Vehicle-mounted millimeter wave radar antenna, vehicle-mounted millimeter wave radar and vehicle

Abstract

This invention provides a vehicle-mounted millimeter-wave radar antenna, a vehicle-mounted millimeter-wave radar, and a vehicle, belonging to the field of vehicle-mounted vital sign detection. The vehicle-mounted millimeter-wave radar antenna includes a dielectric substrate and a transmitting array, a receiving array, and a radar chip pad area disposed thereon. The transmitting / receiving array includes multiple transmitting / receiving units, each unit including a patch and a feed line. The feed lines are independent and do not intersect each other, and the patches have slots. Multiple transmitting patches are arranged in parallel along a first side adjacent to the dielectric substrate and close to that side; multiple receiving patches are arranged in parallel along a second side adjacent to the dielectric substrate and close to that side; the first and second sides are perpendicular. The radar chip pad area is located in a region away from the first and second sides of the dielectric substrate. This invention spatially reduces unit mutual coupling, achieving extreme miniaturization of the antenna and expanding the operating bandwidth.

Description

Technical Field

[0001] This invention generally relates to the field of vehicle-mounted vital sign detection, and more specifically, to a vehicle-mounted millimeter-wave radar antenna, a vehicle-mounted millimeter-wave radar, and a vehicle. Background Technology

[0002] With the development of automotive technology, vehicle safety issues, especially in-vehicle vital sign monitoring, are receiving increasing attention. Euro NCAP (European New Car Assessment Programme) and C-NCAP (China New Car Assessment Program) have included child abandonment detection and in-vehicle occupant breathing and heart rate monitoring as important new car safety items. The 60–64 GHz unlicensed ISM (Industrial, Scientific, and Medical) millimeter-wave band has become the mainstream solution for in-vehicle cockpit radar due to its good privacy, ability to penetrate obstructions, low power consumption, and high accuracy in detecting minute movements.

[0003] Currently, 60 GHz vehicle-mounted vital signs radar antennas mainly include the following solutions:

[0004] (1) Traditional microstrip fed patch arrays, such as patent document CN110098468A, use microstrip lines for series / parallel feeding, and the array form is 4×4 or 2×2. The transceiver units are all ordinary rectangular patch arrays. This scheme has a microstrip radiation loss of >1.5dB / cm at 60GHz, and the energy utilization rate of the feeding network is low. The operating bandwidth is <2GHz, which cannot fully cover the 60–64GHz ISM band. The horizontal field of view is <±40°, and there are blind spots in the rear seats and foot areas of the vehicle, which cannot fully cover the cabin.

[0005] (2) Metal waveguide slot antenna, for example, see patent documents CN114740430A and CN121307481A, adopts a metal cavity structure and forms a radiation unit by opening a slot in the waveguide wall; the cavity profile is high, making it impossible to integrate it into a single-layer printed circuit board (PCB); the overall volume and weight are relatively large; the mass production cost is much higher than that of the standard PCB solution due to the use of metal milling and assembly processes.

[0006] (3) Single-channel CPW patch antenna, for example, see patent document CN108400439B, is fed by only a single-port coplanar waveguide (CPW), and the array size is a single patch or a binary small array; it cannot build a multi-channel architecture, and the multi-occupant / child multi-target resolution capability is insufficient; the number of elements is small, the beam coverage is narrow, and the detection range inside the vehicle is limited; there is no transmit / receive partition layout, no decoupling structure, the cabin metal reflection brings serious common-mode interference, and the channel isolation is poor.

[0007] (4) Traditional external structure decoupling antenna, for example, see patent document CN116191014A, relies on adding external parasitic metal branches between units to achieve unit decoupling; the decoupling function is achieved by additional auxiliary structures in addition to the patch, and parasitic branches, isolation walls and grounding vias occupy PCB substrate space, which is not conducive to the implementation of small-size arrays.

[0008] Existing technologies generally cannot simultaneously meet the core requirements of cockpit vital sign monitoring, such as compact size, wide frequency band coverage, wide field of view (FOV), high radiation efficiency, and low power consumption. Summary of the Invention

[0009] To address the aforementioned problems in the prior art, in a first aspect, embodiments of the present invention provide a vehicle-mounted millimeter-wave radar antenna. The vehicle-mounted millimeter-wave radar antenna includes a dielectric substrate and a transmitting array, a receiving array, and a radar chip pad area disposed on the dielectric substrate. The transmitting array includes multiple transmitting units, each transmitting unit including a transmitting patch and a transmitting feed line. Each transmitting feed line extends from its corresponding transmitting patch into the radar chip pad area. The transmitting feed lines are independent of each other and do not intersect. The transmitting patch has a slot on the side connecting to the transmitting feed line. The receiving array includes multiple receiving units, each receiving unit including a receiving patch and a receiving feed line. Each receiving feed line extends from its corresponding receiving patch into the radar chip pad area. The receiving feed lines are independent of each other and do not intersect. The receiving patch has a slot on the side connecting to the receiving feed line. Multiple transmitting pads are arranged parallel to the first edge of the dielectric substrate at a location adjacent to the first edge of the dielectric substrate, and close to a first side of the first edge of the dielectric substrate. Multiple receiving pads are arranged parallel to the second edge of the dielectric substrate at a location adjacent to the second edge of the dielectric substrate, and close to a second side of the second edge of the dielectric substrate. The first edge and the second edge of the dielectric substrate are perpendicular, and the first side of the first edge of the dielectric substrate is the side of the first edge of the dielectric substrate that is away from the second edge. The radar chip pad area is located in the region away from the first edge and the second edge of the dielectric substrate.

[0010] In some embodiments, the transmitting patch and the receiving patch are circular patches, and the slots on the transmitting patch include two rectangular slots that are symmetrical about the starting end of the transmitting feed line, and the slots on the receiving patch include two rectangular slots that are symmetrical about the starting end of the receiving feed line.

[0011] In some embodiments, both the transmitting feed and the receiving feed sequentially include a front microstrip line, a transition section, and a coplanar waveguide feed, wherein the starting end of the front microstrip line is connected to a corresponding patch, and the ending end of the coplanar waveguide feed is connected to the interior of the radar chip pad area.

