Shaped double-reflection terahertz compact field

Abstract

The invention discloses a shaped double-reflection terahertz compact range, and belongs to the technical field of antenna testing. The device comprises a main reflector, an auxiliary reflector, an irradiation feed source, a spread spectrum module, a polarization rotary table and a six-degree-of-freedom rotary table. The primary and secondary reflectors are shaped to provide an aperture field with a uniform phase and a desired amplitude distribution. The irradiation feed source emits terahertz spherical waves to the auxiliary reflector. And the spread spectrum module performs spread spectrum on the radio frequency signal, so that the working frequency of the signal reaches a terahertz wave band consistent with that of the irradiation feed source. The polarization turntable drives the irradiation feed source and the spread spectrum module to rotate in the polarization direction; a polarization rotary table is placed on the six-degree-of-freedom rotary table and used for adjusting the relative position relation between the irradiation feed source and the auxiliary reflector. Based on the shaping design, the defects of the existing terahertz compact range are overcome, and the problem of accurate test of the high-performance terahertz antenna is effectively solved.

Description

Technical Field

[0001] The invention relates to a shaped double-reverse terahertz compact field, belonging to the technical field of antenna testing. Background Art

[0002] The three existing types of reflective terahertz compact fields all have their own advantages and disadvantages, and it is difficult to fully meet the testing needs of high-performance terahertz antennas. For example, the cross-polarization performance of plane waves in the quiet zone of a single-reflection compact field is poor, the standard card-type double-reflection compact field has serious leakage, resulting in an energy loss of about 9dB, and the three-reflection compact field has a complex structure and is difficult to install. As the requirements for test accuracy of various parameters of terahertz antennas continue to increase, the existing terahertz compact field has the problem of being unable to meet its precise testing needs. Summary of the invention

[0003] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art and propose a shaped double-reverse terahertz compact field, which, based on the shaped design, overcomes the shortcomings of the existing type of terahertz compact field and effectively solves the problem of accurate testing of high-performance terahertz antennas.

[0004] The technical solution of the present invention is:

[0005] A shaped double-reverse terahertz compact field, comprising a main reflector, a sub-reflector, an irradiation feed source, a spectrum expansion module, a polarization turntable and a six-degree-of-freedom turntable;

[0006] The main reflector and the sub-reflector are designed based on the principle of geometric optics ray tracing to provide an aperture field with uniform phase and desired amplitude distribution;

[0007] The irradiation feed source emits a terahertz spherical wave to the sub-reflector, the terahertz spherical wave reaches the main reflector after being reflected by the sub-reflector, and forms a plane wave after being reflected by the main reflector;

[0008] The spectrum spreading module spreads the radio frequency signal so that the operating frequency of the radio frequency signal after the spectrum spreading reaches the terahertz band consistent with the irradiation feed source;

[0009] The irradiation feed source and the spectrum spreading module are placed on the polarization rotating table, driving the irradiation feed source and the spectrum spreading module to rotate in the polarization direction;

[0010] A polarization turntable is placed on the six-degree-of-freedom turntable to adjust the relative position relationship between the irradiation feed source and the sub-reflector.

[0011] Furthermore, the main reflector and the sub-reflector are shaped and designed based on the principle of geometric optics ray tracing, that is, the surface shapes of the two reflectors are calculated according to the aperture field with uniform phase and amplitude distribution; in the distribution of aperture field amplitude, not only the amplitude uniformity of the aperture field within the quiet zone is guaranteed, but also the amplitude of the aperture field outside the quiet zone is controlled to achieve a high roll-off outside the quiet zone, so that the energy leaked outside the quiet zone is less than 0.5dB.

[0012] Furthermore, the configurations of the main reflector and the sub-reflector satisfy the circular symmetry condition, and the cross-polarization components generated by the two reflectors are 0, and the cross-polarization in the quiet zone is only generated by the irradiation feed source.

[0013] Furthermore, the irradiation feed source adopts an axial slot corrugated horn. By carrying out electromagnetic field simulation, an optimization target of low cross-polarization is set, and the contour of the corrugated horn is shaped and optimized to obtain the parameters of the irradiation feed sources in different frequency bands.

[0014] Furthermore, according to the requirements of the terahertz compact field test, with the phase center of the lowest frequency band irradiation feed as a reference, the irradiation feeds of other frequency bands increase the structural length at the rear end of the axial slot corrugated horn of the lowest frequency band, so that the irradiation feeds of different frequency bands have the same phase center position, and there is no need to readjust the feed position when replacing the irradiation feeds of different frequency bands.

