Space electromagnetic field intensity measuring device based on unmanned aerial vehicle

Abstract

The utility model relates to the field of antenna emission lobe and space electromagnetic wave intensity measurement, in particular to a space electromagnetic field intensity measuring device based on an unmanned aerial vehicle. The antenna comprises an analog unit and a digital unit, the analog unit comprises an omnidirectional receiving antenna and a receiving channel, the receiving channel internally comprises at least three receiving channel branches, the output of the omnidirectional receiving antenna is connected to a receiving channel coupler, and the receiving channel is expanded into a plurality of branch channels by using two couplers. And the equipment measurement range is expanded. The device provided by the utility model can measure the intensity of space electromagnetic waves, completes the measurement of radar antenna emission lobes, and solves the problem that the resultant magnetic field of a plurality of radiation sources is difficult to test.

Description

Technical Field

[0001] This utility model relates to the fields of space electromagnetic field strength measurement and unmanned aerial vehicles (UAVs), and specifically to a space electromagnetic field strength measurement device based on UAVs. Background Technology

[0002] With the development of modern electronic countermeasures technology, radar decoy systems have been widely used as an effective means of radar countering anti-radiation missiles (ARMs). National military standards such as GJB7210-2011 stipulate that radar decoys must be able to cover the average sidelobe power of the protected radar. This requires testing the transmitted beam of the radar antenna to obtain the average sidelobe when the radar is operating normally.

[0003] Currently, there is no equipment available that can perform low-cost, convenient, and rapid testing of radar antenna transmit lobes during normal radiation. Anechoic chamber testing is costly, time-consuming, and cannot directly obtain measured data of the antenna's transmit lobes during normal radar transmission. When using elevated towers for field testing, the height and limitations of the towers restrict the measurement of radar lobes, often focusing on the horizontal lobes and failing to measure the elevation lobes. While large-payload UAVs carrying spectrum analyzers can test the elevation lobes, this method is challenging due to testing difficulties, data acquisition difficulties, and high costs. While methods for using UAVs for antenna field testing are becoming increasingly sophisticated, a low-cost, convenient device capable of directly measuring and storing spatial electromagnetic wave intensity is still lacking. Summary of the Invention

[0004] To address the shortcomings of the prior art, this invention provides a space electromagnetic field strength measurement device based on an unmanned aerial vehicle (UAV). This invention includes an analog unit and a digital unit. The analog unit includes an omnidirectional receiving antenna and a receiving channel. The receiving channel internally includes at least three receiving channel branches, and the output of the omnidirectional receiving antenna is connected to a receiving channel coupler. This invention solves the problem of insufficient detection capability of a single linear detector.

[0005] The technical solution of this utility model is: a space electromagnetic field strength measurement device based on a UAV, comprising an analog unit and a digital unit. The analog unit includes an omnidirectional receiving antenna and a receiving channel. The receiving channel includes at least three receiving channel branches. The output of the omnidirectional receiving antenna is connected to a receiving channel coupler. The characteristic feature is that one output of the receiving channel coupler is connected to a first limiter, the output of the first limiter is connected to a first bandpass filter, the output of the first bandpass filter is connected to a first detector, and the output of the first detector is connected to the AD port I processed by the digital unit. Another output of receiving channel coupler I is connected to coupler II, and one output of coupler II (…) The output of the direct-through port is connected to the second limiter, the output of the second limiter is connected to the second bandpass filter, the output of the second bandpass filter is connected to the second detector, and the output of the second detector is connected to the AD port II of the digital unit processing. The other output of coupler II (coupler port) is connected to the third limiter, the output of the third limiter is connected to the low-noise amplifier, the output of the low-noise amplifier is connected to the third bandpass filter, the output of the third bandpass filter is connected to the first amplifier, the output of the first amplifier is connected to the matching attenuator, the output of the matching attenuator is connected to the second amplifier, the output of the second amplifier is connected to the third detector, and the output of the third detector is connected to the AD port III of the digital unit processing.

[0006] The beneficial effects of this invention are: by using drones, electromagnetic wave measurement equipment can easily measure the radar's transmission lobes in the far field and plot the radar transmission lobes based on the test results; at the same time, it can also measure the intensity of the electromagnetic field of interest in space; using this equipment to test the transmission lobes of radar or other equipment greatly reduces the investment of manpower and material resources, and the test of lobe data is more complete. Attached Figure Description

[0007] Figure 1 This is a block diagram of the components of this utility model.

[0008] Figure 2 This is a block diagram of the electromagnetic wave intensity measuring device of this utility model.

[0009] Figure 3 This is a block diagram of the principle of the simulation unit of this utility model.

[0010] Figure 4 This is a block diagram of the principle of the digital unit of this utility model. Detailed Implementation

[0011] The present invention will be further described below with reference to the accompanying drawings.

[0012] like Figures 1 to 4 As shown, this utility model is based on a modular design, which separates the functions of the analog unit and the digital unit. The receiving channel of the analog unit adopts a multi-branch design to expand its microwave amplitude measurement range.

[0013] like Figure 3 and Figure 4 As shown, this utility model discloses a space electromagnetic field strength measurement device based on an unmanned aerial vehicle (UAV), comprising an analog unit and a digital unit. The analog unit includes an omnidirectional receiving antenna and a receiving channel. The receiving channel internally includes at least three receiving channel branches. The output of the omnidirectional receiving antenna is connected to a receiving channel coupler. One output (coupler port) of receiving channel coupler I is connected to a first limiter. The output of the first limiter is connected to a first bandpass filter. The output of the first bandpass filter is connected to a first detector. The output of the first detector is connected to the AD port I processed by the digital unit. Another output (straight-through port) of receiving channel coupler I is connected to coupler II. One output (straight-through port) of coupler II is connected to a second limiter. The output of the second limiter is connected to a second bandpass filter. The output of the second bandpass filter is connected to a second detector. The output of the second detector is connected to the AD port II processed by the digital unit. The other output of coupler II (coupler port 2) is connected to the third limiter. The output of the third limiter is connected to the low-noise amplifier. The output of the low-noise amplifier is connected to the third bandpass filter. The output of the third bandpass filter is connected to the first amplifier. The output of the first amplifier is connected to the matching attenuator. The output of the matching attenuator is connected to the second amplifier. The output of the second amplifier is connected to the third detector. The output of the third detector is connected to the AD port III of the digital unit.

[0014] The first, second, and third detectors of this utility model are linear detectors.

[0015] Each receiving channel branch of this invention has a linear detector to detect the amplitude of the microwave signal entering the detector. The detection amplitude range of the linear detector is typically -20dBm to 10dBm, with a detection range of 30dB. Taking a certain type of radar as an example, the radar has a transmit power of 16kW, an antenna gain of 33dB, a maximum sidelobe of -30dBc, a minimum sidelobe of approximately -70dBc, and a far-field range of the radar... (D is the maximum size of the radar array aperture) When the wavelength is 6.5m and D is 6.5m, the far-field range is 395m. In this case, R is taken as 500m. According to the radar radiated power density formula... (P) t Radar transmit power, G t Using antenna gain (where R is the distance to the radar), the power densities of the main lobe, maximum sidelobe, and minimum sidelobe at a distance of 500m can be calculated to be 34dBm / m. 2 4dBm / m 2 -36dBm / m 2If the measuring equipment has only one receiving channel and one linear detector, its measurement range is only 30dB, which cannot meet the measurement requirement of this type of radar with a beam amplitude range of 70dB. By expanding the receiving channels of the measuring equipment, allowing each branch of the receiving channel to measure microwave signals of different ranges, the problem of insufficient detection capability of a single linear detector can be solved.

[0016] The digital unit of this invention comprises a microprocessor, a high-stability crystal oscillator, a high-precision BeiDou positioning module, a FLASH memory, and a communication interface. The microprocessor serves as the data processing core, sending the detector voltage output from the receiving channel to the microprocessor's AD sampling interface for sampling. The high-stability crystal oscillator provides a stable sampling clock for the microprocessor. The high-precision BeiDou positioning module transmits the device's spatial coordinates and time stamp information to the microprocessor in real time. The FLASH memory stores the real-time data generated by the microprocessor. The communication interface is used to read and erase data in the FLASH memory, and to send the spatial coordinates and time stamp information output by the UAV into the device as backup data during data processing. The measuring device can be combined with a human-machine interface, utilizing the spatial accessibility of the UAV to deliver the device to any area of ​​interest to measure the electromagnetic field strength of that space and automatically record the measurement results.

[0017] The analog unit, or receiving channel module, is the core component of this invention and a replaceable part for extending the applicable frequency band of the equipment. Utilizing an extended receiving channel design, it expands the detection amplitude range several times to approximately 90dB, overcoming the shortcomings of a single linear detector that cannot fully cover the amplitude range of the radar antenna's transmitted beam. Simultaneously, the microprocessor's AD sampling interface quantizes the detected signals output from each corresponding receiving channel branch, performs a comprehensive judgment on each sampled value, and adds the channel compensation value for that branch to obtain the final measurement result. Ideally, the analog and digital units of this invention are connected via connectors; that is, the analog unit is a detachable module. By replacing the corresponding analog unit module according to the radar operating frequency band to be measured, without replacing the digital unit, the applicable frequency band of the measurement equipment can be quickly changed. This provides a universal hardware platform for modifying existing measurement equipment to measure radar transmitted beams at different frequency bands, shortening the development cycle and reducing technical risks.

[0018] The measuring equipment boasts a wide dynamic range, enabling it to test radar transmit lobes and perform spatial synthetic magnetic field measurements and pattern mapping for multi-source systems. Mounted on a UAV, the equipment, operated by a pilot, flies along a pre-planned or arbitrary path. Microwave signals received from the omnidirectional antenna on the equipment enter the receiving channel, then are routed through three receiving channel branches via signal distribution circuits. These branches process the incoming signals before sending them to a microprocessor for analog-to-digital conversion. Simultaneously, a highly stable clock circuit provides a reliable sampling clock signal to the microprocessor, while a high-precision BeiDou positioning module sends the equipment's spatial location (latitude, longitude, altitude, and time scale) to the microprocessor. The microprocessor comprehensively analyzes the signals from the three receiving channel branches, processing data from the high-precision BeiDou module and the UAV to ultimately generate complete test data including longitude, latitude, and altitude (from the equipment's built-in BeiDou module); longitude, latitude, and altitude (provided by the UAV); and electromagnetic field strength (in dBm / m). 2 Time information and other data are stored in the FLASH memory. After the device completes testing, the data is exported via the communication interface, and then processed to obtain the antenna transmit lobe diagram or the spatial electromagnetic field distribution map.

[0019] The components and modules used in the measurement equipment can all be obtained through market procurement. Currently, the relevant mature components or modules are relatively small in size and weight. By analogy with the size and weight of a single-channel microwave measurement equipment, the weight of this measurement equipment is no more than 500g, the size is no more than 150mm×100mm×30mm, and the antenna weight is no more than 50g.

[0020] In the operation of this invention, it is assumed that the gain of the omnidirectional receiving antenna of the microwave measurement equipment is 0dB. The operation of each branch is analyzed when different transmit lobes enter the three branches.

[0021] The antenna main lobe energy enters the measuring equipment: receiving channel branch 1. Utilizing the coupler's function, after the high-power microwave signal enters the main receiving channel, only a weak signal is allowed to enter receiving channel branch 1. Assuming the coupler's coupling is -30dB, the amplitude of the microwave signal entering receiving channel branch 1 from the radar main lobe is 4dBm (channel loss is not considered here), which is just within the detection range of the linear detector. At this time, the amplitudes of the microwave signals entering receiving channel branches 2 and 3 are 34dBm and 24dBm respectively. With the action of the limiter, the input amplitude is limited to 10dBm. The detection amplitudes of receiving channel branches 2 and 3 are in a saturated output state, but without damaging these two branches.

[0022] When the energy at the largest sidelobe enters the measuring device: the microwave signal amplitude entering receiver branch 1 under the action of the coupler is -26dBm, which is below the effective detection amplitude of the detector, and the detection output value is zero. At this time, the amplitude signal entering receiver branch 2 is 4dBm, which is within the detection amplitude range of receiver branch 2; the signal amplitude entering receiver branch 3 is -6dBm. Receiver branch 3 contains a linear amplifier circuit (amplification factor of 40dB, saturation output value of 10dBm). At this time, the output power of the amplifier circuit in branch 3 is saturated, and the output of the detector is in a saturated state.

[0023] When the energy at the smallest sidelobe enters the measuring device: the microwave signal amplitude entering the receiving channel branch 1 under the action of the coupler is -66dBm, which is below the effective detection amplitude of the detector, and the detection output value is zero. At this time, the energy entering the receiving channel branch 2 is -36dBm, which is below the effective detection amplitude of the receiving channel branch 2. The energy entering the receiving channel branch 3 is -46dBm. The receiving channel branch 3 contains a linear amplifier circuit (amplification factor of 40dB, saturation output value of 10dBm). At this time, the microwave signal amplitude sent to the linear detector from branch 3 is -6dBm, which is within the effective detection amplitude of the detector.

[0024] The receiving channel module of this invention has only one external antenna interface. The receiving channel is divided into three receiving channel branches through splitting devices such as -30dB couplers and -10dB couplers. The three receiving channel branches share a single receiving antenna. The three divided receiving channels can process the electromagnetic field within their respective measurement ranges. The output value of the linear detector in each receiving channel branch is considered valid only if it is within the linear detection range; saturation or a zero output indicates that the data output of that receiving channel branch is invalid.

[0025] At a distance of 500m from the radar (far field), receiver channel branch 1 is used to measure the microwave amplitude of the antenna's main lobe beam, with a measurable amplitude range of [10dBm / m]. 2 40dBm / m 2 The receiving channel branch 2 is used to measure the microwave amplitude of the antenna sidelobes, and its measurable amplitude range is [-20 dBm / m]. 2 10dBm / m 2 The receiving channel branch 3 is used to measure the microwave amplitude of the antenna sidelobes, and its measurable amplitude range is [-50 dBm / m]. 2 -20dBm / m 2This measurement equipment completely covers the antenna transmit beam of the radar. The three measurement ranges are divided, and attention needs to be paid to the coverage at the critical points to prevent missed measurements. The integrity of the measurement range is ensured by extending the receiving channel branches and allowing a limited overlap of measurements at the three critical points. Specific adjustments will need to be fine-tuned during engineering implementation.

[0026] The measurement results are sent to the microprocessor's AD sampling interface for AD sampling. After comprehensive processing of the data sampled from each AD port, the final measurement results, along with the device's latitude, longitude, altitude, and time information, are generated into a batch file and stored in the FLASH chip. The receiving channel is a high dynamic range receiving and processing channel. When testing the antenna transmission lobes and spatial magnetic fields of radiation sources such as radar, it can adaptively measure the magnetic field strength of the current beam in the face of the radar's main lobe and side lobe signals, and output the correct measurement results.

[0027] The features of this utility model device are: Large measurement range: When measuring the same radar transmit lobe, no additional operation or parameter settings are required when facing beams with different gains. After setting the UAV's flight path, the device can complete the required data acquisition in one go. High versatility: The product fully considers the transmit lobe testing needs of different radar models operating in the same frequency band. Small size and light weight: The device's size and weight are much smaller than spectrum analyzers and other similar equipment, resulting in lower payload requirements for the UAV carrying the device. Modular design and strong scalability: The device adopts a modular design, allowing for expansion of the applicable frequency bands by replacing the receiving channel module. Continuous operation capability: The device has a large data storage space, enabling real-time storage and retrieval of test data, with data read back after the test is completed.

Claims

1. A device for measuring spatial electromagnetic field intensity based on unmanned aerial vehicle, comprising an analog unit and a digital unit, the analog unit comprising an omnidirectional receiving antenna and a receiving channel, the receiving channel internally comprising at least 3 receiving channel branches, the omnidirectional receiving antenna being connected to a receiving channel coupler, characterized in that: The one-way output of the receiving channel coupler I is connected with the first limiting amplifier, the output of the first limiting amplifier is connected with the first band-pass filter, the output of the first band-pass filter is connected with the first detector, and the output of the first detector is connected with the AD port I of the digital unit processing; the other-way output of the receiving channel coupler I is connected with the coupler II, the one-way output of the coupler II is connected with the second limiting amplifier, the output of the second limiting amplifier is connected with the second band-pass filter, the output of the second band-pass filter is connected with the second detector, and the output of the second detector is connected with the AD port II of the digital unit processing; the other-way output of the coupler II is connected with the third limiting amplifier, the output of the third limiting amplifier is connected with the low-noise amplifier, the output of the low-noise amplifier is connected with the third band-pass filter, the output of the third band-pass filter is connected with the first amplifier, the output of the first amplifier is connected with the matching attenuator, the output of the matching attenuator is connected with the second amplifier, the output of the second amplifier is connected with the third detector, and the output of the third detector is connected with the AD port III of the digital unit processing. 2.The unmanned aerial vehicle space electromagnetic field strength measuring device according to claim 1, wherein: The first detector, the second detector and the third detector are linear detectors. 3.The unmanned aerial vehicle space electromagnetic field strength measuring device according to claim 1, wherein: The digital unit comprises a microprocessor, a high-stability crystal oscillator, a high-precision Beidou positioning module, a FLASH and a communication interface; the microprocessor samples the AD port; the high-stability crystal oscillator provides a stable sampling clock for the microprocessor; the high-precision Beidou positioning module transmits the spatial coordinate information and time scale information of the device to the microprocessor in real time; the FLASH stores the real-time data generated by the microprocessor; and the communication interface is used for reading and erasing the data in the FLASH. 4.The unmanned aerial vehicle space electromagnetic field strength measuring device according to claim 1, wherein: The analog unit and the digital unit are connected through a plug-in interface.

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