[0012] In some implementations, the front-end microstrip line has a first width, the coplanar waveguide feed line has a second width, the first end of the transition section is connected to the front-end microstrip line and has a first width, the second end of the transition section is connected to the coplanar waveguide feed line and has a second width, and the transition section gradually changes from the first width to the second width between the first end and the second end.

[0013] In some embodiments, the transmitting array includes three transmitting units and the receiving array includes four receiving units.

[0014] In some implementations, the transmit feed line extends through a first side of the radar chip pad area into the radar chip pad area, and the receive feed line extends through a second side of the radar chip pad area into the radar chip pad area, with the first side of the radar chip pad area being perpendicular to the second side of the radar chip pad area.

[0015] In some implementations, the bends in the transmit and receive feeds are impedance continuous.

[0016] In some embodiments, the area between the transmitting array and the receiving array on the dielectric substrate is filled with grounding metal.

[0017] In a second aspect, embodiments of the present invention provide an in-vehicle millimeter-wave radar, the in-vehicle millimeter-wave radar including a radar chip and an in-vehicle millimeter-wave radar antenna as described in any of the above embodiments.

[0018] In a third aspect, embodiments of the present invention provide a vehicle including the vehicle-mounted millimeter-wave radar described in the above embodiments.

[0019] The vehicle-mounted millimeter-wave radar antenna, vehicle-mounted millimeter-wave radar, and vehicle proposed in the above embodiments of the present invention can realize a MIMO partitioned array layout on an extremely small dielectric substrate, overcoming the problem of insufficient miniaturization of existing MIMO antennas. This achieves extreme miniaturization of the antenna, allowing it to be embedded in narrow interior spaces such as the roof console, A / B pillars, and rearview mirror bases, without occupying the overall interior structural space of the vehicle. The physically isolated transmit and receive partitions reduce unit mutual coupling spatially. The embodiments of the present invention feature slots on the transmit and receive patches, which can expand the operating bandwidth. The slots alter the surface current path of the patches, forming dual resonant peaks, widening the bandwidth of the original narrowband micro-pattern to 4 GHz, fully covering the 60~64 GHz ISM band (Industrial, Scientific and Medical Band). Attached Figure Description

[0020] The above and other objects, features, and advantages of embodiments of the present invention will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings by way of example and not limitation, wherein:

[0021] Figure 1 A schematic diagram of an example of a vehicle-mounted millimeter-wave radar antenna according to an embodiment of the present invention is shown;

[0022] Figure 2 A schematic diagram of an example of a radiation patch according to an embodiment of the present invention is shown;

[0023] Figure 3 A simulation diagram of the return loss of the transmitting antenna according to an embodiment of the present invention is shown.

[0024] In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts. Detailed Implementation

[0025] The principles and spirit of the present invention will now be described with reference to several exemplary embodiments. It should be understood that these embodiments are given merely to enable those skilled in the art to better understand and implement the present invention, and are not intended to limit the scope of the present invention in any way.

[0026] In one aspect, embodiments of the present invention provide a vehicle-mounted millimeter-wave radar antenna. (See reference...) Figure 1 The diagram illustrates an example of an automotive millimeter-wave radar antenna according to an embodiment of the present invention. The automotive millimeter-wave radar antenna includes a dielectric substrate 110 and a transmitting array 120, a receiving array 130, and a radar chip pad area 140 disposed on the dielectric substrate.

[0027] As an example only, the dielectric substrate can be a high-frequency Rogers substrate. Substrate parameters could be, for example: dielectric constant εr = 3.48, loss tangent tanδ = 0.0037, total substrate thickness 0.289 mm (dielectric 0.254 mm + double-sided copper foil 0.0175 mm each), and copper foil etching thickness 35 μm.

[0028] The transmitting array comprises multiple transmitting units, each including a transmitting patch and a transmitting feed line. Each transmitting feed line extends from its corresponding transmitting patch into the radar chip pad area, and the transmitting feed lines are independent of each other and do not intersect. The transmitting patch has a slot on the side connecting to the transmitting feed line.

[0029] The receiver array includes multiple receiver units, each receiver unit includes a receiver patch and a receiver feed line. Each receiver feed line extends from the corresponding receiver patch into the radar chip pad area. Each receiver feed line is independent of each other and does not cross. The receiver patch has a slot on the side connected to the receiver feed line.

[0030] The slots on the transmitter and receiver patches can be created using PCB etching processes, for example, by using depth etching control, with a slot width tolerance of ±0.02mm.

[0031] Existing slotless surface mount technology only has a single TM. 11 The resonant mode has only a narrow impedance bandwidth. For example, conventional microstrip fed patch array solutions in the prior art use a patchless slotted design, relying solely on the array spacing to adjust the beam. The array spacing can only adjust the array's synthesized radiation pattern and cannot improve the inherent RF performance of the radiating element itself. The bandwidth of the element itself, the isolation between elements, and the wide-angle radiation performance all have shortcomings. The embodiments of the present invention set slots on the transmitting and receiving patches, which can expand the operating bandwidth. The slots change the current path on the patch surface, forming a dual resonant peak, thus widening the original narrowband micro-patch bandwidth to 4 GHz, fully covering the 60~64 GHz ISM band (Industrial, Scientific and Medical Band).

[0032] In one embodiment of the present invention, the transmitting array may include three transmitting units, and the receiving array may include four receiving units. As an example only, the spacing between the transmitting units may be, for example, 5 mm (λ0), and the spacing between the receiving units may be, for example, 2.5 mm (0.5λ0). As another example, the spacing between the transmitting / receiving units may be finely adjusted between 0.8λ0 and 1.2λ0, or between 0.4λ0 and 0.6λ0. Figure 1As shown, the transmitting array 120 includes a first transmitting unit (Tx1) 121, a second transmitting unit (Tx2) 122, and a third transmitting unit (Tx3) 123, forming three transmitting channels. The receiving array 130 includes a first receiving unit (Rx1) 131, a second receiving unit (Rx2) 132, a third receiving unit (Rx3) 133, and a fourth receiving unit (Rx4) 134, forming four receiving channels.

