CN112859028B - Method and system for collecting and spectrum analyzing scattering time domain echo of external field object - Google Patents
Method and system for collecting and spectrum analyzing scattering time domain echo of external field object Download PDFInfo
- Publication number
- CN112859028B CN112859028B CN202110077803.7A CN202110077803A CN112859028B CN 112859028 B CN112859028 B CN 112859028B CN 202110077803 A CN202110077803 A CN 202110077803A CN 112859028 B CN112859028 B CN 112859028B
- Authority
- CN
- China
- Prior art keywords
- time domain
- scattering
- field
- ground
- measurement
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000000034 method Methods 0.000 title claims abstract description 75
- 238000001228 spectrum Methods 0.000 title claims description 36
- 238000005259 measurement Methods 0.000 claims abstract description 85
- 238000012360 testing method Methods 0.000 claims abstract description 61
- 238000010183 spectrum analysis Methods 0.000 claims abstract description 34
- 238000002474 experimental method Methods 0.000 claims abstract description 29
- 238000010276 construction Methods 0.000 claims abstract description 11
- 238000004364 calculation method Methods 0.000 claims abstract description 5
- 230000005684 electric field Effects 0.000 claims description 30
- 239000002689 soil Substances 0.000 claims description 30
- 239000004568 cement Substances 0.000 claims description 20
- 230000008569 process Effects 0.000 claims description 16
- 230000009466 transformation Effects 0.000 claims description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 13
- 239000011358 absorbing material Substances 0.000 claims description 9
- 230000008859 change Effects 0.000 claims description 7
- 244000025254 Cannabis sativa Species 0.000 claims description 6
- 241000196324 Embryophyta Species 0.000 claims description 6
- 238000012545 processing Methods 0.000 claims description 6
- 230000003595 spectral effect Effects 0.000 claims description 6
- 238000009795 derivation Methods 0.000 claims description 5
- 230000000694 effects Effects 0.000 claims description 5
- 230000001131 transforming effect Effects 0.000 claims description 4
- 230000006870 function Effects 0.000 claims description 3
- 230000001105 regulatory effect Effects 0.000 claims description 3
- 230000008054 signal transmission Effects 0.000 claims description 3
- 239000008247 solid mixture Substances 0.000 claims description 2
- 238000004458 analytical method Methods 0.000 abstract description 4
- 230000008092 positive effect Effects 0.000 description 8
- 238000010586 diagram Methods 0.000 description 5
- 238000002592 echocardiography Methods 0.000 description 4
- 230000007547 defect Effects 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 238000004088 simulation Methods 0.000 description 3
- 238000003491 array Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 241000238631 Hexapoda Species 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000007405 data analysis Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 230000001932 seasonal effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000009897 systematic effect Effects 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
- G01S7/411—Identification of targets based on measurements of radar reflectivity
Landscapes
- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Computer Networks & Wireless Communication (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Radar Systems Or Details Thereof (AREA)
- Geophysics And Detection Of Objects (AREA)
Abstract
The invention belongs to the technical field of target scattering characteristic measurement and analysis, and discloses an external field object scattering time domain echo acquisition and spectrum analysis method and system, wherein the external field object scattering time domain echo acquisition and spectrum analysis system comprises the following steps: the device comprises an environment building module, a device connecting module, a test frame adjusting module, a calibration module, a target measuring module, a data acquisition module and a time domain echo spectrum analysis module; according to the external field object time domain echo measuring equipment, different grounds are selected to measure the time domain echo, a construction method of external field ground target measurement is provided, and the construction of an external field environment is simplified and facilitated by adopting a method of delineating a region. According to the invention, a theoretical calculation formula of the effective irradiation area of the antenna is analyzed, vertical incidence is provided, the height is reduced, the effective irradiation area of the antenna is obtained by combining the built external field measurement environment in a quick and approximate way, and the alignment problem of an external field experiment is solved.
Description
Technical Field
The invention belongs to the technical field of measurement and analysis of scattering characteristics of targets, and particularly relates to a method and a system for collecting and analyzing echoes of an external field object scattering time domain.
Background
At present, when a radar detects a target, the radar emits electromagnetic waves to detect the target, and the electromagnetic wave signals received after scattering contain scattering signals of the detected target and signals of environmental noise. The scattering echo measurement of the external ground object can obtain a large amount of ground object scattering characteristic data, a scattering characteristic database of the object is further established, and the scattering characteristic database of the terrain region is established through the ground object background scattering characteristic measurement, so that effective parameters can be provided for object identification and instrument guidance.
The built external field target scattering characteristic database has wide application prospect and remarkable academic value in both military and civil fields. In the military field, when a target radar detects, due to the existence of various background noises, a large amount of clutter is contained in a received echo signal, so that the accurate recognition of the radar to the target can be greatly influenced, the clutter problem is solved, firstly, a ground object scattering characteristic measurement experiment is required to be carried out, a target scattering characteristic database is established, spectrum analysis is carried out on different ground object scattering characteristics, the rule of the ground object background scattering characteristics is found out, and the clutter is removed, so that the recognition precision of the radar to the target is improved. In the civil field, the water content of plants and soil can be inverted according to the measured scattering coefficient by carrying out a measurement experiment on the scattering coefficient of a crop area, the growth of crops is accurately monitored, predicted and forecasted, and the environmental information of seasonal change such as weed and insect damage and the soil humidity condition is monitored.
The method for researching the ground object scattering comprises an experiment method and a simulation method, and the simulation method has relatively low practical value of scattering characteristic data obtained by performing simulation experiments due to the difficulty in modeling ground object targets such as cement ground, sandy soil, snow and the like. Therefore, the specific ground object scattering characteristic measurement experiment is the most effective method for performing ground object scattering research, and the ground object scattering characteristic data obtained through the experimental method has higher practical value.
According to different experimental environments, the ground object scattering characteristic research experiment is generally divided into internal field measurement and external field measurement. At present, the main internal field measurement is mainly performed by a microwave darkroom, the measurement condition of the microwave darkroom is harsh, and the requirement on the wave absorbing capacity of the environment is extremely high, so that the clutter filtering effect is very good, and meanwhile, the experimental environment also causes that the darkroom measurement result is not consistent with the actual situation. Therefore, for the research of the scattering characteristics of the ground objects, the optimal effect can be achieved by adopting an external field experiment to measure.
