A compact range device with high aperture utilization and ultra-large quiet zone

Abstract

The application discloses a high-aperture utilization rate ultra-large quiet zone tight-field device, which comprises a tight-field reflecting surface, a feed source and a plane wave quiet zone; the feed source is an electromagnetic wave radiation source of the tight-field device; a diagonal feed layout is adopted, the vertex of the tight-field reflecting surface is arranged at a position close to the aperture diagonal line, the center of the feed source and the focal point of the reflecting surface are copointed on the virtual rotation symmetry axis of the reflecting surface; the tight-field reflecting surface is a quadric surface structure, the central entity is a rotation parabolic surface part, and is used for correcting the spherical wave radiated by the feed source into a plane wave in the quiet zone; and the plane wave quiet zone is a limited three-dimensional space region which meets the requirement of far-field test after the electromagnetic wave radiated by the feed source is corrected by the reflecting surface.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of radar stealth measurement, in particular to a high-aperture-utilization ultra-large quiet zone tight-field device. BACKGROUND

[0002] With the demand for full-size test of super-large-scale ultra-large aviation, aerospace and electronic equipment, such as full-size test of actual installation aircraft and large shipboard phased array radar, the demand for precise measurement of full-size radar target scattering and large-aperture antenna is increasingly urgent. The utilization rate of the quiet zone of the traditional single-reflector tight-field is about 40% to 50%, which is relatively low. If the test of large electronic equipment is to be realized, the scale of the reflector needs to be increased, which will increase the development risk, development difficulty and manufacturing cost of the reflector. Moreover, the quiet zone of the ultra-large tight-field presents a flat rectangular feature, which is troubled by the imbalance between the width and the height, and it is difficult to guarantee the low-frequency performance (aperture 30 times the electrical size or less), especially in the short side direction of the reflector. Therefore, the current traditional tight-field solution is not conducive to the realization of the ultra-large tight-field for the test of super-large electronic equipment, and the performance of the low-frequency and high-frequency quiet zones is excellent. For example, the large ear radio telescope in Ohio State University in the United States has the function of tight-field. SUMMARY

[0003] The purpose of the present application is to provide a high-aperture-utilization ultra-large quiet zone tight-field device, which adopts diagonal feed layout, sawtooth structure and small amount of control of virtual vertex offset technology to increase the uniformity of the reflector irradiation by the feed beam, control the influence of edge diffraction on the quiet zone, and reduce the bending amount of the reflector surface and the amount of offset feed, so as to realize the ultra-large quiet zone tight test field with controlled cost, easy realization, high-aperture utilization and low cross-polarization.

[0004] In order to achieve the above-mentioned purpose of the present application, the following technical solutions are adopted:

[0005] A high-aperture-utilization ultra-large quiet zone tight-field device, which comprises a tight-field reflector, a feed and a plane wave quiet zone; the feed is an electromagnetic wave radiation source of the tight-field device; the diagonal feed layout is adopted, the vertex of the tight-field reflector is close to the diagonal line of the aperture, and the center of the feed and the focal point of the reflector are copointed on the virtual rotational symmetry axis of the reflector;

[0006] The tight-field reflector is a quadric surface structure, the central entity is a part of a rotational parabolic surface, which is used to correct the spherical wave radiated by the feed into a plane wave in the quiet zone;

[0007] The plane wave quiet zone is a limited three-dimensional space region which meets the requirements of far-field test after the electromagnetic wave radiated by the feed is corrected by the reflector.

[0008] Further, the high-aperture-usage ultra-large quiet zone tight-field device has the advantages that the solid angle of the reflector to the feed source is reduced under the same focal length constraint, the beam of the feed source is more uniformly irradiated to the reflector, and the amplitude taper of the quiet zone is reduced.

[0009] Further, the tight-field reflector has an unbalanced rectangular structure in width and height, and the difference between the horizontal and vertical aperture sizes is more than 30% of the shorter side.