[0033] like Figure 1 As shown, taking the third transmitting unit (Tx1) 123 as an example, the third transmitting unit 123 includes a transmitting patch 1231 and a transmitting feed line (in Figure 1 The combination of 1232, 1233, and 1234 is shown in the figure. The transmit feed line (the combination of 1232, 1233, and 1234) extends from the corresponding transmit patch 1231 to the interior of the radar chip pad area 140. Figure 1 The three transmit feed lines are independent of each other and do not cross, with independent power supply for each channel, unlike the pure microstrip shared power supply networks in existing technologies. The three transmit patches have slots on the side connecting to the transmit feed lines.

[0034] The above implementation achieves a 3-transmit 4-receive MIMO (Multipie Input Multiple Output) architecture. In automotive cabin vital sign monitoring applications, the 3T4R array can distinguish multiple targets, accurately locate occupants / children, improve the ability to identify weak respiratory and heartbeat signals, and is suitable for matching with low-power radar chips (e.g., TIIWR6843).

[0035] Multiple emitter patches are arranged parallel to the first edge of the dielectric substrate at a location adjacent to the first edge of the dielectric substrate, and close to a first side of the first edge of the dielectric substrate. Multiple receiver patches are arranged parallel to the second edge of the dielectric substrate at a location adjacent to the second edge of the dielectric substrate, and close to a second side of the second edge of the dielectric substrate. The first edge and the second edge of the dielectric substrate are perpendicular, the first side of the first edge of the dielectric substrate is the side of the first edge of the dielectric substrate that is away from the second edge, and the second side of the second edge of the dielectric substrate is the side of the second edge of the dielectric substrate that is away from the first edge.

[0036] like Figure 1 In a specific example, in a 3-transmit 4-receive example architecture, the three transmitter patches are located adjacent to the top edge of the dielectric substrate. The line connecting the three transmitter patches is substantially parallel to the top edge and closer to the right side of the top edge, i.e., away from the left side, thus away from the receiver patches or receiver array. The four receiver patches are located adjacent to the left side of the dielectric substrate. The line connecting the four receiver patches is substantially parallel to the left side and closer to the lower left side, i.e., away from the top edge, thus away from the transmitter patches or transmitter array.

[0037] exist Figure 1 In the example shown, the transmitting units are centrally located on the upper right side of the substrate. The transmitting patches of the three transmitting units, Tx1, Tx2, and Tx3, are arranged linearly with equal spacing in a horizontal line. Each transmitting patch has an independent trace, and the end of the trace is connected to the radar chip pad. The four receiving units are independently arranged in the lower left area of ​​the substrate, and the four receiving feed lines are independent and do not intertwine. This achieves fully independent power supply for 7 channels, which is different from the design of sharing a microstrip power divider network in the prior art.

[0038] exist Figure 1 In the example shown, the transmitting array is arranged on the upper right side of the substrate, and the receiving array is arranged on the lower left side of the substrate, increasing the physical spatial distance between the transmitting and receiving units. This physical partitioning and isolation arrangement of the transmitting and receiving arrays initially suppresses transceiver coupling at the spatial level.

[0039] The overall outer contour of the substrate can be controlled within 20mm × 20mm. This substrate size facilitates ultra-miniaturized integration and is suitable for use in vehicle rearview mirrors and narrow A-pillar mounting spaces. According to the arrangement of the transmitting and receiving arrays proposed in the above embodiments, physical partitioning and isolation can be achieved on a very small substrate size (e.g., 20mm × 20mm), achieving spatial suppression of transmit-receive coupling and solving the problem of existing vehicle radar antennas being too large and unable to be embedded in vehicles.

[0040] The above-described implementation uses a physical isolation layout for transmitting and receiving zones, which reduces unit coupling in space and achieves channel isolation of more than 30dB with the help of patch slots.

[0041] In one embodiment of the present invention, the area between the transmitting array and the receiving array on the dielectric substrate can be filled with grounding metal. A large-area grounding copper foil fills the space between the two arrays, thereby reducing the impact of spatial distance and grounding isolation copper foil. Spatial coupling between transmit and receive is reduced, suppressing mutual coupling between transmit and receive at the physical level and improving channel isolation by ≥30dB.

[0042] The radar chip pad area is located in the region away from the first and second edges of the dielectric substrate. The radar chip pad area is concentrated in this region, which allows for direct surface mounting of low-power 60GHz radar chips (such as the TI IWR6843 radar chip). This results in short traces, low signal loss, and suitability for low-power monitoring scenarios in vehicle sleep mode.

[0043] In such Figure 1 In the specific example shown, the radar chip pad area is located in the lower right region of the dielectric substrate, away from the upper edge adjacent to the transmitting patch and the left edge adjacent to the receiving patch.

[0044] It is important to note that Figure 1The illustrated arrangement of the transmitting array, receiving array, and radar chip pads on the upper right, lower left, and lower right regions of the dielectric substrate is merely a specific example. In practice, these components can be arranged in any other suitable manner. For instance, the transmitting array, receiving array, and radar chip pads could be arranged in the upper left, lower right, and lower left regions of the dielectric substrate, respectively. Alternatively, they could be arranged in the lower left, upper right, and lower right regions of the dielectric substrate, respectively. The key is to ensure that the adjacent edges of the transmitting and receiving pads are mutually perpendicular, i.e., to maintain a certain physical spatial distance between the transmitting and receiving arrays.

[0045] The vehicle-mounted millimeter-wave radar antenna proposed in the above embodiments of the present invention can achieve a complete 3-transmit 4-receive MIMO partitioned array layout on an extremely small dielectric substrate (e.g., 20mm × 20mm), overcoming the problem of insufficient miniaturization of existing 3T4R antennas. It achieves extreme miniaturization of the antenna, allowing it to be embedded in narrow interior spaces such as the roof console, A / B pillars, and rearview mirror bases, without occupying any space in the vehicle's interior structure. The physically isolated transmit and receive partitioned layout reduces unit coupling spatially.

[0046] In one embodiment of the present invention, the emitting patch and the receiving patch (collectively referred to herein as radiating patches) are circular patches. Reference Figure 2 This illustrates a schematic diagram of an example of a radiation patch according to an embodiment of the present invention. Figure 2 In the specific example shown, the radial patch is roughly circular. In other examples, the radial patch can also be polygonal, elliptical, or other shapes.

