CN112162233B - Two-dimensional wide-angle high-precision angle measurement method based on eight-port four-baseline radio frequency equipment - Google Patents
Two-dimensional wide-angle high-precision angle measurement method based on eight-port four-baseline radio frequency equipment Download PDFInfo
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- 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
- G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
- G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
- G01S3/14—Systems for determining direction or deviation from predetermined direction
- G01S3/46—Systems for determining direction or deviation from predetermined direction using antennas spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems
- G01S3/48—Systems for determining direction or deviation from predetermined direction using antennas spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems the waves arriving at the antennas being continuous or intermittent and the phase difference of signals derived therefrom being measured
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
The invention discloses a two-dimensional wide-angle high-precision angle measurement method based on eight-port four-baseline radio frequency equipment, which is characterized by comprising the following steps of: step 1, building eight-port four-baseline radio frequency equipment; step 2, determining a baseline interval and a frequency factor according to the angle range and the wavelength of the radiation source; step 3, determining the number of steps where the pitch angle of the radiation source is located; step 4, restoring the actual pitch angle phase value; step 5, calculating a pitch angle of the radiation source; step 6, determining the number of steps where the azimuth angle of the radiation source is located; step 7, restoring the actual azimuth phase value; and 8, calculating the azimuth angle of the radiation source. The two-dimensional wide-angle high-precision angle measurement method based on the eight-port four-baseline radio frequency equipment is simple and convenient, has wider angle measurement range and higher precision under the condition of the same cost or volume or the number of antenna units, and can be used for engineering practice.
Description
Technical Field
The invention belongs to the technical field of radar radiation source direction finding methods, and particularly relates to a two-dimensional wide-angle high-precision angle finding method based on eight-port four-baseline radio frequency equipment.
Background
The radar radiation source direction finding technology can demodulate the azimuth of electromagnetic waves by utilizing the principle of different amplitude or phase responses generated by the electromagnetic waves in different directions reaching a direction finding antenna system. Depending on different factors, it can be divided into an amplitude method and a phase method. The phase method angle measurement utilizes the wave path difference of the electromagnetic wave signal of the target radiation reaching the antenna base line to measure the angle, namely, the direction of the signal is determined according to the relative phase difference of the same signal detected by the direction finding antenna system, and then the angle error signal is demodulated through the phase difference, so that the antenna is driven to track the radiation source passively. The relative phase difference is derived from the ratio of the relative wave path difference to the wavelength, and the principle is simpler. However, the phase method has a great disadvantage in angle measurement, when the base line width between two antennas is too large, the measurement is blurred, and when the base line width is too small, the problem of large measurement error is generated. The novel wide angle and high-precision angle measuring method researched by the technical scheme is based on phase method direction finding, a set of simple and feasible novel angle measuring method is researched, and the problem of measurement ambiguity existing in the traditional phase method angle measuring is solved.
1. Principle of double base line angle measurement
Currently, angle measurement equipment based on phase method direction measurement is mainly an interferometer, and utilizes the principle of dual-baseline phase method angle measurement, namely angle measurement is performed by utilizing phase differences among echo signals received by a plurality of antennas. As shown in fig. 1, when an object radiates an electromagnetic wave signal in the θ direction, the electric wave reflected by the object reaching the receiving point is approximately a plane wave. Since the base line interval between the two antennas is d, the received signals reach the difference DeltaR of the base lines to generate phase differenceThe relationship between phase difference and baseline interval is:
where λ is the wavelength of the electromagnetic wave signal radiated by the object. The phase difference resulting from the wave path difference can be measured by a phase meter. Therefore, the angle θ of the electromagnetic wave signal of the target radiation can be derived from the formula (1)
Knowing the wavelength of the electromagnetic wave signal of the target radiation, the azimuth of the target signal can be calculated from the equation (2) by using the phase difference measured by the phase.
2. Problem of angle measurement ambiguity and precision
The simple dual baseline phase method direction finding actually has a great problem, namely the measurement ambiguity problem.
