Transmitting antenna array, transmitting antenna system and millimeter wave radar

Abstract

The present invention relates to the field of antenna technology, and discloses a transmitting antenna array, a transmitting antenna system, and a millimeter wave radar. The transmitting antenna array includes a feeding network and a plurality of transmitting array elements. The feeding network includes a plurality of serpentine feeding units and a plurality of first feed lines. Each serpentine feeding unit is electrically connected between two adjacent first feed lines. The plurality of transmitting array elements correspond one to one with the plurality of first feed lines. Each transmitting array element is electrically connected to the corresponding first feed line. The feeding network can feed in current signals with frequencies that increase or decrease in sequence, so that the maximum radiation direction of the antenna beam output by the plurality of transmitting array elements points to the corresponding angle in the vertical direction in sequence, thereby realizing scanning in the vertical direction. Therefore, by adjusting the frequency of the current signal fed into the transmitting antenna array, the transmitting antenna array can be scanned in the vertical direction, has vertical resolution, and has height measurement capability, so that the target type can be accurately identified.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a transmitting antenna array, a transmitting antenna system and a millimeter wave radar. Background Art

[0002] Compared with traditional antennas, millimeter-wave radar antennas can more easily achieve higher gain and narrower beam width in a smaller antenna volume, resulting in higher detection accuracy and longer detection distance. Therefore, millimeter-wave radar antennas are widely used in transportation, communications and other fields.

[0003] Generally, accurate detection of high-altitude targets (such as road signs) requires millimeter-wave radar antennas to have vertical angular resolution to obtain complete information about the target and accurately identify it. However, traditional millimeter-wave radar antennas generally only have horizontal angular resolution, not vertical angular resolution. This makes it impossible to detect the target's height and thus obtain complete information about the target, leading to failure in target type identification. Summary of the Invention

[0004] The embodiments of the present invention provide a transmitting antenna array, a transmitting antenna system and a millimeter wave radar, which can improve the technical problem of inaccurate target type discrimination in related technologies.

[0005] The embodiments of the present invention provide the following technical solutions to improve the above technical problems:

[0006] In a first aspect, an embodiment of the present invention provides a transmitting antenna array, including:

[0007] A feeding network comprising a plurality of serpentine feeding units and a plurality of first feed lines, wherein each of the serpentine feeding units is electrically connected between two adjacent first feed lines;

[0008] a plurality of transmitting array elements, corresponding one-to-one to the plurality of first feed lines, each of the transmitting array elements being electrically connected to a corresponding first feed line;

[0009] The feeding network can feed current signals with frequencies that increase or decrease sequentially, so that the maximum radiation directions of the antenna beams output by the multiple transmitting array elements are directed to corresponding angles in the vertical direction in sequence, thereby achieving scanning in the vertical direction.

[0010] Optionally, the equivalent circuit of the serpentine feed unit includes an equivalent capacitor and an equivalent inductor, and the transfer function of the equivalent circuit is as follows:

[0011] F(f,L,C)=A·e j·φ(f,L,C)

[0012] Wherein, F(f, L, C) is the phase offset, f is the frequency of the current signal flowing through the serpentine feed unit, L is the equivalent inductance, C is the equivalent capacitance, A is the amplitude of the current signal, and Φ(f, L, C) is the phase difference between two adjacent transmitting array elements.

[0013] Optionally, the feeding network further includes an impedance matching unit, one end of the impedance matching unit is used to feed a current signal, and the other end is electrically connected to the first feeder.

[0014] Optionally, the impedance matching unit includes a second feeder and an impedance matching branch, one end of the second feeder is used to feed the current signal, and the other end is electrically connected to the first feeder, and the impedance matching branch is arranged on the second feeder.

[0015] Optionally, each of the serpentine feeding units includes a first bending portion, a third feeder and a second bending portion, the first bending portion and the second bending portion are symmetrical about the center of the third feeder, one end of the first bending portion is electrically connected to one end of one of the first feeder, and the other end is electrically connected to one end of the third feeder, one end of the second bending portion is electrically connected to the other end of the third feeder, and the other end is electrically connected to one end of another first feeder.

[0016] Optionally, a first coupling slot is provided between the first bending portion and the third feeder, and a second coupling slot is provided between the second bending portion and the third feeder, and the lengths of the first coupling slot and the second coupling slot are both less than 0.25 times the waveguide wavelength.

[0017] Optionally, the first bending portion includes a fourth feeder and a fifth feeder, one end of the fourth feeder is electrically connected to one end of the first feeder, the other end of the fourth feeder is electrically connected to one end of the fifth feeder, and the other end of the fifth feeder is electrically connected to one end of the third feeder.

[0018] Optionally, the second bending portion includes a sixth feeder and a seventh feeder, one end of the sixth feeder is electrically connected to one end of the third feeder, the other end of the sixth feeder is electrically connected to one end of the seventh feeder, and the other end of the seventh feeder is electrically connected to one end of the first feeder.