[0010] Further, the virtual vertex of the tight-field reflector can be offset by a predetermined small amount without increasing the direct echo of the reflector and the shielding quiet zone beam of the feed source, the predetermined small amount refers to an offset amount less than 10% of the size of the reflector, and the advantages are that the stiffness requirement of the back frame of the reflector is reduced, the cross polarization introduced by the offset amount is reduced, and the erection height of the measured target is reduced.

[0011] Further, the edge of the high-aperture-usage ultra-large quiet zone tight-field device adopts an optimized serrated edge, the influence of edge diffraction on the quiet zone is controlled, and the advantages are that the aperture usage is further improved, and the quiet zone performance near the lower limit of the frequency is ensured.

[0012] Further, the aperture usage of the tight-field is greater than 60%, and the width of the ultra-large quiet zone is greater than 20 m.

[0013] The technical principle of the application is as follows:

[0014] The high-aperture-usage ultra-large quiet zone tight-field device mainly comprises a tight-field reflector, a feed source and a plane wave quiet zone. The tight-field reflector has a rectangular cross-section structure with a significant difference between the horizontal and vertical directions, and adopts a diagonal feed layout. Under the same focal length constraint, the solid angle of the reflector to the feed source is reduced, the uniformity of the beam of the feed source irradiated to the reflector is increased, and the amplitude taper of the quiet zone is reduced.

[0015] The low-frequency quiet zone imbalance in width and height caused by the rectangular flattening of the tight-field aperture is compensated by the forward quiet zone after the short-focus design and the edge optimization.

[0016] The small offset of the virtual vertex of the tight-field reflector can reduce the bending amount of the reflector surface, thereby reducing the stiffness requirement of the back frame, and can also reduce the offset amount of the tight-field device, thereby reducing the cross polarization and the erection height of the target in the darkroom.

[0017] The edge of the tight-field reflector adopts an optimized serrated structure to control the influence of edge diffraction on the quiet zone, that is, all the serrations are distributed along the radial direction at equal lengths around the geometric center of the reflector, and the inner edge profiles of all the serrations are concave around the geometric center, thereby increasing the area of the central solid part of the tight-field reflector system, and the advantages are that the aperture usage is further improved, and the quiet zone performance near the lower limit of the frequency is improved.

[0018] The present application has the following advantages compared with the prior art:

[0019] (1) The present application improves the aperture utilization of the compact range device under the typical index constraint of less than 1dB amplitude taper in the quiet zone, and the aperture utilization can reach 60% to 65%, or even 70%, which is about 25% higher than the traditional compact range scheme.

[0020] (2) The compact range reflecting surface of the present application is a rotating parabolic surface, which is different from the common square aperture with similar horizontal and vertical dimensions. The aperture of the present application is a rectangle with obvious difference between the horizontal and vertical dimensions, and the aperture and the quiet zone have a width-height imbalance. The width-height ratio of the quiet zone of the present application is greater than or equal to 2:1, the width-height ratio of the reflecting surface is not greater than 3:2, the focal length is close to the long side of the aperture of the reflecting surface, and the short focal length and the aperture design solve the problem of width-height imbalance, so that the low-frequency quiet zone performance is improved.

[0021] (3) The compact range of the present application adopts a diagonal feed arrangement, which can reduce the solid angle of the reflecting surface to the feed source under the same focal length constraint, reduce the illumination level of the feed source to the reflecting surface, thereby reducing the amplitude taper of the quiet zone and improving the aperture utilization of the super-large compact range. The diagonal feed arrangement can move the quiet zone forward to alleviate the width-height imbalance contradiction introduced by the rectangular aperture under the premise of not increasing the quiet zone taper, and improve the low-frequency performance of the compact range. The low-frequency lower limit of the compact range of the present application can achieve a quiet zone performance of 300MHz in the range of a quiet zone size of more than 20m.