As can be seen from equation (2), if the phase differenceInaccurate measurement of the value may result in angular errors. To study the relevant factors affecting the angular accuracy, the two sides of the formula (1) are differentiated, and the method comprises
As can be seen from (3), the reading accuracy is highThe phase meter of (2) or the lambda/d value is reduced, and the angle measurement precision can be improved. In addition, when θ=0, that is, when the target is in the antenna normal direction, the angle measurement error dθ is minimum, and when θ increases, dθ also increases, so that there is also a certain limit to the range of θ in order to secure a certain angle measurement accuracy. Although the reduction of the lambda/d value can also improve the angle measurement accuracy, in a certain angle measurement range theta, when the lambda/d value is reduced to a certain degree, the lambda/d value is reduced to a certain degree>The value may exceed 2 pi, at which timeWhere N is an integer, ψ < 2π, the actual reading of the phaser is ψ. Since the value of N is unknown, true +.>If the value is not determined, a blurring problem (multi-value) occurs.
3. Current methods of solving the ambiguity problem
In order to avoid the measurement ambiguity, only the range of the measured angle can be reduced, but when the measurement range is reduced, the measurement accuracy is correspondingly reduced, that is, the problem that the measurement accuracy contradicts the measurement range exists. The key to solve the contradiction is to solve the blurring problem, so how to deblur becomes a hot spot to be considered when the phase method is applied to direction finding, and many methods for solving the blurring problem are researched and developed.
1. Robust baseline solution blurring
In order to solve the problem of direction finding ambiguity in the direction finding by a phase method, a staggered baseline interferometer direction finding method for solving the ambiguity problem by utilizing the Chinese remainder theorem is provided by imitating a multi-frequency continuous wave distance finding technology, the remainder theorem is applied to interferometer direction finding, and a basic angle finding schematic diagram of the method for solving the ambiguity is shown in figure 2.
An M-dimensional baseline interferometer with baseline lengths of l respectively i (i=1, 2,., M-1), a base baseline l is taken 0 ≤λ min 2, all baselines are l 0 Integer multiple of (1) has
l 1 :l 2 :…:l M-1 ＝m 1 :m 2 :…:m M-1 (4)
Wherein m is i (i=1, 3,., M-1) is an integer
The interferometer measures a baseline interval of l i At the time, the corresponding phase difference isWhile the actual phase difference is 2 pi l i sin theta/lambda, the relation between the two is
Wherein k is i Indicating a baseline interval of l i Direction finding ambiguity number at that time.
Equation (5) is a system of equations with the same homonym as the remainder in the real number domain with divisor as an integer, if the choice is from pairwise interpoly, it can be known from the Chinese remainder theorem thatThe determined maximum unambiguous direction finding range has a unique set of solutions k i . But the methodThe method is easy to cause disambiguation failure due to phase errors caused by antenna units, microwave channels, receivers and the like, and has large calculated amount.
2. Virtual baseline defuzzification
By virtual baseline is meant the difference in length between two different baselines. When the length difference is smaller than the half wavelength of the highest frequency of the broadband signal, the phase difference of the virtual base line is the phase without ambiguity. The schematic diagram is shown in figure 3, the base line intervals between the base lines 1 and 2 and the base lines 2 and 3 are respectively l 1 ，l 2 (l 2 ＞l 1 ) Subtraction of two different baseline intervals gives a spacing of l 2 -l 1 Virtual short baseline of (2), baseline interval of virtual short baseline and corresponding phase differenceThe relation of (2) is that
However, the virtual baseline method can cause deblurring errors and even can not deblur due to the influence of systematic errors and random errors in wide angle direction finding.
3. Long and short base line defuzzification
The long and short baseline method is also called a three-baseline angle measurement method, which is to use three baselines with proper two different baseline intervals to regulate, one baseline is long and the other baseline is short. The schematic diagram is shown in fig. 4, 1 and 3 antennas with large intervals are used for obtaining high-precision measurement, and 1 and 2 antennas with small intervals are used for solving the measurement multiple-value property. Let the object radiate electromagnetic wave signal with direction theta outwards and the distance between the antennas 1,2 be d 12 The distance between the antennas 1,3 is d 13 . Properly select d 12 The phase difference between the signals received by the antennas 1 and 2 is satisfied in the angle measurement range
Read by the phase meter 1.