[0047] As an example, the patch diameter can be 1.58-1.70 mm. For instance, a patch diameter of 1.62 mm can be used in the 60 GHz band. This diameter range falls within the millimeter-scale micro-radiating unit range, suitable for ultra-compact 20 mm substrates. Copper foil patches within this diameter range are suitable for stable processing with standard PCB etching, facilitating mass production.

[0048] The diameter of the patch can be determined based on the center frequency of the frequency band and the circular microstrip patch™. 11 The empirical formula for mode resonant diameter, combined with corrections for base dielectric constant, dielectric loading, and edge shortening effect, ensures that the inherent resonance of the patch falls within the desired frequency band (e.g., 60-64 GHz).

[0049] like Figure 1 and Figure 2 The specific example shown includes two rectangular slots on the transmitter patch that are axisymmetric about the starting end of the transmitter feed. The receiver patch also includes two rectangular slots that are axisymmetric about the starting end of the receiver feed.

[0050] As an example, the slot width Ws (slot width in the vertical feeding direction) can be, for example, 0.15-0.2 mm. In subsequent simulations, a slot width of 0.18 mm is used, for example. The slot width mainly controls the equivalent capacitance disturbance at the slot, and is also constrained by the PCB process window. For example, if the minimum reliable PCB etching gap is ≥0.12 mm, and process tolerances are allowed, 0.15-0.2 mm can be selected. The determination of the slot width will affect the equivalent radiation aperture of the patch and the resonant frequency.

[0051] As an example, the slot depth Ls (the length of the slot along the feed axis) can be, for example, 0.50-0.60 mm. In subsequent simulations, a slot depth of 0.56 mm is used, for example. The slot depth is mainly used to disturb the current path on the patch surface and control the resonant frequency of the second resonant mode. As an example, the slot depth can be approximately 0.69 times the radius of the circular patch; for example, when the patch radius R = 0.81 mm, Ls ≈ 0.69R. By adjusting the slot depth, the second resonant peak can be tuned to around 64 GHz, allowing the two resonant peaks (~61 GHz, ~64 GHz) to be spliced ​​together to form a continuous 4 GHz bandwidth. The determination of the slot depth needs to comprehensively consider the strength of the current disturbance and the radiation resistance. The strength of the current disturbance affects the emergence of the second resonance and the resulting bandwidth expansion effect, while the radiation resistance will cause changes in matching and radiation efficiency.

[0052] As an example only, bandwidth and isolation specifications can still be achieved within a slot size range of ±0.03mm.

[0053] In the embodiment of the present invention, symmetrical rectangular slots are set on both sides of the central axis of the patch feed. The slots cut off the local conductive path of the patch, forcing the surface current to detour along the side wall of the slot, introducing an additional current path, and using the cavity perturbation effect to excite the second resonant mode. The two resonant peaks are tuned to around 61GHz and 64GHz, and the two resonant modes are connected to each other, extending the narrow bandwidth of the original micro patch to 4GHz, and fully covering the 60-64GHz ISM operating frequency band.

[0054] Traditional microstrip-fed patch array solutions in the prior art use large-size slotless rectangular patches, which have narrow bandwidth and severe gain attenuation at large angles, with measured / simulated horizontal field of view <+ / -40°. With slotless patches, the magnetic field at the cell edges diffuses outward, inducing surface currents of the same phase between adjacent radiating cells, causing significant spatial electromagnetic coupling. The above-described embodiment of the present invention uses symmetrical rectangular slots. These slots can adjust the surface current distribution; specifically, they can reconstruct the patch surface current distribution, inducing opposite-phase currents in adjacent cells at the slot positions. The electromagnetic fields generated by these reverse currents cancel each other out, thereby weakening near-field spatial electromagnetic coupling between adjacent transceiver cells, i.e., suppressing cell mutual coupling and improving channel isolation. This decoupling effect is achieved through the slots within the patch itself, eliminating the need for additional space-consuming decoupling branches / isolation walls, and not requiring additional substrate area, making it suitable for ultra-miniaturized arrays (e.g., 20mm × 20mm).

[0055] In existing technologies, the surface current of slotless patches is mainly concentrated at the outer circumference edge of the patch, with little current component in the lateral (large oblique angle) direction. Electromagnetic wave radiation energy is concentrated in the normal direction, and the gain drops rapidly after deviating from the normal. In contrast, the above-described embodiment of this invention uses symmetrical rectangular slots. After slotting, a large number of lateral current components distributed along the slot edge are generated on the slot sidewalls, changing the equivalent radiation aperture of the patch, effectively widening the antenna radiation aperture, and enhancing the electromagnetic wave radiation capability at oblique angles. Combined with array arrangement coordination, this compensates for the gain drop at large detection angles, and with the array layout, achieves a wide field of view detection of the entire vehicle cabin at a horizontal ±65° angle, optimizing wide-angle radiation performance.

[0056] Traditional MIMO decoupling antennas rely on external metal parasitic stubs, grounding vias, metal isolation walls, and other additional structures to achieve unit decoupling, which occupies substrate area. The embodiment of this invention only relies on the rectangular slots opened in the radiating patch itself to complete unit decoupling, without requiring additional auxiliary structures and without increasing the overall size of the array.

[0057] Existing slotted antenna designs are mostly used only for single bandwidth expansion, failing to simultaneously achieve element mutual coupling suppression and large-angle (wide-angle) gain optimization. The embodiments of this invention feature a pair of symmetrical rectangular slots on a circular patch body. These slots reconstruct the current distribution on the patch surface, achieving a triple technical effect based on cavity perturbation: stimulating the second resonant mode to expand the operating bandwidth, inducing reverse coupling current between adjacent elements to achieve mutual coupling suppression, and generating lateral current components to improve large-angle gain drop. The same patch body structure simultaneously achieves multi-functional synergistic gain for bandwidth, decoupling, and wide-angle radiation, offering significant advantages compared to existing slotted antennas in the field.

[0058] The embodiments of the present invention use a slotting method on the patch body to achieve the above functions without adding external components.

[0059] In one embodiment of the present invention, both the transmitting feed line and the receiving feed line sequentially include a front-end microstrip line, a transition section, and a coplanar waveguide feed line. The starting end of the front-end microstrip line is connected to a corresponding patch, and the ending end of the coplanar waveguide feed line is connected to the interior of the radar chip pad area. The coplanar waveguide (CPW) is a planar transmission line structure where the signal line and the ground plane are located on the same dielectric layer surface, offering advantages such as low radiation loss, easy integration, and no need for via grounding.

