Low-coupling direction-finding antenna array

Abstract

The utility model relates to a low-coupling direction-finding antenna array, which comprises a sealed cavity, an annular hollow support, a first antenna array, a second antenna array, a third antenna array, a radio frequency matrix switch, a one-to-four switch, a synthesizer, a low-noise amplifier and a switch box, and is characterized in that the first antenna array, the second antenna array and the third antenna array are arranged on the annular hollow support in a staggered manner on the same layer; the radio frequency matrix switch, the one-to-four switch, the synthesizer and the low-noise amplifier are all arranged in the switch box, the synthesizer is used for switching a signal path of the third antenna array into a synthesized signal, and the low-noise amplifier is used for carrying out active and passive switching on a directional diagram. The beneficial effects of the utility model lie in that the directional diagram of the array elements can be controlled and the coupling among the dense array elements can be reduced, thereby preventing the interference among the array elements from influencing the performance, and simultaneously realizing the miniaturization and light weight of the antenna array.

Description

Technical Field

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

[0002] At present, the domestic direction-finding antenna arrays are mostly used in radio monitoring stations and large and medium-sized monitoring vehicles. The antenna arrays are large (more than 1 meter in diameter) and weigh more than 20 kilograms. Interferometer direction-finding systems are mostly used. Antennas are usually supported by iron towers and brackets on the ground or on the roof, a few meters to a hundred meters above the ground. Even so, its electromagnetic environment cannot be compared with that of high altitudes. With the rapid development of drone technology in recent years, the use of unmanned helicopters to launch monitoring and direction-finding equipment has emerged in order to obtain a better electromagnetic environment; secondly, through the unmanned helicopter platform, its rapid mobility can be used to realize the function of single-machine positioning; thirdly, through the unmanned helicopter platform, the utilization rate of the equipment can be improved.

[0003] Most existing antenna arrays are single omnidirectional elements, whose directivity patterns are difficult to control, and whose primary and secondary identification strengths are the same, resulting in large coupling between dense array elements, which easily interfere with each other and affect performance. For the launch of monitoring equipment, the design of airborne direction-finding antenna arrays is a key and difficult point, especially the need to address the problem of miniaturization and lightweight of antenna arrays. Utility Model Content

[0004] The purpose of the utility model is to overcome the shortcomings of the prior art and provide a low-coupling direction-finding antenna array, which can control the directional pattern of the array elements and reduce the coupling between dense array elements, thereby preventing interference between the array elements from affecting the performance, and at the same time can achieve miniaturization and lightweight of the antenna array.

[0005] The purpose of the utility model is achieved through the following technical solutions:

[0006] A low-coupling direction-finding antenna array comprises a sealed cavity, an annular hollow bracket, a first antenna array, a second antenna array, a third antenna array, a radio frequency matrix switch, a one-to-four switch, a synthesizer and a low-noise amplifier. The annular hollow bracket is arranged in the sealed cavity, the first antenna array, the second antenna array and the third antenna array are arranged on the annular hollow bracket in a staggered manner on the same layer, a switch box is arranged at the bottom of the sealed cavity, the radio frequency matrix switch, the one-to-four switch, the synthesizer and the low-noise amplifier are all arranged in the switch box, the first antenna array and the second antenna array are both connected to the input end of the radio frequency matrix switch, the third antenna array is connected to the input end of the one-to-four switch, one output end of the one-to-four switch is connected to the input end of the radio frequency matrix switch, the other three output ends of the one-to-four switch are connected to the input end of the radio frequency matrix switch through the synthesizer, the low-noise amplifier is electrically connected to the output end of the radio frequency matrix switch, the synthesizer is used to switch the signal path of the third antenna array to a synthesized signal, and the low-noise amplifier is used to perform active and passive switching on the directional pattern of the array element.