According to the requirement, a larger d is selected 13 The phase difference of the signals received by the antennas 1,3 is
In this case, the phase meter 2 reads psi less than 2pi, and the following relationship is used to determine the value of N
When the error of the phase meter 1 is within an acceptable range, based on the readings of the phase meter 1And (10) can be calculatedAnd then according to the formula (9), the value of N and the value of theta can be determined. d, d 13 The lambda value is large, ensuring the required accuracy.
Although the method for measuring angles of long and short baselines can solve the problem of direction finding ambiguity by using a short baseline and solve the problem of direction finding range by using a long baseline, in broadband direction finding, when a target signal is a high-frequency signal, the method has high requirements on the short baseline, and often cannot be widely applied due to engineering limitation of physical realization of the short baseline.
Disclosure of Invention
The invention aims to provide a two-dimensional wide-angle high-precision angle measurement method based on eight-port four-baseline radio frequency equipment, which solves the problem that the existing angle measurement method cannot realize high measurement precision and wide measurement range at the same time.
The technical scheme adopted by the invention is as follows: a two-dimensional wide angle high-precision angle measurement method based on eight-port four-baseline radio frequency equipment comprises the following steps:
step 1, building eight-port four-baseline radio frequency equipment;
step 2, determining a baseline interval and a frequency factor according to the angle range and the wavelength of the radiation source;
step 3, determining the number of steps where the pitch angle of the radiation source is located;
step 4, restoring the actual pitch angle phase value;
step 5, calculating a pitch angle of the radiation source;
step 6, determining the number of steps where the azimuth angle of the radiation source is located;
step 7, restoring the actual azimuth phase value;
and 8, calculating the azimuth angle of the radiation source.
The beneficial effects of the invention are as follows: the two-dimensional wide-angle high-precision angle measurement method based on the eight-port four-baseline radio frequency equipment is simple and convenient, has wider angle measurement range (can measure all angles) and higher precision under the condition of the same cost or volume or the number of antenna units, and can be used for engineering practice.
Drawings
FIG. 1 is a schematic diagram of a double baseline goniometer;
FIG. 2 is a schematic diagram of a spread baseline solution ambiguity;
FIG. 3 is a schematic diagram of a virtual baseline defuzzification;
FIG. 4 is a schematic diagram of a long and short baseline defuzzification;
FIG. 5 is a schematic diagram of an eight port goniometer principle;
FIG. 6 is a test chart of two of the baselines of an antenna in an eight port goniometer system;
FIG. 7 is a diagram showing the relationship between the electromagnetic wave to be measured and the antenna in an eight-port goniometer system;
FIG. 8 is a schematic diagram of an eight port junction;
fig. 9 shows the fuzzy phase value θ measured with an eight port device when q=0.8 E And theta H ；
Fig. 10 shows an angle value θ obtained by calculating the ambiguity phase values measured by the eight-port device at two frequencies when q=0.8 E ；
Fig. 11 shows the angle value θ calculated at two frequencies when q=0.8 E Subtracting the obtained step diagrams;
fig. 12 is a graph of θ different at two frequencies when q=0.8 E Angle value theta obtained by calculating fuzzy phase value measured by eight-port device H ；
Fig. 13 is a graph of θ different at two frequencies when q=0.8 E Value of the ambiguous phase value θ measured with eight port devices H A step diagram obtained by subtracting the angle values obtained by the calculation;
fig. 14 shows a blur-free angle value θ obtained by restoring the measured angle value by a step method when q=0.8 E ；
Fig. 15 shows the difference θ when q=0.8 E The value of the angle value theta without ambiguity is obtained by recovering the measured angle value by a step method H ；
Fig. 16 shows a blur-free angle value θ obtained by recovering a measured angle value by a step method in a positive and negative 90 degree range when q=0.8 E ；
Fig. 17 is a graph of q=0.8 for different θ E The measured angle value is restored by a step method within the range of plus or minus 90 degrees under the value to obtain the non-fuzzy angle value theta H ；
Fig. 18 shows the angle value θ obtained by resolving the two frequencies at plus or minus 90 degrees when q=0.6 E ；
Fig. 19 shows the angle value θ obtained by resolving the two frequencies at plus or minus 90 degrees when q=0.6 E Subtracting the obtained step diagrams;