According to different measurement system modes, the scattering measurement experiment can be divided into a frequency domain measurement system and a time domain measurement system. The frequency domain measuring system emits a single frequency harmonic signal when measuring, and the scattering intensity of the single frequency harmonic signal is determined by the received echo envelope. The time domain measurement system transmits pulse signals, and performs high-speed broadband sampling on the pulse response of the target, so that the transient response of the ground object target can be obtained, and the target scattering information with a certain bandwidth can be obtained after one-time Fourier transformation. Compared with a frequency domain system, the time domain measurement system has higher measurement efficiency and is more suitable for external field experiments.
When the external field experiment is carried out, the experimental conditions are constrained by various conditions due to the complex environment of the external field experiment, and different experimental schemes are designed according to different measured ground object targets, so that the specific experimental scheme of the external field object scattering characteristic experiment is scarce, and the specific method for carrying out spectrum analysis on the acquired time domain echo is also rare.
Through the above analysis, the problems and defects existing in the prior art are as follows:
(1) The experimental theory about ground object scattering time domain echo collection is fewer, and many problems in the aspect of measurement technology still need to be solved, and the overall design scheme of measurement experiments is fewer, and the introduction of detailed experimental flows is blank.
(2) The method for carrying out spectrum analysis on the time domain echo signals obtained by external field measurement is less, no systematic and detailed theory is adopted to process the time domain echo signals, and useful information in the time domain echo signals is extracted to carry out characteristic distinction on different ground object targets.
The difficulty of solving the problems and the defects is as follows: under the condition of an external field experiment, the calibration problem of a measurement system is carried out; and selecting an experimental background, and performing spectrum analysis on the time domain echo signals.
The meaning of solving the problems and the defects is as follows: the invention fills the blank of the time-domain echo signal acquisition experiment of the external field object, provides a spectrum analysis method of the time-domain echo signal, lays a certain theoretical foundation for the subsequent experiment, and promotes the development of the electromagnetic measurement experiment.
Disclosure of Invention
Aiming at the problems existing in the prior art, the invention provides a method and a system for collecting and analyzing the scattering time domain echo of an external field object.
The invention is realized in such a way that an external field object scattering time domain echo collecting and spectrum analyzing method comprises the following steps:
firstly, constructing external field conditions suitable for experiments, wherein the external field conditions are required to be constructed according to actual ground object target requirements, and the ground object targets are roughly divided into cement ground, bare soil, grasslands and the like; when the environment is built, after a certain range of ground environment is selected, the periphery of the ground environment is paved with wave-absorbing materials to limit the irradiation area of the loudspeaker, and the effective irradiation area is calculated. The method has the advantages of providing good measurement conditions for the external field object measurement experiment, and facilitating the realization of the measurement experiment;
step two, preparing an experimental instrument, and connecting a time domain measurement system integrated computer with a computer display screen. The method has the positive effects that whether the core equipment of the measurement experiment operates normally or not is checked;
and thirdly, stably placing the test frame, keeping the transverse shaft of the test frame horizontal to the ground, and then installing the horn antenna on the test frame. The method has the positive effects that the position of the loudspeaker relative to the ground to be tested can reach the condition of experimental requirements;
and fourthly, connecting the lines of the whole measuring system, wherein the connection process is strictly carried out according to the steps, and after wiring is completed, the system is powered by using a portable mobile power supply. The positive effect is to ensure that the whole measuring system can be normally connected and operated;
and fifthly, after the experimental environment is built and a time measuring system is ready, covering the test ground with a wave absorbing material, placing a calibration ball under the horn antenna for calibration, and taking the measured time domain echo signal as successful calibration when the jitter is less than 3dB after Fourier transformation. The method has the positive effects that the measurement error of the time domain measurement system is checked, so that the error reaches the allowable range, and then the experiment is carried out;
and step six, in the built experimental environment, the placement and rotation directions of the transmitting and receiving horns are regulated, the measurement of the target ground under different angles is carried out, and the time domain echo signals are acquired. The method has the positive effects of measuring the echoes of ground targets in different polarization modes;
and step seven, processing the time domain echo signals, and carrying out section Fourier transform on the time domain echo signals obtained by measurement. The method has the positive effects that the spectrum analysis is easier to carry out by transforming the disordered time domain waveform into the frequency domain;
and step eight, observing the converted frequency spectrum characteristics, performing spectrum analysis, and analyzing the scattering characteristics of different ground targets. The method has the positive effect that the scattering characteristics of different floors can be known by analyzing the frequency spectrums of the different floors.
In the first step, the indexes of the environment construction are specifically:
(1) The cement floor can be regarded as a rough surface under the irradiation of a radar in a C, X, ku, ka frequency band, a relatively flat cement floor is selected as a test site, and a wave-absorbing material is used for auxiliary construction, so that a square area with the side length of 0.5m is used as a vertical irradiation surface;
(2) The bare soil mainly comprises water and solid mixture, and the reflection coefficients of the soil with different water contents are greatly different, so the water content of the bare soil is used as the main basis for selecting the test soil, and the limitation of the practical experimental conditions is considered, and the selected soil has a volume weight of 1.10-1.50g/cm 3 Is a soil of (2);
(3) The grasslands are selected, the heights of grass plants are smaller than 20cm, the grass plants are distributed sparsely, weeds have no certain spatial orientation, and the water content of soil is about 20%.