[0007] Furthermore, the annular hollow bracket is an integrated structure made of honeycomb sandwich material, the annular hollow bracket includes a circular hollow plate and a support plate, there are three circular hollow plates, the three circular hollow plates are concentric and arranged in sequence from bottom to top, the diameters of the three circular hollow plates decrease in sequence from bottom to top, the three circular hollow plates are connected and supported in the sealed cavity through the support plate, the first antenna array, the second antenna array, and the third antenna array are arranged in sequence from bottom to top on the outer edges of the three circular hollow plates, the top of the second antenna array is at the same height as the top of the first antenna array, and the third antenna array is located above the first antenna array.

[0008] Furthermore, the first antenna array includes seven first dipole antennas with an operating frequency band of 30 MHz-1.3 GHz, and the first dipole antennas are distributed on the outer edge of the corresponding circular hollow plate in a circular array with the center of the circular hollow plate as the center.

[0009] Furthermore, the second antenna array includes seven second dipole antennas with an operating frequency band of 1 GHz-3.6 GHz. The second dipole antennas are distributed in a circular array on the outer edge of the corresponding circular hollow plate with the center of the circular hollow plate as the center. The second dipole antennas are staggered with the first dipole antennas.

[0010] Furthermore, the third antenna array includes seven FPC antennas with an operating frequency band of 3GHz-8GHz. The FPC antennas are distributed in a circular array on the outer edge of the corresponding circular hollow plate with the center of the circular hollow plate as the center. The FPC antennas are staggered with the first dipole antenna and the second dipole antenna.

[0011] Furthermore, a flange is provided at the bottom of the sealed cavity, a shielding plate is provided between the flange and the bottom of the sealed cavity, and the switch box is provided in the middle of the flange and is integrally formed with the flange.

[0012] Furthermore, the RF matrix switch includes 28 input terminals and 3 output terminals, the switch box is provided with 21 RF input interfaces located in the sealed cavity, the switch box is also provided with 3 RF output interfaces located outside the sealed cavity, 1 calibration signal input interface and 1 control interface, 3 low-noise amplifiers are provided, 7 synthesizers are provided, 7 one-to-four switches are provided, the first dipole antenna and the second dipole antenna are both connected to the input terminal of the RF matrix switch through the RF input interface, each FPC antenna corresponds to 1 synthesizer and 1 one-to-four switch, and the FPC antenna is connected to the RF matrix switch through the RF input interface. The port is connected to the input end of the corresponding one-to-four switch, one output end of the one-to-four switch is connected to the input end of the RF matrix switch, the other three output ends of the one-to-four switch are respectively connected to the input end of the corresponding synthesizer and the input ends of two synthesizers adjacent to the corresponding synthesizer, the output end of the synthesizer is connected to the input end of the RF matrix switch, the three output ends of the RF matrix switch are respectively connected to the input ends of three adjustable gain low noise amplifiers, the output ends of the three adjustable gain low noise amplifiers are respectively connected to the three RF output interfaces, and the calibration signal input interface and the control interface are electrically connected to the RF matrix switch.

[0013] Furthermore, 21 radio frequency input interfaces are distributed in an array around the central circumference of the switch box.

[0014] Compared with the prior art, the utility model has the following beneficial effects:

[0015] 1. The utility model can realize the directional pattern control of the array element, change the sensitivity of the array element and the size of the directional pattern, and change the sharpness of the directional pattern by merging the array elements, thereby reducing the coupling between dense array elements, and further reducing the impact of the coupling through a highly robust algorithm.

[0016] 2. The utility model solves the electrical coupling problem of dense array technology. Through the same-layer staggered array technology, the height requirement of space is reduced compared with the existing staggered array method. It has a smaller volume and lighter weight than the existing five-channel and nine-channel space spectrum direction finding systems, making the direction finding antenna array technology feasible on the flight platform. At the same time, it meets the airborne aerodynamic requirements and reduces the impact of large external antenna arrays on the aerodynamic structure of the flight platform. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the external structure of the utility model;

[0018] Figure 2 This is a schematic diagram of the overall internal structure of the sealed cavity in the utility model;

[0019] Figure 3 It is a front view schematic diagram of the internal structure of the sealing cavity in the utility model;

[0020] Figure 4 It is a top view schematic diagram of the internal structure of the sealed cavity in the utility model;

[0021] Figure 5 This is a bottom view structural diagram of the sealed cavity in the utility model;

[0022] Figure 6 It is a schematic diagram comparing the morphology of the composite array element in the present invention and the existing single omnidirectional array element;

[0023] Figure 7 It is a schematic diagram comparing the array element responses of the synthetic array element in the utility model and the existing single omnidirectional array element.

