second network analyzer is communicatively connected to the second radar receiving antenna and configured to determine the received power of the second radio frequency signal reflected from the countermeasures units dispersed above the antenna platform; and radar absorbing material is linearly located between the second radar transmitting antenna and the second radar receiving antenna.

[0017] A test method for a passive chaff interference RCS test device based on a vector network analyzer is characterized by: at least one radar transmitting antenna and at least one radar receiving antenna, both connected to a transmitting and receiving mechanism; transmitting continuous wave or pulse electromagnetic radiation to a 3D target via the radar transmitting antenna, and then receiving the reflected electromagnetic radiation pulse via the radar receiving antenna; then measuring the returned pulse at the site to determine the characteristics of the object; the frequency of the transmitted electromagnetic radiation depends on the target; the ratio between the transmitted signal and the returned signal is used to calculate the two-dimensional (2D) projected area of ​​the 3D target measured by the radar wave, and this ratio represents the radar cross section of the object; Formula 1 shows the method for calculating the radar cross section RCS (σc) of a sphere.

[0018] (1)

[0019] Where R is the distance to the target; S r and S t These are the return power and the transmit power, respectively, G t and G r These are the gains of the transmitting and receiving antennas, respectively, and λ is the wavelength of the radiated signal used.

[0020] The beneficial effects include the ability to conduct mid-range ground tests of countermeasures units such as chaff, including measuring radar cross-section. This testing allows for the manufacture of higher-quality units and their delivery to countermeasures unit operators with greater convenience, security, and lower testing costs; areas not detailed in this invention are existing, commonly used techniques. Attached Figure Description

[0021] The present invention will be further described below with reference to the accompanying drawings:

[0022] Figure 1 A schematic diagram of an exemplary radar system is shown, based on certain aspects.

[0023] Figure 2 A schematic diagram of a currently disclosed measuring device or setup is shown, based on certain aspects.

[0024] Figure 3 A chart showing the acceptance criteria for adversarial unit tests based on certain aspects is presented.

[0025] Figure 4 Demonstrates a use Figure 2 The flowchart shows the method for testing the radar cross-section of countermeasures devices. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0027] like Figure 1 The passive chaff interference RCS test device shown includes at least one first radar transmitting antenna 3 and at least one first radar receiving antenna 4, both of which are connected to a transmitting / receiving station or equipment; the first transmitting antenna 3 transmits continuous wave or pulse electromagnetic radiation to the countermeasure unit 8, and then the first receiving antenna 4 receives the reflected electromagnetic radiation pulse;

[0028] Then, the returned pulse is measured at the site to determine the characteristics of the countermeasure unit 8. The frequency of the emitted radiation depends on the desired target. The ratio between the emitted signal and the returned signal is used to calculate the two-dimensional (2D) projected area of ​​the countermeasure unit 8 measured by radar waves. This ratio represents the radar cross section of the object. Equation 1 shows the method for calculating the radar cross section RCS.

[0029] (1)

[0030] Where R is the distance to the target; S r and S t These are the return power and the transmit power, respectively, G t and G r These are the gains of the transmitting and receiving antennas, respectively, and λ is the wavelength of the radiated signal used. Example

[0031] Unlike infrared countermeasures, radar chaff is passive, meaning it does not actively emit jamming signals. Instead, chaff is designed to reflect radar signals. Therefore, a radar energy source pointed at the chaff is needed to measure its radar cross-section. Although it is assumed that the radar source can use any frequency, considering the application of chaff in certain frequency bands, at least two radar bands may be implemented for optimal testing of chaff: the X-band 8-12 GHz and the Ka-band 26.5-40 GHz.

[0032] like Figure 2 The passive chaff interference RCS testing device based on a vector network analyzer shown includes an antenna platform 2, which is mounted on a support member 1 on the ground. The support member 1 raises the antenna platform 2 to a certain distance above the ground, which in some respects ranges from 0.3 meters to 1.8 meters, but the invention is not limited thereto. The antenna platform 2 itself includes a bottom support frame or member, such as a tripod, on which one or more antenna supports are mounted. The antenna supports are in turn used to mount one or more first transmitting antennas 3 and second transmitting antennas 3.1, as well as one or more first receiving antennas 4 and second receiving antennas 4.1. In the example shown, two pairs of transmitting / receiving antennas are shown, each pair of antennas operating at different frequencies to provide measurements using two different radar bands.