In the first step, the method for calculating the effective irradiation area of the antenna is as follows:
two receiving and transmitting antennas which are arranged in parallel are selected, the area irradiated to the ground is an elliptic area, the long sides of the ellipses a1 and a2 are respectively a 1 And a 2 Short sides are b respectively 1 And b 2 The central point is K 1 And K 2 The calculation expression is as follows:
wherein:
wherein θ is 1 、φ 1 And theta 2 、φ 2 Beam widths representing the receive and transmit antenna depression and azimuth planes, respectively; the elliptical overlapping area irradiated by the two antennas is the effective irradiation area of the antennas, and the expression is as follows:
taking into account the bandwidth deltaf of the intermediate frequency filter in the receiver I The expression is:
in the middle of
There are two limiting angles alpha c When alpha < alpha c The effective radiating area of the antenna is the overlapping area of two ellipses, when alpha > alpha c The effect of receiver bandwidth needs to be considered; when measuring, the height of the horn antenna is not exceeded, the time domain reflection echo of the vertical irradiation is mainly measured, the irradiation angle of the antenna is always smaller than the limiting angle, and the irradiation area can be reduced to:
A＝2absin -1 x 1 -adx 1 ；
wherein the method comprises the steps of
When the antenna irradiates vertically, the height of the antenna is lower due to the fact that the test environment is built in advance, the divided measurement ground area is controlled within the effective irradiation area of the antenna, and therefore the area of the delineating area can be approximately regarded as the effective irradiation area of the antenna only by calculating the area of the delineating area.
In the third step, according to different pulse frequency bands of measurement and emission, selecting horn antennas corresponding to the same frequency band for measurement, after the antennas are selected, vertically and downwards mounting the horn mouth on a test support, and adjusting the test support when mounting, so that two horns are positioned right above the center of the test ground;
according to the derivation of the effective irradiation area of the test ground, a proper distance needs to be selected, so that the whole delineated test ground is positioned in the effective irradiation area of the antenna, and the height of the test ground is about 1.5m.
Further, when the antenna is installed, the laser level is used as an aid, the wheel disc of the test support is adjusted, the rotating arm of the test support is enabled to be horizontal to the ground, and the horn antenna opening is perpendicular to the ground.
Further, in the fourth step, the specific process of line connection of the whole measurement system is as follows:
firstly, connecting a time domain measurement system integrated computer with an output power amplifier, then connecting the output power amplifier with a transmitting horn antenna, then connecting a receiving horn antenna with a receiving power amplifier, and finally connecting the receiving power amplifier with the time domain measurement system integrated computer.
In the fourth step, after the environment is ready for construction before testing, when the system circuit is connected, the system circuit is ensured to be connected accurately, otherwise, the power amplifier and the time domain measurement system may be damaged, and the connection steps must be gradually performed as follows:
the time domain measuring system is connected with the transmitting power amplifier through a radio frequency line, and the selecting of the transmitting power amplifier also selects the corresponding power amplifier according to the frequency of the transmitting pulse;
connecting a transmitting power amplifier with a transmitting antenna;
connecting a receiving antenna and a receiving power amplifier;
connecting a receiving power amplifier and a time domain measuring system;
the signal transmission process of the whole measurement experiment needs to form a closed loop, and the power supply can be switched on after the connection is ready;
after the circuit is switched on without errors, measuring the calibration body and the ground object target, and storing the acquisition result in a time domain echo measurement system; wherein, the ground object target includes: scaling bodies and cement plots, bare soil and grassland targets.
Further, in the seventh step, the process of processing the acquired time domain echo is as follows:
when measuring in the near field of a time domain plane, two methods can be used for carrying out spectrum analysis of a time domain echo signal to obtain RCS data:
the first is that time domain signal data obtained by time domain scattering measurement is subjected to Fourier transform to obtain frequency domain scattering data, and then near-field and far-field transformation is performed by a spectrum unfolding theory to obtain far-field scattering data, so that RCS data of the scattered data are obtained;
secondly, directly carrying out spectrum expansion theory on time domain incoming scattering data to obtain far-field time domain scattering data, and carrying out Fourier transformation to obtain far-field frequency domain scattering data so as to obtain RCS data;
the basic derivation of the time-frequency domain near-field scatterometry equation is as follows:
the near-far field transform pair is:
first, a spectral function is establishedRelationship with near field electric field component E (x, y, z):
wherein the method comprises the steps of
Then according to the resident phase method, the approximate expression of the method can be obtained:
and then according to the definition formula of radar scattering interface:
wherein: e (E) s (r) is the far field scattering electric field; e (E) i Is the incident electric field; the equation for calculating the RCS from the far field electric field can be deduced by combining the above two equations:
on the basis of the above derived formula, the field point coordinates are set as r according to the Fourier transform 0 ，For a unit vector from a source point to an observation point, k is a wave number, c is a far field electric field equation of a light velocity derivable time domain, and is as follows:
the time-harmonic spectrum is defined as:
the relation between the obtained time domain spectrum and the far field electric field is that
The relationship between the frequency domain near field electric field and the time harmonic spectrum is obtained in a comprehensive way:
and then obtaining the relation between the time domain near field electric field and the time domain spectrum according to Fourier transformation:
while the expression of the time domain far field electric field can be simplified as:
can be defined according to RCSAnd solving RCS after Fourier transforming the far-field time domain electric field.
In the eighth step, the transformed spectrum characteristics are observed, and the specific process of spectrum analysis is as follows:
when the acquired time domain echo is processed, after the acquired near field data is transformed to a far field, the acquired near field data is transformed according to the equation of frequency domain fast Fourier transform:
the time domain signal is programmably transformed to the frequency domain and its spectral characteristics are analyzed.
Another object of the present invention is to provide an external field object scattering time domain echo collecting and spectrum analyzing system for implementing the external field object scattering time domain echo collecting and spectrum analyzing method, the external field object scattering time domain echo collecting and spectrum analyzing system comprising:
the environment building module is used for building experimental objects required by the time domain echo measurement of the external field object;
the equipment connection module is used for connecting the whole external field time domain testing system with the time domain measuring system integrated computer, the transmitting power amplifier, the transmitting horn antenna, the receiving horn antenna and the receiving power amplifier through radio frequency lines, and finally, supplying power by using a portable mobile power supply;
the test frame adjusting module is used for adjusting the horizontal rotation angle and the height of the horn antenna arranged on the test frame;
the calibration module is used for checking the measurement error of the system after the experimental environment is built;
the target measurement module is used for measuring the built background environment and setting the transmitted pulse waveform and frequency;
the data acquisition module is used for measuring three groups of data on different ground object targets under the same measurement condition, wherein the difference of the maximum and minimum voltage amplitude values of each group of data is smaller than that of the data, namely the data can be regarded as acquired echo data, and the optimal data group is selected for subsequent spectrum analysis;
and the time domain echo spectrum analysis module is used for carrying out Fourier change on the acquired time domain echo waveform to obtain a frequency spectrum of the acquired time domain echo waveform and carrying out spectrum analysis.