fig. 20 shows a blur-free angle value θ obtained by recovering a measured angle value by a step method at plus or minus 90 degrees when q=0.6 E ；
Fig. 21 shows that q=0.6 is different θ at two frequencies of plus or minus 90 degrees E Angle value theta obtained by calculating fuzzy phase value measured by eight-port device H ；
Fig. 22 shows the difference θ between the positive and negative 90 degrees at q=0.6 E Angle value theta obtained by calculating fuzzy phase value measured by eight-port device H Subtracting the obtained step diagrams;
fig. 23 shows that q=0.6 is different θ at two frequencies of plus or minus 90 degrees E The value is used for restoring the measured angle value by a step method to obtain a non-fuzzy angle value theta H ；
Fig. 24 shows the angle value θ obtained by resolving the two frequencies at plus or minus 90 degrees when q=0.3 E Subtracting the obtained step diagrams;
fig. 25 shows a blur-free angle value θ obtained by recovering a measured angle value by a step method at plus or minus 90 degrees when q=0.3 E ；
Fig. 26 shows that q=0.3 is different θ at two frequencies of plus or minus 90 degrees E Angle value theta obtained by calculating fuzzy phase value measured by eight-port device H Subtracting the obtained step diagrams;
fig. 27 shows the difference θ between the positive and negative 90 degrees at q=0.3 E The value is used for restoring the measured angle value by a step method to obtain a non-fuzzy angle value theta H ；
Fig. 28 shows the angle value θ obtained by resolving the two frequencies at plus or minus 90 degrees when q=0.1 E Subtracting the obtained step diagrams;
fig. 29 shows a blur-free angle value θ obtained by recovering a measured angle value by a step method at plus or minus 90 degrees when q=0.1 E ；
Fig. 30 shows that q=0.1 is different θ at two frequencies of plus or minus 90 degrees E Angle value theta obtained by calculating fuzzy phase value measured by eight-port device H Subtracting the obtained step diagrams;
fig. 31 shows that q=0.1 is different θ at two frequencies of plus or minus 90 degrees E The value is used for restoring the measured angle value by a step method to obtain a non-fuzzy angle value theta H 。
Detailed Description
The invention will be described in detail with reference to the accompanying drawings and detailed description.
The invention provides a two-dimensional wide-angle high-precision angle measurement method based on eight-port four-baseline radio frequency equipment, which comprises the steps of firstly building eight-port four-baseline radio frequency equipment, namely providing radio frequency equipment, wherein two ports are arranged in each direction around the radio frequency equipment, baselines are arranged on the four ports of the radio frequency equipment in the opposite directions, and a Schottky diode detector is respectively connected with the other four ports of the radio frequency equipment, and the method comprises the following steps:
first, determining a base line length and a frequency factor according to the angle range and the wavelength of a radiation source
The schematic diagram of the method is shown in fig. 5, four large dots are top views of the antenna base line positions, the intervals between the base lines 5 and 7 and the intervals between the base lines 6 and 8 are d, the ports 1,2, 3 and 4 are respectively connected with the same four Schottky diode detectors, and the radiation source angles can be calculated through the readings of the detectors. Fig. 6 is a side view of two of the baselines of the antenna, the remaining two baselines being identical to the side view of the figure, except that the direction is perpendicular.
Assume an angle θ of an electromagnetic wave signal of target radiation E And theta H Within (-80 °,80 °), d=18mm is chosen for ease of engineering implementation. Unlike prior art methods, the inventive method requires only a ratio q=f of two frequencies at which the system operates 1 /f 2 (hereinafter abbreviated as frequency factor) is definite, so on the other hand, except some special values, the frequency factor can be arbitrarily taken, q=0.8, 24GHz is selected as the center frequency, two working frequencies are 21.3GHz and 26.7GHz, and the corresponding wavelength is lambda 1 =14.1 mm and λ 2 ＝11.2mm。
Second, determining the number of steps of the radiation source
The eight-port device can be used for measuring the angle values with fuzzy values of two baseline intervals at two frequencies respectivelyAnd->n=1, 2, representing the nth frequency. The step principle proposed by the method of the invention shows that when the angle of incidence is +>Andin the (-80 DEG, 80 DEG) rangeIn the case of the inner circumference, the two are at different +.>And->The angle differences measured at different frequencies have only a limited fixed value, called step value, the steps being numbered in a left to right order. The second step is to determine +_ based on the actual measured values>And->The step number is located.
