Radio direction finding antenna system

Abstract

The utility model provides a radio direction-finding antenna system, comprising at least four directional antenna units which respectively point to different azimuth angles, and the directional antenna units are used for receiving signals to be detected; the system further comprises a receiver and radio frequency change-over switches, the receiver is connected with the directional antenna units through at least one radio frequency change-over switch, the radio frequency change-over switches are used for switching the directional antenna units connected with the receiver, and the receiver is used for receiving signal information of the directional antenna units and sending the signal information to the directional antenna units. And obtaining a maximum likelihood direction by using the prior information of each directional antenna unit. Each directional antenna unit works independently, and antenna units in opposite directions do not need to be combined, so that the antenna system has no special requirement and limitation on the antenna array size or the mechanical structure.

Description

Technical Field

[0001] The utility model relates to the technical field of radio direction finding, in particular to a radio direction finding antenna system. Background Art

[0002] Radio direction finding is a process of using instruments and equipment to determine the direction of incoming radio waves based on the propagation characteristics of electromagnetic waves. Its main principle is to use the radio propagation characteristics to determine the position of the signal source (transmitter).

[0003] In the current mainstream amplitude comparison direction finding method, the Adcock antenna system is adopted. Please refer to Figure 1 ., the Adcock antenna system uses four omnidirectional antenna elements, and these four omnidirectional antennas are arranged in a quadrilateral at equal intervals in the four directions of east (E), west (W), south (S), and north (N). According to the Adcock antenna principle, the antenna elements in the north-south and east-west directions respectively form an antenna group, and the combined radiation pattern of the antenna groups in the opposite directions is the Figure 1 spindle shape shown in the figure. When radio signals are incident from any direction, it will cause changes in the amplitude of the induced current on the four omnidirectional antenna elements. By comparing the amplitudes of the signals on the four antenna elements, the direction of the signal source relative to the antenna system can be calculated.

[0004] According to the working characteristics of the Adcock antenna system, it is necessary to ensure the spindle-shaped radiation pattern formed by the antenna groups (N-S direction, W-E direction), otherwise pattern distortion errors will occur. Specifically, according to the antenna principle, the distance between Adcock antennas needs to be less than or equal to one wavelength of the antenna operating frequency band. If this condition is not met, grating lobes will be generated, thereby introducing pattern errors. Therefore, this limits the size of the Adcock antenna system.

[0005] Moreover, in actual use of wideband or multi-band systems, the antenna operating wavelengths corresponding to high and low frequencies often approach or exceed 2:1, which limits the application scenarios of the Adcock antenna system. Limiting the application scenarios of the Adcock antenna system means that for a relatively wide operating bandwidth, the shortest and longest operating wavelengths often exceed 2:1. If the longest wavelength is adopted, the conditions for direction finding in the high-frequency range will not be met.

[0006] Therefore, antenna systems that measure direction based on the comparison of received signal amplitudes usually have special requirements and limitations in terms of antenna array size or mechanical structure. Summary of the Utility Model

[0007] To solve the above technical problems, an embodiment of the utility model provides a radio direction finding antenna system, including:

[0008] At least four directional antenna units respectively pointing to different azimuth angles, and the directional antenna units are used for receiving signals to be measured;

[0009] A receiver and a radio frequency switch, the receiver is respectively connected to each of the directional antenna units through at least one of the radio frequency switches, the radio frequency switch is used for switching the directional antenna unit connected to the receiver, and the receiver is used for:

[0010] Receiving the signal information of each of the directional antenna units, and using the prior information of each of the directional antenna units to obtain the maximum likelihood direction.

[0011] Preferably, the prior information of each of the directional antenna units includes the radiation pattern and the installation position of each of the directional antenna units.

[0012] Preferably, all the directional antenna units are arranged at 360° circumferential intervals in the same plane and are arranged in a ring shape.

[0013] Preferably, the plane is a horizontal plane.