Another object of the present invention is to provide a method for detecting an object by radar emission electromagnetic waves, which operates the system for collecting and analyzing the time-domain echoes of the scattering of the external field object.
By combining all the technical schemes, the invention has the advantages and positive effects that: according to the external field object time domain echo measuring equipment, different grounds are selected to measure the time domain echo, a construction method of external field ground target measurement is provided, and the construction of an external field environment is simplified and facilitated by adopting a method of delineating a region. According to the invention, a theoretical calculation formula of the effective irradiation area of the antenna is analyzed, vertical incidence is provided, the height is reduced, the effective irradiation area of the antenna is obtained by combining the built external field measurement environment in a quick and approximate way, and the alignment problem of an external field experiment is solved. The invention combines a theoretical formula to provide theoretical analysis of a spectrum analysis method of the time domain echo, and carries out Fourier spectrum transformation on the acquired time domain echo.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following description will briefly explain the drawings needed in the embodiments of the present application, and it is obvious that the drawings described below are only some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of an external field object scattering time domain echo acquisition and spectrum analysis system provided by an embodiment of the invention.
Fig. 2 is a flowchart of a method for collecting and spectrum analyzing an external field object scattering time domain echo according to an embodiment of the present invention.
Fig. 3 is a schematic diagram of ground construction to be tested according to an embodiment of the present invention.
Fig. 4 is a schematic diagram of a dual-antenna illumination area according to an embodiment of the present invention.
Fig. 5 is a schematic diagram of cement floor time domain echo provided by an embodiment of the present invention.
Fig. 6 is a schematic diagram of bare land time domain echo provided by an embodiment of the present invention.
Fig. 7 is a time-domain echo spectrogram of cement floor provided by an embodiment of the invention.
Fig. 8 is a time-domain echo spectrogram of a bare land provided by an embodiment of the present invention.
In the figure: 1. an environment building module; 2. a device connection module; 3. a test rack adjustment module; 4. a scaling module; 5. a target measurement module; 6. a data acquisition module; 7. and the time domain echo spectrum analysis module.
Detailed Description
The present invention will be described in further detail with reference to the following examples in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Aiming at the problems in the prior art, the invention provides a method and a system for collecting and analyzing the scattering time domain echo of an external field object, and the invention is described in detail below with reference to the accompanying drawings.
As shown in fig. 1, the system for collecting and analyzing the scattering time-domain echo of the external field object provided by the embodiment of the invention comprises:
the environment building module 1 is used for building experimental objects required by the time domain echo measurement of the external field object.
The equipment connection module 2 is used for connecting the whole external field time domain testing system with the time domain measuring system integrated computer, the transmitting power amplifier, the transmitting horn antenna, the receiving horn antenna and the receiving power amplifier through radio frequency wires, and finally, the portable mobile power supply is used for supplying power.
And the test frame adjusting module 3 is used for adjusting the horizontal rotation angle and the height of the horn antenna arranged on the test frame.
And the calibration module 4 is used for checking the measurement error of the system after the experimental environment is built.
And the target measuring module 5 is used for measuring the built background environment and setting the transmitted pulse waveform and frequency.
The data acquisition module 6 is used for measuring three groups of data on different ground object targets under the same measurement condition, the maximum and minimum voltage amplitude differences of each group of data are smaller than the maximum and minimum voltage amplitude differences, the data can be regarded as acquired echo data, and the optimal data group is selected for subsequent spectrum analysis.
The time domain echo spectrum analysis module 7 is used for carrying out Fourier transform on the acquired time domain echo waveform to obtain a frequency spectrum thereof and carrying out spectrum analysis.
As shown in fig. 2, the method for collecting and analyzing the scattering time domain echo of the external field object provided by the embodiment of the invention includes:
s101: constructing external field conditions suitable for experiments, wherein the external field conditions are required to be constructed according to actual ground object target requirements, and the ground object targets are basically divided into cement ground, bare soil and grasslands; when the environment is built, after a certain range of ground environment is selected, the periphery of the ground environment is fully paved with wave-absorbing materials to limit the irradiation area of the loudspeaker, so that the effective irradiation area is calculated more conveniently.
S102: the preparation of the experimental instrument is that the time domain measurement system integrated computer is connected with the computer display screen.
S103: the test rack is placed stably, the transverse axis of the test rack is kept horizontal to the ground, and then the horn antenna is mounted on the test rack.
S104: and (3) carrying out line connection of the whole measuring system, wherein the connection process is carried out strictly according to steps, and after wiring is finished, a portable mobile power supply is used for supplying power to the system.
S105: after the experimental environment is built and a time domain measuring system is ready, the test ground is covered by a wave absorbing material, a calibration ball is placed under a horn antenna for calibration, and the measured time domain echo signal is subjected to Fourier transformation and then jitter is smaller than 3dB, so that calibration is successful.
S106: in the built experimental environment, the placement and rotation directions of the transmitting and receiving horns are regulated, the measurement of the target ground under different angles is carried out, and the time domain echo signals are acquired.
S107: processing of the time domain echo signals. And performing section Fourier transform on the measured time domain echo signals.
S108: and observing the converted frequency spectrum characteristics, and performing spectrum analysis to analyze the scattering characteristics of different ground targets.
In S101 provided by the embodiment of the present invention, the indexes of the environment construction are specifically:
(1) The cement floor can be regarded as a rough surface under the irradiation of a radar in a C, X, ku, ka frequency band, a relatively flat cement floor is selected as a test site, and the cement floor is built in an auxiliary mode by using a wave-absorbing material, so that the vertical irradiation surface is a square area with the side length of 0.5m, and the concrete building mode is shown in figure 1.