[0024] In the figure: 1. Sealed cavity; 2. Circular hollow plate; 3. Support plate; 4. First dipole antenna; 5. Second dipole antenna; 6. FPC antenna; 7. Flange; 8. Shielding plate; 9. Switch box; 10. RF input interface; 11. RF output interface; 12. Calibration signal input interface; 13. Control interface. DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following description.

[0026] A low-coupling direction-finding antenna array comprises a sealed cavity 1, a ring-shaped hollow bracket, a first antenna array, a second antenna array, a third antenna array and a radio frequency matrix switch. Figure 1 As shown, the top of the sealed cavity 1 is streamlined, with specific dimensions of Φ720*350mm and a weight of 5.6kg. An annular hollow bracket is arranged in the sealed cavity.

[0027] like Figure 2 As shown, the first antenna array, the second antenna array and the third antenna array, a total of three sets of antenna array elements, can cover the commonly used VHF / UHF frequency bands; wherein, the first antenna array includes seven first dipole antennas 4 with a working frequency band of 30MHz-1.3GHz; the second antenna array includes seven second dipole antennas 5 with a working frequency band of 1GHz-3.6GHz, and the third antenna array includes seven FPC antennas 6 with a working frequency band of 3GHz-8GHz.

[0028] like Figure 1 , Figure 4 , Figure 5As shown, a switch box is provided at the bottom of the sealed cavity 1, and the RF matrix switch is provided in the switch box 9. The RF matrix switch includes 28 input terminals and 3 output terminals. The switch box 9 is provided with 21 RF input interfaces 10 located in the sealed cavity 1, and the switch box 9 is also provided with 3 RF output interfaces 11 located outside the sealed cavity 1, 1 calibration signal input interface 12 and 1 control interface 13. The first dipole antenna 4, the second dipole antenna 5 and the FPC antenna 6 are all electrically connected to the input terminal of the RF matrix switch through the RF input interface 10, and the three RF output interfaces 11 are respectively electrically connected to the three output terminals of the RF matrix switch. The calibration signal input interface 12 and the control interface 13 are both electrically connected to the RF matrix switch, so that the first antenna array, the second antenna array, the third antenna array and the RF matrix switch constitute a three-channel seven-element spatial spectrum direction finding system.

[0029] In order to facilitate the control of the directional pattern of the array elements and reduce the coupling between dense array elements while the antenna array is communicating, the utility model further provides three adjustable gain low noise amplifiers, seven synthesizers and seven one-to-four switches in the switch box 9. The first dipole antenna 4 and the second dipole antenna 5 are both connected to the input end of the RF matrix switch through the RF input interface 10, so that the signal path of the first antenna array and the second antenna array is a direct signal; each FPC antenna 6 corresponds to a synthesizer and a one-to-four switch, the FPC antenna 6 is connected to the input end of the corresponding one-to-four switch through the RF input interface 10, an output end of the one-to-four switch is connected to the input end of the RF matrix switch, and the other three output ends of the one-to-four switch are respectively connected to the input end of the corresponding synthesizer and the input ends of two synthesizers adjacent to the corresponding synthesizer, and the output end of the synthesizer is further connected to the input end of the RF matrix switch, thereby making the signal path of the third antenna array a direct signal, and the signal path of the third antenna array can also be switched to a synthesized signal, the three output ends of the RF matrix switch are respectively connected to the input ends of three adjustable gain low noise amplifiers, and the output ends of the three adjustable gain low noise amplifiers are respectively connected to three RF output interfaces 11. The calibration signal enters the RF matrix switch through the calibration signal input interface 12, and then is divided into 28 channels in the RF matrix switch and connected to the 28 input terminals of the RF matrix switch, thereby obtaining the channel errors of the 28 input signals; the control signal enters the RF matrix switch through the control interface 13, thereby controlling the RF matrix switch.