[0019] In a second aspect, an embodiment of the present invention provides a transmitting antenna system, including:

[0020] a dielectric substrate; and

[0021] The transmitting antenna array as described above is arranged on the dielectric substrate.

[0022] In a second aspect, an embodiment of the present invention provides a millimeter wave radar, comprising the transmitting antenna system as described above.

[0023] The beneficial effects of the embodiments of the present invention include: providing a transmitting antenna array, a transmitting antenna system and a millimeter wave radar. The transmitting antenna array includes a feeding network and a plurality of transmitting array elements, the feeding network includes a plurality of serpentine feeding units and a plurality of first feed lines, each serpentine feeding unit is electrically connected between two adjacent first feed lines, a plurality of transmitting array elements correspond one to one with the plurality of first feed lines, each transmitting array element is electrically connected to the corresponding first feed line, and the feeding network can feed in a current signal with a frequency that increases or decreases in sequence, so that the maximum radiation direction of the antenna beam output by the plurality of transmitting array elements points to the corresponding angle in the vertical direction in sequence, thereby realizing scanning in the vertical direction. Therefore, by adjusting the frequency of the current signal fed into the transmitting antenna array, the transmitting antenna array can be scanned in the vertical direction, has vertical resolution, and has height measurement capability, so that the target type can be accurately identified. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] One or more embodiments are illustrated only as examples through the pictures in the corresponding drawings, and these exemplary descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute a scale limitation.

[0025] Figure 1 is a structural diagram of a transmitting antenna system provided by an embodiment of the present invention;

[0026] Figure 2a is a structural diagram of a transmitting antenna array provided by an embodiment of the present invention;

[0027] Figure 2b is a structural diagram of another transmitting antenna array provided by an embodiment of the present invention;

[0028] Figure 2c is a structural diagram of another transmitting antenna array provided by an embodiment of the present invention;

[0029] Figure 3 is an equivalent circuit diagram of a serpentine feeding unit provided by an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of a simulation of an antenna beam during a frequency scanning process provided by an embodiment of the present invention;

[0031] Figure 5 It is a schematic diagram of target height detection provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] It should be noted that when an element is described as being "connected" to another element, it may be directly connected to the other element, or one or more intermediate elements may exist therebetween. In addition, the terms "first," "second," etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance.

[0034] The embodiment of the present invention provides a transmitting antenna system. Figure 1 The transmitting antenna system includes a dielectric substrate 100 and a transmitting antenna array 200.

[0035] The transmit antenna array 200 is arranged on a surface of a dielectric substrate 100. A surface of the dielectric substrate 100, which is remote from the transmit antenna array 200, is grounded 300. Dielectric substrate parameters include dielectric constant, thickness, and loss tangent. To meet antenna design requirements, a dielectric substrate with appropriate parameters must be selected. For example, when designing a millimeter-wave radar antenna for the 77 GHz-81 GHz frequency band, Rogers RO3003 substrate material is used as the dielectric substrate. In this embodiment, the parameters of the dielectric substrate 100 or the material material can be freely selected based on different applications and design requirements.

[0036] Please also refer to Figures 2a to 2c ,like Figure 2a As shown, the transmit antenna array 200 includes a feed network 21 and a plurality of transmit array elements 22 .

[0037] The feeding network 21 includes a plurality of serpentine feeding units 211 and a plurality of first feed lines 212 . Each serpentine feeding unit 211 is electrically connected between two adjacent first feed lines 212 .

[0038] The plurality of transmit array elements 22 correspond to the plurality of first feed lines 212 in a one-to-one manner, that is, each transmit array element 22 corresponds to one first feed line 212 , and each transmit array element 22 is electrically connected to the corresponding first feed line 212 .

[0039] The feed network 21 can feed current signals with successively increasing or decreasing frequencies. For example, within a specific bandwidth of 76 GHz to 78.5 GHz, the feed network 21 sequentially feeds current signals with working center frequencies of 76 GHz, 76.5 GHz, 77 GHz, 77.5 GHz, 78 GHz, and 78.5 GHz, thereby performing frequency scanning in the direction of energy advancement, so that the maximum radiation direction of the antenna beam output by the multiple transmitting array elements 22 is sequentially pointed at corresponding angles in the vertical direction. For example, the frequency scanning range is f1-fn, and the frequencies from f1 to fn increase or decrease sequentially. When the feed network 21 feeds a current signal with a working center frequency of f1, the antenna beam is pointed at 0 degrees in the vertical direction. When the feed network 21 feeds a current signal with a working center frequency of fn, the antenna beam is pointed at the maximum angle in the vertical direction. When the feed network 21 feeds current signals with working center frequencies of other frequencies, the antenna beam is pointed at other angles in the vertical direction. Therefore, by adjusting the working center frequency of the current signal fed into the feeding network 21, the vertical direction of the antenna beam output by the transmitting antenna array 200 can be controlled to achieve scanning in the vertical direction, effectively obtain the height information of the target, and achieve accurate judgment of the target type (especially targets with height).