(2) Bare land is composed of mainly water and solid mixtureThe soil reflection coefficients of different water contents have great difference, so the water content of bare soil is used as the main basis for selecting test soil, and the soil is selected to have a volume weight of 1.10-1.50g/cm in consideration of the limitation of experimental practical conditions 3 Is a soil of the plant.
(3) The grasslands are selected, the heights of grass plants are smaller than 20cm, the grass plants are distributed sparsely, weeds have no certain spatial orientation, and the water content of soil is about 20%.
In S101 provided by the embodiment of the present invention, the method for calculating the effective irradiation area of the antenna is as follows:
two parallel transmitting and receiving antennas are selected, the area irradiated to the ground is elliptic area, as shown in figure 4, the ellipses a1 and a2 have long sides of a respectively 1 And a 2 Short sides are b respectively 1 And b 2 The central point is K 1 And K 2 The calculation expression is as follows:
wherein:
wherein θ is 1 、φ 1 And theta 2 、φ 2 Beam widths representing the receive and transmit antenna depression and azimuth planes, respectively; the elliptical overlapping area of the two antennas shown in the figure is the effective irradiation area of the antennas, and the expression is:
taking into account the bandwidth deltaf of the intermediate frequency filter in the receiver I The expression is:
in the middle of
There are two limiting angles alpha c When alpha < alpha c The effective radiating area of the antenna is the overlapping area of two ellipses, when alpha > alpha c The effect of receiver bandwidth needs to be considered when. Horn antenna during measurementThe height is not exceeded, the time domain reflection echo of the vertical irradiation is mainly measured, the antenna irradiation angle is always smaller than the limiting angle, and the irradiation area can be reduced to:
A＝2absin -1 x 1 -adx 1 ；
wherein the method comprises the steps of
When the antenna irradiates vertically, the height of the antenna is lower due to the fact that the test environment is built in advance, the divided measurement ground area is controlled within the effective irradiation area of the antenna, and therefore the area of the delineating area can be approximately regarded as the effective irradiation area of the antenna only by calculating the area of the delineating area.
In S103 provided in the embodiment of the present invention, according to different pulse frequency bands of measurement and emission, horn antennas corresponding to the same frequency band are selected for measurement, after the antennas are selected, the horn mouth is vertically and downwardly mounted on a test support, and the test support is required to be adjusted during mounting, so that two horns are located right above the center of the test ground, and the main steps are as follows:
according to the deduction of the effective irradiation area of the test ground, proper distance is required to be selected, so that the whole delineated test ground is positioned in the effective irradiation area of the antenna, and the height of the test ground is generally about 1.5 m;
when the antenna is installed, the laser level gauge is used as an aid, the wheel disc of the test support is adjusted, the rotating arm of the test support is enabled to be horizontal to the ground, and the horn antenna opening is perpendicular to the ground.
In S104 provided by the embodiment of the present invention, a specific process of line connection of the whole measurement system is:
firstly, connecting a time domain measurement system integrated computer with an output power amplifier, then connecting the output power amplifier with a transmitting horn antenna, then connecting a receiving horn antenna with a receiving power amplifier, and finally connecting the receiving power amplifier with the time domain measurement system integrated computer.
In S104 provided in the embodiment of the present invention, after the environment before testing is set up and ready, when the system circuit is connected, the system circuit is ensured to be connected accurately, otherwise, the power amplifier and the time domain measurement system may be damaged, and the connection steps must be performed step by step as follows:
the time domain measuring system is connected with the transmitting power amplifier through a radio frequency line, and the selecting of the transmitting power amplifier also selects the corresponding power amplifier according to the frequency of the transmitting pulse;
connecting a transmitting power amplifier with a transmitting antenna;
connecting a receiving antenna and a receiving power amplifier;
connecting a receiving power amplifier and a time domain measuring system;
the signal transmission process of the whole measurement experiment needs to form a closed loop, and the power supply can be switched on after the connection is ready.
And after the circuit is switched on, measuring the calibration body and the ground object target, and storing the acquisition result in the time domain echo measurement system. Wherein, the ground object target includes: scaling bodies and cement plots, bare soil and grassland targets.
Table 1 test floor and condition list
| Test object | Effective area of | Antenna angle | Pulse center frequency | Bandwidth of a communication device |
| Cement floor | 0.25m 2 | 90° | 10GHz | 4GHz |
| Bare soil | 0.25m 2 | 90° | 10GHz | 4GHz |
| … | … | … | … | … |
Measuring a time domain echo result: the measured cement floor and bare land time domain echoes are shown in fig. 3 and 4:
case 1, the cement floor in table 1 is used for measurement, the parameters are shown in table 1, the time domain echo represents the change relation of the field intensity amplitude of the electromagnetic wave scattered from the cement floor section at 20ns to 40ns time after pulse transmission, and the amplitude change range is between-0.8 and 0.8.
Case 2, the measurement is performed by using the bare land in table 1, the parameters are shown in table 1, the time domain echo thereof represents the change relation of the voltage amplitude of the electromagnetic wave scattered by the bare land in the time period from 20ns to 40ns after pulse transmission, and the amplitude change range is between-0.5 and 0.5.
In S107 provided by the embodiment of the present invention, a process of processing the acquired time domain echo is as follows:
when measuring in the near field of a time domain plane, two methods can be used for carrying out spectrum analysis of a time domain echo signal to obtain RCS data:
the first is that time domain signal data obtained by time domain scattering measurement is subjected to Fourier transform to obtain frequency domain scattering data, and then near-field and far-field transformation is performed by a spectrum unfolding theory to obtain far-field scattering data, so that RCS data of the scattered data are obtained;
and secondly, directly carrying out spectrum expansion theory on the time domain incoming scattering data to obtain far-field time domain scattering data, and carrying out Fourier transformation to obtain far-field frequency domain scattering data so as to obtain RCS data.