[0022] (4) The virtual vertex of the compact range reflecting surface can be slightly offset (the offset is less than 10% of the size of the reflecting surface) without increasing the direct echo of the reflecting surface and the shielding of the feed source to the quiet zone beam, which can reduce the stiffness requirement of the reflecting surface back frame, the cross polarization introduced by the offset feed amount, and the erection height of the measured target. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a schematic diagram of the whole compact range device with high aperture utilization and super-large quiet zone;

[0024] Figure 2 (a) is a horizontal cross-sectional amplitude distribution diagram of the front quiet zone of the compact range device (0.3, 0.6, 1.2, 2.4GHz);

[0025] Figure 2 (b) is a horizontal cross-sectional phase distribution diagram of the front quiet zone of the compact range device (0.3, 0.6, 1.2, 2.4GHz);

[0026] Figure 3 (a) is a horizontal cross-sectional amplitude distribution diagram of the middle quiet zone of the compact range device (0.3, 0.6, 1.2, 2.4GHz);

[0027] Figure 3 (b) is the phase distribution plot of the horizontal cross-section of the quiet zone in the compact range (0.3, 0.6, 1.2, 2.4 GHz);

[0028] Figure 4 (a) is the amplitude distribution plot of the horizontal cross-section of the quiet zone behind the compact range (0.3, 0.6, 1.2, 2.4 GHz);

[0029] Figure 4 (b) is the phase distribution plot of the horizontal cross-section of the quiet zone behind the compact range (0.3, 0.6, 1.2, 2.4 GHz);

[0030] Figure 5 (a) is the amplitude distribution plot of the vertical cross-section of the quiet zone in front of the compact range (0.3, 0.6, 1.2, 2.4 GHz);

[0031] Figure 5 (b) is the phase distribution plot of the vertical cross-section of the quiet zone in front of the compact range (0.3, 0.6, 1.2, 2.4 GHz);

[0032] Figure 6 (a) is the phase distribution plot of the vertical cross-section of the quiet zone in the compact range (0.3, 0.6, 1.2, 2.4 GHz);

[0033] Figure 6 (b) is the amplitude distribution plot of the vertical cross-section of the quiet zone in the compact range (0.3, 0.6, 1.2, 2.4 GHz);

[0034] Figure 7 (a) is the phase distribution plot of the vertical cross-section of the quiet zone behind the compact range (0.3, 0.6, 1.2, 2.4 GHz);

[0035] Figure 7 (b) is the amplitude distribution plot of the vertical cross-section of the quiet zone behind the compact range (0.3, 0.6, 1.2, 2.4 GHz).

[0036] The meaning of the reference signs in the figures is:

[0037] Figure 1 M: 1 is the reflecting surface of the compact range, 2 is the feed (located at the focal point of the reflecting surface), 3 is the quiet zone of the plane wave, 4 is the observation plane of the near field, 5 is the axis of rotational symmetry of the reflecting surface, 6 is the electrical axis of the reflecting surface, virtual apex 7.

[0038] Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , and Figure 7Middle: the intercepts are located at the horizontal line (x[m]) and vertical line (y[m]) of the central quiet zone, and the operating frequencies are 0.3, 0.6, 1.2, 2.4 GHz. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0040] According to the embodiments of the present application, a high-aperture-usage ultra-large quiet zone tight-field device is provided, referring to Figure 1 The tight-field device comprises a tight-field reflecting surface 1, a tight-field feed 2 (located at the focal point of the reflecting surface), a plane wave quiet zone 3, a near-field observation surface 4, a rotationally symmetric axis 5 of the reflecting surface, an electric axis 6 of the reflecting surface, and a virtual vertex 7.

[0041] The tight-field reflecting surface 1 is a precisely machined quadric surface, usually a rotationally symmetric paraboloid, and the edge adopts a sawtooth structure, which is used to correct the spherical wave radiated by the feed into a plane wave in the quiet zone.

[0042] The feed 2 is the initial electromagnetic wave radiation source of the tight-field device.

[0043] The plane wave quiet zone 3 is a limited three-dimensional space region in which the electromagnetic wave radiated by the feed is corrected by the reflecting surface to meet the specific far-field test requirements.

[0044] The high-aperture-usage ultra-large quiet zone tight-field device adopts a diagonal feed layout, and the feed 2 is placed near the focal point of the tight-field reflecting surface 1 and close to the diagonal projection of the tight-field reflecting surface, so that under the same focal length constraint, the three-dimensional angle of the reflecting surface to the feed is reduced, and thus the feed beam irradiates the reflecting surface more uniformly, which is beneficial to reducing the quiet zone amplitude tapering.