Third, the actual phase value is restored
Because each step corresponds to an angle interval, the step value can be restored to the actual phase value by adopting a certain restoration criterion. For this purpose, a reduction criterion is established:
let L m M=e, H is the number of steps, X m For the position number of the step, the interval factor t=1 or 2 or 3 or 4 is selected according to the specific condition of the angle measurement, the manual adjustment of 360 DEG interval is carried out, and the phase measured by any one of two frequencies is selectedWith actual phase value->Is that
Simulation verification is performed according to the above-described restoration procedure, and in this example, when t=1, the blurred phase value can be restored to an actual phase value.
Using formula (11), a reduced can be obtainedActual phase
Fourth, calculating the angle of the radiation source
After the actual phase value is obtained, the actual incident angle theta can be easily calculated according to the formula (2-1) m 。
The invention relates to a two-dimensional wide-angle high-precision angle measurement method based on eight-port four-baseline radio frequency equipment, which is based on the principle that:
1. eight-port angle measurement principle
The antenna layout shown by the red dots in fig. 5 is drawn as a perspective view, as in fig. 7, red linesTo reach the plane wave of the antenna, θ E For pitch angle of incoming wave, θ H For azimuth angle of incoming wave, beta x 、β y 、β z Projection of incoming waves on x, y and z axes respectively.
The plane wave set to reach the antenna can be expressed as:
wherein t represents the time period in which,representing a position vector +.>The wave propagation vector is represented, so that the wave propagation vector can be decomposed into:
β x ＝β 0 cosθ E sinθ H (13)
β y ＝β 0 cosθ E cosθ H (14)
β z ＝β 0 sinθ E (15)
it can be seen that, assuming the receiving unit 5 as the center of the coordinate system, it can be derived that:
the phase of the incident plane wave at each receiving unit in the coordinate system with the receiving unit 5 as the origin can be expressed as:
now assume phi E ＝β 0 dsinθ E Phi is the phase difference of antennas 5 and 7 H ＝β 0 dcosθ E sinθ H For the phase difference of antennas 6 and 8, i.e. phi E Corresponding to elevation angle phi H For azimuth angles. The above can be written as:
the eight-port network proposed by Zhang Xuchun is composed of 4 180 DEG directional couplers (namely annular bridge) and 1 90 DEG item shifter, and the concept of incident wave and reflected wave in the S parameter of the microwave network is utilized, and the eight-port principle diagram is drawn independently as shown in figure 8, then there is
According to the S parameter characteristics of the eight-port network
Combined with (28) and (29)
The square of the modulus value is taken on both sides of each equation in the equation (31), the ratio of the reflected voltage on the left side of the equation to the incident voltage becomes the ratio of the reflected power on each port to the incident power, and the result after conversion is simplified as follows:
and due to P i /P k ＝|S ik | 2 Can be obtained by combining (32)
Thus, x= (phi) can be solved E +φ H ) 2 and y= (phi) E -φ H ) According to phi/2 E ＝β 0 dsinθ E And phi H ＝β 0 dcosθ E sinθ H The two angles can be solved as
θ E 、θ H The phase difference measured by the two baseline intervals respectively shows that the eight ports can measure the phase difference of the two baseline intervals, but the two phase differences have the fuzzy problem as the prior method, so the step concept is proposed.
2. Principle of step
First, when the radiation source reaches the receiving device, at a wavelength lambda corresponding to the two frequencies 1 And lambda (lambda) 2 The actual phase difference in two directions and the fuzzy phase value phi measured by the eight-port device E And phi H As shown in fig. 9. At this point, it can be seen that both baseline intervals have phase ambiguity problems and that the ambiguity-free phase intervals for different frequencies are different.
As can be seen from the observation (34), the incidence angle θ is to be calculated E And theta H Must first find out noFuzzy theta E Values. For this purpose, firstly to theta E And (5) performing deblurring.
The measured fuzzy phase value is first resolved into an angle value according to equation (34), and then the relationship between the angle value and the actual incident angle is shown in fig. 10. It can be seen that θ measured at two frequencies E The values are equal to the true values only near 0 degrees, and after the values exceed a certain range, fuzzy characteristics exist, so that the angle measurement is inaccurate.
However, when the angle values measured at these two frequencies are subtracted, a step chart as shown in fig. 11 is obtained, and the value of each step is different, that is, the correspondence between the angle difference value measured at two different frequencies and the true angle value of the callback signal is the step shape. However, each step is not perfectly flat and has small deviations, that is to say the angle difference value after the actual subtraction is not a constant over the corresponding part interval, but the number of steps is substantially equal, so that in order to make the step effect more obvious, it is easier to determine the steps, and we allow these angle differences to fluctuate within ±1, thus obtaining 7 steps with a determined height of-27, 9, -36, 0, 36, -9, 27, numbered 1 to 7 in sequence from left to right.
The second step in the method of the present invention is therefore based on θ E Is used to determine the step number. The wide angle theta of (-80 DEG, 80 DEG) can be realized by different values of the steps E The measurement is even the omnidirectional measurement of (-90 degrees, 90 degrees), and the high-precision advantage is ensured because the high-frequency test result can be adopted.
At this time, an elevation angle θ without blurring is obtained E Based on equation (34), the measured azimuth angle θ can be calculated H . Note θ H Measured values of specific theta E Influence of the values, so different θ E Corresponding to different theta H Is a measurement of (a). Due to the function cos theta E With respect to theta E Symmetrical =0, so θ H The measurement of θ is also related to E Symmetrical =0, so here equidistant θ is chosen E ＝[-80，0]The measured θ is solved for using the second equation of equation (34) H The values are shown in fig. 12.The corresponding difference is shown in FIG. 13, and it can be seen that θ E The difference maps are all relatively flat step maps (or a straight line) and all contain a limited number of different step values.
At this time although it is different from theta E The value results in a solution to θ using equation (34) H Different measured values are obtained, but fig. 12 shows that the step phenomenon still exists at the moment, so that the process of deblurring is the same, and the same calculation method can be adopted.
The third step in the process of the present invention is therefore based on θ H Is used to determine the step number. By different values of steps and no blurring θ calculated in the second step E A value of (-80 DEG, 80 DEG) wide angle theta E The measurement is even the omnidirectional measurement of (-90 degrees, 90 degrees), and the high-precision advantage is ensured because the high-frequency test result can be adopted.
The two-dimensional wide-angle high-precision angle measurement method based on the eight-port four-baseline radio frequency equipment has the beneficial effects that:
1. evidence of high accuracy advantage
Restoring the fuzzy angle value theta after the second step E From the actual angle value theta E In comparison, the reduction degree was observed, and the simulation result is shown in fig. 14. It can be seen that the restored angle curve completely coincides with the actual angle curve, indicating the restored angle θ according to this method E From the actual angle theta E And the advantages of high precision are ensured because the test results of high frequency can be adopted.
Similarly, the fuzzy angle value theta after the third step of reduction is reduced H From the actual angle value theta H In comparison, the reduction degree was observed, and the simulation result is shown in fig. 15. It can be seen that the restored angle curve completely coincides with the actual angle curve, indicating the restored angle θ according to this method H From the actual angle theta H And the advantages of high precision are ensured because the test results of high frequency can be adopted.
2. Evidence of wide angle advantage
The above discussion is of the measurement of the angle of incidence in the (-80 °,80 °) interval, but it has not been demonstrated that this method can measure the angle of incidence in the (-90 °, -80 °) and (80 °,90 °) intervals. The maximum angular range of the method of the invention is next studied.
Therefore, the incident angle is only required to be expanded to (-90 degrees, 90 degrees), then the angle measurement principle is simulated, the incident angle in the (-90 degrees, 90 degrees) interval can be measured under the feasible frequency factor q, namely the method can measure targets at all angles in the space, and the simulation results are shown in fig. 16 and 17.
In conclusion, the method can be realized in physical practice, and the incident angle in a wide angle range can be measured with high precision.
Examples
This section illustrates the selection range of the frequency factor q and the interval factor t.
The simulation conditions of the conditions under the condition that the frequency factors q=0.8 are given above, the frequency factors are assigned one by one, and the angle measurement principle under different frequency factors is simulated and verified one by one.
1. Let lambda when q=0.6 1 =16.6 mm and λ 2 ＝10mm
From equation (1), the measured fuzzy phase θ at two frequencies is derived E And the first equation of equation (34) is used to model the phase θ E Resolving to obtain the angle value theta with blur E As shown in fig. 18.
The two measured angle values are subtracted to obtain a step, and the step condition is shown in fig. 19. The number of steps at this time is 7, namely-11, 21, -32, 0, 32, -21, 11. To restore the actual phase theta E Taking t=1, the reduction results are shown in fig. 20. The observation result shows that the phase θ after the reduction E Completely coincide with the actual phase curve, indicating the reduction phase theta E And the actual phase theta E Exactly equal, fuzzy phase θ E The reduction was successful.
Reuse of reduced theta E And measured θ H The value of the second equation pair blur phase θ according to equation (34) H Resolving to obtainThe angle value theta with the blur tested at the moment is obtained H As shown in fig. 21. The two measured angle values are subtracted to obtain a step, and the step condition is shown in fig. 22. At this time different theta E Although the values correspond to different step numbers, it is clear from the foregoing that one program can be used to disambiguate these cases. To restore the actual phase theta H Taking t=1, the reduction result is shown in fig. 23. The observation result shows that the phase θ after the reduction H Completely coincide with the actual phase curve, indicating the reduction phase theta H And the actual phase theta H Exactly equal, fuzzy phase θ H The reduction was successful.
Therefore, the method of the present invention is effective when the frequency factor q=0.6.
2. Let λ when q=0.3 1 =27.1 mm and λ 2 ＝8.1mm
Still according to the above method, the step diagrams are shown in fig. 24 and 26, and when t=2 is taken, the angle value calculated by the reduction phase is also completely equal to the actual incident angle value, and the result is shown in fig. 25 and 27. Explaining q=0.3, the method of the present invention works.
3. Let λ when q=0.1 1 =68.8mm and λ 2 ＝6.9mm
Still according to the above method, the step diagrams are shown in fig. 28 and 30, and when t=3 is taken, the calculated angle value of the reduction phase is also completely equal to the actual incident angle value, and the result is shown in fig. 29 and 31. Explaining q=0.1, the method of the present invention works.
4. Summary
And then taking other values of q, and carrying out simulation one by one according to the process, wherein simulation results are not listed one by one.
And determining the value range of k as (0, 1), sweeping the k at intervals of 0.1, and obtaining the following conclusion through multiple simulation.
When q is E (0, 1), the frequency factors can be used for angle measurement by the method.
Further by way of generalization, the interval factor t=3 when q e (0,0.2), the interval factor t=2 when q e (0.2,0.3), and the interval factor t=1 when q e (0.3,1).
Claims (8)
1. The two-dimensional wide-angle high-precision angle measurement method based on the eight-port four-baseline radio frequency equipment is characterized by comprising the following steps of:
step 1, building eight-port four-baseline radio frequency equipment; the method comprises the following steps: providing radio frequency equipment, wherein two ports are arranged in each direction around the radio frequency equipment, baselines are arranged on the four ports of the radio frequency equipment corresponding to the two directions, and a Schottky diode detector is connected to the other four ports of the radio frequency equipment;
step 2, determining a baseline interval and a frequency factor according to the angle range and the wavelength of the radiation source;
step 3, determining the number of steps where the pitch angle of the radiation source is located, wherein the steps are angle difference values of the pitch angles of the radiation source under two different frequencies;
step 4, restoring the actual pitch angle phase value
Step 5, calculating the pitch angle theta of the radiation source E ；
Step 6, determining the number of steps where the azimuth angles of the radiation sources are located, wherein the steps are angle difference values of the azimuth angles of the radiation sources under two different frequencies;
step 7, restoring the actual azimuth phase value
Step 8, calculating the azimuth angle theta of the radiation source H 。
2. The two-dimensional wide-angle high-precision angle measurement method based on eight-port four-baseline radio frequency equipment according to claim 1, wherein the step 2 is specifically: according to the angle range and wavelength of the dual-frequency radiation source, determining the ratio of two frequencies of the radiation source as a frequency factor q, and selecting any distance larger than the size of an antenna receiving the radiation source as a baseline interval d between every two opposite baselines.
3. The two-dimensional wide-angle high-precision angle measurement method based on eight-port four-baseline radio frequency equipment according to claim 2, wherein the step 3 is specifically:
step 3.1, solving all fuzzy pitch values θ that may be measured at two frequencies at all angles of the radiation source angle range using the first equation of equation (34) E1 And theta E2 The subscript numerals 1 and 2 denote a first frequency and a second frequency;
in the formula (34), x= (phi) E +φ H ) 2 and y= (phi) E -φ H ) 2, which can be calculated according to the following formula (33):
in the formula (33), S i5 ＝P i /P5，i＝1,2,3,4；P i The power of the signal output by the Schottky diode detector connected with the ith port of the radio frequency equipment is P5, and the power of the signal received by the base line connected with the 5 th port of the radio frequency equipment is P5;
step 3.2, subtracting the fuzzy pitch angle values under two frequencies, namely theta E1 -θ E2 Obtaining a step diagram of a pitch angle, wherein the total number of steps is L E The steps are numbered from small to large according to the corresponding radiation source angles and are 1,2, … and L E ；
Step 3.3, measuring and calculating the corresponding fuzzy pitch angle difference theta 'of the actual radiation source under the interval of two baselines by adopting eight-port four-baseline dual-frequency radio frequency equipment and a first formula of formula (34)' E1 -θ′ E2 This value is the actual step value;
step 3.4, carrying out the actual step value obtained in step 3.3 and the step diagram obtained in step 3.2Mapping to obtain the actual step number X E 。
4. The two-dimensional wide-angle high-precision angle measurement method based on the eight-port four-baseline radio frequency equipment according to claim 3, wherein the step 4 is specifically:
step 4.1, selecting the phase of any one of the two frequencies for measurementn=1, 2 represents the nth frequency;
step 4.2, obtaining the actual phase value by the following formula (11-1)
In the formula (11-1), t is a section factor, and when q∈ (0,0.2), the section factor t=3, when q∈ (0.2,0.3), the section factor t=2, and when q∈ (0.3,1), the section factor t=1.
5. The two-dimensional wide-angle high-precision angle measurement method based on the eight-port four-baseline radio frequency equipment according to claim 4, wherein the step 5 is specifically: according to the actual phase value obtained in step 4Obtaining the pitch angle theta of the radiation source through a formula (2-1-1) E ：
6. The two-dimensional wide-angle high-precision angle measurement method based on the eight-port four-baseline radio frequency equipment according to claim 5, wherein the step 6 is specifically:
step 6.1, utilizing the non-fuzzy radiation source pitch angle theta obtained in step 5 E And equation (34) a second equation for resolving all ambiguous azimuth values θ that may be measured at two frequencies for all angles of the source angular range H1 And theta H2 The subscript numerals 1 and 2 denote a first frequency and a second frequency;
step 6.2, subtracting the values of the fuzzy azimuth angles under two frequencies, namely theta H1 -θ H2 To obtain the actual pitch angle theta E A step diagram of a lower azimuth angle, wherein the total number of steps is L H The steps are numbered from small to large according to the corresponding radiation source angles and are 1,2, … and L H ；
Step 6.3, measuring and calculating the corresponding fuzzy azimuth angle difference theta 'of the actual radiation source under the interval of two baselines by adopting eight-port four-baseline dual-frequency radio frequency equipment and a second formula of the formula (34)' H1 -θ′ H2 This value is the actual step value;
step 6.4, mapping the actual step value obtained in step 6.3 and the step map obtained in step 6.2 to obtain an actual step number X H 。
7. The two-dimensional wide-angle high-precision angle measurement method based on the eight-port four-baseline radio frequency equipment according to claim 6, wherein the step 7 is specifically:
step 7.1, selecting the phase of any one of the two frequencies for measurementn=1, 2 represents the nth frequency;
step 7.2, obtaining the actual phase value by the following formula (11-2)
In the formula (11-2), t is a section factor, the size is determined by a frequency factor q, when q is e (0,0.2), the section factor t=3, when q is e (0.2,0.3), the section factor t=2, and when q is e (0.3,1), the section factor t=1.
8. The two-dimensional wide-angle high-precision angle measurement method based on the eight-port four-baseline radio frequency equipment according to claim 7, wherein the step 8 is specifically: according to the actual phase value obtained in step 7Obtaining the radiation source angle theta through a formula (2-1-2) H ：
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