[0030] The gain of the adjustable gain low noise amplifier is controllable, with three levels of 0db, 10db, and 20db. When 0db is selected, the adjustable gain low noise amplifier is in the off state. At this time, the radiation pattern of the entire antenna array is equivalent to a passive array, with good consistency; when 10db or 20db is selected, the adjustable gain low noise amplifier is in the amplification state. At this time, the radiation pattern of the entire antenna array is equivalent to an active array. Compared with the passive array, all directions are expanded at the same time, increasing the sensitivity of the array elements.

[0031] For 3G-8G signals, when the amplifier is at 20db or the directionality jitter is too large, the signal path can be switched to the synthetic signal through the synthesizer, and the direction finding algorithm is changed from a 3-channel spatial spectrum or correlation interferometer to a 2-channel correlation interferometer. At this time, the directional pattern of the entire antenna array is sharper than that of the passive array, which increases the sensitivity of the array element or the signal-to-noise ratio of the signal.

[0032] like Figure 6 As shown in the figure, a is a single omnidirectional array element form in the prior art without using a synthesizer, and the directional array elements are homogeneous; b is a synthesized array element form when the signal path is switched to a synthesized signal through a synthesizer in the utility model.

[0033] like Figure 7 As shown in the figure, c is the existing single omnidirectional array element at 0 o -360 o The array element response within the range, d is the synthetic array element 0 in the utility model o -360 o It can be seen that the primary and secondary recognition strengths of a single omnidirectional array element are the same, resulting in greater coupling between dense array elements, while the primary recognition strength of the composite array element is enhanced and the secondary recognition is weakened. Therefore, the present invention switches the signal path to the composite signal through the synthesizer, which can reduce the coupling between dense array elements while changing the sharpness of the directional pattern, and further reduce the impact of coupling through a robust algorithm.

[0034] In order to reduce the overall weight of the airborne direction finding antenna array and make the structure more compact, such as Figure 4 , Figure 5 As shown, a flange 7 is fixed at the bottom of the sealed cavity 1, a shielding plate 8 is provided between the flange 7 and the bottom of the sealed cavity 1, a switch box 9 is provided in the middle of the flange 7 and is integrally connected with the flange 7, and thus the space at the connection with the body is fully utilized through the integrated design, 21 RF input interfaces 10 are distributed in a circular array around the center of the switch box 9, and thus the height of the entire switch is shortened and the length of the RF connecting line is shortened through the circumferential arrangement of the RF interfaces.

[0035] In addition, in order to further realize the miniaturization and lightweight of the overall structure of the antenna array, the utility model combines an annular hollow bracket and adopts a same-layer staggered array method to install and layout the first antenna array, the second antenna array and the third antenna array on the hollow bracket.

[0036] Specifically, Figure 2-Figure 4 As shown, the first antenna array, the second antenna array and the third antenna array are arranged in sequence from the outer edge of the annular hollow bracket to the center of the annular hollow bracket, wherein the top of the second antenna array is at the same height as the top of the first antenna array, and the third antenna array is located above the first antenna array.

[0037] like Figure 2 , Figure 3 As shown, the annular hollow bracket is an integrated structure made of honeycomb sandwich material, and the annular hollow bracket includes a circular hollow plate 2 and a support plate 3. There are three circular hollow plates 2, which are concentric and arranged in sequence from bottom to top. The diameters of the three circular hollow plates 2 decrease in sequence from bottom to top. The three circular hollow plates 2 are connected and supported in the sealed cavity 1 through the support plate 3, and the first antenna array, the second antenna array, and the third antenna array are fixed on the three circular hollow plates 2 in sequence from bottom to top.

[0038] like Figure 4 As shown, the first dipole antenna 4 is distributed in a circular array around the outer edge of the corresponding circular hollow plate 2 with the center of the circular hollow plate 2 as the center. The first antenna array adopts a spatial spectrum estimation direction finding system to reduce the phase ambiguity caused by the antenna aperture, thereby effectively reducing the diameter of the antenna. This frequency band uses the DML (Determinacy Maximum Likelihood) algorithm in the spatial spectrum estimation direction finding technology. Although it involves a large amount of two-dimensional search calculations, it has high estimation accuracy and strong anti-interference ability, and the impact caused by phase ambiguity is small. The root mean square error of the direction finding accuracy within the frequency band is 2 degrees.

[0039] like Figure 4 As shown, the second dipole antenna 5 is distributed in a circular array around the outer edge of the corresponding circular hollow plate 2 with the center of the circular hollow plate 2 as the center, and the second dipole antenna 5 is staggered with the first dipole antenna 4. This frequency band usually adopts the MUSIC (Multiple Signal Classification) algorithm in the spatial spectrum estimation technology, which has accurate direction finding and fast direction calculation. When the coherent signal is directionally found, the DML algorithm is used, and the root mean square error of the direction finding accuracy within the frequency band is 1 degree.

[0040] like Figure 4As shown, the FPC antenna 6 is distributed in a circular array around the outer edge of the corresponding circular hollow plate 2 with the center of the circular hollow plate 2 as the center, and the FPC antenna 6 is staggered with the first dipole antenna 4 and the second dipole antenna 5. This frequency band uses an interferometer algorithm, which has a small amount of calculation, fast direction indication, and is conducive to moving target tracking. The root mean square error of the direction finding accuracy within the frequency band is 1 degree.

[0041] Based on the structure of the above-mentioned annular hollow bracket and the installation layout of the three sets of antenna array elements, the annular hollow bracket of the utility model has high strength and light weight, taking into account the strength and weight requirements, while achieving a more compact installation of the three sets of antenna array elements, reducing the overall weight of the airborne direction-finding antenna array; through the same-layer staggered array technology, the height requirement of the space is reduced, the overall structure is more compact and meets the miniaturization requirements, making the direction-finding antenna array technology feasible on the flight platform, while meeting the airborne aerodynamic requirements and reducing the impact of large external antenna arrays on the aerodynamic structure of the flight platform. In addition, when the antenna array is used on an airborne platform, the incident source will maintain an angle, and the inter-layer interference will naturally decrease due to the change in the incident environment.

[0042] The low-coupling direction-finding antenna array of the utility model supports a 3-channel interferometer and a spatial spectrum direction-finding system, and is suitable for mounting on large and medium-sized UAVs. Through actual testing and application, the low-coupling direction-finding antenna array of the utility model can be mounted on a UAV as a part of a communication signal detection subsystem, thereby forming an electromagnetic spectrum detection unmanned helicopter, which can quickly, efficiently and accurately locate a mobile communication vehicle.

[0043] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A low-coupling direction-finding antenna array, characterized in that: The invention comprises a sealed cavity (1), an annular hollow bracket, a first antenna array, a second antenna array, a third antenna array, a radio frequency matrix switch, a one-to-four switch, a synthesizer and a low noise amplifier. The annular hollow bracket is arranged in the sealed cavity (1). The first antenna array, the second antenna array and the third antenna array are arranged on the annular hollow bracket in a staggered manner on the same layer. A switch box is arranged at the bottom of the sealed cavity (1). The radio frequency matrix switch, the one-to-four switch, the synthesizer and the low noise amplifier are all arranged in the switch box. The first antenna array and the second antenna array are both connected to the input end of the radio frequency matrix switch. The third antenna array is connected to the input end of the one-to-four switch. One output end of the one-to-four switch is connected to the input end of the radio frequency matrix switch. The other three output ends of the one-to-four switch are connected to the input end of the radio frequency matrix switch through the synthesizer. The low noise amplifier is electrically connected to the output end of the radio frequency matrix switch. The synthesizer is used to switch the signal path of the third antenna array to a synthesized signal. The low noise amplifier is used to perform active and passive switching on the directional pattern of the array element.

2. The low coupling direction finding antenna array according to claim 1, characterized in that: The annular hollow support is an integrated structure made of a honeycomb sandwich material, the annular hollow support comprises a circular hollow plate (2) and a support plate (3), three circular hollow plates (2) are provided, the three circular hollow plates (2) are concentric and arranged in sequence from bottom to top, the diameters of the three circular hollow plates (2) decrease in sequence from bottom to top, the three circular hollow plates (2) are connected and supported in the sealed cavity (1) through the support plate (3), the first antenna array, the second antenna array, and the third antenna array are arranged in sequence from bottom to top on the outer edges of the three circular hollow plates (2), the top of the second antenna array is at the same height as the top of the first antenna array, and the third antenna array is located above the first antenna array.

3. The low coupling direction finding antenna array according to claim 2, characterized in that: The first antenna array comprises seven first dipole antennas (4) with an operating frequency band of 30 MHz-1.3 GHz. The first dipole antennas (4) are distributed in a circular array on the outer edge of the corresponding circular hollow plate (2) with the center of the circular hollow plate (2) as the center.

4. The low coupling direction finding antenna array according to claim 3, characterized in that: The second antenna array comprises seven second dipole antennas (5) with an operating frequency band of 1 GHz to 3.6 GHz. The second dipole antennas (5) are distributed in a circular array on the outer edge of the corresponding circular hollow plate (2) with the center of the circular hollow plate (2) as the center. The second dipole antennas (5) are arranged in an alternating manner with the first dipole antennas (4).

5. The low coupling direction finding antenna array according to claim 4, characterized in that: The third antenna array comprises seven FPC antennas (6) with an operating frequency band of 3 GHz to 8 GHz. The FPC antennas (6) are arranged in a circular array around the center of the circular hollow plate (2) and on the outer edge of the corresponding circular hollow plate (2). The FPC antennas (6) are arranged in an alternating manner with the first dipole antenna (4) and the second dipole antenna (5).

6. The low coupling direction finding antenna array according to claim 1, characterized in that: A flange (7) is provided at the bottom of the sealed cavity (1), a shielding plate (8) is provided between the flange (7) and the bottom of the sealed cavity (1), and a switch box (9) is provided in the middle of the flange (7) and is integrally formed with the flange (7).

7. The low coupling direction finding antenna array according to claim 5, characterized in that: The radio frequency matrix switch comprises 28 input terminals and 3 output terminals. The switch box (9) is provided with 21 radio frequency input interfaces (10) located in a sealed cavity (1). The switch box (9) is also provided with 3 radio frequency output interfaces (11) located outside the sealed cavity (1), 1 calibration signal input interface (12) and 1 control interface (13). There are 3 low noise amplifiers, 7 synthesizers and 7 one-to-four switches. The first dipole antenna (4) and the second dipole antenna (5) are both connected to the input terminal of the radio frequency matrix switch through the radio frequency input interface (10). Each FPC antenna (6) corresponds to 1 synthesizer and 1 one-to-four switch. The antenna (6) is connected to the input end of the corresponding one-to-four switch through the radio frequency input interface (10); one output end of the one-to-four switch is connected to the input end of the radio frequency matrix switch; the other three output ends of the one-to-four switch are respectively connected to the input end of the corresponding synthesizer and the input ends of two synthesizers adjacent to the corresponding synthesizer; the output end of the synthesizer is connected to the input end of the radio frequency matrix switch; the three output ends of the radio frequency matrix switch are respectively connected to the input ends of three adjustable gain low noise amplifiers; the output ends of the three adjustable gain low noise amplifiers are respectively connected to three radio frequency output interfaces (11); and the calibration signal input interface (12) and the control interface (13) are both electrically connected to the radio frequency matrix switch.

8. The low coupling direction finding antenna array according to claim 7, characterized in that: The 21 radio frequency input interfaces (10) are distributed in an array around the central circumference of the switch box (9).

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