A tight-fitting field device for a roll-off cylindrical wave

Abstract

The application discloses a crimped cylindrical wave tight field device, which mainly comprises a crimped parabolic cylindrical reflector, a feed source, a quiet zone and a virtual line source. The parabolic cylindrical reflector can correct the cylindrical wave formed by the spherical wave emitted by the feed source in the quiet zone. In order to control the diffraction of the edge of the reflector, the edge of the parabolic cylindrical reflector needs to be processed. The crimped edge of the parabolic cylindrical reflector can reduce the low-frequency limit of the cylindrical wave tight field. Compared with the sawtooth cylindrical wave tight field, the electric size of the reflector working at the low-frequency limit is smaller, and the engineering realization of the large cylindrical wave tight field is more favorable.

Description

Technical Field

[0001] This invention relates to cylindrical wave compaction fields in the form of reflective surfaces, used in the fields of antenna pattern and radar cross section testing, to improve the low-frequency testing capability of electromagnetic radiation and electromagnetic scattering. Background Technology

[0002] Compacted fields are a critical infrastructure for target radiation / scattering testing. As targets under test become larger, the required size of the compacted field reflector also increases. The aperture utilization rate of plane wave compacted fields is typically around 50%, and the precision manufacturing cost and engineering difficulty of ultra-large compacted field reflectors are increasing. To address the challenges of testing ultra-large targets, point source near-field and cylindrical wave field solutions have been proposed in recent years, both domestically and internationally. The near-field quiet zone of a point source is a spherical wave. To obtain the far-field RCS of the target, two-dimensional testing in both azimuth and elevation directions is required, which is time-consuming. Furthermore, the radiation direction of point source near-field spherical waves is divergent, resulting in high background clutter, which significantly impacts the scattering test accuracy for low-stealth targets. In contrast, the cylindrical wave compacted field reflector is parabolic in the elevation direction and planar in the azimuth direction. The spherical waves emitted by the feed can diffuse through a relatively small parabolic cylinder to form a large cylindrical wave quiet zone, and the aperture utilization rate of the cylindrical wave compacted field is typically around 150%. Cylindrical wave compaction fields require only one-dimensional azimuth testing of the target, resulting in high testing efficiency and low background noise due to plane wave convergence in the elevation direction. Therefore, cylindrical wave compaction fields are the preferred solution for high-efficiency and high-precision testing of ultra-large targets.

[0003] In recent years, the competition between meter-wave stealth and anti-stealth technologies has intensified, creating an urgent need for compact field low-frequency operation. Diffraction at the edges of compact field reflectors interferes with the performance of the static field, particularly at low frequencies. To ensure low-frequency performance, it is necessary to increase the electrical dimensions of the reflector. Existing cylindrical wave compact field reflectors employ serrated edges to improve low-frequency diffraction. Summary of the Invention

[0004] To further reduce the low-frequency limit of the cylindrical wave compaction field reflecting surface, reduce the size of the reflecting surface, and improve the aperture utilization rate of the reflecting surface, this invention proposes a rolled-edge cylindrical wave compaction field device.

[0005] The purpose of this invention is to provide a rolled-edge cylindrical wave compression field device to reduce the low-frequency limit of the cylindrical wave compression field.

[0006] To achieve the above-mentioned objectives, the present invention employs the following technical solution:

[0007] A device for compressing a cylindrical wave field with rolled edges, the compressed field mainly consists of a rolled-edge parabolic cylindrical reflector, a feed source, a quiet zone, and a virtual line source, wherein...

[0008] The feed source is an approximate spherical wave radiation source, used to provide spherical wave illumination when the system finally forms a cylindrical wave in the quiet zone;

[0009] The aforementioned rolled-edge compacted field reflecting surface is a precision-machined curved surface, with the central solid part being a parabolic cylinder, used to correct the excitation wavefront and compact it into the desired cylindrical wavefront within a small distance.

[0010] The aforementioned rolled-edge compaction field reflector has rolled edges to control the interference of edge diffraction on the quiet zone, thereby forming a more ideal cylindrical wave in the quiet zone.

[0011] The virtual line source, located at the feed mirror position on the back of the reflecting surface, is a virtual source for forming cylindrical waves from the compressed field of the rolled-edge cylindrical wave.

[0012] The advantages of this invention compared to the prior art are:

[0013] Existing cylindrical wave compaction fields employ serrated edges, with a low-frequency limit of 20-25 times the wavelength. The cylindrical wave compaction field proposed in this invention uses a curled edge treatment, reducing the low-frequency limit to 10 times the wavelength. This effectively reduces the electrical dimensions of the cylindrical wave compaction field's reflecting surface, decreases the cost of the cylindrical wave compaction field system, and is more conducive to the engineering implementation of ultra-large cylindrical wave compaction fields. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a compressed field of a rolled-edge cylindrical wave, where 1 is the rolled-edge parabolic cylindrical reflecting surface, 2 is the feed source, 3 is the quiet zone, and 4 is the virtual line source.

