A UWB radar antenna

Abstract

This application discloses a UWB radar antenna, including a radiating layer, a feed layer, a dielectric substrate, a ground layer, two feed probes, and multiple ground probes. The radiating layer and feed layer are respectively disposed on the top and bottom surfaces of the dielectric substrate, and the ground layer is built-in. The radiating layer contains two spaced radiating elements, and the feed layer contains an insulated ground section and a signal section. Each radiating element has a chamfered structure at both ends of the same diagonal, and has an arc-shaped first slot centered on the geometric center, four second slots distributed around the first slot along the four directions extending from the two diagonals, and four third slots extending inward from the four sides and distributed along the two orthogonal central axes. The signal section includes a signal input line and first and second transmission lines electrically connected to it, which together form a 1-to-2 power divider feed network for outputting two equal-amplitude and in-phase signals. The two feed probes pass through the dielectric substrate and are insulated from the ground layer, with their ends respectively connected to the two transmission lines and the two radiating elements; each ground probe passes through the dielectric substrate and conducts between the ground section and the ground layer.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to a narrow-beam circularly polarized UWB radar antenna. Background Technology

[0002] Ultra-wideband (UWB) radar detects targets by transmitting and receiving narrow pulses. It has a wide operating bandwidth, high range resolution, and good penetration capability under certain conditions. Unlike UWB ranging methods that require two devices to exchange signals, UWB radar can transmit detection signals through a single device and obtain the target's range, velocity, and position information based on the signals reflected from the target.

[0003] The wide bandwidth and high resolution of UWB radar enable it to operate effectively in both line-of-sight and non-line-of-sight environments, while its strong penetration capability allows it to maintain high detection accuracy in complex environments. Therefore, UWB radar antennas can be applied to smart wearable devices, smart homes, vehicle occupant detection (especially child presence detection, CPD), and vital sign monitoring, among other fields.

[0004] Existing UWB radar antennas typically employ a single radiating element, and are mostly linearly polarized antennas. The beam formed by a single radiating element is usually wide, the antenna's directivity and gain are relatively limited, and the radiated energy is distributed over a large spatial angular range, making it difficult to concentrate the radiated energy onto a predetermined target detection area. At the same transmit power, the effective detection range of UWB radars equipped with this type of antenna is limited. When multiple adjacent targets exist within the detection area, the wide beam can easily cover multiple targets simultaneously, making it difficult for UWB radars equipped with this type of antenna to effectively distinguish between nearby targets.

[0005] Furthermore, the receiving performance of linearly polarized UWB radar antennas is easily affected by the relative attitude between the antenna and the target, the target's reflection direction, and the complex surrounding environment. When the polarization direction of the target's reflected signal does not match the polarization direction of this type of UWB radar antenna, polarization mismatch loss is likely to occur, leading to a reduction in the received signal strength and consequently affecting the detection accuracy of UWB radar equipped with this type of UWB radar antenna. Especially in applications such as vehicle-mounted radar, vehicle occupant detection, and vital sign monitoring, the target attitude and reflection environment may be constantly changing, easily affecting the receiving stability and environmental adaptability of linearly polarized UWB radar antennas, making it difficult to meet the requirements for stable detection.

[0006] To reduce the antenna beam, multiple radiating elements can be used to form an antenna array. However, each radiating element in the array needs to receive a feed signal with matching amplitude and phase. If there is a deviation in the amplitude or phase of the feed between different radiating elements, it can easily cause beam shift, beam broadening, or pattern distortion, making it difficult to obtain a stable narrow beam.

[0007] Meanwhile, existing UWB radar antennas used in UWB radar also need to balance resonant characteristics, impedance matching, operating bandwidth, and polarization performance within a limited size. Existing radiating elements typically use relatively simple radiating patches, which have limited ability to adjust the local current path and resonant mode of the radiating element, making it difficult to adjust the antenna's resonant frequency, impedance matching, operating bandwidth, and circular polarization performance separately through different structural parameters.

[0008] Therefore, it is necessary to provide a UWB radar antenna for UWB radar to improve the problems of existing single-radiating element antennas, such as wide beamwidth, relatively low gain, dispersed radiated energy, and short detection range. This would reduce the impact of target attitude and surrounding environment changes on antenna reception performance, improve the amplitude and phase consistency of feed signals among multiple radiating elements, and enable the UWB radar antenna to balance resonant characteristics, impedance matching, operating bandwidth, and circular polarization performance within a limited size. This would improve the UWB radar antenna's ability to distinguish nearby targets, its environmental adaptability, and its detection accuracy. Summary of the Invention

[0009] The UWB radar antenna provided by this invention aims to solve at least some of the defects of existing UWB radar antennas.

[0010] This invention provides a UWB radar antenna. The UWB radar antenna includes: Radiation layer, feed layer, dielectric substrate, ground layer, two feed probes and multiple ground probes; The radiating layer and the feeding layer are respectively disposed on the top and bottom surfaces of the dielectric substrate opposite to each other in the thickness direction, and the grounding layer is disposed inside the dielectric substrate; The radiation layer includes two radiation units spaced apart, and the feed layer includes a grounding part and a signal part, wherein the signal part is insulated from the grounding part. The radiating unit has a chamfered structure at each end of one of its diagonal directions, and the radiating unit also has a first slit, four second slits and four third slits; The first gap is an arc centered on the geometric center of the radiating unit. The four second gaps are spaced around the first gap and are located in the four extending directions of the two diagonals of the radiating unit. The four third gaps extend inward from the four sides of the radiating unit and are distributed along the two mutually perpendicular central axes of the radiating unit. The signal unit includes a signal input line, a first transmission line, and a second transmission line, wherein the signal input line is electrically connected to one end of the first transmission line and the second transmission line, respectively. The signal input line, the first transmission line, and the second transmission line together constitute a 1-to-2 power divider network. The two signals output from the 1-to-2 power divider network via the first transmission line and the second transmission line are of equal amplitude and in phase. Both feed probes pass through the dielectric plate and are insulated from the ground layer. One end of each feed probe is electrically connected to the other end of the first transmission line and the second transmission line, respectively. The other end of each feed probe is electrically connected to the two radiating units one by one. Multiple grounding probes pass through the dielectric plate, and the two ends of each grounding probe are respectively connected to the grounding part and the grounding layer.

[0011] In some embodiments, the two radiating elements have a predetermined distance in the direction of the line connecting their geometric centers, the distance being 0.4λ to 0.8λ; Wherein, λ is the free space wavelength formed by the UWB radar antenna at the center frequency of its operating frequency band.

[0012] In some embodiments, the four sides of the radiating unit are respectively located on the straight lines of the four sides of the same square, and the two chamfered structures are respectively located at the two corners along one diagonal of the square. The projections of the two chamfered structures on the dielectric substrate are both hypotenuses of isosceles right triangles.

[0013] In some embodiments, the side length of the square is a preset first length dimension, and the right-angled side length of the isosceles right triangle is a preset second length dimension; Wherein, the second length dimension is smaller than the first length dimension.

[0014] In some embodiments, the first gap has a preset radius, arc length, and arc-shaped gap width; The first gap has openings spaced apart at both ends.

[0015] In some embodiments, the second gap includes: First seam segment, second seam segment, and third seam segment; The first seam segment and the second seam segment are respectively connected to the two opposite ends of the third seam segment in its length direction, and the first seam segment and the second seam segment are respectively parallel to two mutually orthogonal sides of the square; The third seam segment has a center line that extends along its width direction and bisects the third seam segment equally along its length direction, the center line coinciding with a corresponding diagonal line in the square.

[0016] In some embodiments, the first seam segment has a first gap width in its width direction, the second seam segment has a second gap width in its width direction, and the third seam segment has a third gap width in its width direction; The first seam segment has a first gap length in its length direction, the second seam segment has a second gap length in its length direction, and the third seam segment has a third gap length in its length direction; Wherein, the width of the first gap, the width of the second gap, and the width of the third gap are equal, and the length of the first gap and the length of the second gap are equal.

[0017] In some embodiments, the third gap has a fourth gap length in its length direction and a fourth gap width in its width direction; The third slit has a notch at one end along its length, and the notch is located on the side corresponding to the radiating unit.

[0018] In some embodiments, the first transmission line and the second transmission line have the same shape and size; The signal input line has a signal input terminal, the first transmission line has a first output terminal, and the second transmission line has a second output terminal; The end of the signal input line away from the signal input terminal is electrically connected to the end of the first transmission line away from the first output terminal and the end of the second transmission line away from the second output terminal, respectively.

[0019] In some embodiments, a feed point is provided at the geometric center of the radiating element; One end of each of the two feed probes is electrically connected to the first output terminal and the second output terminal, respectively, and the other end of each of the two feed probes is electrically connected to the feed points of the two radiation units in a one-to-one correspondence.

[0020] Unlike existing technologies, at least one beneficial effect of the UWB radar antenna provided in this embodiment of the invention is that, through the combination of dual radiating elements, an equal-amplitude and in-phase one-to-two power divider feed network, a chamfered structure set along a diagonal of the radiating element, multiple sets of slot structures composed of a first slot, a second slot, and a third slot, and a stacked feed and grounding structure, the UWB radar antenna can obtain a relatively stable narrow beam and circular polarization radiation characteristics, making the radiated energy more concentrated, reducing the polarization mismatch caused by target attitude and complex reflection environment, and taking into account the antenna's resonance characteristics, impedance matching, and operating bandwidth, thereby improving the detection range, nearby target discrimination capability, anti-interference capability, and detection accuracy of the UWB radar antenna. Attached Figure Description

[0021] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0022] Figure 1 This is a schematic diagram of the structure of the UWB radar antenna provided in an embodiment of the present invention; Figure 2 This is an exploded view of the UWB radar antenna provided in an embodiment of the present invention; Figure 3 This is a top view schematic diagram of the UWB radar antenna provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of the grounding layer and grounding probe provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the feeding layer structure provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of the radiating unit provided in an embodiment of the present invention; Figure 7 This is a schematic diagram (a) showing the dimensions of the radiating element provided in an embodiment of the present invention. Figure 8 This is a schematic diagram (II) showing the dimensions of the radiating element provided in an embodiment of the present invention. Figure 9 This is a schematic diagram (III) showing the dimensions of the radiating element provided in an embodiment of the present invention; Figure 10 This is a schematic diagram of the signal unit provided in an embodiment of the present invention; Figure 11 This is an S-parameter diagram of the UWB radar antenna provided in an embodiment of the present invention; Figure 12 This is an efficiency diagram of the UWB radar antenna provided in an embodiment of the present invention; Figure 13 This is the aspect ratio diagram of the UWB radar antenna provided in this embodiment of the invention at the 8 GHz frequency point; Figure 14 This is the radiation pattern of the UWB radar antenna provided in the embodiment of the present invention in the principal plane at phi=0°; Figure 15 This is the radiation pattern of the UWB radar antenna provided in the embodiment of the present invention in the principal plane with phi=90°.

[0023] Figure label: 100. UWB radar antenna; 10. Radiation unit; 11. First slot; 12. Second slot; 13. Third slot; 101. Chamfered structure; 102. Feed point; 111. Opening; 121. First slot segment; 122. Second slot segment; 123. Third slot segment; 131. Notch; 20. Feed layer; 21. Grounding section; 22. Signal section; 221. Signal input line; 222. First transmission line; 223. Second transmission line; 2211. Signal input terminal; 2221. First output terminal; 2231. Second output terminal; 30. Dielectric substrate; 31. First metal layer; 32. Second metal layer; 40. Grounding layer; 50. Feed probe; 60. Grounding probe; S, distance; L1, first length dimension; L2, second length dimension; L3, first gap length; L4, second gap length; L5, third gap length; L6, fourth gap length; R, radius dimension; AL, arc length dimension; W1, arc gap width; W2, first gap width; W3, second gap width; W4, third gap width; W5, fourth gap width. Detailed Implementation

[0024] The present invention will now be described in detail with reference to specific embodiments. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope and application of the present invention.

[0025] It should be noted that, unless otherwise expressly specified and limited, the terms "perpendicular to each other," "length direction," "thickness direction," "width direction," "top," "bottom," "center," "inner," etc., used in this specification to indicate the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. The terms "installed," "connected," "joined," "fixed," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features; thus, a feature defined as "first," "second," "third," or "fourth" may explicitly or implicitly include one or more of that feature; "a plurality of" or "several" means two or more; and "and / or" includes any and all combinations of one or more of the associated listed items. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0026] The term "geometric center" refers to the central location of the corresponding structural outline or corresponding geometric figure. When the corresponding structural outline or corresponding geometric figure is a square, the geometric center is the intersection of the two diagonals; when the corresponding structural outline or corresponding geometric figure is an arc, the geometric center is the center of the arc. The corresponding structural outline or corresponding geometric figure includes, but is not limited to, radial units with their two corners not cut off and the first arc-shaped gap.

[0027] The term "feed point" refers to the location where the feed probe forms an electrical connection with the corresponding radiating element. It is used to input the radio frequency signal output from the 1-to-2 power divider feed network to the radiating element, or to transmit the radio frequency signal received by the radiating element to the 1-to-2 power divider feed network.

[0028] The term "free space wavelength" refers to the free space propagation wavelength formed by a UWB radar antenna at the center frequency of its operating band. It is mainly used to describe the array spacing between radiating elements and related dimensional parameters.

[0029] The term "equal amplitude and phase" refers to the fact that the two feed signals output from the first and second transmission lines to the two feed probes have essentially the same signal amplitude and a phase difference of essentially zero (theoretically, equal amplitude and phase can be understood as an amplitude ratio of 1:1 and a phase difference of 0°). The terms "essentially the same" or "essentially zero" allow for minor deviations caused by manufacturing errors, material errors, changes in operating frequency, or testing errors, as long as the two radiating elements can form coordinated radiation.

[0030] The term "circular polarization" refers to a polarization mode in which the radiated electric field vector rotates continuously over time, and its trajectory approximates a circle. This includes left-hand circular polarization and right-hand circular polarization. The embodiments in this application do not limit the specific direction of rotation.

[0031] The term "narrow beam" refers to the relatively small half-power beamwidth of the main beam of a UWB radar antenna, which concentrates radiated energy more towards the target, improving directivity and target resolution. The half-power beamwidth refers to the angle between two angular positions on either side of the main beam where the radiated power drops by 3 dB relative to the peak power of the main beam.

[0032] The term "high gain" refers to the high energy concentration capability of a UWB radar antenna in the main radiation direction, which can achieve better directivity and detection range compared to a single radiating element.

[0033] The term "impedance matching" refers to a good matching relationship between the input impedance of a UWB radar antenna and the characteristic impedance of the feeding system, thereby reducing signal reflection and improving the efficiency of radio frequency energy transmission.

[0034] The term "array radiation" refers to the overall radiation pattern formed by multiple radiation elements working together under predetermined amplitude and phase relationships, rather than a simple superposition of the independent radiation effects of multiple radiation elements.

[0035] In the following description, such as Figures 1-10 As shown, the following situation exists: the thickness direction of the dielectric plate 30 is set as the Z direction, the direction of the line connecting the geometric centers of the two radiating units 10 or the length direction of the dielectric plate 30 is set as the Y direction, and the width direction of the dielectric plate 30 is set as the X direction; wherein, the X direction, Y direction and Z direction are orthogonal to each other.

[0036] Please see Figures 1-10 The UWB radar antenna 100 includes: a radiating layer, a feeding layer 20, a dielectric substrate 30, a grounding layer 40, two feeding probes 50, and multiple grounding probes 60.

[0037] The radiation layer and the feed layer 20 are respectively disposed on the top and bottom surfaces of the dielectric substrate 30 in the Z direction, and the ground layer 40 is disposed inside the dielectric substrate 30.

[0038] The radiation layer is a conductive radiation structure, the feed layer 20 is a feed conductor structure, and the ground layer 40 is used to form a stable reference ground plane and improve the feed performance.

[0039] The dielectric substrate 30 can be made of printed circuit board materials suitable for UWB radar antenna manufacturing, such as FR-4 dielectric substrate (dielectric constant of 4.3, tangent loss of 0.025), or other high-frequency dielectric substrates with similar dielectric constant and tangent loss characteristics. In this embodiment, the specific material and thickness of the dielectric substrate 30 are not limited, and those skilled in the art can select them according to the operating frequency band and processing technology.

[0040] The dielectric substrate 30 is composed of a first metal layer 31 and a second metal layer 32. Specifically, the radiating layer is disposed on the side of the first metal layer 31 that is away from the second metal layer 32, the feeding layer 20 is disposed on the side of the second metal layer 32 that is away from the first metal layer 31, and the ground layer 40 is disposed between the first metal layer 31 and the second metal layer 32 (it can also be understood that the radiating layer and the ground layer 40 are separated by the first metal layer 31, and the feeding layer 20 and the ground layer 40 are separated by the second metal layer 32).

[0041] The above structure enables the radiating layer, the feeding layer 20, and the grounding layer 40 to respectively undertake the functions of radiation, feeding, and grounding, thereby reducing the mutual coupling between different functional structures, improving the overall integration of the UWB radar antenna 100, and helping to reduce the overall size of the UWB radar antenna 100.

[0042] The grounding layer 40 is made of metal, the grounding probe 60 is a conductive connection structure made of metal, and the power supply probe 50 is also a conductive connection structure. Both the power supply probe 50 and the grounding probe 60 can be formed by metallized through holes, metal pillars, conductive pins or other conductive connectors with the same function.

[0043] The radiation layer includes two radiation units 10 spaced apart, and the power supply layer 20 includes a grounding part 21 and a signal part 22, with the signal part 22 being insulated from the grounding part 21.

[0044] The feed layer 20 mainly undertakes functions such as radio frequency signal transmission, power distribution and impedance transition, and does not directly undertake the main electromagnetic radiation function.

[0045] The signal unit 22 is mainly used to form a one-to-two power divider feed network for the UWB radar antenna 100.

[0046] The grounding part 21 is used to form a grounding reference plane of the feed layer 20 and together with the grounding layer 40 forms a ground.

[0047] Insulation isolation refers to the absence of direct conductive connections between conductive structures, which are isolated by a dielectric substrate 30 or a reserved insulating gap, thereby enabling high-frequency signals to be transmitted along a predetermined path without being directly discharged to the grounding structure.

[0048] Specifically, the grounding part 21 forms a large-area grounding region of the feed layer 20, which can provide a stable reference ground potential for the feed network and together with the grounding layer 40 described later, constitute the grounding system of the UWB radar antenna 100; the signal part 22 forms the radio frequency feed network of the UWB radar antenna 100, which receives high-frequency signals output from the radar radio frequency front-end module and evenly distributes one input signal to the two radiating elements 10.

[0049] In this embodiment of the application, two radiating elements 10 are arranged along the line connecting their geometric centers to form a dual-radiating element array structure; specifically, the two radiating elements 10 together constitute the array radiation structure of the UWB radar antenna 100.

[0050] The two radiating units 10 are used to generate ultra-wideband electromagnetic radiation, and obtain feed signals of equal amplitude and phase through the power divider network described later, thereby jointly completing the transmission and reception of UWB radar signals.

[0051] It should be noted that the radiation unit 10 refers to a conductor radiation structure that can convert the high-frequency signal output by the one-to-two power divider feed network into free-space electromagnetic waves, or convert electromagnetic waves in free space into high-frequency electrical signals; wherein, each radiation unit 10 can independently complete electromagnetic radiation, and can form an array radiation effect when multiple radiation units work together.

[0052] The radiating unit 10 has a chamfered structure 101 at each end of one of its diagonal directions. The radiating unit 10 also has a first slit 11, four second slits 12 and four third slits 13.

[0053] The first slit 11 is an arc centered on the geometric center of the radiating unit 10. The four second slits 12 are spaced around the first slit 11 and are located in the four extension directions of the two diagonals of the radiating unit 10. The four third slits 13 extend inward from the four sides of the radiating unit 10 and are distributed along the two mutually perpendicular central axes of the radiating unit 10.

[0054] The first slot 11, the second slot 12 and the third slot 13 are all slotted structures formed on the radiating unit 10. Their specific size, shape and position can be optimized and adjusted according to the operating frequency band of the UWB radar antenna 100 to achieve technical effects such as improving current distribution, adjusting resonance mode, optimizing impedance matching, widening operating bandwidth and improving circular polarization performance, and are not limited to the specific structural forms shown in the embodiments of this application.

[0055] Therefore, the aforementioned multiple chamfered structures and multiple sets of slot structures together constitute the current adjustment structure of the radiating element 10, so as to adjust the surface current distribution, resonance mode and polarization characteristics of the radiating element 10, thereby improving the antenna's operating bandwidth, impedance matching and circular polarization performance.

[0056] The signal unit 22 includes a signal input line 221, a first transmission line 222, and a second transmission line 223. The signal input line 221 is electrically connected to one end of the first transmission line 222 and the second transmission line 223, respectively.

[0057] Signal input line 221, first transmission line 222 and second transmission line 223 together constitute a one-to-two power distribution network. The two signals output by the one-to-two power distribution network through the first transmission line 222 and the second transmission line 223 are of equal amplitude and in phase.

[0058] The first transmission line 222 and the second transmission line 223 both extend along the Y direction, and the signal input line 221 extends along the X direction. Therefore, the one-to-two power-dividing feeder network is T-shaped.

[0059] A 1-to-2 power divider network is a power divider network that can divide one input signal into two output signals. The 1-to-2 power divider network can not only complete the power distribution, but also maintain the predetermined amplitude and phase relationship between the two output signals.

[0060] Equal amplitude and phase feeding can ensure that the two radiating elements 10 obtain consistent excitation conditions, enabling the two radiating elements 10 to form stable cooperative radiation, improving array directivity and reducing beam spread.

[0061] Both feed probes 50 pass through the dielectric plate 30 and are insulated from the ground layer 40. One end of each feed probe 50 is electrically connected to the other end of the first transmission line 222 and the second transmission line 223, respectively. The other end of each feed probe 50 is electrically connected to the two radiating units 10 in a one-to-one correspondence.

[0062] Specifically, when the feed probe 50 passes through the ground layer 40, it remains insulated from the ground layer 40 to prevent the feed signal from being directly coupled to the ground layer 40, thus ensuring that the feed signal can be stably transmitted to the corresponding radiating unit 10.

[0063] Multiple grounding probes 60 pass through the dielectric plate 30, and the two ends of each grounding probe 60 are electrically connected to the grounding part 21 and the grounding layer 40, respectively.

[0064] In this embodiment, multiple grounding probes 60 can be distributed around the 1-to-2 power distribution feeder network and near the radiation unit 10 to form multiple grounding points, improve grounding continuity, reduce parasitic radiation, and help improve the electromagnetic shielding performance and overall radiation performance of the 1-to-2 power distribution feeder network.

[0065] It should be noted that the UWB radar antenna 100 has two radiating elements 10 arranged at intervals in the radiating layer, and uses the signal input line 221, the first transmission line 222 and the second transmission line 223 to form a one-to-two power-dividing feed network to output equal amplitude and in-phase feed signals to the two radiating elements 10 respectively; the two feed probes 50 transmit the above two feed signals to the two radiating elements 10 one-to-one, so that the two radiating elements 10 can radiate in coordination with matching amplitude and phase, which is beneficial to make the radiation fields of the two radiating elements 10 superimpose in phase in the predetermined radiation direction, thereby reducing the antenna beam, improving the antenna directivity and gain, and making the radiated energy more concentrated in the target detection area.

[0066] Specifically, the equal amplitude and phase feeding method can reduce beam offset, beam broadening and radiation pattern distortion caused by deviations in the feeding amplitude or feeding phase between two radiating elements, enabling the UWB radar antenna 100 to form a more stable narrow beam, thereby improving the effective detection range of the UWB radar antenna 100 used for UWB radar and its ability to distinguish nearby targets.

[0067] Understandably, the UWB radar antenna 100 has chamfered structures 101 at both ends of a diagonal direction in each radiating element 10. By changing the surface current distribution and resonant mode in the radiating element 10 through the chamfered structures 101, it is beneficial to form circularly polarized radiation in the radiating element 10. Compared with linearly polarized antennas, circularly polarized UWB radar antennas are less sensitive to changes in target attitude and polarization direction of target reflected signals. This can reduce the polarization mismatch loss between the target reflected signal and the UWB radar antenna 100, thereby improving the receiving stability, environmental adaptability and anti-interference capability of the UWB radar antenna 100. It is especially suitable for application scenarios such as vehicle occupant detection, child presence detection and vital sign monitoring where the target attitude and reflection environment are prone to change.

[0068] To further explain, the UWB radar antenna 100 has multiple slot structures on each radiating element 10, consisting of a first slot 11, four second slots 12, and four third slots 13. The arc-shaped first slot 11 is located in the central region of the radiating element 10. By adjusting the current path formed by the first slot, the equivalent electrical length and input impedance of the radiating element can be changed, which is beneficial for adjusting the antenna's resonance characteristics and standing wave performance. The four second slots 12 are respectively arranged along the four extending directions of the two diagonals of the radiating element, and the four third slots 13 extend inward from the four sides of the radiating element 10 and are distributed along two mutually perpendicular central axes. The multiple slot structures adjust the surface current path and resonance mode of the radiating element 10 in different directions, which is beneficial for expanding the antenna's operating bandwidth. The first slot 11, second slots 12, and third slots 13 cooperate with the chamfered structure 101, enabling the UWB radar antenna 100 to balance resonance characteristics, impedance matching, operating bandwidth, and circular polarization performance within a limited size within the operating frequency band.

[0069] Specifically, the UWB radar antenna 100 has a radiating layer and a feeding layer 20 respectively disposed on the top and bottom surfaces of the dielectric substrate 30, and a ground layer 40 disposed inside the dielectric substrate 30. This allows the radiating layer, feeding layer 20, and ground layer 40 to form a stacked structure, which helps to reduce the planar space occupied by the UWB radar antenna 100 and makes the overall structure of the UWB radar antenna 100 more compact. The two feeding probes 50 are kept insulated from the ground layer 40 during their passage through the dielectric substrate 30, which can prevent the feeding signal from being directly connected to the ground layer 40, and transmit the signals output from the first transmission line 222 and the second transmission line 223 to the corresponding radiating elements 10 respectively.

[0070] Meanwhile, multiple grounding probes 60 respectively connect the grounding portion 21 of the feed layer 20 to the grounding layer 40 inside the dielectric substrate 30, thereby forming multiple grounding connection paths between the feed layer 20 and the grounding layer 40, which is beneficial to maintaining the grounding continuity and feed stability of the feed network. The grounding layer 40, the grounding probes 60 and the feed layer 20 cooperate to form a coplanar grounding waveguide feed structure, which can provide reliable signal transmission and grounding conditions for the one-to-two power-dividing feed network, thereby ensuring that the two radiating units 10 obtain stable equal-amplitude and in-phase feed signals. The above-mentioned stacked structure and probe connection method also facilitate the integration of the radiation, power-dividing feed and grounding of the UWB radar antenna 100 on the same dielectric substrate 30, so that the UWB radar antenna 100 has the advantages of compact structure, high integration and easy manufacturing and installation.

[0071] In some embodiments, such as Figures 1-10 As shown, the two radiating elements 10 have a preset distance S in the Y direction, and the distance S is 0.4λ to 0.8λ.

[0072] It should be noted that λ is the free space wavelength formed by the UWB radar antenna 100 at the center frequency of its operating frequency band.

[0073] In this embodiment of the application, the UWB radar antenna 100 operates in the CH9 band (7.75 GHz to 8.25 GHz), and therefore the center frequency of the operating band is 8 GHz.

[0074] Specifically, λ = c / f, where c is the speed of light and f is the center frequency, so λ is approximately 3.75 cm.

[0075] It should be noted that the spacing between the radiating elements 10 affects both the array pattern and the array gain and sidelobe level. Specifically, when the spacing between two radiating elements 10 is too small, strong electromagnetic coupling is easily generated between the two radiating elements, thereby affecting the array directivity and gain. When the spacing between two radiating elements 10 is too large, large grating lobes or sidelobes are easily generated, which is not conducive to forming a stable narrow beam. Therefore, in this embodiment, the distance S is set in the range of 0.4λ to 0.8λ, so that the UWB radar antenna 100 can take into account array gain, directivity and sidelobe suppression capability.

[0076] In some embodiments, such as Figures 1-10 As shown, the four sides of the radiating unit 10 are located on the straight lines of the four sides of the same square, and the two chamfered structures 101 are located at the two corners of one diagonal of the square. The projections of the two chamfered structures 101 on the dielectric substrate 30 are the hypotenuses of isosceles right triangles.

[0077] The aforementioned square refers to the geometric shape that forms the basic outline of the radiating unit 10. It is mainly used to define the overall structural dimensions of the radiating unit 10, and does not mean that the four corners of the radiating unit 10 are all right angles. In other words, after the radiating unit 10 is provided with the chamfered structure 101, the first gap 11, the second gap 12 and the third gap 13, its overall outline can still be considered to be based on the corresponding square.

[0078] Therefore, the shape of the radiating unit 10 can be understood as an irregular shape after cutting two centrally symmetrical isosceles right triangles (i.e., cutting off a set of vertical angles) from a square. The chamfered structure 101 is the two oblique cut surfaces on the radiating unit 10.

[0079] In some embodiments, such as Figures 1-10 As shown, the side length of the square is a preset first length dimension L1, and the right-angled side length of the isosceles right triangle is a preset second length dimension L2.

[0080] The first length dimension L1 corresponds to the basic size of the radiating element 10. The size of the radiating plate can be adjusted by adjusting the first length dimension L1 to adjust the resonant frequency of the operating frequency band.

[0081] In other words, the first length dimension L1 can be determined according to the operating frequency band of the UWB radar antenna 100 so that the radiating element 10 can resonate near the target frequency.

[0082] The second length dimension L2 is smaller than the first length dimension L1.

[0083] It should be noted that when the second length dimension L2 is small, the frequency interval between the two orthogonal modes is small; as the second length dimension L2 gradually increases, the frequency relationship between the two orthogonal modes changes, thereby obtaining better circular polarization characteristics; therefore, in this embodiment of the application, by setting two chamfered structures 101 distributed along the same diagonal, the radiation unit 10 can form two orthogonal radiation modes with similar amplitudes and a phase difference of about ninety degrees, thereby achieving circular polarization radiation.

[0084] Therefore, by changing the second length dimension L2, the surface current distribution near the edge of the radiating element 10 can be changed, thereby adjusting the resonant mode and polarization characteristics of the radiating element 10.

[0085] In some embodiments, such as Figures 1-10 As shown, the first gap 11 has a preset radius dimension R, arc length dimension AL, and arc-shaped gap width W1.

[0086] The first gap 11 has openings 111 spaced apart at both ends.

[0087] Opening 111 refers to the gap area formed by the unconnected ends of the first arc-shaped slit 11; by setting opening 111, the formation of a closed conductive loop can be avoided, thereby facilitating the adjustment of the current bypass path on the internal surface of the radiation unit 10.

[0088] The radius R mainly determines the position of the first slot 11 from the geometric center of the radiating unit 10; the arc length AL determines the current winding length corresponding to the first slot 11; the arc width W1 affects the local impedance and current distribution. Therefore, according to the operating frequency band, the first slot 11 can obtain the required resonance adjustment capability by adjusting the radius R, the arc length AL and the arc width W1.

[0089] In some embodiments, such as Figures 1-10 As shown, the second gap 12 includes: a first gap segment 121, a second gap segment 122 and a third gap segment 123.

[0090] The first seam segment 121 and the second seam segment 122 are respectively connected to the two opposite ends of the third seam segment 123 in its length direction. The first seam segment 121 and the second seam segment 122 are respectively parallel to two mutually orthogonal sides of the square.

[0091] The third seam segment 123 has a center line that extends along its width direction and bisects the third seam segment 123 equally along its length direction, and the center line coincides with a corresponding diagonal line in the square.

[0092] The above-mentioned symmetrical structure helps to ensure that the four second gaps 12 produce a basically consistent adjustment effect on the surface current in different directions of the radiation unit 10, thereby improving the overall current distribution symmetry of the radiation unit 10.

[0093] Understandably, the second slit 12 can not only increase the length of the local current path, but also change the local current distribution in different directions, so that the radiating element 10 can form multiple mutually coupled resonant modes, which is beneficial to broadening the operating bandwidth of the UWB radar antenna 100.

[0094] In some embodiments, such as Figures 1-10 As shown, the first seam segment 121 has a first gap width W2 in its width direction, the second seam segment 122 has a second gap width W3 in its width direction, and the third seam segment 123 has a third gap width W4 in its width direction.

[0095] The first seam segment 121 has a first seam length L3 in its length direction, the second seam segment 122 has a second seam length L4 in its length direction, and the third seam segment 123 has a third seam length L5 in its length direction.

[0096] Among them, the widths of the first gap W2, the second gap W3, and the third gap W4 are equal, and the lengths of the first gap L3 and the second gap L4 are equal.

[0097] In some embodiments, such as Figures 1-10 As shown, the third gap 13 has a fourth gap length L6 in its length direction and a fourth gap width W5 in its width direction.

[0098] The third slit 13 has a notch 131 at one end in the length direction, and the notch 131 is located on the side corresponding to the radiation unit 10.

[0099] The notch 131 refers to the opening area formed by the connection between the third slit 13 and the edge of the radiating unit 10. By setting the notch 131, the third slit 13 can be directly connected to the edge of the radiating unit 10, thereby further changing the surface current path of the edge area and increasing the degree of participation of the edge area in resonance.

[0100] The third slit 13 and the second slit 12 work together to further improve the current distribution in different directions of the radiating element 10 and increase the coupling between multiple resonant modes, which is beneficial to further broaden the operating bandwidth and optimize impedance matching performance.

[0101] In summary, the UWB radar antenna 100, by setting a chamfered structure 101, a first slot 11, a second slot 12, and a third slot 13 on the radiating element 10, allows each structure to act on the surface current distribution and resonant mode in different regions of the radiating element 10. Specifically, the chamfered structure 101 is mainly used to improve circular polarization performance; the first slot 11 is mainly used to adjust the resonant characteristics of the central region of the radiating element 10; the second slot 12 is mainly used to adjust the current path in the diagonal direction and broaden the operating bandwidth; and the third slot 13 is mainly used to adjust the current distribution in the edge region and further optimize impedance matching and broadband performance. The two chamfered structures 101, in conjunction with multiple slot structures, enable the radiating element 10 to balance resonant characteristics, impedance matching, operating bandwidth, and circular polarization performance within a limited size, providing a good radiation foundation for the UWB radar antenna 100 to form narrow beams, high gain, and stable circular polarization radiation.

[0102] In some embodiments, such as Figures 1-10 As shown, the power distribution network in this embodiment adopts a symmetrical structure design. The first transmission line 222 and the second transmission line 223 have the same shape and size (including but not limited to the same structural shape, the same line length and the same conductor width). The first transmission line 222 and the second transmission line 223 are symmetrically arranged about the center line of the signal input line 221 to ensure that the two radiating units 10 have basically the same electrical length, characteristic impedance, resonant frequency and radiation characteristics, which is conducive to obtaining better array consistency.

[0103] It should be noted that when the two output transmission paths have the same electrical length, the propagation time of the high-frequency signal on the two transmission paths is basically the same, thus ensuring that the two output terminals obtain basically the same signal phase. At the same time, by reasonably designing the connection relationship between the signal input line 221 and the first transmission line 222 and the second transmission line 223, the input power can be evenly distributed to the two output branches, thereby obtaining basically the same output amplitude. Therefore, the one-to-two power divider feeder network in this embodiment can output two feeder signals with equal amplitude and in phase.

[0104] The signal input line 221 has a signal input terminal 2211, the first transmission line 222 has a first output terminal 2221, and the second transmission line 223 has a second output terminal 2231.

[0105] The signal input terminal 2211 is used to connect to the radar radio frequency module, and the first output terminal 2221 and the second output terminal 2231 are respectively connected to the corresponding feed probe 50.

[0106] The end of the signal input line 221 away from the signal input terminal 2211 is electrically connected to the end of the first transmission line 222 away from the first output terminal 2221 and the end of the second transmission line 223 away from the second output terminal 2231, so that the entire power supply network forms a left-right symmetrical one-to-two branch structure.

[0107] It is understandable that the left-right symmetrical one-to-two branch structure not only helps to improve the amplitude and phase consistency between the two feed signals, but also reduces the additional phase error caused by the asymmetry of the feed network.

[0108] In some embodiments, such as Figures 1-10 As shown, a feed point 102 is provided at the geometric center of the radiating unit 10.

[0109] One end of each of the two feed probes 50 is electrically connected to the first output terminal 2221 and the second output terminal 2231, respectively, and the other end of each of the two feed probes 50 is electrically connected to the feed points 102 of the two radiation units 10 in a one-to-one correspondence.

[0110] Both feed probes 50 are insulated from the ground layer 40 when passing through the dielectric substrate 30; that is, the feed probes 50 do not make conductive connections with the ground layer 40 when passing through its location. Preferably, the ground layer 40 forms a clearance hole or insulating gap corresponding to the position of the feed probes 50, so that the feed probes 50 can pass through the ground layer 40 while maintaining electrical insulation. Therefore, this design can prevent the feed signal from being directly discharged to the ground layer 40, improve the feed efficiency, and ensure that the radio frequency signal can be completely transmitted to the radiating unit 10.

[0111] The radio frequency signal output from the first output terminal 2221 can be directly transmitted to one of the radiation units 10 via the corresponding feed probe 50; the radio frequency signal output from the second output terminal 2231 is transmitted to another radiation unit 10 via another feed probe 50.

[0112] In addition, since the two feed probes 50 correspond to the two radiation elements 10 respectively, the two radiation elements 10 can obtain independent and consistent feed excitation.

[0113] Multiple grounding probes 60 are preferably arranged around the signal section 22 and the power supply probe 50.

[0114] Multiple grounding probes 60 can form multiple conductive connection paths between the grounding part 21 and the grounding layer 40, so that the grounding part 21 and the grounding layer 40 are grounded as a whole.

[0115] It should be noted that, under high-frequency operating conditions, multiple grounding probes 60 can reduce the grounding loop impedance and improve grounding continuity, thereby improving the electromagnetic field distribution near the power supply network. Simultaneously, multiple grounding probes 60 can also suppress the formation of unnecessary parasitic modes by high-frequency signals at the edge of the grounding layer, which is beneficial for improving the stability of the power supply network.

[0116] Furthermore, in the embodiments of this application, the grounding part 21, the grounding layer 40, and the multiple grounding probes 60 together form the feeding environment of the coplanar waveguide (CPW).

[0117] Among them, the signal section 22 serves as the central signal conductor, the grounding section 21 serves as the same-layer reference ground, the internal grounding layer 40 serves as the auxiliary grounding plane, and the multiple grounding probes 60 realize the electrical connection between the two grounding structures.

[0118] In addition, the grounding part 21, the grounding layer 40 and the multiple grounding probes 60 can form a continuous grounding reference surface, so that the signal input line 221, the first transmission line 222 and the second transmission line 223 maintain good impedance continuity during the transmission of high-frequency signals, and reduce the reflection and radiation loss generated by the high-frequency signals during transmission.

[0119] Furthermore, since the radiating layer, the feeding layer 20, and the grounding layer 40 are located on different layers of the dielectric substrate 30, the radiating structure and the feeding network can be spatially separated.

[0120] It is understandable that the 1-to-2 power divider feed network is mainly located on the bottom surface of the dielectric substrate 30, while the radiating element 10 is located on the top surface of the dielectric substrate 30, with a grounding layer 40 set in between for isolation. This can reduce the impact of the 1-to-2 power divider feed network on the radiation characteristics of the radiating element 10 and help improve the overall electromagnetic compatibility performance of the UWB radar antenna 100.

[0121] Thus, the UWB radar antenna, by forming a symmetrical 1-to-2 power divider feed network with signal input line 221, first transmission line 222, and second transmission line 223, enables the two radiating elements 10 to obtain feed signals with equal amplitude and in phase. Two feed probes 50 achieve a vertical feed connection between the feed layer 20 and the radiating layer. Multiple ground probes 60 reliably connect the grounding part 21 to the grounding layer 40, forming a stable grounding system. The aforementioned feed layer 20, 1-to-2 power divider feed network, feed probes 50, and ground probes 60 work together to not only improve the amplitude and phase consistency of the feed signals between the two radiating elements 10, but also improve feed stability, impedance continuity, and high-frequency transmission performance, providing a reliable feed foundation for the UWB radar antenna 100 to form stable narrow beams, high gain, and circularly polarized radiation.

[0122] To help readers understand the concept of this invention, a simulation experiment of the actual UWB radar antenna 100 is presented below.

[0123] In this simulation experiment, please refer to Figure 2 The dielectric substrate 30 is made of FR4 material with a dielectric constant of 4.3 and a tangent loss of 0.025.

[0124] like Figure 11 As shown, the reflection coefficient S11 of the UWB radar antenna 100 in the range of approximately 7.39 GHz to 9.29 GHz is lower than that of other antennas. 10 dB (the frequency range of approximately 7.39 GHz to 9.29 GHz includes the operating frequency band of 7.75 GHz to 8.25 GHz), with an absolute impedance bandwidth of approximately 1.9 GHz and a relative impedance bandwidth of approximately 22.8%.

[0125] The operating frequency band of this embodiment is 7.75 GHz to 8.25 GHz, the center frequency is 8.00 GHz, the absolute impedance bandwidth is 0.50 GHz, and the relative impedance bandwidth is approximately 6.25%.

[0126] The UWB radar antenna 100 forms two main resonant points at approximately 7.75 GHz and 8.72 GHz, respectively, with reflection coefficients S11 of approximately [missing values]. 26.3 dB and 19.7 dB.

[0127] There is a peak between the two main resonant points, with a frequency of approximately 8.25 GHz and a reflection coefficient S11 of approximately 16.3 dB; specifically, the reflection coefficient S11 at this peak is significantly lower than... 10 dB, which indicates that the two adjacent resonant modes can be interconnected, enabling the UWB radar antenna 100 to form a continuous wide impedance band.

[0128] At a frequency of 8.00 GHz, the reflection coefficient S11 is approximately 18.7 dB.

[0129] This demonstrates that the UWB radar antenna 100 exhibits good input impedance matching performance and a certain matching margin in the range of approximately 7.39 GHz to 9.29 GHz and throughout the entire operating frequency band (7.75 GHz to 8.25 GHz).

[0130] like Figure 12 As shown, the efficiency of the UWB radar antenna 100 is in the low-frequency band ( Figure 12 The low-frequency band shown in the image is approximately 6.5 GHz to 7.75 GHz, which increases significantly with increasing frequency.

[0131] like Figure 12 As shown, at approximately 7.39 GHz and 9.29 GHz, the efficiency of the UWB radar antenna 100 is approximately -3.1 dB and -2.31 dB, respectively, which translates to a linearity of approximately 49% to 59%; at approximately 7.75 GHz and 8.72 GHz, the efficiency is approximately -2.16 dB and -1.76 dB, respectively, which translates to a linearity of approximately 60.8% and 67%; at approximately 8.25 GHz, the efficiency is approximately -2.33 dB, which translates to a linearity of approximately 58.5%; and at 8 GHz, the efficiency is approximately -2.45 dB, which translates to a linearity of approximately 56.9%.

[0132] Therefore, it can be seen that within the frequency range of approximately 7.39 GHz to 9.29 GHz, the efficiency of this UWB radar antenna 100 remains basically maintained at approximately 3.1 dB to Between 1.76 dB, which translates to a linearity of approximately 49% to 67%; therefore, the frequency range of approximately 7.39 GHz to 9.29 GHz has a good overlap with the relatively stable efficiency band, indicating that the wideband formed by the UWB radar antenna 100 is not composed of isolated narrow resonant points.

[0133] Specifically, the efficiency within the operating frequency band (7.75 GHz to 8.25 GHz) is -2.45 dB to -2.6 dB, which translates to a linearity of approximately 56.9% to 60.8%, with frequency band fluctuations not exceeding approximately 0.5 dB. This indicates that the UWB radar antenna 100 is generally quite stable within the operating frequency band.

[0134] To further illustrate, there is no significant drop in efficiency within the operating frequency band (7.75 GHz to 8.25 GHz), indicating that not only is the port matching good, but the energy conversion state of the UWB radar antenna 100 remains relatively stable within the operating frequency band.

[0135] like Figure 13 As shown, at the 8 GHz frequency, the axial ratio of the UWB radar antenna 100 near the main radiation direction θ=0° is approximately 0 dB to 0.34 dB (the closer the axial ratio is to 0 dB, the better the circular polarization performance).

[0136] It should be noted that in engineering, a axial ratio of no more than 3 dB is typically used as the criterion for circular polarization. Figure 13 As shown, the UWB radar antenna 100 is approximately It maintains circular polarization characteristics within an angular range of 43.4° to +41.2°, corresponding to a 3 dB axial ratio angular width of approximately 84.6°.

[0137] like Figure 14 As shown, at the 8 GHz frequency, the peak value of the UWB radar antenna 100 in the main plane with phi=0° appears at θ=0°, which indicates that the main beam of the UWB radar antenna 100 in the main plane with phi=0° points in the direction of θ=0°.

[0138] like Figure 14 As shown, in the principal plane where phi=0°, the θ values ​​corresponding to the 3dB drop in peak value are approximately -50° and +48.4°, respectively; therefore, the half-power beamwidth of the principal plane where phi=0° is approximately 98.4°.

[0139] Therefore, the UWB radar antenna 100 forms a wide-angle main beam in the main plane with phi=0°, and the half-power beamwidth is about 98.4°, which has a wide angular coverage range.

[0140] like Figure 15 As shown, at the 8 GHz frequency, the peak value of the UWB radar antenna 100 in the main plane with phi=90° also appears at θ=0°, which indicates that the main beam of the UWB radar antenna 100 in the main plane with phi=90° also points in the direction of θ=0°.

[0141] like Figure 15 As shown, in the principal plane with phi=90°, the θ corresponding to the 3dB drop in peak value is approximately -28° and +27°, respectively; therefore, the half-power beamwidth of the principal plane with phi=90° is approximately 55°.

[0142] It can be seen that the main beam of the main plane with phi=90° is significantly narrower than that of the main plane with phi=0°. This indicates that under the equal amplitude and phase feeding, the two radiating elements 10 form beam compression in the main plane (main plane with phi=90°) corresponding to the array arrangement direction, thereby improving the spatial direction selectivity in the main plane with phi=90°.

[0143] To further clarify, the half-power main beam in the principal plane with phi=90° lies within the range of approximately -28° and +27°, which includes... Figure 7 Approximately Within the 3 dB axial ratio angular range of 43.4° to +41.2°, the UWB radar antenna 100 maintains good circular polarization characteristics within its narrower and more energy-concentrated main beam range (approximately -28° and +27°).

[0144] Specifically, the UWB radar antenna 100 has good spatial directional selectivity in the main plane of phi=90°, which is beneficial for suppressing interference signals from outside the main beam range (approximately -28° and +27°) of the main plane of phi=90°.

[0145] The narrower main beam allows the UWB radar antenna 100 to maintain a high response in the main radiation direction, while exhibiting a lower response to signals deviating from the main beam direction. This helps reduce the received strength of interference signals outside the main beam range. Simultaneously, the axial ratio of the UWB radar antenna 100 near the main radiation direction is no greater than 3 dB, exhibiting good circular polarization characteristics. This helps reduce polarization mismatch caused by target attitude changes and suppresses interference signals that do not match the antenna polarization rotation. Therefore, Figure 15 Spatial selectivity and Figure 7 The polarization selectivity exhibited by the central axis ratio works in combination to improve the anti-interference capability of the UWB radar antenna 100 in complex electromagnetic environments.

[0146] Figures 11 to 15 The results shown indicate that, through the cooperation of two radiating elements 10, chamfered structure 101, first slot 11, second slot 12, third slot 13, and a one-to-two power divider feed network, the embodiments of this application can achieve continuous impedance band, relatively stable antenna efficiency, circular polarization of the main radiation direction, and a narrow radiation beam in the array plane (i.e., in the main plane where phi=90°).

[0147] Specifically, the UWB radar antenna 100 can perform UWB application scenarios such as ranging. The UWB radar antenna 100 can be used for vital sign monitoring, gesture recognition and search and positioning. The UWB radar antenna 100 can be used for automotive CPD radar (CPD, Child Presence Detection) and kick radar.

[0148] It should be noted that foot-operated radar usually refers to a radar sensing system installed on the rear bumper, below the tailgate, or near the sliding door of a car, used to identify the driver's foot movements and trigger the tailgate to open or close automatically. It is also known as foot-operated sensor radar or foot-operated tailgate radar.

[0149] In summary, the UWB radar antenna provided in this embodiment of the invention, through the combination of dual radiating elements, an equal-amplitude and in-phase one-to-two power divider feed network, a chamfered structure set along a diagonal of the radiating element, multiple sets of slot structures composed of a first slot, a second slot, and a third slot, and a stacked feed and grounding structure, can obtain relatively stable narrow beam and circular polarization radiation characteristics, making the radiated energy more concentrated, reducing the influence of polarization mismatch caused by target attitude and complex reflection environment, and taking into account the antenna's resonance characteristics, impedance matching, and operating bandwidth, thereby improving the detection range, nearby target discrimination capability, anti-interference capability, and detection accuracy of the UWB radar antenna.

[0150] The above description, in conjunction with specific / preferred embodiments, provides a further detailed explanation of the present invention, but it should not be construed as limiting the specific implementation of the invention to these descriptions. Those skilled in the art will recognize that various modifications and improvements can be made without departing from the concept of the present invention, and all such modifications and improvements fall within the scope of protection of the present invention.

Claims

1. A UWB radar antenna, characterized in that, include: Radiation layer, feed layer, dielectric substrate, ground layer, two feed probes and multiple ground probes; The radiating layer and the feeding layer are respectively disposed on the top and bottom surfaces of the dielectric substrate opposite to each other in the thickness direction, and the grounding layer is disposed inside the dielectric substrate; The radiation layer includes two radiation units spaced apart, and the feed layer includes a grounding part and a signal part, wherein the signal part is insulated from the grounding part. The radiating unit has a chamfered structure at each end of one of its diagonal directions, and the radiating unit also has a first slit, four second slits and four third slits; The first gap is an arc centered on the geometric center of the radiating unit. The four second gaps are spaced around the first gap and are located in the four extending directions of the two diagonals of the radiating unit. The four third gaps extend inward from the four sides of the radiating unit and are distributed along the two mutually perpendicular central axes of the radiating unit. The signal unit includes a signal input line, a first transmission line, and a second transmission line, wherein the signal input line is electrically connected to one end of the first transmission line and the second transmission line, respectively. The signal input line, the first transmission line, and the second transmission line together constitute a 1-to-2 power divider network. The two signals output from the 1-to-2 power divider network via the first transmission line and the second transmission line are of equal amplitude and in phase. Both feed probes pass through the dielectric plate and are insulated from the ground layer. One end of each feed probe is electrically connected to the other end of the first transmission line and the second transmission line, respectively. The other end of each feed probe is electrically connected to the two radiating units one by one. Multiple grounding probes pass through the dielectric plate, and the two ends of each grounding probe are respectively connected to the grounding part and the grounding layer.

2. The UWB radar antenna according to claim 1, characterized in that, The two radiating elements have a predetermined distance of 0.4λ to 0.8λ in the direction of the line connecting their geometric centers; Wherein, λ is the free space wavelength formed by the UWB radar antenna at the center frequency of its operating frequency band.

3. The UWB radar antenna according to claim 1, characterized in that, The four sides of the radiation unit are located on the straight lines of the four sides of the same square, and the two chamfered structures are located at the two corners of one diagonal of the square. The projections of the two chamfered structures on the dielectric plate are the hypotenuses of isosceles right triangles.

4. The UWB radar antenna according to claim 3, characterized in that, The side length of the square is a preset first length dimension, and the right-angled side length of the isosceles right triangle is a preset second length dimension; Wherein, the second length dimension is smaller than the first length dimension.

5. The UWB radar antenna according to claim 1, characterized in that, The first gap has a preset radius, arc length, and arc-shaped gap width; The first gap has openings spaced apart at both ends.

6. The UWB radar antenna according to claim 3, characterized in that, The second gap includes: First seam segment, second seam segment, and third seam segment; The first seam segment and the second seam segment are respectively connected to the two opposite ends of the third seam segment in its length direction, and the first seam segment and the second seam segment are respectively parallel to two mutually orthogonal sides of the square; The third seam segment has a center line that extends along its width direction and bisects the third seam segment equally along its length direction, the center line coinciding with a corresponding diagonal line in the square.

7. The UWB radar antenna according to claim 6, characterized in that, The first seam segment has a first gap width in its width direction, the second seam segment has a second gap width in its width direction, and the third seam segment has a third gap width in its width direction; The first seam segment has a first gap length in its length direction, the second seam segment has a second gap length in its length direction, and the third seam segment has a third gap length in its length direction; Wherein, the width of the first gap, the width of the second gap, and the width of the third gap are equal, and the length of the first gap and the length of the second gap are equal.

8. The UWB radar antenna according to claim 1, characterized in that, The third gap has a fourth gap length in its length direction and a fourth gap width in its width direction; The third slit has a notch at one end along its length, and the notch is located on the side corresponding to the radiating unit.

9. The UWB radar antenna according to claim 1, characterized in that, The first transmission line and the second transmission line have the same shape and size; The signal input line has a signal input terminal, the first transmission line has a first output terminal, and the second transmission line has a second output terminal; The end of the signal input line away from the signal input terminal is electrically connected to the end of the first transmission line away from the first output terminal and the end of the second transmission line away from the second output terminal, respectively.

10. The UWB radar antenna according to claim 9, characterized in that, A feed point is provided at the geometric center of the radiating unit; One end of each of the two feed probes is electrically connected to the first output terminal and the second output terminal, respectively, and the other end of each of the two feed probes is electrically connected to the feed points of the two radiation units in a one-to-one correspondence.

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