Radar antenna and radar level gauge
By incorporating an inclined surface in the lens structure of the radar antenna to reflect electromagnetic waves, the problem of high return loss in radar antennas is solved, resulting in more efficient radiation performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HANGZHOU MICROIMAGE INTELLIGENT CONTROL TECHNOLOGY CO LTD
- Filing Date
- 2026-04-30
- Publication Date
- 2026-06-05
AI Technical Summary
Existing radar antennas suffer from significant return loss, resulting in poor radiation performance.
Design a radar antenna in which the first phase calibration part of the lens structure has an inclined surface. Electromagnetic waves are reflected inside the lens structure and then reflected again by the inner surface of the antenna body, avoiding reverse transmission and reducing return loss.
By optimizing the lens structure design, the return loss of the radar antenna was significantly reduced, and the radiation performance was improved.
Smart Images
Figure CN122158915A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of antenna technology, specifically relating to a radar antenna and a radar level gauge. Background Technology
[0002] A radar antenna is a structure that directionally transmits and receives electromagnetic waves and can focus them into a beam. It features high gain, adjustable beam, and strong anti-interference capabilities. Currently, radar antennas are mainly used in meteorological monitoring, intelligent transportation, smart homes, underground detection, and space target tracking.
[0003] Existing radar antennas consist of two core components: the antenna body and the lens structure. The antenna body acts as a primary radiator, generating divergent spherical waves. The lens structure, mounted at the open end of the antenna body, creates phase delay differences through varying medium thicknesses in different regions, converting the spherical waves into plane waves and thus forming a directional beam. However, due to the high reflectivity of the lens structure, the radar antenna experiences significant return loss. Summary of the Invention
[0004] The purpose of this application is to provide a radar antenna and a radar level gauge that can solve the problem of high return loss in current radar antennas.
[0005] To solve the above-mentioned technical problems, this application is implemented as follows: In a first aspect, embodiments of this application provide a radar antenna, including: The antenna body includes a connected waveguide structure and a fixed structure, wherein the cross-sectional area of the fixed structure gradually increases in the direction in which the waveguide structure extends toward the fixed structure. A lens structure is disposed within the receiving cavity of the fixed structure, and the peripheral surface of the lens structure is fitted to the inner surface of the fixed structure. The lens structure has a first phase calibration part, the first phase calibration part has a first surface, the first surface faces the waveguide cavity of the waveguide structure, and the first surface is opposite to the inner surface of the antenna body.
[0006] Secondly, embodiments of this application also provide a radar level gauge, including a housing, a feed source, and the aforementioned radar antenna. Both the feed source and the radar antenna are disposed within the housing, and the feed source is connected to the waveguide structure of the radar antenna.
[0007] In this embodiment, the lens structure has a first phase calibration section with a first surface facing the waveguide cavity and opposite to the inner surface of the antenna body. When electromagnetic waves in the waveguide cavity strike the first phase calibration section of the lens structure, most of the electromagnetic waves enter the lens structure from the first surface of the first phase calibration section. A small portion of the electromagnetic waves, when incident from air into the medium, undergoes energy reflection due to a change in the dielectric constant. This portion of the electromagnetic waves is reflected by the first surface to the inner surface of the antenna body, and then, after reflection by the inner surface of the antenna body, propagates towards the second phase calibration section of the lens structure. Under the action of the lens structure, the electromagnetic waves are converted from spherical waves into plane waves, thereby forming a directional beam, which then exits from the second phase calibration section of the lens structure. This solution, by changing the arrangement of the first surface of the lens structure, allows the electromagnetic waves reflected by the first surface to be reflected again by the inner surface of the antenna body before exiting from the second phase calibration section of the lens structure. This avoids the portion of the electromagnetic waves being reflected back into the waveguide cavity for reverse transmission, thereby reducing the return loss of the radar antenna and improving its radiation performance. Therefore, this application can solve the problem of high return loss in current radar antennas. Attached Figure Description
[0008] Figure 1 This is a schematic diagram of the radar antenna structure disclosed in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a radar antenna transmitting electromagnetic waves as disclosed in an embodiment of this application; Figure 3 This is a schematic diagram of the structure of a radar antenna receiving electromagnetic waves disclosed in an embodiment of this application; Figure 4 This is a schematic diagram of the structure of a radar antenna disclosed in another embodiment of this application; Figure 5 This is a schematic diagram of the structure of a radar antenna transmitting electromagnetic waves, as disclosed in another embodiment of this application; Figure 6 This is a schematic diagram of a radar antenna receiving electromagnetic waves according to another embodiment of this application; Figure 7 This is a graph showing the return loss curve of the radar antenna disclosed in the embodiments of this application. The dashed line represents the return loss curve of the radar antenna in the prior art (i.e., before optimization), and the dashed line represents the return loss curve of the radar antenna in this application (i.e., after optimization).
[0009] Explanation of reference numerals in the attached figures: 100 - Antenna body, 110 - Waveguide structure, 120 - Fixed structure; 200 - Lens structure, 210 - First phase calibration part, 211 - First surface, 220 - Second phase calibration part, 230 - Groove, 240 - Protrusion. Detailed Implementation
[0010] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0011] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.
[0012] The radar antenna and radar level gauge provided in this application will be described in detail below with reference to the accompanying drawings, through specific embodiments and application scenarios.
[0013] like Figures 1 to 6 As shown in the figure, this application discloses a radar antenna, which includes: The antenna body 100 includes a connected waveguide structure 110 and a fixed structure 120. Optionally, the waveguide structure 110 can be fed by a feed probe, or by coupling, excitation, or other methods, thereby transmitting electromagnetic waves into the waveguide cavity of the waveguide structure 110. Optionally, the central axis of the waveguide structure 110 and the central axis of the fixed structure 120 can coincide, which helps to improve the uniformity and symmetry of the electromagnetic beam radiated by the antenna body 100. In the direction extending from the waveguide structure 110 to the fixed structure 120, the cross-sectional area of the fixed structure 120 (the cross-sectional area refers to the cross-sectional area perpendicular to the extension direction of the central axis of the fixed structure 120) gradually increases, that is, the fixed structure 120 has a horn structure. In this case, the antenna body 100 can also be a horn antenna, which has the characteristics of simple structure, high gain, strong directivity, and low reflection loss. Optionally, the antenna body 100 can be a metal structure.
[0014] A lens structure 200 is disposed within the receiving cavity of the fixed structure 120, and the peripheral surface of the lens structure 200 is fitted to the inner surface of the fixed structure 120. Optionally, the lens structure 200 can be made of a non-metallic material with a dielectric constant greater than 1, such as polymer dielectric materials, ceramic composite materials, metamaterials, etc., and this application embodiment does not impose specific limitations on this. The lens structure 200 has a first phase calibration part 210, which has a first surface 211 facing the waveguide cavity of the waveguide structure 110, so that the electromagnetic waves transmitted in the waveguide cavity are directed toward the first surface 221, and the first surface 211 is opposite to the inner surface of the antenna body 100, that is, the first surface 211 is an inclined surface. The electromagnetic waves in the waveguide cavity are emitted after passing through the lens structure 200, thereby converting the spherical wave into a plane wave. This is beneficial for realizing the narrow beam and high directionality radiation characteristics of the radar antenna; and, by designing the refractive index distribution of the lens structure 200, the beam shape can be flexibly controlled to meet practical needs.
[0015] In this embodiment, the lens structure 200 has a first phase calibration section 210. The first phase calibration section 210 has a first surface 211 facing the waveguide cavity of the waveguide structure 110 and opposite to the inner surface of the antenna body 100. When electromagnetic waves in the waveguide cavity strike the first phase calibration section 210 of the lens structure 200, most of the electromagnetic waves enter the lens structure 200 from the first surface 211 of the first phase calibration section 210. A small portion of the electromagnetic waves are reflected due to the change in dielectric constant when they enter the medium from air. At this time, this portion of the electromagnetic waves is reflected by the first surface 211 to the inner surface of the antenna body 100, and then reflected by the inner surface of the antenna body 100 before being transmitted toward the second phase calibration section 220 of the lens structure 200. Under the action of the lens structure 200, the electromagnetic waves are converted from spherical waves into plane waves, thereby forming a directional beam, which is then emitted from the second phase calibration section 220 of the lens structure 200. This solution modifies the arrangement of the first surface 211 of the lens structure 200, causing the electromagnetic waves reflected from the first surface 211 to be reflected again by the inner surface of the antenna body 100 and then emitted from the second phase calibration section 220 of the lens structure 200. This avoids the electromagnetic waves being reflected back into the waveguide cavity for reverse transmission, thereby reducing the return loss of the radar antenna and improving its radiation performance. Therefore, this application can solve the problem of high return loss in current radar antennas.
[0016] It should be noted that the first surface 211 mentioned above serves as both the incident surface and the reflecting surface. When electromagnetic energy enters the fixed structure 120 from the waveguide cavity, the electromagnetic energy collides with the medium (i.e., the lens structure 200), thereby generating reflection. This application reduces reflection by changing the shape of the interface (i.e., the first surface 211) so that the electromagnetic energy is refracted to other areas. At the same time, since the electromagnetic energy path is changed, other curved surface structures of the medium (such as the second phase calibration section) also need to be modified accordingly, thereby optimizing the return loss without sacrificing other performance characteristics of the radar antenna.
[0017] In other words, this application sets the first surface 211 as an inclined surface and calculates the inclined angle of the first surface 211 to reflect or refract the electromagnetic energy that would originally bounce back to the opening of the waveguide cavity to the inner surface of the antenna body 100, thereby reducing the loss of the return energy.
[0018] In one optional embodiment, the central axis of the first phase calibration section 210, the central axis of the fixed structure 120, and the central axis of the waveguide cavity coincide. This allows the entire radar antenna to have a centrally symmetrical structure, thereby improving the uniformity and symmetry of the electromagnetic beam radiated by the radar antenna. Of course, the central axis of the first phase calibration section 210 can also be parallel to the central axis of the fixed structure 120 and / or the central axis of the waveguide cavity.
[0019] like Figure 1As shown, in a further optional embodiment, the lens structure 200 is provided with a groove 230, the opening of which faces the waveguide cavity of the waveguide structure 110. In the direction extending from the waveguide structure 110 to the fixed structure 120, the cross-sectional area of the groove 230 (the cross-sectional area refers to the cross-sectional area perpendicular to the extension direction of the central axis of the groove 230) gradually decreases. The groove 230 serves as the first phase calibration part 210, and the inner surface of the groove 230 forms a first surface 211. This solution achieves this by creating a groove 230 on the incident surface of the lens structure 200, with the inner surface of the groove 230 forming the first surface 211. Specifically, the first surface 211 includes a first portion and a second portion in its circumferential direction. The first portion and the second portion are located on opposite sides of the central axis of the groove 230. Of the electromagnetic waves emitted from the waveguide cavity towards the first portion, most of the electromagnetic waves enter the lens structure 200. A small portion of the electromagnetic waves is reflected by the first portion to the second portion. Most of this portion of electromagnetic waves then enters the lens structure 200 and, after refraction within the lens structure 200, further propagates towards the inner surface of the fixed structure 120. After reflection by the inner surface of the fixed structure 120, it is transmitted towards the second phase calibration section 220 of the lens structure 200. A small portion of the electromagnetic waves is reflected again by the second portion to the first portion, and the above transmission process is repeated. This solution uses a lens structure 200 with this structure, which is not only simple in structure and easy to manufacture, but also saves on the materials used in manufacturing the lens structure 200, thereby reducing the manufacturing cost of the radar antenna.
[0020] It should be noted that when the incident surface of the first phase calibration section 210 of the lens structure 200 changes, the rate of curvature change at various points on the exit surface of the second phase calibration section 220 of the lens structure 200 needs to be adjusted accordingly. For example, in the above embodiment, when the lens structure 200 is provided with a groove 230, the groove 230 is the first phase calibration section 210, and the inner surface of the groove 230 forms a first surface 211, the rate of curvature change at various points on the exit surface of the second phase calibration section 220 of the lens structure 200 can be increased during the manufacturing of the radar antenna, thereby better realizing the conversion of spherical waves to plane waves.
[0021] like Figure 4As shown, in another optional embodiment, the lens structure 200 is provided with a protrusion 240, which is located inside the waveguide cavity of the waveguide structure 110. In the direction extending from the waveguide structure 110 to the fixed structure 120, the cross-sectional area of the protrusion 240 (the cross-sectional area refers to the cross-sectional area perpendicular to the extension direction of the central axis of the protrusion 240) gradually increases. The protrusion 240 serves as the first phase calibration part 210, and its outer peripheral surface forms a first surface 211. This solution provides a protrusion 240 on the lens structure 200, with its outer peripheral surface forming the first surface 211. Specifically, of the electromagnetic waves incident on the first surface 211 within the waveguide cavity, most of the electromagnetic waves enter the interior of the lens structure 200, while a small portion is reflected to the inner surface of the waveguide structure 110. This portion of electromagnetic waves is then reflected back to the first surface 211 via the inner surface of the waveguide structure 110, repeating the aforementioned transmission process. This solution uses a lens structure 200 with this structure, which is not only simple in structure and easy to manufacture, but also can shorten the transmission path of electromagnetic waves in the air. This helps to reduce the return loss of electromagnetic waves, thereby improving the radiation performance of the radar antenna.
[0022] It should be noted that when the incident surface of the first phase calibration section 210 of the lens structure 200 changes, the rate of curvature change at various points on the exit surface of the second phase calibration section 220 of the lens structure 200 needs to be adjusted accordingly. For example, in the above embodiment, when the lens structure 200 is provided with a protrusion 240, the protrusion 240 is the first phase calibration section 210, and the outer peripheral surface of the protrusion 240 forms a first surface 211, the rate of curvature change at various points on the exit surface of the second phase calibration section 220 of the lens structure 200 can be reduced during the manufacturing process of the radar antenna, thereby better realizing the conversion of spherical waves to plane waves.
[0023] In another optional embodiment, the curvature of the first surface 211 is equal in the circumferential direction of the first phase calibration part 210, that is, the cross-section of the first phase calibration part 210 (the cross-section refers to the cross-section extending perpendicular to the central axis of the first phase calibration part 210) is a circular structure. This can make the reflected energy of the electromagnetic wave incident on the first surface 211 basically consistent at all points in the circumferential direction of the first phase calibration part 210, thereby further improving the uniformity and symmetry of the electromagnetic beam emitted by the lens structure 200. Of course, the curvature of the first surface 211 can also be unequal in the circumferential direction of the first phase calibration part 210, that is, the cross-section of the first phase calibration part 210 can be triangular, rectangular, etc.
[0024] In one optional embodiment, the first surface 211 is planar, meaning that the line connecting the second and third surfaces of the first phase calibration part 210 along its axial direction is a straight line. When the first surface 211 is planar, this not only facilitates the fabrication of the first phase calibration part 210, but also ensures that the reflected electromagnetic energy is transmitted in the same direction. This helps to reduce the reflective area of the antenna body 100, thereby facilitating the miniaturization of the radar antenna.
[0025] Alternatively, in another optional embodiment, the first surface 211 is a convex surface, that is, the first surface 211 protrudes in a direction away from the central axis of the first phase calibration part 210, which helps to reduce the transmission path of the reflected electromagnetic wave in the air.
[0026] Alternatively, in another optional embodiment, the first surface 211 is concave, that is, the first surface 211 protrudes along the direction close to the central axis of the first phase calibration part 210. This is beneficial to the convergence of reflected energy, thereby reducing the reflective area of the antenna body 100, and thus facilitating the miniaturization of the radar antenna.
[0027] Optionally, the first phase calibration unit 210 can be a trapezoidal structure; or, in other optional embodiments, the first phase calibration unit 210 is a conical structure, in which case the area of the first surface 211 is larger, and correspondingly the reflection area of the first surface 211 is also larger, which is beneficial to further reduce the return loss of the radar antenna, thereby further improving the radiation performance of the radar antenna.
[0028] In a further optional embodiment, the central angle of the longitudinal section of the first phase calibration part 210 (the longitudinal section refers to the section passing through the central axis of the first phase calibration part 210) is 40~150°, that is, the longitudinal section of the first phase calibration part 210 is an isosceles triangle structure, and the included angle between the first side and the second side of the isosceles triangle structure is 40~150°. This can avoid the electromagnetic energy reflected by the first surface 211 having an excessively small or large emission angle, thereby ensuring that the reflected energy can be directed to the inner surface of the antenna body 100, thereby reducing the return loss of electromagnetic energy in the waveguide cavity. Of course, the central angle of the longitudinal section of the first phase calibration part 210 can also be less than 40°, or the central angle of the longitudinal section of the first phase calibration part 210 can be greater than 150°. In both cases, with the size of the antenna body 100 unchanged, some of the reflected energy may be directed into the waveguide cavity for reverse transmission, or the size of the antenna body 100 can be increased to increase the reflective area of the antenna body 100.
[0029] In an optional embodiment, the cross-sectional area (cross-sectional area refers to the cross-sectional area extending perpendicular to the central axis of the waveguide structure 110) of the waveguide cavity of the waveguide structure 110 is equal along its axial direction, meaning that the width of the waveguide structure 110 remains constant along its axial direction. The maximum cross-section of the first phase calibration part 210 is located at the connection between the waveguide structure 110 and the fixed structure 120, and the maximum cross-sectional area of the first phase calibration part 210 is equal to the cross-sectional area of the waveguide cavity. At this time, the outer peripheral surface of the light-transmitting structure 200 can be equal to the area of the inner peripheral surface of the fixed structure 120, and the two can fit together completely. This ensures that the electromagnetic waves in the waveguide cavity enter the light-transmitting structure 200 before diffusion, so as to convert the spherical wave into a plane wave. This is beneficial to reducing the size of the lens structure 200; and, adopting this arrangement is beneficial to improving the compactness of the various structural arrangements of the radar antenna.
[0030] Based on the radar antenna provided in the embodiments of this application Figure 7 This is a graph showing the reflection coefficient at the waveguide cavity opening of the radar antenna disclosed in this application at different resonant frequencies. The horizontal axis represents the resonant frequency, and the vertical axis represents the ratio of the energy input to the waveguide cavity opening of the radar antenna to the energy reflected back. The larger the absolute value of this ratio, the less energy is reflected back, and the more energy enters the radar antenna. Combined with... Figure 7 It is known that, compared with the prior art (i.e. before optimization), the return loss of the radar antenna disclosed in this application is improved by about 10 dB, which greatly improves the radiation performance of the radar antenna.
[0031] Based on the radar antenna provided in this application, this application also provides a radar level gauge. A radar level gauge is an instrument that uses microwave radar technology for non-contact level measurement. Its core function is to accurately measure the height or level of materials inside a container by transmitting and receiving high-frequency electromagnetic waves (microwaves), and convert the data into a readable signal output. Currently, radar level gauges are widely used in various fields such as chemical, pharmaceutical, food, and energy industries, and are a key measurement and control tool in modern automated production.
[0032] Optionally, the radar antenna of a radar level gauge can be a shared transmit and receive antenna. Therefore, it is necessary to maintain good isolation between the receiving path and the transmitting path of the radar antenna, and high antenna gain and sealing are required. Therefore, the radar antenna of a radar level gauge generally has a lens structure 200 set at the port of the antenna body. However, due to the reflection of the medium (i.e., the lens structure 200), the transmit and receive isolation of the radar antenna decreases, which leads to a decrease in the performance of the entire radar level gauge, an increase in noise floor, and a larger blind zone.
[0033] Based on this, the radar level gauge disclosed in this application includes a housing, a feed source, and a radar antenna as described in any of the above embodiments. Both the feed source and the radar antenna are disposed within the housing. The feed source is connected to the waveguide structure 110 of the radar antenna, thereby transmitting the electromagnetic waves emitted by the feed source to the waveguide cavity of the waveguide structure 110. This radar antenna employs a special structural design: with the first surface 211 of the lens structure 200 facing the waveguide cavity of the waveguide structure 110, the first surface 211 of the lens structure 200 is opposite to the inner surface of the antenna body 100. This allows the electromagnetic waves reflected by the first surface 211 to strike the inner surface of the antenna body 100, and after a second reflection, exit from the second phase calibration section 220 of the lens structure. This reduces electromagnetic energy reflection caused by changes in the dielectric constant when incident from air into the medium, effectively reducing the return loss caused by the lens structure 200, thereby effectively improving the near-range target detection accuracy of the radar level gauge and reducing the blind zone distance.
[0034] It should be noted that the radar antenna disclosed in this application can also be applied to other devices, such as airplanes, automobiles, and household items (such as robot vacuum cleaners), and this application does not impose specific limitations on this.
[0035] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.
Claims
1. A radar antenna, characterized in that, include: The antenna body (100) includes a waveguide structure (110) and a fixed structure (120) connected together. In the direction in which the waveguide structure (110) extends toward the fixed structure (120), the cross-sectional area of the fixed structure (120) gradually increases. A lens structure (200) is disposed in the receiving cavity of the fixed structure (120), and the peripheral surface of the lens structure (200) is fitted to the inner surface of the fixed structure (120). The lens structure (200) has a first phase calibration part (210), and the first phase calibration part (210) has a first surface (211). The first surface (211) faces the waveguide cavity of the waveguide structure (110), and the first surface (211) is opposite to the inner surface of the antenna body (100).
2. The radar antenna according to claim 1, characterized in that, The central axis of the first phase calibration unit (210), the central axis of the fixed structure (120), and the central axis of the waveguide cavity coincide.
3. The radar antenna according to claim 1, characterized in that, The lens structure (200) is provided with a groove (230), the opening of the groove (230) faces the waveguide cavity, and the cross-sectional area of the groove (230) gradually decreases in the direction of the waveguide structure (110) extending towards the fixed structure (120). The groove (230) is the first phase calibration part (210), and the inner side of the groove (230) forms the first surface (211).
4. The radar antenna according to claim 1, characterized in that, The lens structure (200) is provided with a protrusion (240), which is located inside the waveguide cavity. In the direction that the waveguide structure (110) extends toward the fixed structure (120), the cross-sectional area of the protrusion (240) gradually increases. The protrusion (240) is the first phase calibration part (210), and the outer peripheral surface of the protrusion (240) forms the first surface (211).
5. The radar antenna according to claim 1, characterized in that, In the circumferential direction of the first phase calibration section (210), the curvature of the first surface (211) is equal.
6. The radar antenna according to claim 1, characterized in that, The first surface (211) is a plane; or, The first surface (211) is a convex surface; or, The first surface (211) is concave.
7. The radar antenna according to claim 1, characterized in that, The first phase calibration unit (210) has a conical structure.
8. The radar antenna according to claim 7, characterized in that, The central angle of the longitudinal section of the first phase calibration unit (210) is 40~150°.
9. The radar antenna according to claim 1, characterized in that, Along the axial direction of the waveguide structure (110), the cross-sectional area of the waveguide cavity is equal at all points. The maximum cross-section of the first phase calibration part (210) is located at the connection between the waveguide structure (110) and the fixed structure (120), and the maximum cross-sectional area of the first phase calibration part (210) is equal to the cross-sectional area of the waveguide cavity.
10. A radar level gauge, characterized in that, The system includes a housing, a feed source, and a radar antenna as described in any one of claims 1 to 9, wherein the feed source and the radar antenna are both disposed within the housing, and the feed source is connected to the waveguide structure (110) of the radar antenna.