[0060] like Figure 1 As shown, taking the third transmitting unit 123 as an example, the transmitting feed line includes a front microstrip line 1232, a transition section 1233, and a coplanar waveguide feed line 1234. The starting end of the front microstrip line 1232 is connected to the corresponding third transmitting patch 1231, and the ending end of the coplanar waveguide feed line 1234 is connected to the interior of the radar chip pad area 140.

[0061] In one embodiment of the present invention, the front-end microstrip line has a first width, and the coplanar waveguide feed line has a second width. A first end of a transition section is connected to the front-end microstrip line and has the first width, while a second end of the transition section is connected to the coplanar waveguide feed line and has the second width. The transition section gradually transitions from the first width to the second width between the first and second ends.

[0062] As an example, the end of the trace is located on the radiating patch side, at the starting point of the CPW-microstrip gradient transition section. The bottom feed point of the circular radiating patch is the root of the microstrip feed section extending downwards from the patch. The short microstrip segment extending downwards from the circular patch is the CPW-microstrip gradient transition section. The starting point of the CPW feed line is the lower end of the CPW-microstrip gradient transition section. After a certain length (e.g., 1.4 mm) of gradient, the signal line width and the width of the ground gaps on both sides are fixed to the design values ​​(e.g., signal line width 0.22 mm, ground gap 0.14 mm). From this point downwards, the standard GCPW structure of the center signal line + constant width ground gaps on both sides officially begins, which is the starting position of the CPW feed line. From this position, it extends to the chip pad, and the entire route is a standard CPW feed line. In short, the feed line route is roughly as follows: radiating patch → front microstrip line → CPW-microstrip gradient transition section → standard CPW feed line → radar chip pad. The entire power supply path from the radar chip pad to the radiating patch consists of a hybrid power supply architecture composed of a CPW power supply section, a gradient transition section, and a front microstrip feed section connected in series.

[0063] As an example, a short section immediately following the root of the circular patch is a pure microstrip structure with only a central signal line and no CPW grounding gaps on either side (e.g., 0.14 mm). Then, it enters a linear gradient transition region (e.g., 1.4 mm in length), where the signal line width gradually changes while grounding gaps on both sides are slowly generated, smoothly transitioning from a microstrip shape to a GCPW coplanar waveguide. After the gradient section ends, the signal line width is, for example, 0.22 mm, and the grounding gaps on both sides are fixed, for example, 0.14 mm, becoming a standard CPW feed line that connects to the radar chip pad area.

[0064] The feeder structure proposed in the above embodiments of the present invention solves the defects of high transmission loss and low radiation efficiency of pure microstrip feeder in the prior art at 60GHz high frequency. The CPW structure naturally matches the impedance of the chip pads, eliminating the need for additional matching branches and further compressing the overall size. Each transmit and receive channel has an independent CPW feeder, with no shared feeder coupling, providing a basis for channel isolation ≥30dB.

[0065] As one embodiment of the present invention, such as Figure 1 In the specific example shown, the transmit feed line extends into the radar chip pad area through the first side of the radar chip pad area. The receive feed line extends into the radar chip pad area through the second side of the radar chip pad area. The first side of the radar chip pad area is perpendicular to the second side of the radar chip pad area.

[0066] In one embodiment of the invention, the bent portions of the transmitting feed line and the receiving feed line are impedance continuous. For example... Figure 1 As shown, although the geometric bending shapes of the traces are different (Tx1 and Tx3 have arc bends, Tx2 is close to a straight line; the bending paths of the four Rx lines are all different), the characteristic impedance of each feeder remains unchanged (for example, it remains at 50Ω). The impedance continuity design of the bending part will not introduce additional impedance discontinuities; the transmission loss of each feeder link is basically the same, and there will be no significant difference in the loss of a certain feeder.

[0067] refer to Figure 3This diagram illustrates a simulation of the return loss of the transmitting antenna according to an embodiment of the present invention. The horizontal axis represents frequency (Freq) in GHz, covering the target operating range of 60-64 GHz (dedicated ISM band for automotive applications). The vertical axis represents return loss in dB (shown as Amplitude [dB]), an industry standard. The curves represent the S-parameter frequency response. An S-parameter ≤ -10 dB indicates good antenna port impedance matching, effective RF energy radiation, and low reflection loss. The three curves dB(S1,1) / dB(S2,2) / dB(S3,3) correspond to the return losses of the three transmitting units Tx1 / Tx2 / Tx3, respectively. The curve trend of the receiving unit is consistent with that of the transmitting channel. The black dashed line y = -10 dB represents the matching qualification threshold.

[0068] The performance of the simulation curves is explained below.

[0069] Complete coverage of the 60~64 GHz frequency band: Within the 60 GHz to 64 GHz range, the S-parameters of all channels are consistently below -10dB, achieving continuous bandwidth matching of 4GHz; verifying the bandwidth expansion effect of micro circular patch + precise rectangular slot, solving the pain points of existing micro millimeter wave patches that are inherently narrow in bandwidth and prone to temperature drift and mismatch.

[0070] The double resonance valley feature verifies the technical effect of slotting: each curve has two resonance valleys (approximately 61 GHz and 64 GHz), corresponding to the double resonance mode introduced by slotting, proving that the slotted structure successfully broadens the resonance bandwidth; in contrast, the slotless structure in the prior art only has a single resonance point, with a bandwidth of less than 2 GHz, which cannot fully cover 60-64 GHz.

[0071] Excellent consistency across all channels: The high overlap of the three curves Tx1 / Tx2 / Tx3 indicates good consistency in the CPW hybrid power supply routing and slotted patch unit process. The 7 transceiver channels have balanced matching performance, and the multi-channel detection signal-to-noise ratio is stable, avoiding missed detection of vital signs due to single-channel frequency shift, and providing power assurance for a ±65° large FOV.

[0072] The premise of a stable signal-to-noise ratio (SNR) is that the port matching, radiation capability, and feeder loss of each antenna channel should be as close as possible. There should be no channel with large reflection, high loss, and weak radiation, which would result in a significantly weaker received echo signal for that channel.