[0015] Furthermore, the main reflector is provided with a sawtooth outer edge to reduce scattering at the edge of the main reflector.

[0016] Furthermore, a baffle is provided to separate the leakage, diffraction and scattering fields of the illumination feed source and the sub-reflector position from the main reflector and the quiet zone. The baffle is positioned so as not to block the main optical path from the illumination feed source to the sub-reflector and then to the main reflector.

[0017] Furthermore, a supporting structure is provided to realize the integrated installation of various components of the compression yard.

[0018] The advantages of the present invention compared with the prior art are:

[0019] (1) Through reasonable design, the present invention reduces the cross-polarization component generated by the reflector system composed of the main reflector and the sub-reflector to 0, and the cross-polarization in the quiet zone is only generated by the illumination feed; the illumination feed adopts an axial groove corrugated horn and the corrugated horn profile is shaped and optimized, the cross-polarization level is better than -45dB, and good cross-polarization performance in the quiet zone is achieved.

[0020] (2) The present invention uses a baffle to isolate the leakage, diffraction and scattering fields of the feed source and the secondary reflector from the main reflector and the quiet zone, so that the jitter ripples of the plane wave in the quiet zone are greatly reduced, which is an important means to obtain superior plane wave performance.

[0021] (3) The present invention realizes the integrated installation of various components of the compact field through the support structure, reduces the difficulty of installation, and facilitates overall movement. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0023] Figure 1 A schematic diagram of a double-reverse terahertz compact field according to an embodiment of the present invention;

[0024] Figure 2 A schematic diagram of the optical path of the double-reverse terahertz compact field according to an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the shaped double-reverse terahertz compact field support structure according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0027] The present invention proposes a shaped double-reverse terahertz compact field, which has the characteristics of superior plane wave performance in the quiet zone, high reliability, easy installation and strong adaptability.

[0028] Shaped double-reflected terahertz compression field Figure 1 As shown, it includes a main reflector 1, a sub-reflector 3, an illumination feed source 4, a baffle 5, a supporting structure 6, a spectrum expansion module 7, a polarization turntable 8, and a six-degree-of-freedom turntable 9.

[0029] The main reflector 1 and the sub-reflector 3 are designed based on the geometric optics (GO) ray tracing principle, that is, the surface shape of the reflector is calculated according to the aperture field with uniform phase and amplitude distribution. In the amplitude distribution of the aperture field, it is necessary not only to ensure the amplitude uniformity of the aperture field within the quiet zone, but also to strictly control the amplitude of the aperture field outside the quiet zone, so that a high roll-off is achieved outside the quiet zone, so that the energy leaked outside the quiet zone is less than 0.5dB. The sub-reflector 3 can receive most of the feed source irradiation energy, reduce leakage, and increase the dynamic range of the antenna test by 9dB under the same conditions. At the same time, the configuration design of the main reflector 1 and the sub-reflector 3 meets the circular symmetry condition, and the cross-polarization component generated by the reflector system composed of the main reflector 1 and the sub-reflector 3 is 0, and the cross-polarization in the quiet zone is only generated by the irradiation feed 4.

[0030] The irradiation feed 4 uses an axial groove corrugated horn, and adopts general electromagnetic field simulation software to set the optimization target of low cross-polarization, optimize the contour of the corrugated horn, obtain the parameters of the irradiation feeds of different frequency bands, and achieve good cross-polarization performance in the quiet zone. The structural design of the irradiation feed 4 ensures that the irradiation feeds of different frequency bands have the same phase center position. The specific implementation method is to use the phase center of the irradiation feed of the lowest frequency band as the benchmark, and increase the structural length of the irradiation feeds of other frequency bands at the rear end. Therefore, there is no need to readjust the feed position when replacing different irradiation feeds, which is extremely convenient for the use of compact fields.

[0031] The support structure 6 realizes the integrated installation of various components of the compact field, such as Figure 3 As shown, the installation difficulty is reduced and the overall movement is facilitated.

[0032] The spectrum spreading module 7 is a standard product, which realizes the spectrum spreading of the radio frequency signal so that the signal operating frequency reaches the terahertz band consistent with the irradiation feed source 4.

[0033] The polarization turntable 8 drives the spectrum spreading module 7 and the irradiation feed source 4 to rotate in the polarization direction, thereby realizing the testing of different polarization methods.

[0034] The six-degree-of-freedom turntable 9 is used to accurately adjust the relative position relationship between the illumination feed source 4 and the sub-reflector 3 to reduce installation errors.

[0035] like Figure 2 As shown, the terahertz spherical wave emitted by the irradiation feed source 4 reaches the sub-reflector 3, reaches the main reflector 1 after being reflected by the sub-reflector 3, and forms a plane wave after being reflected by the main reflector 1, which is used for testing the terahertz antenna.

[0036] Preferably, the main reflector 1 is provided with a main reflector sawtooth edge 2 to reduce the scattering at the edge of the main reflector 1. A baffle 5 is provided to separate the leakage, diffraction and scattering fields of the feed source and the sub-reflector position from the main reflector and the quiet zone, and the position of the baffle cannot block the main optical path of the feed source → sub-reflector → main reflector. The above two components are used to improve the performance of the plane wave.

[0037] The shaped double-reverse compact field designed by the present invention has excellent quiet zone plane wave performance: quiet zone cross polarization: better than -35dB, amplitude jitter better than ±0.5dB (pp value), phase jitter ±5° (pp value). In addition, the system leakage is greatly reduced by 9dB, effectively improving the dynamic range of the terahertz test system.

[0038] The above-described embodiments are only preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A shaped double-reverse terahertz compact field, characterized in that: It includes a main reflector, a sub-reflector, an illumination feed source, a spectrum expansion module, a polarization turntable and a six-degree-of-freedom turntable; The main reflector and the sub-reflector are designed based on the principle of geometric optics ray tracing to provide an aperture field with uniform phase and desired amplitude distribution; The irradiation feed source emits a terahertz spherical wave to the sub-reflector, the terahertz spherical wave reaches the main reflector after being reflected by the sub-reflector, and forms a plane wave after being reflected by the main reflector; The spectrum spreading module spreads the radio frequency signal so that the operating frequency of the radio frequency signal after the spectrum spreading reaches the terahertz band consistent with the irradiation feed source; The irradiation feed source and the spectrum spreading module are placed on the polarization rotating table, driving the irradiation feed source and the spectrum spreading module to rotate in the polarization direction; A polarization turntable is placed on the six-degree-of-freedom turntable to adjust the relative position relationship between the irradiation feed source and the sub-reflector.

2. A shaped double-reverse terahertz compact field according to claim 1, characterized in that: The main reflector and the sub-reflector are shaped and designed based on the principle of geometric optics ray tracing, that is, the surface shapes of the two reflectors are calculated according to the aperture field with uniform phase and amplitude distribution; in the aperture field amplitude distribution, not only the amplitude uniformity of the aperture field within the quiet zone is guaranteed, but also the amplitude of the aperture field outside the quiet zone is controlled, and a high roll-off is achieved outside the quiet zone, so that the energy leaked outside the quiet zone is less than 0.5dB.

3. The shaped double-reverse terahertz compact field according to claim 1, characterized in that: The configurations of the main reflector and the sub-reflector satisfy the circular symmetry condition, the cross-polarization components generated by the two reflectors are 0, and the cross-polarization in the quiet zone is only generated by the irradiation feed source.

4. The shaped double-reverse terahertz compact field according to claim 1, characterized in that: The irradiation feed source adopts an axial groove corrugated horn. By carrying out electromagnetic field simulation, setting an optimization target of low cross-polarization, and optimizing the contour of the corrugated horn, the parameters of the irradiation feed sources in different frequency bands are obtained.

5. The shaped double-reverse terahertz compact field according to claim 4, characterized in that: According to the requirements of the terahertz compact field test, taking the phase center of the lowest frequency band irradiation feed as a reference, the irradiation feeds of other frequency bands increase the structural length at the rear end of the axial slot corrugated horn of the lowest frequency band, so that the irradiation feeds of different frequency bands have the same phase center position, and there is no need to readjust the feed position when replacing the irradiation feeds of different frequency bands.

6. The shaped double-reverse terahertz compact field according to claim 1, characterized in that: The main reflector is provided with a serrated outer edge to reduce scattering at the edge of the main reflector.

7. The shaped double-reverse terahertz compact field according to claim 1, characterized in that: A baffle is also provided to separate the leakage, diffraction and scattering fields of the irradiation feed source and the sub-reflector position from the main reflector and the quiet zone. The position of the baffle cannot block the main optical path from the irradiation feed source to the sub-reflector and then to the main reflector.

8. The shaped double-reverse terahertz compact field according to claim 1, characterized in that: A supporting structure is also provided to realize the integrated installation of various components of the compression yard.

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