[0033] The antenna platform 2 also includes radar absorbing material 5, which is located or arranged between the first transmitting antenna 3, the second transmitting antenna 3.1 and the first receiving antenna 4, the second receiving antenna 4.1 on the antenna platform 2, for attenuating direct or linear signal transmission between the transmitting and receiving antennas. As shown in the figure, the radar absorbing material 5 is arranged linearly between the transmitting and receiving antennas along a direction parallel to the top surface of the support frame 5 to attenuate or block the linear transmission of radio frequency signals directly from the transmitting antenna to the receiving antenna, so that all or at least most of the radio frequency signals received by the first receiving antenna 4 and the second receiving antenna 4.1 are those signals transmitted from the first transmitting antenna 3 and the second transmitting antenna 3.1, and these signals are measured... During the test, the radar absorbing material 5 is reflected away from the countermeasure unit 8 from a volume spatially dispersed within an optimal height range above the antenna platform 2; furthermore, the height of the radar absorbing material 5 above the antenna platform 2 is configured to ensure sufficient radio frequency signal attenuation and minimal or no overflow of direct radio frequency signal transmission between the transmitting and receiving antennas. The radar absorbing material 5 can be composed of various materials, including but not limited to foam absorbing materials, such as polyurethane foam, which is carbon-loaded with conductive carbon black and / or crystalline graphite particles, rubber foam impregnated with carbon and iron, ferrite materials, semiconductors, graphite, carbon nanotubes, iron ball coatings, i.e., microspheres coated with carbonyl iron or ferrite, or carbon nanotube-based coatings; furthermore, although Figure 2 The geometry of the radar absorbing material 5 shown is in block form, but the geometry of the radar absorbing material 5 can be configured according to any geometry to provide optimal or maximum radar attenuation.

[0034] Includes one or more low-power transmitters configured to generate radar signals at a specific frequency or wavelength, and then transmit these signals via a first transmitting antenna 3 or a second transmitting antenna 3.1; Figure 2 In the example, the first low-power transmitter 6 is configured to generate a signal in the X-band 8-12 GHz, and the second low-power transmitter 6.1 is configured to generate a signal in the Ka-band 26.5-40 GHz. The first low-power transmitter 6 and the second low-power transmitter 6.1 are communicatively connected to their respective first transmitting antenna 3 or second transmitting antenna 3.1 via power output cables to transmit and drive the signals transmitted by the antennas. The length of the power output cables is set to allow a safe operating distance between the first transmitting antenna 3 or the second transmitting antenna 3.1 and the personnel operating the system at the first low-power transmitter 6 and the second low-power transmitter 6.1.

[0035] Includes one or more network analyzers configured to receive reflected radar signals received by a first receiving antenna 4 and a second receiving antenna 4.1 to determine the radar cross-section of the countermeasure unit 8. Figure 2 In the example, the first network analyzer 7 is configured to receive and analyze X-band signals received by the first receiving antenna 4, and the second signal or network analyzer 7.1 is configured to receive and analyze Ka-band signals received by the second receiving antenna 4.1; the first network analyzer 7 and the second network analyzer 7.1 are communicatively connected to the first receiving antenna 4 and the second receiving antenna 4.1 via power receiving cables, the lengths of which are set to allow a safe operating distance between the first receiving antenna 4 and the second receiving antenna 4.1 and the personnel operating the system at the first network analyzer 7 and the second network analyzer 7.1.

[0036] The countermeasure dispersion mechanism is configured to release and disperse the countermeasure units 8 into the spatial volume above the antenna platform 2, such as... Figure 2The countermeasure unit cloud 8 is shown in the diagram. In one example, the countermeasure dispersion mechanism may include the use of an airflow facility that allows controlled airflow of the countermeasure units during testing to achieve consistent dispersion. Variations in measurement distance are eliminated by fixing the positions of the countermeasure dispersion mechanism and antenna platform 2 during testing. Although there is more background noise in this arrangement than in clean air, the background noise can be reduced by zeroing the countermeasure units each time they are launched or dispersed, as releasing the countermeasure units in the same area does not simulate an aircraft. However, this is not necessary for batch acceptance testing, as repeatability between tests is a primary objective of batch acceptance testing. A benchmark is then established from testing known "good" units under the same conditions as subsequent units. In some respects, the distance of the countermeasure unit 8 above antenna platform 2 may be in the range of approximately 4.5 meters to 7.5 meters above the platform, but this disclosure is not necessarily limited to this.

[0037] use Figure 2 The passive chaff interference RCS testing device based on a vector network analyzer shown above determines the radar cross section. First, it should be noted that by rearranging Equation 1 above to solve for the return power Sr, we obtain the following Equation 2:

[0038] (2)

[0039] Equation 2 can be used to model device setups to determine which device pairs can work optimally together. The equation primarily focuses on the relationship between return power and transmit power.

[0040] Table 1 below illustrates, for example, the return signal power as the transmit power changes for a target with a radar cross-section of one square meter within a 15-meter range at 9.3 GHz, and for a moderately focused transmit and receive antenna with an omnidirectional antenna power gain of 22.1.

[0041] Table 1

[0042] From the data in Table 1 above, it can be inferred that when testing countermeasure units, if the returned power is significantly less than the transmitted power, it will result in a large loss. This means that the low-power transmitter needs to drive the transmission at or above a certain minimum power level, and the network analyzer needs to be sensitive enough to measure the returned signal. In one example, a low-power transmitter capable of providing 21 dBmw peak power at 9.3 GHz was used. Given the same settings as in Table 1, this low-power transmitter allowed a return of approximately -62 dBm. In the Ka band, the same low-power transmitter with a 20 dBi antenna gain can output 20 dBm at 35 GHz, achieving an echo of -75 dBm. Due to non-ideal conditions, the expected returned signal will be less than those calculated in Table 1; this means that most basic power sensors on the market will be unable to detect the returned signal from the noise; therefore, for example, when measuring the radar cross section at 15 meters, network analyzers such as the first network analyzer 7 and the second network analyzer 7.1 are used to be able to measure lower power signals; however, the invention is not limited thereto, and any equivalent device capable of measuring low power signals can be used. In a further aspect, the first network analyzer 7 and the second network analyzer 7.1 may be configured to calculate and / or determine the radar cross section of the countermeasure unit from the measured signal, for example by implementing the above equations (1) and / or (2).