[0014] Preferably, the number of the directional antenna units is N, N is an integer greater than or equal to 4, the N directional antenna units are evenly arranged, and the beam width of each of the directional antenna units is (360 / N) + / - 10°.

[0015] Preferably, the directional antenna unit is installed in a protective cover.

[0016] Preferably, the receiver includes a control unit and a signal processing unit, the control unit and the signal processing unit are both connected to the radio frequency switch, the control unit is used for controlling the radio frequency switch to switch with several of the directional antenna units, and the signal processing unit is used for sampling each of the directional antenna units, acquiring the signal information of each of the directional antenna units, and performing interpolation algorithm and calibration algorithm on the received signal information of each of the directional antenna units, so as to obtain the maximum likelihood direction through the determination of the rationality of direction finding.

[0017] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects:

[0018] In the radio direction finding antenna system of the technical solution of the present invention, the receiver can collect the signal information of different directional antenna units by using the radio frequency switch, and at the same time calculate the maximum likelihood propagation direction of the received signal by using the prior information such as the radiation pattern characteristics of the directional antenna unit and the installation position of the antenna unit, so as to realize the radio direction finding function. Since each of the directional antenna units works independently and does not require the combination of antenna units in the relative direction, therefore, there are no special requirements and restrictions on the size of the antenna array or the mechanical structure of this antenna system. Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of an Adcock antenna system;

[0020] Figure 2 It is a schematic structural diagram of a radio direction-finding antenna system provided by an embodiment of the present invention;

[0021] Figure 3 It is a schematic installation structure diagram of multiple directional antenna units provided by an embodiment of the present invention;

[0022] Figure 4 It is a schematic distribution diagram of multiple directional antenna units provided by an embodiment of the present invention;

[0023] Figure 5 It is a radiation pattern of multiple directional antenna units provided by an embodiment of the present invention;

[0024] Figure 6 It is a radiation pattern of the first directional antenna unit provided by an embodiment of the present invention;

[0025] Figure 7 It is a radiation pattern of the eighth directional antenna unit provided by an embodiment of the present invention;

[0026] Figure 8 It is a radiation pattern of the seventh directional antenna unit provided by an embodiment of the present invention;

[0027] Figure 9 It is a radiation pattern of the third to fifth directional antenna units provided by an embodiment of the present invention;

[0028] Figure 10 It is a schematic diagram of the direction-finding process of the radio direction-finding antenna system provided by an embodiment of the present invention.

[0029] Description of the Reference Numerals:

[0030] 1 - Directional antenna unit;

[0031] 101 - First directional antenna unit;

[0032] 1010 - First radiation pattern;

[0033] 102 - Second directional antenna unit;

[0034] 1020 - Second radiation pattern;

[0035] 103 - Third directional antenna unit;

[0036] 1030 - Third radiation pattern;

[0037] 104 - Fourth directional antenna unit;

[0038] 1040 - Fourth radiation pattern;

[0039] 105 - Fifth directional antenna unit;

[0040] 1050 - Fifth radiation pattern;

[0041] 106 - Sixth directional antenna unit;

[0042] 1060 - Sixth radiation pattern;

[0043] 107 - Seventh directional antenna unit;

[0044] 1070 - Seventh radiation pattern;

[0045] 108 - Eighth directional antenna unit;

[0046] 1080 - Eighth radiation pattern;

[0047] 2 - Receiver;

[0048] 3 - RF switch;

[0049] 4 - Protective cover;

[0050] 5 - Signal to be measured. Detailed implementation mode

[0051] As described in the background art, currently, antenna systems for determining direction based on received signal amplitude comparison usually have special requirements and limitations in terms of antenna array size or mechanical structure. To solve the above technical problems, the present utility model provides a radio direction finding antenna system, including:

[0052] At least four directional antenna units respectively pointing to different azimuth angles, the directional antenna units being used for receiving the signal to be measured;

[0053] A receiver and an RF switch, the receiver being respectively connected to each of the directional antenna units through at least one of the RF switches, the RF switch being used for switching the directional antenna unit connected to the receiver, and the receiver being used for:

[0054] Receiving the signal information of each of the directional antenna units, and using the prior information of each of the directional antenna units to obtain the maximum likelihood direction.