[0015] Figure 2 This is a side view of the compressed field of the rolled-edge cylindrical wave, where 1 is the rolled-edge parabolic cylindrical reflecting surface, 2 is the feed source, 3-1 is the front section of the quiet zone, 3-2 is the middle section of the quiet zone, and 3-3 is the rear section of the quiet zone.

[0016] Figure 3 It is an orthographic projection of the reflective surface of a parabolic cylindrical wave with rolled edges;

[0017] Figure 4 It is the amplitude distribution of the cross section at the center of the static zone of the compressed field of the rolled-edge cylindrical wave. The curve is the residual between the ideal cylindrical wave generated by the virtual line source at this section and the quasi-cylindrical wave calculated at this section.

[0018] Figure 5 It is the phase distribution of the cross section at the center of the static zone of the compressed field of the rolled-edge cylindrical wave. The curve is the residual between the ideal cylindrical wave generated by the virtual line source at this section and the quasi-cylindrical wave calculated at this section.

[0019] Figure 6 It is the amplitude distribution of the longitudinal section at the center of the static zone of the compressed field of the rolled-edge cylindrical wave. The curve is the residual between the ideal cylindrical wave generated by the virtual line source at this section and the quasi-cylindrical wave calculated at this section.

[0020] Figure 7 It is the phase distribution of the longitudinal section at the center of the static zone of the compressed field of the rolled-edge cylindrical wave. The curve is the residual between the ideal cylindrical wave generated by the virtual line source at this section and the quasi-cylindrical wave calculated at this section.

[0021] Figure 8 It is the amplitude distribution of the cross section at the center of the static region of the compressed field of the rolled-edge cylindrical wave. The curve is the residual between the ideal cylindrical wave generated by the virtual line source at this section and the quasi-cylindrical wave calculated at this section.

[0022] Figure 9 It is the phase distribution of the cross section at the center of the static region of the compressed field of the rolled-edge cylindrical wave. The curve is the residual between the ideal cylindrical wave generated by the virtual line source at this section and the quasi-cylindrical wave calculated at this section.

[0023] Figure 10 It is the amplitude distribution of the longitudinal section at the center of the static region of the compressed field of the rolled-edge cylindrical wave. The curve is the residual between the ideal cylindrical wave generated by the virtual line source at this section and the quasi-cylindrical wave calculated at this section.

[0024] Figure 11 It is the phase distribution of the longitudinal section at the center of the cross section in the quiet zone of the compressed field of the rolled-edge cylindrical wave. The curve is the residual between the ideal cylindrical wave generated by the virtual line source at this cross section and the quasi-cylindrical wave calculated at this cross section.

[0025] Figure 12 It is the amplitude distribution of the cross section at the center of the static zone of the compressed field of the rolled-edge cylindrical wave. The curve is the residual between the ideal cylindrical wave generated by the virtual line source at this section and the quasi-cylindrical wave calculated at this section.

[0026] Figure 13 It is the phase distribution of the cross section at the center of the static zone of the compressed field of the rolled-edge cylindrical wave. The curve is the residual between the ideal cylindrical wave generated by the virtual line source at this section and the quasi-cylindrical wave calculated at this section.

[0027] Figure 14 It is the amplitude distribution of the longitudinal section at the center of the static zone of the compressed field of the rolled-edge cylindrical wave. The curve is the residual between the ideal cylindrical wave generated by the virtual line source at this section and the quasi-cylindrical wave calculated at this section.

[0028] Figure 15 It is the phase distribution of the longitudinal section at the center of the static zone of the compressed field of the rolled-edge cylindrical wave. The curve is the residual between the ideal cylindrical wave generated by the virtual line source at this section and the quasi-cylindrical wave calculated at this section. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0030] A preferred embodiment of the present invention:

[0031] like Figure 1 The schematic diagram of the compressed cylindrical wave field shown includes a rolled-edge parabolic cylindrical reflector 1, a feed source 2, a quiet zone 3, and a virtual line source 4. The feed source 2 is an approximate spherical wave radiation source, used to provide illumination for the formation of cylindrical waves within the quiet zone 3. The rolled-edge parabolic cylindrical reflector 1 is a precision-machined curved surface with a parabolic cylindrical central portion, used to correct the excitation wavefront to the desired cylindrical wavefront within the compressed distance. The rolled-edge parabolic cylindrical reflector 1 has rolled edges to control edge diffraction interference with the quiet zone 3, forming a more ideal cylindrical wave within the quiet zone 3. The quiet zone 3 is a quasi-cylindrical wave field where the target or test piece is placed for testing. The virtual line source 4, located on the back of the rolled-edge parabolic cylindrical reflector 1 in the mirror image position of the feed source, is a virtual source for forming cylindrical waves within the compressed cylindrical wave field. Virtual line source 4 is located on the back side of the rolled-edge parabolic cylindrical reflector 1, and the distance from the vertex of the rolled-edge parabolic cylindrical reflector 1 is the focal length. See the side view of the compressed field of the rolled-edge cylindrical wave. Figure 2 The parabolic reflector has a focal length of 16m, a virtual vertex elevation of 1.5m, a quiet zone front section 3-1 distance from the feed source of 6.5m, and a quiet zone depth of 24m. To control edge diffraction and reduce the low-frequency limit of the cylindrical compaction field, the parabolic cylindrical surface is edge-rolled. The orthographic projection of the edge-rolled parabolic cylindrical reflector is shown below. Figure 3 As shown, the reflector has dimensions of 16m wide × 12m high. The field distribution in the quiet zone is analyzed and calculated using the multilayer fast multipole algorithm at three sections: front section 3-1, middle section 3-2, and rear section 3-3.

[0032] To evaluate the quiet-zone performance of the cylindrical contraction field, an ideal cylindrical wave generated by a virtual line source at the quiet-zone section was calculated and compared with a quasi-cylindrical wave generated by a rolled-edge parabolic cylindrical reflector to obtain amplitude and phase residual values. The residual values ​​of the quiet-zone field and the ideal cylindrical wave field at three frequency points (low (0.3 GHz), medium (0.6 GHz), and high (2.0 GHz)) were selected to demonstrate the quiet-zone performance of the rolled-edge cylindrical wave contraction field.

[0033] Figures 4-7 The amplitude and phase residual values ​​of the compressed field of the rolled-edge cylindrical wave and the ideal cylindrical wave field generated by the line source are located at the front section of the quiet zone.

[0034] Figures 8-11 The amplitude and phase residual values ​​of the cross section in the quiet region are the compression field of the rolled-edge cylindrical wave and the ideal cylindrical wave field generated by the line source.

[0035] Figures 12-15 The amplitude and phase residual values ​​of the compressed field of the rolled-edge cylindrical wave and the ideal cylindrical wave field generated by the line source are located at the cross section in the quiet zone.

[0036] As shown in the figure, the cylindrical wave generated by the rolled-edge cylindrical wave compaction field has very small residuals compared to the ideal cylindrical wave generated by the line source within a quiet zone of 24m horizontally × 6m high. The aperture utilization rate in the quiet zone is 150% horizontally and 50% vertically, and the lowest operating frequency can be as low as 0.3GHz (amplitude residual peak-to-peak value less than 2dB, phase residual peak-to-peak value less than 15°). Using a sawtooth cylindrical wave compaction field reflector of the same size, the vertical direction is only 12 times the wavelength (@0.3GHz), which obviously cannot achieve the low-frequency operating limit of 0.3GHz.

[0037] In summary, the rolled-edge cylindrical wave compaction field proposed in this invention has a lower low-frequency operating limit than the existing sawtooth cylindrical wave compaction field. It is more advantageous for the realization of cylindrical wave compaction fields in terms of implementation cost, technical risk, and quiet zone performance. In particular, the benefits of the rolled-edge cylindrical wave compaction field scheme will be more obvious for ultra-large cylindrical wave compaction fields.

[0038] The parts of this invention not described in detail are well-known in the field.

Claims

1. A device for compacting a rolled-edge cylindrical wave field, characterized in that: The device consists of a rolled-edge parabolic cylindrical reflector, a feed source, a quiet zone, and a virtual line source. The feed source is an approximate spherical wave radiation source, used to provide illumination when a cylindrical wave is formed in a quiet region; The aforementioned rolled-edge parabolic cylindrical reflector is a precision-machined curved surface, with the central solid part being a parabolic cylinder, used to correct the excitation wavefront to the desired cylindrical wavefront within a compressed distance. The aforementioned rolled-edge parabolic cylindrical reflector has rolled edges to control the interference of edge diffraction on the quiet zone, thereby forming a more ideal cylindrical wave in the quiet zone. The quiet zone is a quasi-cylindrical wave field in which the target or test piece is placed for testing. The virtual line source, located at the feed mirror position on the back of the rolled-edge parabolic cylindrical reflector, is a virtual source for the formation of cylindrical waves by the compressed field of the rolled-edge cylindrical wave.

2. The rolled-edge cylindrical wave compaction field device as described in claim 1, characterized in that: The aforementioned rolled-edge parabolic cylindrical reflector has an edge-rolled treatment to control low-frequency edge diffraction; compared with the traditional sawtooth cylindrical wave compaction field, the rolled-edge cylindrical wave compaction field has a lower low-frequency limit.

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