[0043] Figure 3 A graph is shown to illustrate the acceptance criteria for the countermeasure unit test; curve 302 shows the lower limit or envelope threshold, and curve 304 shows the data obtained from the actual unit being tested, indicating that it meets the minimum setting criteria for passing the unit.

[0044] Although the tests are designed for the X and Ka bands, measurements can be performed at any desired wavelength using appropriate antennas, low-power transmitters, and network analyzers. This invention offers commercial value to any company wishing to manufacture products or materials with specific radar characteristics, and provides a low-cost means of testing products within a limited space. Companies manufacturing radio frequency equipment will benefit from using this system for internal quality control testing.

[0045] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A passive foil interference testing device based on a vector network analyzer, characterized in that: An antenna platform 2 is mounted on a ground-supported member 1, and at least one first radar transmitting antenna 3 is mounted on the antenna platform; at least one first radar receiving antenna 4 is mounted on the antenna platform, and the first radar receiving antenna 4 is configured to transmit in Ka-band or X-band frequencies. The radar absorbing material 5 is set on the antenna platform, and the radar absorbing material 5 is linearly located between the first radar transmitting antenna 3 and the first radar receiving antenna 4, and is used to attenuate the linear transmission of the signal between the radar transmitting antenna and the radar receiving antenna. The first low-power transmitter 6 is communicatively connected to the first radar transmitting antenna 3 and is configured to generate radio frequency signals in a predetermined frequency band for the radar transmitting antenna to transmit. The first network analyzer 7 is communicatively connected to the first radar receiving antenna 4 and is configured to determine the received power of the transmitted radio frequency signal reflected from the countermeasures units dispersed above the antenna platform 2. The countermeasure dispersion mechanism disperses the countermeasure elements into a volume at a certain distance above the antenna platform 2.

2. The passive foil interference testing device based on a vector network analyzer according to claim 1, characterized in that: The radar absorbing material 5 includes one or more of the following: foam absorber, polyurethane foam, Holland shield, rubber foam, ferrite material, semiconductor, graphite, carbon nanotubes, iron ball coating, or carbon nanotube-based coating, wherein the polyurethane foam is carbon loaded with conductive carbon black and / or crystalline graphite particles, and the rubber foam is impregnated with carbon and iron.

3. The passive foil interference testing device and method based on a vector network analyzer according to claim 1, characterized in that: The counter-dispersion mechanism is located 4.5-15M above the antenna platform 2. The counter-dispersion mechanism includes an airflow unit configured to control the airflow passing through the counter-dispersion unit during testing to achieve consistent dispersion.

4. The passive foil interference testing device based on a vector network analyzer according to claim 1, characterized in that: At least one second radar transmitting antenna 3.1 and a second radar receiving antenna 4.1 are provided on the antenna platform 2; a second low-power transmitter 6.1 is communicatively connected to the second radar transmitting antenna and configured to generate a second radio frequency signal in a second frequency band for transmission with the second radar transmitting antenna; A second network analyzer 7.1 is communicatively connected to the second radar receiving antenna 4.1 and configured to determine the received power of the second radio frequency signal reflected from the countermeasures units dispersed above the antenna platform 2; The radar absorbing material 5 is linearly located between the second radar transmitting antenna 3.1 and the second radar receiving antenna 4.

1.

5. The passive foil interference testing device based on a vector network analyzer according to claim 1, characterized in that: The first low-power transmitter 6 and the second low-power transmitter 6.1 are configured to operate within the range of 20-21 dBmw.

6. A test method for a passive foil interference testing device based on a vector network analyzer as described in claim 1, characterized in that: At least one first radar transmitting antenna 3 and at least one first radar receiving antenna 4 are provided, both connected to the transmitting and receiving mechanism. The first radar transmitting antenna 3 transmits continuous wave or pulse electromagnetic radiation to the countermeasure unit 8, and then the first radar receiving antenna 4 receives the reflected electromagnetic radiation pulse. The returned pulse is then measured at the site to determine the characteristics of the object. The frequency of the transmitted electromagnetic radiation depends on the desired target. The ratio between the transmitted signal and the returned signal is used to calculate the two-dimensional projected area of ​​the countermeasure unit 8 measured by the radar wave. This ratio represents the radar cross section of the object. Formula 1 shows the method for calculating the radar cross section (RCS) of a sphere. (1) Where R is the distance to the target; S r and S t These are the return power and the transmit power, respectively, G t and G r These are the gains of the transmitting and receiving antennas, respectively, and λ is the wavelength of the radiated signal used.

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