The basic derivation of the time-frequency domain near-field scatterometry equation is as follows:
the near-far field transform pair is:
first, a spectral function is establishedRelationship with near field electric field component E (x, y, z):
wherein the method comprises the steps of
Then according to the resident phase method, the approximate expression of the method can be obtained:
and then according to the definition formula of radar scattering interface:
wherein: e (E) s (r) is the far field scattering electric field; e (E) i Is the incident electric field. Combined withThe two equations above can be deduced from the equation that ultimately calculates RCS from the far field electric field:
on the basis of the above derived formula, the field point coordinates are set as r according to the Fourier transform 0 ，For a unit vector from a source point to an observation point, k is a wave number, c is a far field electric field equation of a light velocity derivable time domain, and is as follows:
the time-harmonic spectrum is defined as:
the relation between the obtained time domain spectrum and the far field electric field is that
The relationship between the frequency domain near field electric field and the time harmonic spectrum is obtained in a comprehensive way:
and then obtaining the relation between the time domain near field electric field and the time domain spectrum according to Fourier transformation:
while the expression of the time domain far field electric field can be simplified as:
can be defined according to RCSAnd solving RCS after Fourier transforming the far-field time domain electric field.
In S108 provided by the embodiment of the present invention, the specific process of observing the transformed spectrum characteristics and performing spectrum analysis is:
when the acquired time domain echo is processed, after the acquired near field data is transformed to a far field, the acquired near field data is transformed according to the equation of frequency domain fast Fourier transform:
the time domain signal is programmably transformed to the frequency domain and its spectral characteristics are analyzed.
In order to verify the reliability of the time domain acquisition data, RCS test of a typical target and a standard body is carried out, a comparison result shown in the following table is obtained, and the error of the RCS predicted by using the time domain measurement method provided by the patent is less than 3dB compared with the true value of the standard body through data analysis.
It should be noted that the embodiments of the present invention can be realized in hardware, software, or a combination of software and hardware. The hardware portion may be implemented using dedicated logic; the software portions may be stored in a memory and executed by a suitable instruction execution system, such as a microprocessor or special purpose design hardware. Those of ordinary skill in the art will appreciate that the apparatus and methods described above may be implemented using computer executable instructions and/or embodied in processor control code, such as provided on a carrier medium such as a magnetic disk, CD or DVD-ROM, a programmable memory such as read only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The device of the present invention and its modules may be implemented by hardware circuitry, such as very large scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., as well as software executed by various types of processors, or by a combination of the above hardware circuitry and software, such as firmware.
The foregoing is merely illustrative of specific embodiments of the present invention, and the scope of the invention is not limited thereto, but any modifications, equivalents, improvements and alternatives falling within the spirit and principles of the present invention will be apparent to those skilled in the art within the scope of the present invention.
Claims (10)
1. The method for collecting and analyzing the external field object scattering time domain echo is characterized by comprising the following steps of:
constructing external field conditions suitable for experiments, wherein the external field conditions are required to be constructed according to actual ground object target requirements, and the ground object targets are divided into cement ground, bare soil and grasslands; when an environment is built, after a ground environment with a certain range is selected, spreading wave-absorbing materials around the ground environment to limit the irradiation area of the loudspeaker, and calculating the effective irradiation area;
preparing an experimental instrument, namely connecting a time domain measurement system integrated computer with a computer display screen;
placing the test frame stably, keeping the transverse shaft of the test frame horizontal to the ground, and then mounting the horn antenna on the test frame;
the circuit connection of the whole measuring system is carried out, the connection process is carried out strictly according to the steps, and after wiring is completed, the system is powered by using a portable mobile power supply;
after the experimental environment is built and a time domain measuring system is ready, covering the test ground with a wave absorbing material, placing a calibration ball under a horn antenna for calibration, and taking the measured time domain echo signal as successful calibration when the jitter is less than 3dB after Fourier transformation;
in the built experimental environment, the placement and rotation directions of a transmitting loudspeaker and a receiving loudspeaker are regulated, the measurement of the target ground under different angles is carried out, and the time domain echo signals are acquired;
processing the time domain echo signals, and performing section Fourier transform on the time domain echo signals obtained by measurement;
and observing the converted frequency spectrum characteristics, and performing spectrum analysis to analyze the scattering characteristics of different ground targets.
2. The method for collecting and analyzing the scattering time-domain echo of the external field object according to claim 1, wherein the indexes of the environment construction are as follows:
(1) The cement floor can be regarded as a rough surface under the irradiation of a radar in a C, X, ku, ka frequency band, a relatively flat cement floor is selected as a test site, and a wave-absorbing material is used for auxiliary construction, so that a square area with the side length of 0.5m is used as a vertical irradiation surface;
(2) The bare soil mainly comprises water and solid mixture, and the reflection coefficients of the soil with different water contents are greatly different, so the water content of the bare soil is used as the main basis for selecting the test soil, and the limitation of the practical experimental conditions is considered, and the selected soil has a volume weight of 1.10-1.50g/cm 3 Is a soil of (2);
(3) The grasslands are selected, the heights of grass plants are smaller than 20cm, the grass plants are distributed sparsely, weeds have no certain spatial orientation, and the water content of soil is 20%.
3. The method for collecting and analyzing the scattering time-domain echo of the external field object according to claim 1, wherein the method for calculating the effective irradiation area of the antenna is as follows: two receiving and transmitting antennas which are arranged in parallel are selected, the area irradiated to the ground is an elliptic area, the long sides of the ellipses a1 and a2 are respectively a 1 And a 2 Short sides are b respectively 1 And b 2 The central point is K 1 And K 2 The calculation expression is as follows:
wherein:
wherein θ is 1 、φ 1 And theta 2 、φ 2 Beam widths representing the receive and transmit antenna depression and azimuth planes, respectively; the elliptical overlapping area irradiated by the two antennas is the effective irradiation area of the antennas, and the expression is as follows:
taking into account the bandwidth deltaf of an intermediate frequency filter in a receiver I The expression is:
wherein:
there are two limiting angles alpha c When alpha < alpha c The effective radiating area of the antenna is the overlapping area of two ellipses, when alpha > alpha c The effect of receiver bandwidth needs to be considered; the height of the horn antenna is not exceeded during measurement, the time domain reflection echo of the vertical irradiation is mainly measured, and the antennaThe irradiation angle is always smaller than the limiting angle, and the irradiation area can be simplified as:
A＝2absin -1 x 1 -adx 1 ；
wherein the method comprises the steps of
When the antenna irradiates vertically, the height of the antenna is lower due to the fact that the test environment is built in advance, the divided measurement ground area is controlled within the effective irradiation area of the antenna, and therefore the area of the delineating area can be approximately regarded as the effective irradiation area of the antenna only by calculating the area of the delineating area.