[0045] The tight-field reflecting surface 1 has a rectangular cross-sectional structure with a significant difference (more than 30% of the short side size) between the horizontal aperture and the vertical aperture, which is beneficial to moving the quiet zone position forward under short-focus design (i.e., the focal length is less than the maximum size of the aperture), avoiding the problem of imbalance between width and height, and improving the quiet zone low-frequency performance.

[0046] The virtual vertex of the compressed field reflector 1 can be slightly offset (slightly offset in any direction) without increasing the direct echo of the reflector and the obstruction of the quiet zone beam by the feed source. This is beneficial for reducing the stiffness requirements of the reflector back frame, reducing the cross polarization introduced by the offset feed, and reducing the erection height of the target under test.

[0047] The edges of the high-aperture utilization ultra-large quiet zone compact field system are treated with optimized sawtooth edges to control the impact of edge diffraction on the quiet zone, which helps to further improve the aperture utilization while ensuring the quiet zone performance at the low-frequency lower limit.

[0048] A preferred embodiment of the present invention:

[0049] like Figure 1 The ultra-large quiet zone compact field device shown operates at frequencies of 0.3, 0.6, 1.2, and 2.4 GHz. The reflector has a width of 38 longest wavelengths, a height of 28 longest wavelengths, a focal length of 38 longest wavelengths, and the feed is located at the focal point of the reflector.

[0050] like Figures 2 to 7 As shown, under the typical constraints of amplitude taper of less than 1dB and phase peak-to-peak value of less than 10 degrees in the quiet zone, the utilization rate of the horizontal and vertical cross-sections of the compact field can reach more than 65%.

[0051] The low-frequency lower limit of the preferred ultra-large compact field example, under the conditions of unbalanced reflector width and height and narrow side less than 30 times the wavelength, the compact field achieves a typical index of 300MHz in a range of more than 20m in the entire quiet zone.

[0052] As can be seen from the examples, this invention can achieve a compact field for ultra-large quiet zones with high aperture utilization.

[0053] Although the illustrative specific embodiments of the present invention have been described above to enable those skilled in the art to understand the invention, it should be understood that the invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes will be obvious as long as they are within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of the present invention are protected.

Claims

1. A compact range device having a high aperture utilization and a large quiet zone, characterized by: The tight-field reflector, the feed source and the plane wave quiet zone are included; the feed source is the electromagnetic wave radiation source of the tight-field device; the diagonal feed layout is adopted, the vertex of the tight-field reflector is close to the position of the aperture diagonal line, and the heart of the feed source is coincident with the focal point of the reflector and is located on the virtual rotation symmetry axis of the reflector; The tight-field reflector is a quadric surface structure, the central entity is a rotation parabolic surface part, and the spherical wave radiated by the feed source is corrected to the plane wave in the quiet zone; The plane wave quiet zone is a limited three-dimensional space region which meets the far-field test requirements after the electromagnetic wave radiated by the feed source is corrected by the reflector; The tight-field device with high aperture utilization and super large quiet zone adopts the diagonal feed layout, under the same focal length constraint, the three-dimensional angle of the reflector to the feed source is reduced, so that the feed source beam irradiates the reflector more uniformly, which is beneficial to reduce the quiet zone amplitude tapering; The virtual vertex of the tight-field reflector can be offset by a predetermined small amount under the premise of not increasing the direct echo of the reflector and the shielding of the quiet zone beam by the feed source, the predetermined small amount refers to the offset amount being less than 10% of the size of the reflector, which is beneficial to reduce the stiffness requirement of the reflector back frame, reduce the cross polarization introduced by the offset feed amount and reduce the erection height of the measured target; The edge of the tight-field device with high aperture utilization and super large quiet zone adopts the optimized serrated edge, controls the influence of the edge diffraction on the quiet zone, which is beneficial to further improve the aperture utilization and ensure the quiet zone performance near the low frequency limit.

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