CN112003025A

CN112003025A - Reflecting surface and compact range measuring system with same

Info

Publication number: CN112003025A
Application number: CN202010900054.9A
Authority: CN
Inventors: 漆一宏; 刘列; 吴济宇; 张颖; 蔡张华; 张辉彬
Original assignee: GENERAL TEST SYSTEMS Inc
Current assignee: GENERAL TEST SYSTEMS Inc
Priority date: 2020-08-31
Filing date: 2020-08-31
Publication date: 2020-11-27

Abstract

The present disclosure provides a reflective surface and a compact range measurement system having the same. Wherein, this plane of reflection includes: the working surface is used for converting spherical electromagnetic waves emitted by the feed source antenna into plane electromagnetic waves after being reflected; the wave-absorbing structure is made of an electromagnetic wave absorbing material and arranged at the edge of the working face and used for reducing edge scattering of the working face. The reflective surface of the disclosed embodiments can be used in compact range measurement systems. The disclosed embodiments can reduce edge scattering and improve the quiet zone performance of compact range measurement systems.

Description

Reflecting surface and compact range measuring system with same

Technical Field

The disclosure relates to the field of compact range measurement, in particular to a reflecting surface and a compact range measuring system with the reflecting surface.

Background

Compact field measurement systems can provide a quasi-plane wave measurement zone of excellent performance at close range. The compact range measuring system adopts a precise reflecting surface to convert spherical waves emitted by the feed source antenna into plane waves in a short distance, thereby meeting the far field measuring requirement. The compact field measurement system can simulate the plane wave electromagnetic environment of a far field in a small anechoic chamber to carry out multiple measurements and researches, for example, the electromagnetic characteristics such as the distribution of a main lobe, a side lobe and a back lobe of a directional diagram of an antenna to be measured can be obtained, and further, the active or passive performance of the antenna or a terminal can be obtained.

If the reflecting surface is an infinite paraboloid, the spherical electromagnetic wave emitted by the feed source antenna can be completely converted into a plane wave theoretically and reflected to the measuring area. Since the size of the reflecting surface in the anechoic chamber is limited, the edge scatters the incident spherical wave, and the generated scattering adversely affects the dead space.

In the related art, the edge scattering of the reflecting surface is generally reduced in two ways: in the first mode, the edge of the reflecting surface is set to be a zigzag structure, so that the edge scattering is redirected, and scattered waves avoid a dead zone and are reflected to a darkroom wave-absorbing material; the second way eliminates scattering by providing a convex transition bead at the edge of the reflective surface.

Disclosure of Invention

The object of the present disclosure is to solve at least to some extent one of the above-mentioned technical problems.

To this end, a first object of the present disclosure is to propose a reflecting surface.

A second object of the present disclosure is to propose a compact range measurement system.

In order to achieve the above object, an embodiment of a first aspect of the present disclosure provides a reflective surface, including: the working surface is used for converting spherical electromagnetic waves emitted by the feed source antenna into plane electromagnetic waves after being reflected; the wave-absorbing structure is made of an electromagnetic wave absorbing material and arranged at the edge of the working face and used for reducing edge scattering of the working face.

The compact range measuring system provided by the embodiment of the second aspect of the disclosure comprises an anechoic chamber, a feed source antenna and the reflecting surface provided by the embodiment of the first aspect of the disclosure.

According to the reflecting surface and the compact range measuring system with the reflecting surface, the wave absorbing structure is arranged on the edge of the working surface of the reflecting surface, and the wave absorbing structure is used for reducing the edge scattering of the reflecting surface, so that the quiet zone performance of the compact range measuring system is improved.

Additional aspects and advantages of the disclosure will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the disclosure.

Drawings

The foregoing and/or additional aspects and advantages of the present disclosure will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic diagram of the internal electric field distribution within a compact field;

2a-2b are schematic structural views of a reflective surface according to one embodiment of the present disclosure;

figures 3a-3b are schematic partial shapes of a wave-absorbing structure according to an embodiment of the present disclosure;

FIG. 4 is a schematic structural diagram of a reflective surface according to one embodiment of the present disclosure;

FIG. 5 is a schematic structural diagram of a reflective surface according to one embodiment of the present disclosure;

FIG. 6 is a schematic structural diagram of a compact range measurement system according to one embodiment of the present disclosure;

7a-7b are dead band performance schematics of a compact range measurement system according to one embodiment of the present disclosure.

Detailed Description

Reference will now be made in detail to the embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and intended to be illustrative of the present disclosure, and should not be construed as limiting the present disclosure.

The compact range measuring system adopts a designed reflecting surface to convert spherical waves generated by the feed source antenna into plane waves or quasi-plane waves within a short distance, so that the far field measuring requirement is met. According to the principle of reciprocity between transmission and reception, in some application scenarios, the reflecting surface may also be used to receive a signal transmitted by the measured object, for example, to focus and receive energy radiated by the measured object in a direction parallel to the focal axis of the reflecting surface. The compact field measurement system can realize a plane wave electromagnetic environment of a far field in a small anechoic chamber, and perform related measurement and research, such as obtaining electromagnetic characteristics of main lobe, side lobe, back lobe distribution and the like of a directional diagram of an antenna to be measured, and further obtaining active or passive performance of the antenna or a terminal. Fig. 1 shows the distribution of the electric field inside the compact field, and as shown in fig. 1, the electromagnetic wave emitted from the feed antenna changes into a plane wave after reaching the reflecting surface from the initial spherical wave shape. However, abnormal scattering occurs at the upper and lower edges of the reflecting surface, and the energy components of these non-planar waves will certainly affect the flatness of the phase and amplitude of the dead zone.

The reflecting surface and the compact range measuring system having the reflecting surface of the embodiments of the present disclosure are described below with reference to the accompanying drawings.

A reflective surface according to one embodiment of the present disclosure includes: the working surface is used for converting spherical electromagnetic waves emitted by the feed source antenna into plane electromagnetic waves after being reflected; and the wave-absorbing structure is made of an electromagnetic wave absorbing material and is arranged at the edge of the working surface and used for reducing the edge scattering of the working surface. In particular, the working surface may be a conductive material, such as a conductive material having a surface resistance of less than 10Ohm/sq, and may be, for example, metal, metallic paint, conductive carbon fiber, or the like. As an example, the part of the reflecting surface except the wave-absorbing structure can be all metal; or, as another example, the supporting structure of the reflecting surface is made of any material, and the working surface is arranged on the supporting structure and is made of the conductive material. The edge of the working surface refers to a portion farther from the center of the working surface, i.e., a region on the working surface where electromagnetic wave scattering occurs.

Fig. 2a and 2b are schematic structural views of a reflective surface according to one embodiment of the present disclosure. As shown in fig. 2a and 2b, the reflective surface 200 may include: a working surface 210 and a wave-absorbing structure 220. The working surface 210 is used for converting the spherical electromagnetic wave emitted by the feed antenna 14 into a planar electromagnetic wave after being reflected. The wave-absorbing structure 220 is matched with the working surface 210, the wave-absorbing structure 220 is made of an electromagnetic wave absorbing material, and the wave-absorbing structure 220 is arranged at the edge of the working surface and used for reducing edge scattering of the working surface 210. Alternatively, the absorbent structure 220 may be mounted by bonding or using fasteners for attachment.

The electromagnetic wave absorbing material described above is understood to be a material having electromagnetic losses. The type of electromagnetic loss may include, but is not limited to, resistive loss, dielectric loss, or magnetic loss, among others. Accordingly, the types of materials with electromagnetic losses may include, but are not limited to, resistive sheet materials, dielectric materials, magnetic materials, and the like. For example, graphite belongs to a resistance loss type wave-absorbing material, electromagnetic energy is mainly attenuated on the resistance of the material, and specifically, as an example, the resistance sheet material can be a conductive composite material film mixed with carbon powder and an adhesive; the mechanism of the dielectric loss type wave-absorbing material is dielectric polarization relaxation loss, and specifically, the dielectric material can be a polymer composite material mixed with conductive powder; the loss mechanism of the magnetic loss type wave-absorbing material is mainly ferromagnetic resonance absorption, such as ferrite, hydroxyl iron and the like, and specifically, the magnetic material can be a polymer composite material mixed with metal or ferrite powder.

In some embodiments of the disclosure, when the material of the wave-absorbing structure is a resistor material, the surface resistance value of the resistor material may be 10-2000 ohms per square; when the material of the wave-absorbing structure is a dielectric material, the dielectric material has the loss performance, and the loss tangent is more than 0.05; when the material of the wave-absorbing structure is a magnetic material, the magnetic material has the loss performance, and the loss tangent is more than 0.05.

In some embodiments of the present disclosure, the wave-absorbing structure has a first impedance gradually-changing portion disposed along a curvature direction of the reflecting surface, and the first impedance gradually-changing portion is disposed on a side surface of the working surface, or at least partially covers an edge of the working surface. Optionally, the first impedance gradually-varying portion is a multi-layer impedance gradually-varying electromagnetic wave absorption material, or is a sawtooth-shaped (for example, a cone shape or a wedge shape) electromagnetic wave absorption material. Optionally, the edge of the working surface is in a sawtooth shape, and the first impedance gradual change portion is a sawtooth-shaped electromagnetic wave absorption material matched with the edge shape of the working surface, that is, the sawtooth of the working surface is meshed with the sawtooth of the first impedance gradual change portion.

As an example, as shown in fig. 2a and 2b, the wave-absorbing structure 220 has a first impedance gradual-change portion 2201 in a zigzag shape, the first impedance gradual-change portion 2201 covers the edge of the working surface 210, the direction of gradual change of the width of the zigzag shape is consistent with the curvature direction of the working surface 210, and the end of the zigzag shape points to the central area of the working surface 210. Optionally, as shown in fig. 2a, the length L1 of the saw tooth of the first impedance gradual change portion 2201 is 0.5-5 times wavelength. The term "wavelength" as used herein refers to the wavelength of an electromagnetic wave used for measurement. Alternatively, as shown in fig. 3a and 3b, the saw teeth of the first impedance gradual change portion 2201 are configured to gradually increase in thickness from the inner edge to the outer edge of the working surface 210, and specifically, may gradually increase smoothly as shown in fig. 3a, or gradually increase in a step shape as shown in fig. 3 b. So as to better form impedance gradual transition in the incoming wave direction of the scattered wave. Enhancing absorption of the scattered electromagnetic wave. The inner edge as used herein refers to the side of the working surface relatively close to the central region thereof, and the outer edge refers to the side of the working surface relatively far from the central region thereof.

As another example, as shown in fig. 4, the edge of the working surface 210 of the reflection surface 200 is saw-toothed, the first impedance gradual change portion 2201 is disposed at the side of the working surface 210, and the first impedance gradual change portion 2201 is a saw-toothed electromagnetic wave absorption material matched with the edge shape of the working surface 210.

In some embodiments of the present disclosure, the wave-absorbing structure further has a second impedance gradually-changing portion, where the second impedance gradually-changing portion is disposed on a side surface of the working surface, and is configured to absorb multiple-scattering electromagnetic waves generated at an edge of the working surface, or/and is configured to absorb electromagnetic waves from the feed antenna. Optionally, the second impedance gradual change portion is a multilayer impedance gradual change electromagnetic wave absorption material; or a conical electromagnetic wave absorbing material, the tip or edge of the conical electromagnetic wave absorbing material points to the feed source antenna or/and points to the edge of the working face. Fig. 5 shows an example, as shown in fig. 5, the wave-absorbing structure further has a second impedance gradual change part 2202 with a cone shape in addition to the first impedance gradual change part 2201, the second impedance gradual change part 2202 is arranged on the side surface of the working surface 210, and the tip of the second impedance gradual change part 2202 is directed to the feed antenna 14, optionally, the second impedance gradual change part 2202 is a pyramid-shaped wave-absorbing material, the tip of the second impedance gradual change part is directed to the feed antenna 14 and is used for absorbing electromagnetic waves from the feed antenna 14, and some edges of the second impedance gradual change part are directed to the inner side of the edge of the working surface 210 and are used for absorbing multiple-. It will be appreciated that in some compact range measurement systems there are two or more feed antennas, for which the tapered second impedance transitions may be directed towards the primary feed antenna, or a plurality of second impedance transitions may be directed towards different feed antennas respectively.

The present disclosure also provides a compact range measurement system comprising an anechoic chamber, a feed antenna, and a reflective surface as described above.

FIG. 6 illustrates an example of a compact range measurement system according to one embodiment of the present disclosure. As shown in fig. 6, the compact range measurement system includes: anechoic chamber 11, turntable 12, support 13, feed antenna 14, and reflecting surface 200. Wherein, the rotating platform 12, the bracket 13, the reflecting surface 200 and the feed antenna 14 are all arranged in the anechoic chamber 11, the measured object is placed on the bracket 13, the bracket 13 is arranged on the rotating platform 12, and the measured object can rotate along with the rotation of the bracket and the rotating platform. During measurement, spherical waves are emitted through the feed source antenna 14 and irradiate the reflecting surface 200, the spherical waves are converted into plane waves after being reflected, and the plane waves are received by a measured piece in a measurement area. The measuring area/quiet area is an area with the best quality of compact range plane waves, the compact range feed source antenna emits electromagnetic waves, and the antenna to be measured receives the electromagnetic waves in the form of the plane waves to measure the wireless performance.

Optionally, in one embodiment, the second impedance transition of the reflective surface extends to a sidewall of the anechoic chamber to the absorbing material of the anechoic chamber sidewall to create a better quiet zone environment.