4. The method for collecting and analyzing the scattering time domain echo of the external field object according to claim 1, wherein the horn antennas corresponding to the same frequency band are selected for measurement according to different pulse frequency bands of measurement emission, after the antennas are selected, the horn mouth is vertically downwards arranged on a test bracket, and the test bracket is required to be adjusted when the horn mouth is arranged, so that two horns are positioned right above the center of the test ground; according to the derivation of the effective irradiation area of the test ground, a proper distance needs to be selected, so that the whole delineated test ground is positioned in the effective irradiation area of the antenna, and the height is 1.5m.
5. The method for collecting and analyzing the scattering time domain echo of the external field object according to claim 4, wherein when the antenna is installed, a laser level is used as an aid to adjust a wheel disc of the test support, so that a rotating arm of the test support is horizontal to the ground, and a horn antenna opening is vertical to the ground.
6. The method for collecting and analyzing the external field object scattering time domain echo according to claim 1, wherein the specific process of the line connection of the whole measuring system is as follows: firstly, connecting a time domain measurement system integrated computer with an output power amplifier, then connecting the output power amplifier with a transmitting horn antenna, then connecting a receiving horn antenna with a receiving power amplifier, and finally connecting the receiving power amplifier with the time domain measurement system integrated computer.
7. The method for collecting and analyzing the scattered time domain echo of the external field object according to claim 1, wherein after the environment is built and ready before the test, when the system circuit is connected, the connection trend of the system circuit is ensured to be accurate, otherwise, the power amplifier and the time domain measuring system can be damaged, and the connecting steps must be gradually carried out as follows:
the time domain measuring system is connected with the transmitting power amplifier through a radio frequency line, and the selecting of the transmitting power amplifier also selects the corresponding power amplifier according to the frequency of the transmitting pulse;
connecting a transmitting power amplifier with a transmitting antenna;
connecting a receiving antenna and a receiving power amplifier;
connecting a receiving power amplifier and a time domain measuring system;
the signal transmission process of the whole measurement experiment needs to form a closed loop, and the power supply can be switched on after the connection is ready;
after the circuit is switched on without errors, measuring the calibration body and the ground object target, and storing the acquisition result in a time domain echo measurement system; wherein, the ground object target includes: scaling bodies and cement plots, bare soil and grassland targets.
8. The method for collecting and analyzing the time domain echo of the external field object scattering according to claim 1, wherein the process of processing the collected time domain echo is as follows:
when measuring in the near field of a time domain plane, two methods can be used for carrying out spectrum analysis of a time domain echo signal to obtain RCS data:
the first is that time domain signal data obtained by time domain scattering measurement is subjected to Fourier transform to obtain frequency domain scattering data, and then near-field and far-field transformation is performed by a spectrum unfolding theory to obtain far-field scattering data, so that RCS data of the scattered data are obtained;
secondly, directly carrying out spectrum expansion theory on time domain incoming scattering data to obtain far-field time domain scattering data, and carrying out Fourier transformation to obtain far-field frequency domain scattering data so as to obtain RCS data;
the basic derivation of the time-frequency domain near-field scatterometry equation is as follows:
the near-far field transform pair is:
first, a spectral function is establishedRelationship with near field electric field component E (x, y, z):
wherein the method comprises the steps of
Then according to the resident phase method, the approximate expression of the method can be obtained:
and then according to the definition formula of radar scattering interface:
wherein: e (E) s (r) is the far field scattering electric field; e (E) i Is the incident electric field; the equation for calculating the RCS from the far field electric field can be deduced by combining the above two equations:
on the basis of the above derived formula, the field point coordinates are set as r according to the Fourier transform 0 ，For a unit vector from a source point to an observation point, k is a wave number, c is a far field electric field equation of a light velocity derivable time domain, and is as follows:
the time-harmonic spectrum is defined as:
the relation between the obtained time domain spectrum and the far field electric field is that
The relationship between the frequency domain near field electric field and the time harmonic spectrum is obtained in a comprehensive way:
and then obtaining the relation between the time domain near field electric field and the time domain spectrum according to Fourier transformation:
while the expression of the time domain far field electric field can be simplified as:
can be defined according to RCSSolving RCS after Fourier transforming the far-field time domain electric field;
the specific process of observing the converted spectrum characteristics and carrying out spectrum analysis is as follows: when the acquired time domain echo is processed, after the acquired near field data is transformed to a far field, the acquired near field data is transformed according to the equation of frequency domain fast Fourier transform:
the time domain signal is programmably transformed to the frequency domain and its spectral characteristics are analyzed.
9. An external field object scattering time domain echo acquisition and spectrum analysis system for implementing the external field object scattering time domain echo acquisition and spectrum analysis method according to any one of claims 1 to 8, characterized in that the external field object scattering time domain echo acquisition and spectrum analysis system comprises:
the environment building module is used for building experimental objects required by the time domain echo measurement of the external field object;
the equipment connection module is used for connecting the whole external field time domain testing system with the time domain measuring system integrated computer, the transmitting power amplifier, the transmitting horn antenna, the receiving horn antenna and the receiving power amplifier through radio frequency lines, and finally, supplying power by using a portable mobile power supply;
the test frame adjusting module is used for adjusting the horizontal rotation angle and the height of the horn antenna arranged on the test frame;
the calibration module is used for checking the measurement error of the system after the experimental environment is built;
the target measurement module is used for measuring the built background environment and setting the transmitted pulse waveform and frequency;
the data acquisition module is used for measuring three groups of data on different ground object targets under the same measurement condition, wherein the difference of the maximum and minimum voltage amplitude values of each group of data is smaller than that of the data, namely the data can be regarded as acquired echo data, and the optimal data group is selected for subsequent spectrum analysis;
and the time domain echo spectrum analysis module is used for carrying out Fourier change on the acquired time domain echo waveform to obtain a frequency spectrum of the acquired time domain echo waveform and carrying out spectrum analysis.