[0073] As one embodiment of the present invention, the radiating unit body can be completely identical. All seven transceiver units can have the same circular patch diameter and the same symmetrical rectangular slot width / depth. The unit itself has the same resonance characteristics, impedance characteristics, and radiation efficiency, and the radiation capability of a single unit has small dispersion.

[0074] As one embodiment of the present invention, the consistency of the CPW-microstrip hybrid power supply link can be achieved. All 7 channels adopt the same hybrid power supply structure: the same CPW signal line width, the same 0.14mm grounding gap, and the same 1.4mm CPW-microstrip gradient transition section.

[0075] like Figure 3 As shown, the simulation results of the embodiments of the present invention show a high degree of overlap in S-parameters, and the port reflection levels are similar. The high overlap of the Tx1 / Tx2 / Tx3 return loss curves proves that the port reflections of each channel are small and the differences between them are small. If the S11 of a certain channel deteriorates, a large amount of RF signal will be reflected at the port, the actual radiated power will decrease, the corresponding echo received signal will become weaker, and the signal-to-noise ratio of that channel will deteriorate. The seven-channel matching and equalization of the embodiments of the present invention ensures that the radiated output power and receiving sensitivity of each channel are roughly equivalent, the difference in echo signal amplitude of each channel is suppressed, and the detection signal-to-noise ratio is stabilized among multiple channels.

[0076] Vital signs are weak Doppler echo signals; if the performance of the channels is highly discrete and the signal-to-noise ratio of some channels is low, the vital signs signal at that angle is easily submerged in noise, which can easily lead to missed detection; while balanced channel performance ensures that the antenna channels corresponding to each angle within a wide field of view of ±65° have sufficient effective radiation power and receiving sensitivity, which can provide a power basis for large FOV detection.

[0077] Figure 3 The simulation curves shown demonstrate the effectiveness of the 60 GHz high-frequency, low-loss feeding scheme. The lowest resonant trough value for the three channels reaches -22 to -25 dB, with extremely low return loss and minimal port reflection energy. According to the embodiment of this invention, the transmission loss at the 62 GHz center frequency is only 0.42 dB / cm (obtained through simulation based on Rogers RO4350B board parameters), far lower than the high-frequency loss of traditional microstrip lines (>1.5 dB / cm). The extremely low return loss means that there is almost no port reflection of the RF signal, significantly reducing energy dissipation during feed line transmission, and allowing the vast majority of RF power to be completely delivered to the radiating patch for electromagnetic radiation.

[0078] Port reflection loss (return loss S11) indicates how much of the signal at the antenna port is reflected back to the chip, reflecting the quality of port impedance matching. Figure 3 As shown, S11 = -22~-25dB, which means that the port reflection is very small.

[0079] The feeder transmission loss is the energy loss caused by conductor heating and dielectric absorption when the signal propagates along the CPW line. It is the attenuation of the transmission line itself. This parameter cannot be read from the S11 return loss curve. The simulated transmission line yields 0.42dB / cm.

[0080] Both low loss and high efficiency ensure that the maximum proportion of radio frequency power reaches the radiating patch and is converted into spatial electromagnetic waves, thus increasing the antenna radiation efficiency.

[0081] According to the embodiments of the present invention, the low reflection loss at the port and the low transmission loss of the feed line work together to improve the overall radiation efficiency of the antenna to over 80%. Compared with traditional pure microstrip fed arrays, the overall RF power consumption is significantly reduced at the same transmit power, which can meet the automotive-grade requirements for long-term low-power vital sign monitoring after the vehicle is turned off.

[0082] Simulation curves verify that the slotted patch can stably maintain full-band broadband matching within a 20mm ultra-compact array, achieving miniaturization and RF performance compatibility.

[0083] The simulation curves correspond to a miniature circular radiating patch with a diameter of only 1.62 mm. The entire set of 7 units (3 transmitters and 4 receivers) is densely arranged on a 20 mm × 20 mm ultra-small substrate. The unit spacing is compact and the spatial coupling conditions are stringent, but the S-parameters are consistently below -10 dB across the entire 60-64 GHz frequency band, achieving complete 4 GHz broadband impedance matching.

[0084] Existing rectangular patch antennas only satisfy S11≤-10dB in extremely narrow frequency bands, and suffer from poor matching in most frequency bands within the 60~64GHz range. This results in high signal reflection loss during radar operation, high overall power consumption, and poor detection accuracy. In contrast, simulation curves from the embodiments of this invention directly demonstrate that the slotted + hybrid feeding scheme perfectly solves the high-frequency broadband matching problem.

[0085] The various embodiments and combinations thereof of the present invention achieve several significant and beneficial technical effects.

[0086] An ultra-small dielectric substrate (e.g., 20mm×20mm) integrates a 3-transmit + 4-receive (3T4R) MIMO array within partitioned sections. Transmit and receive units are physically partitioned and independently arranged, with each channel equipped with its own dedicated feeder. For example, using a Rogers RO4350B high-frequency substrate (or an equivalent Rogers series substrate of the same specifications, such as RO4003C), the transmit units are horizontally arranged in the upper half of the substrate, and the receive units are vertically arranged in the lower left half. The transmit unit spacing is 5mm (λ0), and the receive unit spacing is 2.5mm (0.5λ0). The seven transmit and receive channels have independent, non-intersecting traces. This design is suitable for confined, embedded installation spaces in automotive interiors, reducing electromagnetic coupling between transmit and receive units from a spatial perspective, laying the structural foundation for high channel isolation, and solving the shortcomings of existing 3T4R antennas, such as excessive size and severe intertwined coupling in multi-channel traces.

[0087] The radar chip to radiating patch employs a hybrid feed architecture of CPW coplanar waveguide + microstrip line. The feed trunk uses a CPW structure with a slot width of, for example, 0.14mm and a characteristic impedance of, for example, 50Ω. The CPW ends are connected to the radiating patch via a transition microstrip line. Each transmit / receive channel is configured with an independent and complete feed link. The pad area is centrally located to match the radar chip (e.g., TI IWR6843). This significantly reduces the transmission loss of high-frequency signals in the 60-64 GHz range, improves the antenna radiation efficiency to over 80%, and eliminates the need for additional matching branches for the natively matched radar chip pad impedance. It is suitable for long-term sleep monitoring of low-power radar chips and overcomes the problems of high high-frequency loss and poor energy efficiency of traditional pure microstrip feeds.