[0055] In the present utility model, each directional antenna unit operates independently and does not require combination with antenna units in the opposite direction. Therefore, there are no special requirements or limitations on the antenna array size or mechanical structure of this antenna system. In the radio direction-finding antenna system of the technical solution of the present utility model, the receiver can collect the radiation patterns of different directional antenna units by using a radio frequency switching switch, and at the same time calculate the maximum likelihood propagation direction of the received signal by using the prior information such as the radiation pattern characteristics of the directional antenna unit and the installation position of the antenna unit, thereby realizing the radio direction-finding function. Since each directional antenna unit operates independently and does not require combination with antenna units in the opposite direction, there are no special requirements or limitations on the antenna array size or mechanical structure of this antenna system.

[0056] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0057] Please refer to Figure 2 , a radio direction-finding antenna system, including at least four directional antenna units 1 respectively pointing to different azimuth angles. Since each directional antenna unit 1 points to a different azimuth angle, the more the number of directional antenna units 1, the higher the measurement accuracy. The present utility model does not specifically limit the number of directional antenna units 1, which can be set according to actual usage requirements.

[0058] The direction-finding antenna system further includes a radio frequency switching switch 3 and a receiver 2. The receiver 2 is respectively connected to each directional antenna unit 1 through at least one radio frequency switching switch 3. The present utility model does not limit the number of radio frequency switching switches 3, which can be set according to actual usage requirements. In one embodiment, the radio frequency switching switch 3 is a single-pole multi-throw radio frequency switch. The receiver 2 is respectively connected to each directional antenna unit 1 through one radio frequency switching switch 3. This radio frequency switching switch 3 is used to control the connection between each directional antenna unit 1 and the receiver 2. During operation, the radio frequency switching switch 3 quickly switches the directional antenna unit 1 connected to the receiver 2. Each directional antenna unit 1 is connected to the receiver 2 in turn through the radio frequency switching switch 3. At the same time, only one directional antenna unit 1 is working.

[0059] In one embodiment, all the directional antenna units 1 are arranged at 360° circumferential intervals on the same horizontal plane and are arranged in a ring shape. In order to ensure that each directional antenna 1 unit faces a specific angle, the directional antenna unit 1 is installed in an antenna protective cover 4. Please refer to Figure 3。In a usage scenario, N directional antenna units 1 are arranged uniformly, where N is an integer greater than or equal to 4, and the beam width of each directional antenna unit 1 is (360 / N) + / - 10°.

[0060] Since the orientations of the respective directional antenna units 1 are different, the radiation patterns of the respective directional antenna units 1 point in different directions. Thus, in the detection state, the signal to be measured is received by each of the directional antenna units 1. However, because the radiation patterns of the respective directional antenna units 1 point in different directions, the gains of the respective directional antenna units 1 for signals at their respective angles are also inconsistent. Therefore, the signal information received by the receiver 2 will show significant differences.

[0061] Taking eight directional antenna units as an example, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0062] In this embodiment, please refer to Figure 4 , eight directional antenna units are arranged at uniform intervals in a 360° circle on the same horizontal plane and are arranged in a ring. The beam width of each directional antenna unit is (360 / 8) + / - 10° = 45° + / - 10°.

[0063] The eight directional antenna units are sorted counterclockwise and are respectively the first directional antenna unit 101, the second directional antenna unit 102, the third directional antenna unit 103, the fourth directional antenna unit 104, the fifth directional antenna unit 105, the sixth directional antenna unit 106, the seventh directional antenna unit 107, and the eighth directional antenna unit 108. The first directional antenna unit 101 points to the due north direction of 0°, the second directional antenna unit 102 points to the northwest direction of 315°, the third directional antenna unit 103 points to the due west direction of 270°, the fourth directional antenna unit 104 points to the southwest direction of 225°, the fifth directional antenna unit 105 points to the due south direction of 180°, the sixth directional antenna unit 106 points to the southeast direction of 135°, the seventh directional antenna unit 107 points to the due east direction of 90°, and the eighth directional antenna unit 108 points to the northeast direction of 45°.

[0064] Figure 5are the radiation patterns of respective directional antenna elements. The first radiation pattern 1010 is the radiation pattern of the first directional antenna element 101, the second radiation pattern 1020 is the radiation pattern of the second directional antenna element 102, the third radiation pattern 1030 is the radiation pattern of the third directional antenna element 103, the fourth radiation pattern 1040 is the radiation pattern of the fourth directional antenna element 104, the fifth radiation pattern 1050 is the radiation pattern of the fifth directional antenna element 105, the sixth radiation pattern 1060 is the radiation pattern of the sixth directional antenna element 106, the seventh radiation pattern 1070 is the radiation pattern of the seventh directional antenna element 107, and the eighth radiation pattern 1080 is the radiation pattern of the eighth directional antenna element 108. In the detection state, the signal under test 5 will be received by each directional antenna element. However, since the radiation patterns of the directional antenna elements point in different directions, the signal gains of each directional antenna element for signals at their respective angles are inconsistent. There will be a significant difference in the signal strengths received by the receiver 2 from each directional antenna element. According to Figures 6 to 9 as shown, the signal serial number of the first directional antenna element 101 obtained is SN1, and the signal strength is Psn1; the signal serial number of the second directional antenna element 102 obtained is SN2, and the signal strength is Psn2; the signal serial number of the third directional antenna element 103 obtained is SN3, and the signal strength is Psn3; the signal serial number of the fourth directional antenna element 104 obtained is SN4, and the signal strength is Psn4; the signal serial number of the fifth directional antenna element 105 obtained is SN5, and the signal strength is Psn5; the signal serial number of the sixth directional antenna element 106 obtained is SN6, and the signal strength is Psn6; the signal serial number of the seventh directional antenna element 107 obtained is SN7, and the signal strength is Psn7; the signal serial number of the eighth directional antenna element 108 obtained is SN8, and the signal strength is Psn8; the signal strengths Psn1 - Ps n 8 received by the receiver 2 from each directional antenna element are as shown in Table 1 below:

[0065] Table 1 Received Level - System Decision Table

[0066] SN1 SN2 SN3 SN4 SN5 SN6 SN7 SN8 Judgment Level -92.4 -97.5 -127.4 -130.1 -110.3 -100.5 -80.1 -65.6 SN8

[0067] Generate a signal strength data table based on the above signal strengths. According to the interpolation algorithm and calibration algorithm, the maximum likelihood direction can be obtained through the determination of the rationality of direction finding, and thus the direction of the signal under test can be calculated.

[0068] Specifically, the receiver includes a control unit and a signal processing unit. Both the control unit and the signal processing unit are connected to the RF switch. The control unit is used to control the RF switch to switch with several of the directional antenna units. The signal processing unit is used to sample each of the directional antenna units, obtain the signal information of each directional antenna unit, and perform interpolation algorithms and calibration algorithms on the signal information received from each of the directional antenna units, so as to obtain the maximum likelihood direction through the determination of the rationality of direction finding.

[0069] The direction finding method of a radio direction finding antenna system provided in this embodiment includes:

[0070] Control the RF switch 3 to switch the connection between each directional antenna unit and the receiver 2. The receiver 2 sequentially collects the signal intensities of each directional antenna unit;

[0071] The receiver stores the signal intensities received from each directional antenna unit in groups, compares and sorts the stored signal intensities, and screens out the most reasonable results.

[0072] Then perform interpolation calculation on the results to obtain a more accurate maximum likelihood direction. Among them, the maximum likelihood direction (the maximum likelihood source position) is based on readable information such as the intensity (non-pure signal level) after receiving signal decoding and the RF channel calibration information.

[0073] The specific steps of the direction finding method are as Figure 10 :

[0074] 1. After the receiver is powered on and initialized, the working time will be marked as the 0 moment (or the initial moment);

[0075] 2. The receiver scans and samples the RF signals of each port through the RF switch;

[0076] 3. Obtain the content of the signal through the decoding module of the receiver, and at the same time obtain the intensity value table of each signal, such as the intensity values listed in Table 1;

[0077] 4. The receiver corrects the intensity value table through the calibration information of the RF channel to obtain a weighted signal intensity value table;

[0078] Among them, the signal serial number of the first directional antenna unit 101 is SN1, the signal strength is Psn1, and the weighted signal strength is Ptsn1; the signal serial number of the second directional antenna unit 102 is SN2, the signal strength is Psn2, and the weighted signal strength is Ptsn2; the signal serial number of the third directional antenna unit 103 is SN3, the signal strength is Psn3, and the weighted signal strength is Ptsn3; the signal serial number of the fourth directional antenna unit 104 is SN4, the signal strength is Psn4, and the weighted signal strength is Ptsn4; the signal serial number of the fifth directional antenna unit 105 is SN5, the signal strength is Psn5, and the weighted signal strength is Ptsn5; the signal serial number of the sixth directional antenna unit 106 is SN6, the signal strength is Psn6, and the weighted signal strength is Ptsn6; the signal serial number of the seventh directional antenna unit 107 is SN7, the signal strength is Psn7, and the weighted signal strength is Ptsn7; the signal serial number of the eighth directional antenna unit 108 is SN8, the signal strength is Psn8, and the weighted signal strength is Ptsn8.

[0079] 5. Check whether the time mark is T0 (initial mark). If it is at the T0 moment, directly record the initial maximum likelihood source position L0.

[0080] 6. If the time mark is not T0, it is necessary to make a rationality judgment in combination with the previous detection result Ln-1.

[0081] 7. If the rationality judgment passes, record the maximum likelihood source position Ln, increment the time mark by 1, and proceed to the next round of direction finding process.

[0082] 8. If the rationality judgment fails, discard the current test result and directly proceed to the next round of direction finding process.

[0083] Although the present utility model is disclosed as above, the present utility model is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present utility model. Therefore, the protection scope of the present utility model should be subject to the scope defined by the claims.

Claims

1. A radio direction finding antenna system, characterized in that: include: At least four directional antenna units pointing to different azimuth angles, respectively, and the directional antenna units are used to receive the signal to be tested; A receiver and a radio frequency switch, wherein the receiver is connected to each of the directional antenna units through at least one radio frequency switch, and the radio frequency switch is used to switch the directional antenna unit connected to the receiver, and the receiver is used to: The signal information of each directional antenna unit is received, and the prior information of each directional antenna unit is used to obtain the maximum likelihood direction.

2. The radio direction finding antenna system according to claim 1, characterized in that: The prior information of each of the directional antenna units includes the directional pattern and installation position of each of the directional antenna units.

3. The radio direction finding antenna system according to claim 1, characterized in that: All the directional antenna units are arranged in a same plane at 360° circumferential intervals and in a ring shape.

4. The radio direction finding antenna system according to claim 3, characterized in that: The plane is a horizontal plane.

5. The radio direction finding antenna system according to claim 3, characterized in that: The number of the directional antenna units is N, where N is an integer greater than or equal to 4, the N directional antenna units are evenly arranged, and the beam width of each directional antenna unit is (360 / N)+ / -10°.

6. The radio direction finding antenna system according to claim 1, characterized in that: The directional antenna unit is installed in a protective cover.

7. The radio direction finding antenna system according to claim 1, characterized in that: The receiver includes a control unit and a signal processing unit, both of which are connected to the radio frequency switching switch. The control unit is used to control the radio frequency switching switch to switch with a plurality of the directional antenna units. The signal processing unit is used to sample each of the directional antenna units, obtain signal information of each of the directional antenna units, and perform interpolation and calibration algorithms on the received signal information of each of the directional antenna units, so as to obtain the maximum likelihood direction through direction finding rationality judgment.

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