10. A method of radar-emitting electromagnetic waves to detect a target, wherein the method of radar-emitting electromagnetic waves to detect a target operates the external object scattering time-domain echo acquisition and spectrum analysis system of claim 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110077803.7A CN112859028B (en) | 2021-01-20 | 2021-01-20 | Method and system for collecting and spectrum analyzing scattering time domain echo of external field object |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110077803.7A CN112859028B (en) | 2021-01-20 | 2021-01-20 | Method and system for collecting and spectrum analyzing scattering time domain echo of external field object |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112859028A CN112859028A (en) | 2021-05-28 |
| CN112859028B true CN112859028B (en) | 2024-01-30 |
Family
ID=76008264
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110077803.7A Active CN112859028B (en) | 2021-01-20 | 2021-01-20 | Method and system for collecting and spectrum analyzing scattering time domain echo of external field object |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112859028B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113552547B (en) * | 2021-07-27 | 2023-05-16 | 北京环境特性研究所 | Method for measuring outdoor target RCS |
| CN114280549B (en) * | 2021-12-26 | 2024-02-27 | 中国电子科技集团公司第十四研究所 | High-speed optical pulse generating device and method |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2737576A1 (en) * | 1989-06-20 | 1997-02-07 | Dassault Electronique | Ground clutter simulation for missile pulse radars - has analogue amplitude or phase frequency dependent signal representing small ground position antenna illuminated distance or doppler segment |
| CN105182329A (en) * | 2015-10-09 | 2015-12-23 | 上海无线电设备研究所 | Small bistation angle composite reflection characteristic time domain measurement method |
| CN106526562A (en) * | 2016-10-17 | 2017-03-22 | 西北工业大学 | Antenna directional pattern-based method for correcting RCS of calculation target |
| CN107783092A (en) * | 2017-09-21 | 2018-03-09 | 北京航空航天大学 | To rcs measurement system and method behind near field based on Chain relation |
| CN107942330A (en) * | 2017-11-20 | 2018-04-20 | 北京航天长征飞行器研究所 | A kind of radar scattering characteristic extracting method and system based on plasma near-field test |
| CN111856425A (en) * | 2020-07-30 | 2020-10-30 | 上海无线电设备研究所 | Non-rigid body target electromagnetic characteristic simulation test method |
-
2021
- 2021-01-20 CN CN202110077803.7A patent/CN112859028B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2737576A1 (en) * | 1989-06-20 | 1997-02-07 | Dassault Electronique | Ground clutter simulation for missile pulse radars - has analogue amplitude or phase frequency dependent signal representing small ground position antenna illuminated distance or doppler segment |
| CN105182329A (en) * | 2015-10-09 | 2015-12-23 | 上海无线电设备研究所 | Small bistation angle composite reflection characteristic time domain measurement method |
| CN106526562A (en) * | 2016-10-17 | 2017-03-22 | 西北工业大学 | Antenna directional pattern-based method for correcting RCS of calculation target |
| CN107783092A (en) * | 2017-09-21 | 2018-03-09 | 北京航空航天大学 | To rcs measurement system and method behind near field based on Chain relation |
| CN107942330A (en) * | 2017-11-20 | 2018-04-20 | 北京航天长征飞行器研究所 | A kind of radar scattering characteristic extracting method and system based on plasma near-field test |
| CN111856425A (en) * | 2020-07-30 | 2020-10-30 | 上海无线电设备研究所 | Non-rigid body target electromagnetic characteristic simulation test method |
Non-Patent Citations (1)
| Title |
|---|
| 宽带扫频RCS自动测量系统;雷洸升，张麟兮，胡楚锋;;电子测量技术;第30卷(第7期);全文 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112859028A (en) | 2021-05-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN103630761B (en) | A kind of Multi probe sphere near field passage calibrating installation and method | |
| CN107238825B (en) | The test method of RCS when a kind of realization antenna transmitting using vector network instrument | |
| CN112859028B (en) | Method and system for collecting and spectrum analyzing scattering time domain echo of external field object | |
| CN102401893B (en) | Symmetric polarization RCS (radar cross-section) testing method for targets at near fields | |
| CN107607797B (en) | Antenna performance measuring method and device based on unmanned aerial vehicle | |
| CN107085150A (en) | A kind of short wavelength emissions antenna 3 D stereo directional diagram aerial mobile measuring system and method | |
| CN103336182B (en) | A kind of antenna phase center calibration system based on place insert loss | |
| CN104931797B (en) | The measuring method of lossy medium dielectric constant based on wave transparent mechanism | |
| CN205608094U (en) | Semi -anechoic chamber field uniformity testing arrangement | |
| CN105823935A (en) | Device and method for field uniformity testing of semi-anechoic chamber | |
| CN102854401A (en) | Array antenna pattern time domain measurement method | |
| CN112505435B (en) | Equivalent far field testing device and method for large cylindrical phased array antenna | |
| CN107783092A (en) | To rcs measurement system and method behind near field based on Chain relation | |
| CN109061322A (en) | A kind of Far-Field antennas measurement system method based on unmanned plane | |
| CN106771673A (en) | A kind of gps antenna directionality method of testing and system | |
| CN113419116A (en) | Passive performance test system and test method suitable for whole vehicle-level antenna | |
| Virone et al. | Antenna pattern measurement with UAVs: Modeling of the test source | |
| CN113109771B (en) | Calibration device for calibration instrument and true value calibration method for weather radar echo intensity | |
| CN113009436B (en) | Spatial angular position parameter calibration method | |
| CN102768309B (en) | Method for eliminating multipath interference in antenna testing environment by adopting frequency difference technology | |
| CN103257340A (en) | Method for calibrating amplitude consistency of a plurality of ground receivers with radar satellite | |
| CN100368822C (en) | Radio emitting source positioning method and system | |
| CN114167365A (en) | Method and system for acquiring characteristics of guide rail type outfield target and environment radar | |
| Fordham | An introduction to antenna test ranges, measurements and instrumentation | |
| CN101477153B (en) | High-frequency electric field tester |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |