A fully compact field measurement system based on ultra-wideband linear array and single cylindrical reflector

Abstract

The present invention relates to a fully compact field measurement system based on an ultra-wideband linear array and a single cylindrical reflector, the system comprising an ultra-wideband linear array, a single cylindrical reflector, a target mounting turntable and bracket, and a microwave darkroom. The system adopts an ultra-wideband linear array as an excitation source to simulate a cylindrical wave incident on a single cylindrical reflector. After being reflected by the single cylindrical reflector, the cylindrical wave is corrected to a quasi-plane wave. The traditional reflector compact field adopts a single feed source to illuminate the reflector, and a balance must be struck between the quiet zone taper and the reflector illumination efficiency. The smaller the quiet zone taper, the higher the reflector illumination efficiency. The larger the quiet zone taper, the higher the reflector illumination efficiency, but the effective quiet zone size is reduced. The advantage of the present invention is that the ultra-wideband linear array as an excitation source can effectively overcome the contradiction between the quiet zone taper and the reflector illumination efficiency in the traditional reflector compact field. Through array shaping, the quiet zone taper is effectively controlled while ensuring the reflector illumination efficiency.

Description

Technical Field

[0001] The invention belongs to the field of microwave measurement, and in particular relates to a fully compact field measurement system based on an ultra-wideband linear array and a single cylindrical reflection surface. Background Art

[0002] Nowadays, factors such as complex outdoor electromagnetic environment and natural environment will cause serious interference to microwave measurement. The evaluation of the electromagnetic scattering characteristics of the target is usually carried out in a microwave darkroom. The compact field technology is one of the many testing technologies that have been applied in microwave darkrooms. The compact field uses the principle of near-field focusing to generate a quasi-plane wave zone near the target. The traditional compact field usually consists of an edge-processed reflective surface and a feed source. The spherical wave radiated by the feed source is calibrated into a quasi-plane wave by the reflective surface, and a quiet zone is generated near the target. The quality of the quiet zone includes two aspects, quiet zone disturbance and quiet zone utilization. The utilization rate of the quiet zone is largely determined by the utilization rate of the reflective surface. The quiet zone size of the traditional single-cylinder compact field is generally half of the size of the reflective surface, and the utilization rate of the reflective surface is not high.

[0003] In some scenarios where the electromagnetic scattering characteristics of large-scale targets are measured, the size of the quiet zone is too small and is often insufficient to cover the entire target. The electromagnetic scattering characteristics of the target can only be evaluated by area, which often results in a large amount of time expenditure. Improving the utilization rate of the reflective surface can significantly increase the size of the quiet zone, but the traditional single-cylinder compact field usually uses a single feed source to illuminate the reflective surface to generate a quasi-plane wave test environment. When designing, it is necessary to strike a balance between the taper of the quiet zone and the illumination efficiency of the reflective surface. The smaller the taper of the quiet zone, the higher the illumination efficiency of the reflective surface. The larger the taper of the quiet zone, the higher the illumination efficiency of the reflective surface, but the size of the effective quiet zone is reduced. Therefore, it is necessary to find a method that takes into account both the taper of the quiet zone and the illumination efficiency of the reflective surface to increase the size of the quiet zone. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the present invention proposes a fully compact field measurement system based on an ultra-wideband linear array and a single cylindrical reflector. The system increases the compact field quiet zone area by improving the reflector utilization rate, while effectively controlling the quiet zone taper, solving the problem that the traditional single cylindrical compact field quiet zone cannot cover a larger test target.

[0005] The present invention is composed of an ultra-wideband linear array, a single cylindrical reflector, a target mounting turntable and bracket, and a microwave darkroom. The ultra-wideband linear array is used as an excitation source to simulate the cylindrical wave incident on the single cylindrical reflector. After being reflected by the single cylindrical reflector, the cylindrical wave is corrected to a quasi-plane wave. The ultra-wideband linear array is used as a cylindrical wave source. Through array shaping, a certain weight is applied to the ultra-wideband antenna unit excitation of each ultra-wideband linear array. The single cylindrical reflector calibrates the cylindrical wave to a quasi-plane wave. In this process, the utilization rate of the reflector surface is improved, and the coverage area of ​​the compact field quiet zone is increased.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A fully compact field measurement system based on an ultra-wideband linear array and a single cylindrical reflector comprises an ultra-wideband linear array, a single cylindrical reflector, a target mounting turntable and a bracket, and a microwave darkroom; the ultra-wideband linear array is used as an excitation source to generate a quiet zone field inside the microwave darkroom; the ultra-wideband linear array is composed of an ultra-wideband antenna unit and an amplitude-phase control network, and the amplitude-phase control network is used to configure the excitation weight; the quiet zone field and the excitation weight satisfy the relationship Where N is the total number of UWB antenna units, n is the number of UWB antenna units, and W n is the incentive weight, X n is the unit radiation field of the ultra-wideband antenna unit, E is the quiet zone field; the excitation weight is determined by the weight function, and the weight function is a, b, c, d are coefficients, l n It represents the position of the ultra-wideband antenna unit of the ultra-wideband linear array; after the weight function is introduced into the ultra-wideband linear array, the lateral aperture utilization rate of the single cylindrical reflector reaches more than 70%.

[0008] Furthermore, the fully compact field measurement system adopts an ultra-wideband linear array as an excitation source to generate cylindrical waves which are corrected into quasi-plane waves after being reflected by a single cylindrical reflection surface, thereby forming a cylindrical quiet zone field at a certain distance from the single cylindrical reflection surface. The ultra-wideband linear array improves the degree of freedom of the compact field, improves the utilization rate of the single cylindrical reflection surface, and increases the coverage area of ​​the quiet zone.

[0009] Furthermore, the aperture of the ultra-wideband antenna unit points in the direction of the focus of the single cylindrical reflection surface; the fully compact field measurement system comprises two groups of ultra-wideband linear arrays, one group of which is used as an electromagnetic wave signal transmitting end, and the other group is used as an electromagnetic wave signal receiving end; the ultra-wideband linear array is composed of N ultra-wideband antenna units, and the ultra-wideband antenna units are distributed at equal intervals or sparsely;

[0010] The total number N of ultra-wideband antenna units and the spacing between ultra-wideband antenna units are set according to the actual working bandwidth of the full compact field measurement system and the extreme position of the quiet zone of the full compact field measurement system, that is, the high-frequency bandwidth range considers more the quality of the quiet zone closest to the antenna position, and the low-frequency bandwidth range considers more the quality of the quiet zone farthest from the antenna position. The spacing between ultra-wideband antenna units is equidistant or sparsely distributed, and the total number N of ultra-wideband antenna units and the spacing between ultra-wideband antenna units are compromised to avoid high-frequency grating lobes caused by high-frequency undersampling and strong coupling of units caused by low-frequency oversampling.

[0011] Furthermore, the ultra-wideband antenna unit is an ultra-wideband Vivaldi antenna, and multiple ultra-wideband Vivaldi antennas constitute an electrically small-size, ultra-wideband tightly coupled array; a V-shaped choke slot is added to the rear of the exponentially open slot of the ultra-wideband Vivaldi antenna, and a 50-ohm matching resistor is loaded between the slots, which effectively reduces the electrical size of the ultra-wideband antenna unit at the lowest operating frequency, improves the high-frequency working capability, and is conducive to the formation of an ultra-wideband antenna array; the polarization mode of the ultra-wideband antenna unit is configured as a horizontal and vertical dual-polarization mode.

[0012] Furthermore, the horizontal section of the single cylindrical reflective surface is a straight line, and the plumb line is a parabola; the edge processing form of the single cylindrical reflective surface is a sawtooth shape, a curled edge, or an absorbing material loading structure.

[0013] Furthermore, the shape of the microwave darkroom is a rectangular parallelepiped, a horn, a cone or a combination of the above shapes; after the cylindrical wave radiation field of the ultra-wideband linear array is reflected by a single cylindrical reflection surface and converted into a quasi-plane wave radiation field, the radiation beam is more concentrated, and the requirements for the shape of the microwave darkroom are reduced.

[0014] The advantages of the present invention compared with the prior art are:

[0015] (1) The present invention can be directly applied to an already equipped single-cylindrical emitting surface test system. When the reflecting surface is large in size, it can provide a large-sized ideal plane wave irradiation area to achieve full coverage of a large-volume target to be tested.

[0016] (2) The present invention effectively controls the taper of the quiet zone while ensuring the irradiation efficiency of the reflective surface.

[0017] (3) The present invention can reduce the two reflection surfaces of the traditional double-cylinder compact field to one.

[0018] (4) The present invention uses an ultra-wideband Vivaldi antenna as an array element of an ultra-wideband linear array and is processed using printed circuit board technology, with high processing accuracy and consistency.

[0019] In summary, the traditional reflector compact field uses a single feed source to illuminate the reflector, and a balance must be struck between the quiet zone taper and the reflector illumination efficiency. The smaller the quiet zone taper, the higher the reflector illumination efficiency. The larger the quiet zone taper, the higher the reflector illumination efficiency, but the effective quiet zone size is reduced. The advantage of this solution is that the ultra-wideband linear array as an excitation source can effectively overcome the contradiction between the quiet zone taper and the reflector illumination efficiency in the traditional reflector compact field. Through array shaping, the quiet zone taper is effectively controlled while ensuring the reflector illumination efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1This is a structural diagram of a fully compact field measurement system based on an ultra-wideband linear array and a single cylindrical reflective surface according to the present invention;

[0021] Figure 2 is a weight function image of an embodiment of the present invention;

[0022] Figure 3 It is a side view of the reflecting surface;

[0023] Figure 4 It is the orthographic projection of the reflecting surface;

[0024] The meanings of the reference numerals in the figure are as follows: 1 is the ultra-wideband linear array at the transmitting end; 2 is the ultra-wideband linear array at the receiving end; 3 is the single cylindrical reflecting surface; 4 is the turntable and bracket for setting up the target; 5 is the microwave darkroom; 6 is the quiet area of ​​the full compact field measurement system; 7 is the cylindrical wave; and 8 is the quasi-plane wave. DETAILED DESCRIPTION

[0025] The present invention is further described below with reference to the accompanying drawings and specific embodiments.

[0026] like Figure 1 As shown, the fully compact field measurement system based on ultra-wideband linear array and single cylindrical reflector of the present invention comprises an ultra-wideband linear array, a single cylindrical reflector 3, a target installation turntable and bracket 4, and a microwave darkroom 5. The ultra-wideband linear array comprises an ultra-wideband linear array 1 at the transmitting end and an ultra-wideband linear array 2 at the receiving end. The ultra-wideband linear array 1 at the transmitting end and the ultra-wideband linear array 2 at the receiving end are both pointed to the vicinity of the center of the single cylindrical reflector 3. The cylindrical wave 7 radiated by the ultra-wideband linear array 1 at the transmitting end is reflected and calibrated to a quasi-plane wave 8 by the single cylindrical reflector 3. A quiet area with stable amplitude and phase can be observed in the quiet area 6 of the fully compact field measurement system. The target installation turntable and the target to be measured loaded on the bracket 4 are located in the quiet area 6 of the fully compact field measurement system. The ultra-wideband linear array 1 at the transmitting end, the ultra-wideband linear array 2 at the receiving end, and the single cylindrical reflector 3 are all located in a rectangular microwave darkroom 5 paved with absorbing materials.

[0027] The ultra-wideband linear array is composed of an ultra-wideband antenna unit and an amplitude and phase control network, and the amplitude and phase control network can be configured with excitation weights. The length of the ultra-wideband linear array 1 at the transmitting end and the ultra-wideband linear array 2 at the receiving end are both 2.6m, and each contains 23 ultra-wideband antenna units. The ultra-wideband antenna units are evenly spaced, and the unit spacing is 30mm. The ultra-wideband antenna unit adopts an ultra-wideband Vivaldi antenna with horizontal and vertical polarization modes. The ultra-wideband characteristics of the ultra-wideband antenna unit enable the system to operate in a wider frequency band range, with an operating frequency band of 4 to 10GHz.

[0028] The ultra-wideband linear array is used as an excitation source to generate a quiet zone field inside a microwave darkroom; the quiet zone field and the excitation weight satisfy the relationship Where N is the total number of UWB antenna units, n is the number of UWB antenna units, and W n is the incentive weight, X n is the unit radiation field of the ultra-wideband antenna unit, and E is the quiet zone field;

[0029] The linear array excitation is determined by a weight function, which is defined as:

[0030]

[0031] Among them l n represents the position coordinates of the antenna unit of the ultra-wideband linear array, and a, b, c, d are the coefficients to be optimized.

[0032] The particle swarm optimization algorithm is used to optimize the weight function and establish the complex coefficient excitation of the ultra-wideband linear array. Based on the complex coefficient excitation, a 1.5m quiet zone can be generated within a range of 14 to 22m from the antenna. The a, b, c, and d coefficient values ​​of the weight function are 1, 8, -9, and 1.495, respectively. The excitation weights configured in the above 23 antenna units are as follows: Figure 2 shown.

[0033] The present invention uses a single cylindrical reflection surface 3 to calibrate the cylindrical wave radiated by the ultra-wideband linear array into a quasi-plane wave. The single cylindrical reflection surface 3 used should be a high-precision smooth reflection surface, such as Figure 3 As shown, the single cylindrical reflector 3 is a part of a rotating parabola, and the focal length of the parabola is 4m. The height H of the parabola is 4.5m, the height A2 of the lower edge is 0.52m, the forward tilt angle α is 74°, and the forward tilt distance A1 is 1.26m. The ultra-wideband linear array feed is placed at the focal position of the single cylindrical reflector, the distance A3 from the lower edge of the reflector is 4.99m, and the feed offset angle β is 33°. Setting the size of the single cylindrical reflector and determining the feed position according to the above parameters is a feasible embodiment of the present invention.

[0034] In order to reduce edge diffraction, the single cylindrical reflective surface 3 adopts a sawtooth edge design, such as Figure 4 As shown, the height of the orthographic projection of the single cylindrical reflective surface 3 is 4.5m and the width is 5m. Distributed around, the center of the single cylindrical reflective surface 3 is a complete rectangular surface, and the saw teeth are distributed around, symmetrically distributed up and down and left and right. There are 16 saw teeth on each side, which are right-angled triangles with a height of 0.6m, distributed along the upper and lower sides of the rectangular surface, and the length of the right-angled sides of the saw teeth that coincide with the upper and lower sides of the rectangular surface decreases from the edge to the inside. There are 12 saw teeth on each side, which are right-angled triangles with a height of 0.7m, distributed along the left and right sides of the rectangular surface, and the length of the right-angled sides that coincide with the left and right sides of the rectangular surface decreases from the edge to the inside.

[0035] Based on the above description, the size of the ultra-wideband linear array and the single cylindrical reflector 3 and the excitation configuration of the ultra-wideband linear array can be established. The cylindrical wave radiated by the ultra-wideband linear array 1 at the transmitting end is irradiated on the single cylindrical reflector 3. After being calibrated as a quasi-plane wave by the single cylindrical reflector, a 1.5×1.5m full compact field measurement system quiet zone 6 can be generated within a range of 10 to 18m from the mouth of the single cylindrical reflector. The full compact field measurement system quiet zone 6 has high quality and can cover a larger area.

[0036] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A fully compact field measurement system based on ultra-wideband linear array and single cylindrical reflector. Features: The invention comprises an ultra-wideband linear array, a single cylindrical reflective surface, a target mounting turntable and a bracket, and a microwave darkroom; the ultra-wideband linear array is used as an excitation source to generate a quiet zone field inside the microwave darkroom; the ultra-wideband linear array is composed of an ultra-wideband antenna unit and an amplitude-phase control network, and the amplitude-phase control network is used to configure the excitation weight; the quiet zone field and the excitation weight satisfy the relationship Where N is the total number of UWB antenna units, n is the number of UWB antenna units, and W n is the incentive weight, X n is the unit radiation field of the ultra-wideband antenna unit, E is the quiet zone field; the excitation weight is determined by the weight function, and the weight function is a, b, c, d are coefficients, l n It represents the position of the ultra-wideband antenna unit of the ultra-wideband linear array; after the weight function is introduced into the ultra-wideband linear array, the lateral aperture utilization rate of the single cylindrical reflector reaches more than 70%.

2. According to claim 1, a fully compact field measurement system based on an ultra-wideband linear array and a single cylindrical reflective surface, Features: The fully compact field measurement system adopts an ultra-wideband linear array as an excitation source, generates cylindrical waves, and corrects them into quasi-plane waves after being reflected by a single cylindrical reflection surface, and forms a cylindrical quiet zone field at a certain distance from the single cylindrical reflection surface. The ultra-wideband linear array improves the degree of freedom of the compact field, improves the utilization rate of the single cylindrical reflection surface, and increases the coverage area of ​​the quiet zone.

3. According to claim 1, a fully compact field measurement system based on an ultra-wideband linear array and a single cylindrical reflective surface, Features: The aperture of the ultra-wideband antenna unit points in the direction of the focus of the single cylindrical reflection surface; the fully compact field measurement system comprises two groups of ultra-wideband linear arrays, one group of which is used as an electromagnetic wave signal transmitting end, and the other group is used as an electromagnetic wave signal receiving end; the ultra-wideband linear array is composed of N ultra-wideband antenna units, and the ultra-wideband antenna units are distributed at equal intervals or sparsely distributed; the total number N of ultra-wideband antenna units and the spacing between ultra-wideband antenna units are compromised to avoid high-frequency grating lobes caused by high-frequency undersampling and strong coupling of units caused by low-frequency oversampling; The total number N of ultra-wideband antenna units and the spacing between ultra-wideband antenna units are set according to the actual working bandwidth of the full compact field measurement system and the extreme position of the quiet zone of the full compact field measurement system, that is, the high-frequency bandwidth range considers the quality of the quiet zone closest to the antenna position, and the low-frequency bandwidth range considers the quality of the quiet zone farthest from the antenna position.

4. According to claim 1, a fully compact field measurement system based on an ultra-wideband linear array and a single cylindrical reflective surface, Features: The ultra-wideband antenna unit is an ultra-wideband Vivaldi antenna, and multiple ultra-wideband Vivaldi antennas constitute an electrically small-size, ultra-wideband tightly coupled array; a V-shaped choke slot is added to the rear of the exponentially open slot of the ultra-wideband Vivaldi antenna, and a 50-ohm matching resistor is loaded between the slots, which effectively reduces the electrical size of the ultra-wideband antenna unit at the lowest operating frequency, improves the high-frequency working capability, and is conducive to the formation of an ultra-wideband antenna array; the polarization mode of the ultra-wideband antenna unit is configured as a horizontal and vertical dual-polarization mode.

5. According to claim 1, a fully compact field measurement system based on an ultra-wideband linear array and a single cylindrical reflective surface, Features: The horizontal section of the single cylindrical reflective surface is a straight line, and the plumb line is a parabola; the edge processing form of the single cylindrical reflective surface is a sawtooth shape, a curled edge or an absorbing material loading structure.

6. According to claim 1, a fully compact field measurement system based on an ultra-wideband linear array and a single cylindrical reflective surface, Features: The shape of the microwave darkroom is a rectangular parallelepiped, a horn, a cone or a combination of the above shapes; after the cylindrical wave radiation field of the ultra-wideband linear array is reflected by a single cylindrical reflection surface and converted into a quasi-plane wave radiation field, the radiation beam is more concentrated, and the requirements for the shape of the microwave darkroom are reduced.

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