As shown in fig. 7a-7b, for the compact field measurement system with the reflecting surface shown in fig. 5, the performance of a vertical 0.3m region of the dead zone is calculated through electromagnetic simulation software, the amplitude and phase fluctuation of the region is large due to the offset feed of the reflecting surface, and the amplitude and phase of the unapplied absorbing structure are improved obviously compared with the amplitude and phase of the applied absorbing structure.

The shape of the working surface of the reflecting surface is not limited in the present disclosure, and the working surface may be, for example, a square, a rectangle, a circle, an ellipse, or any other shape other than the above-described zigzag shape. The shape of the wave-absorbing structure is not limited, and the wave-absorbing structure can be conical, wedge-shaped, sawtooth-shaped or multi-layer impedance gradual change electromagnetic wave absorbing material, thereby achieving the purpose of absorbing electromagnetic wave without reflection.

According to the reflecting surface of the embodiment of the disclosure, the edge scattering of the working surface can be reduced, so that the quiet zone performance of the compact range measuring system is improved. In the related art, in order to reduce edge scattering of the reflecting surface, the edge of the reflecting surface is usually provided with a saw-tooth structure, or a convex transition bead is provided at the edge of the reflecting surface. Both of them increase the weight of the reflecting surface, and increase the cost and workload for the links of processing, transportation, installation, maintenance, etc. The wave-absorbing structure adopted by the technical scheme has light weight, is easy to process, transport, install and maintain, and has lower cost.

In the description of the present disclosure, it is to be understood that the terms "length," "width," "thickness," "inner," "outer," and the like, as used herein, refer to an orientation or positional relationship as shown in the accompanying drawings, which are used for convenience in describing and simplifying the present disclosure, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be considered limiting of the present disclosure.

In the present disclosure, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integral; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meaning of the above terms in the present disclosure can be understood by those of ordinary skill in the art as appropriate.

In the present disclosure, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present disclosure have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present disclosure, and that changes, modifications, substitutions and alterations may be made to the above embodiments by those of ordinary skill in the art within the scope of the present disclosure.

Claims

1. A reflective surface, comprising:

the working surface is used for converting spherical electromagnetic waves emitted by the feed source antenna into plane electromagnetic waves after being reflected;

the wave absorbing structure is made of an electromagnetic wave absorbing material and arranged at the edge of the working face and used for reducing edge scattering of the working face.

2. The reflective surface of claim 1, wherein said electromagnetic wave absorbing material is of the type comprising a resistive sheet material, a dielectric material, and a magnetic material.

3. The reflecting surface of claim 2, wherein the surface resistance of the resistor sheet material is 10-2000 ohms per square; the dielectric material has a loss property with a loss tangent greater than 0.05; the magnetic material has a loss property with a loss tangent of greater than 0.05.

4. The reflecting surface according to claim 1, wherein the wave absorbing structure has a first impedance gradual change portion disposed along a curvature direction of the reflecting surface, and the first impedance gradual change portion is disposed on a side surface of the working surface, or at least partially covers an edge of the working surface.

5. The reflective surface of claim 4, wherein the first impedance gradual change portion is a multi-layer impedance gradual change electromagnetic wave absorbing material or a sawtooth electromagnetic wave absorbing material.

6. The reflection surface according to claim 5, wherein the first impedance gradual change portion is a sawtooth-shaped electromagnetic wave absorption material, and the length of the sawtooth is 0.5 to 5 times the wavelength.

7. The reflecting surface of claim 5, wherein the edge of the working surface is saw-toothed, and the first impedance gradual change portion is a saw-toothed electromagnetic wave absorbing material matched with the shape of the edge of the working surface.

8. The reflecting surface according to claim 4, wherein the wave absorbing structure further comprises a second impedance gradually-changing portion, and the second impedance gradually-changing portion is disposed on a side surface of the working surface and is used for absorbing multiple-scattering electromagnetic waves generated at an edge of the working surface or/and absorbing electromagnetic waves from the feed source antenna.

9. The reflective surface of claim 8, wherein said second impedance tapering portion is a multi-layer impedance tapering electromagnetic wave absorbing material; or the conical electromagnetic wave absorption material is provided, and the tip or edge of the conical electromagnetic wave absorption material points to the feed source antenna or/and points to the edge of the working surface.

10. A compact range measurement system, comprising: anechoic chamber, feed antenna, and a reflective surface according to any one of claims 1 to 9.

11. The compact range measurement system of claim 10, wherein the second impedance taper of the reflective surface extends to a sidewall of the anechoic chamber.