[0088] A dedicated 60 GHz millimeter-scale circular radiating patch (e.g., 1.62 mm in diameter) features symmetrically sized rectangular slots (e.g., 0.18 mm wide and 0.56 mm deep) on its surface. For example, a single radiating unit uses a 1.62 mm diameter circular copper foil patch with two symmetrically sized rectangular slots (0.18 mm wide and 0.56 mm deep) on the bottom, symmetrically distributed on both sides of the feed line. This alters the current distribution on the patch surface, creating dual resonant frequencies and widening the inherently narrow bandwidth of the micro-pattern to 4 GHz, fully covering the 60-64 GHz ISM operating band. This addresses the inherent narrow bandwidth, temperature drift, and frequency mismatch issues of micro-millimeter-wave patches.

[0089] The circular patch with dual rectangular slots synchronously optimizes the electromagnetic coupling characteristics of the cells. By relying on the symmetrical slotting of the patch itself to alter the surface current flow, it weakens spatial radiation coupling between cells without adding additional decoupling stubs, metal vias, or isolation baffles. There is no need for additional space-consuming structures such as decoupling stubs, grounding vias, or isolation metal walls. It relies solely on the slotting of the patch itself to suppress mutual coupling between adjacent cells, achieving a stable isolation of ≥30dB across the entire channel. This avoids signal crosstalk within a small array that could cause distortion of weak vital signs signals.

[0090] By adjusting the equivalent radiating aperture through rectangular slotting on the patch, and coordinating with a 3T4R partitioned array layout, the beam is optimized. Slotting can reconstruct the surface current distribution, widening the effective radiated current distribution range and thus increasing the equivalent radiating aperture. At the element level, slotting improves the large-angle gain drop of a single element. Without slotting, the surface current is mainly concentrated at the outer circumference edge of the circular patch, primarily along the tangent direction; the current in the center of the patch is very weak; the effective radiated current is concentrated in the normal direction, with a low proportion of lateral (large angle) current components. Therefore, electromagnetic wave energy mainly radiates towards the antenna normal, and as the angle of deviation from the normal increases, the gain drops rapidly. Slotting involves etching slots on both sides of the patch feed axis, cutting off part of the conductive path in the center of the patch, forcing the surface current, which originally flowed along the circumference, to meander along the left and right sidewalls of the slot. On the vertical sidewall of the slot, a large number of lateral current components are added and distributed along the slot wall. These newly added lateral currents also participate in radiation, effectively expanding the effective radiation current distribution range outward from the original circular patch, thus widening the equivalent radiation aperture. The lateral current components mainly contribute to large oblique angles, directly increasing the radiation field strength in large-angle directions and alleviating gain roll-off at large angles. This invention utilizes slotting to widen the patch's equivalent radiation aperture and improve large-angle radiation gain, combined with a phase-weighted integrated radiation pattern from a transceiver partitioned linear array. This improves the problem of rapid gain drop at large detection angles, achieving a horizontal ±65° ultra-wide field of view, completely covering the front, rear, and foot areas of the entire vehicle cabin, eliminating blind spots for children, and solving the defect of poor large-angle radiation performance of conventional circular patches.

[0091] Achieving a horizontal ±65° ultra-wide field of view: This is achieved through a combination of patch slotted elements and a T4R transceiver partitioned linear array layout. The patch slotting reconstructs the surface current—adding a lateral current component, widening the equivalent radiation aperture—improving the gain drop of a single element at large angles (element bottoming out)—a 3T4R linear array + phase-weighted beamforming—array scanning synthesizes a wide-angle radiation pattern. Symmetrical rectangular slots are created on the patch, forcing the surface current to meander along the slot sidewalls, adding a lateral radiation current component, and widening the antenna's equivalent radiation aperture. The radiating aperture is improved to mitigate the gain drop of a single element at large angles. Based on this, a transmit / receive zoned linear array is combined, and array pattern synthesis is achieved through multi-channel phase weighting. This first alleviates the problem of rapid gain drop at large detection angles for a single element, and then, with the help of array phase weighting beam synthesis, the two work together to achieve an ultra-wide horizontal field of view of ±65°. The detection range completely covers the front, rear, and foot areas of the entire vehicle cabin, eliminating blind spots for detecting children inside the vehicle and solving the inherent defect of poor large-angle radiation performance of conventional slotless circular patch antennas.

[0092] On a single 20mm miniaturized PCB, multiple structural features are simultaneously coupled, including a 3T4R independent CPW hybrid feed, slotted multi-functional surface mount, and partitioned array arrangement. A single 20mm×20mm single-layer Rogers high-frequency PCB integrates a partitioned 3T4R array, an independent CPW-microstrip hybrid feed network, and a circular radiating surface mount with double rectangular slots; the entire structure is an integrated design without discrete components. This hardware achieves five automotive-grade hard targets simultaneously—60-64GHz full-band coverage, channel isolation ≥30dB, ±65° wide field of view, high radiation efficiency, and ultra-miniaturization—without compromising performance. It overcomes the industry challenge of existing technologies where various performance indicators are mutually restrictive and incompatible.

[0093] All transceiver channels adopt the same slotted circular patch and equal-length symmetrical CPW hybrid feeder topology. The 3-channel transmitter and 4-channel receiver units use slotted circular patches of the exact same size, and the feeder trace lengths and CPW transition structures of each channel are completely symmetrical and uniform. The impedance matching curves of the 7-channel transceiver are highly consistent, and the return loss across the entire frequency band is consistently below -10dB. This reduces performance dispersion caused by PCB manufacturing errors, facilitates standardized mass production, and improves the overall detection stability of the radar system.

[0094] On the other hand, embodiments of the present invention provide an in-vehicle millimeter-wave radar, which includes a radar chip and an in-vehicle millimeter-wave radar antenna as described in any of the above embodiments.

[0095] In another aspect, embodiments of the present invention provide a vehicle including the vehicle-mounted millimeter-wave radar described in any of the above embodiments.

[0096] The embodiments of this invention address the mass production requirements of vehicle-mounted millimeter-wave radar antennas, vehicle-mounted millimeter-wave radars, and vehicle-adaptive 60GHz vital signs radars for vehicle cockpits. They solve the common industry pain points of incompatibility between existing antennas in terms of miniaturization, multi-channel, full-band, wide beam, high isolation, low loss, and high efficiency, and break through the three major technical bottlenecks of millimeter-level micro-patch bandwidth, compact array mutual coupling, and large-angle radiation gain.

[0097] This invention implements an ultra-compact (e.g., 20mm × 20mm) PCB antenna that natively supports the 3T4RMIMO architecture and can be matched with the TI IWR6843 low-power radar chip. It reduces 60GHz high-frequency transmission loss through CPW-microstrip hybrid feeding and, combined with a precise micron-level slotted circular patch, achieves 4GHz broadband extension, unit mutual coupling suppression, and wide-angle radiation gain optimization in a single slotted structure. It simultaneously achieves 60–64GHz full ISM band coverage, channel isolation ≥30dB, a horizontal ±65° ultra-wide field of view, and radiation efficiency ≥80%, while meeting four core automotive-grade performance indicators: miniaturization, full detection coverage, low power consumption, and strong anti-interference. It can be mass-produced using standard Rogers PCB technology, controlling hardware costs, and provides a feasible, highly integrated millimeter-wave radar front-end antenna solution for child abandonment detection, driver status monitoring, and in-vehicle vital sign sensing.

[0098] The embodiments of this invention achieve full-cabin detection without blind spots. For example, it has an ultra-wide field of view of over ±65° horizontally, completely covering the front, rear, and footwell areas, eliminating any missed detection of children. It provides complete coverage of the entire 60–64 GHz ISM band, channel isolation ≥30dB to suppress interference from the cabin's metallic interior trim, and high radiation efficiency to reduce overall power consumption during sleep mode, meeting the requirements for long-term monitoring after the vehicle is turned off, achieving automotive-grade stability and reliability.

[0099] The embodiments of the present invention can be applied to fields such as automotive cabin millimeter-wave vital signs monitoring radar, child abandonment detection system, driver status monitoring equipment, and vehicle-mounted millimeter-wave radar front-end module, and have broad and practical application prospects.

[0100] The foregoing description of embodiments of the invention has been given for illustrative purposes and is not exhaustive, nor is it intended to limit the invention to the exact forms disclosed. Those skilled in the art will understand that various changes can be made without departing from the scope of the invention, and elements therein can be substituted with equivalents. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of the invention without departing from the basic scope of the invention. Therefore, the invention is not intended to be limited to the specific embodiments disclosed as the best mode contemplated for carrying out the invention; the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A vehicle-mounted millimeter-wave radar antenna, characterized in that, The vehicle-mounted millimeter-wave radar antenna includes a dielectric substrate and a transmitting array, a receiving array, and radar chip pads disposed on the dielectric substrate. The transmitting array includes multiple transmitting units, each of which includes a transmitting patch and a transmitting feed line. Each transmitting feed line extends from the corresponding transmitting patch into the radar chip pad area. Each transmitting feed line is independent of each other and does not cross. The transmitting patch has a slot on the side that connects to the transmitting feed line. The receiving array includes multiple receiving units, each receiving unit includes a receiving patch and a receiving feed line. Each receiving feed line extends from the corresponding receiving patch into the radar chip pad area. Each receiving feed line is independent of each other and does not cross. The receiving patch has a slot on the side connected to the receiving feed line. Multiple emitter patches are arranged parallel to the first side of the dielectric substrate at a location adjacent to the first side of the dielectric substrate and close to the first side of the first side of the dielectric substrate; multiple receiver patches are arranged parallel to the second side of the dielectric substrate at a location adjacent to the second side of the dielectric substrate and close to the second side of the second side of the dielectric substrate; the first side of the dielectric substrate is perpendicular to the second side, the first side of the first side of the dielectric substrate is the side of the first side of the dielectric substrate away from the second side, and the second side of the second side of the dielectric substrate is the side of the second side of the dielectric substrate away from the first side; The radar chip pad area is located in the region away from the first and second sides of the dielectric substrate.

2. The vehicle-mounted millimeter-wave radar antenna according to claim 1, characterized in that, The transmitting patch and the receiving patch are circular patches. The slots on the transmitter patch include two rectangular slots that are axially symmetrical about the starting end of the transmitter feed. The slots on the receiving patch include two rectangular slots that are axially symmetrical about the starting end of the receiving feed line.

3. The vehicle-mounted millimeter-wave radar antenna according to claim 1, characterized in that, Both the transmitting feed and the receiving feed sequentially include a front microstrip line, a transition section, and a coplanar waveguide feed. The starting end of the front microstrip line is connected to the corresponding patch, and the ending end of the coplanar waveguide feed is connected to the interior of the radar chip pad area.

4. The vehicle-mounted millimeter-wave radar antenna according to claim 3, characterized in that, The front-end microstrip line has a first width, and the coplanar waveguide feed line has a second width. The first end of the transition section is connected to the front-end microstrip line and has a first width, while the second end of the transition section is connected to the coplanar waveguide feed line and has a second width. The transition segment gradually changes from a first width to a second width between the first end and the second end.

5. The vehicle-mounted millimeter-wave radar antenna according to any one of claims 1 to 4, characterized in that, The transmitting array includes three transmitting units, and the receiving array includes four receiving units.

6. The vehicle-mounted millimeter-wave radar antenna according to any one of claims 1 to 4, characterized in that, The transmit feed line extends from the first side of the radar chip pad area into the radar chip pad area. The receiving feed line extends from the second side of the radar chip pad area into the radar chip pad area. The first side of the radar chip pad area is perpendicular to the second side of the radar chip pad area.

7. The vehicle-mounted millimeter-wave radar antenna according to any one of claims 1 to 4, characterized in that, The bends in the transmit and receive feeds are impedance continuous.

8. The vehicle-mounted millimeter-wave radar antenna according to any one of claims 1 to 4, characterized in that, The area between the transmitting array and the receiving array on the dielectric substrate is filled with grounding metal.

9. A vehicle-mounted millimeter-wave radar, characterized in that, The vehicle-mounted millimeter-wave radar includes a radar chip and a vehicle-mounted millimeter-wave radar antenna according to any one of claims 1 to 8.

10. A vehicle, characterized in that, Including the vehicle-mounted millimeter-wave radar according to claim 9.

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