[0040] Generally, transmitting antennas using traditional technology cannot adjust the antenna propagation phase difference by adjusting the frequency fed into the transmitting antenna. Regardless of whether the frequency fed into the transmitting antenna is high or low frequency, the ratio of the propagation phase difference between adjacent transmitting array elements in the waveguide and the propagation phase difference between adjacent transmitting array elements in free space is extremely small, making it impossible to widen the antenna beam deflection angle, thereby failing to perform large-angle scanning in the vertical direction and, consequently, failing to effectively detect the target height.

[0041] The transmitting antenna array 200 of this embodiment has a reasonable structural design. By adjusting the operating center frequency of the current signal fed into the feeding network 21, the beam deflection angle can be widened to achieve a larger angle scan in the vertical direction, thereby effectively detecting the target height.

[0042] In some embodiments, when the current signal is transmitted on the serpentine feed unit 211, the serpentine feed unit 211 may be equivalent to a circuit structure, wherein the equivalent circuit of the serpentine feed unit 211 includes an equivalent capacitor Ceq and an equivalent inductor Leq, and the transfer function of the equivalent circuit is as follows:

[0043] F(f,L,C)=A·e j·φ(f,L,C)

[0044] Wherein, F(f, L, C) is the phase offset, f is the frequency of the current signal flowing through the serpentine feed unit 211, L is the equivalent inductance Leq, C is the equivalent capacitance Ceq, A is the amplitude of the current signal, and Φ(f, L, C) is the phase difference between two adjacent transmitting array elements 22.

[0045] According to the transfer function of the equivalent circuit, by properly setting the values ​​of the equivalent inductance Leq and the equivalent capacitance Ceq, the propagation phase difference between two adjacent transmitting array elements 22 can change accordingly when the frequency of the current signal fed by the feed network 21 changes, thereby causing the phase offset to vary with frequency. Therefore, when the frequency difference is large, the ratio of the propagation phase difference between adjacent antenna units in the waveguide to the propagation phase difference between adjacent antenna units in free space is relatively different.

[0046] The formula for the antenna beam deflection angle is as follows:

[0047]

[0048] Assume that at low frequencies, the ratio of the propagation phase difference between adjacent antenna elements in a waveguide to the propagation phase difference between adjacent antenna elements in free space is: At high frequencies, the ratio of the propagation phase difference between adjacent antenna elements in a waveguide to the propagation phase difference between adjacent antenna elements in free space is If the frequency difference between low frequency and high frequency is large, then and The difference between them is large enough, so that a larger antenna beam deflection angle can be obtained within a specific bandwidth, thereby achieving a larger angle scan in the vertical direction and effectively detecting the target height.

[0049] In some embodiments, as Figure 2b As shown, the feeding network 21 further includes an impedance matching unit 213 . One end of the impedance matching unit 213 can be fed with a current signal, and the other end is electrically connected to the first feeder 212 .

[0050] Specifically, such as Figure 2b As shown, the impedance matching unit 213 includes a second feeder 2131 and an impedance matching branch 2132 . One end of the second feeder 2131 can be fed with a current signal, and the other end is electrically connected to the first feeder 212 . The impedance matching branch 2132 is disposed on the second feeder 213 .

[0051] By providing an impedance matching branch 2132 on the second feeder 2131, the radiation power of the transmitting antenna array 200 can be increased, the loss on the feeder can be reduced, the power capacity of the feeder can be increased, and a better antenna beam shape can be obtained.

[0052] In some embodiments, as Figure 2bAs shown, each serpentine feeder unit 211 includes a first bend 2111, a third feeder 2112 and a second bend 2113. The first bend 2111 and the second bend 2113 are symmetrical about the center of the third feeder 2112. One end of the first bend 2111 is electrically connected to one end of the first feeder 212, and the other end is electrically connected to one end of the third feeder 2112. One end of the second bend 2113 is electrically connected to the other end of the third feeder 2112, and the other end is electrically connected to one end of the first feeder 212.

[0053] In some embodiments, as Figure 2b As shown, a first coupling slot is defined between the first bend 2111 and the third feeder 2112, and a second coupling slot is defined between the second bend 2113 and the third feeder 2112. To meet coupling requirements and achieve reliable antenna beam deflection, the length L1 of the first coupling slot is less than 0.25 times the waveguide wavelength, and the length L2 of the second coupling slot is less than 0.25 times the waveguide wavelength. It will be appreciated that the lengths of the first and second coupling slots can be freely set by the user based on different applications and design requirements, as long as the lengths of the first and second coupling slots meet the coupling requirements.

[0054] In some embodiments, as Figure 2c As shown, the first bending portion 2111 includes a fourth feeder 21111 and a fifth feeder 21112, one end of the fourth feeder 21111 is electrically connected to one end of the first feeder 212, one end of the fourth feeder 21111 is electrically connected to one end of the fifth feeder 21112, and the other end of the fifth feeder 21112 is electrically connected to one end of the third feeder 2112.

[0055] The second bending portion 2113 includes a sixth feeder 21131 and a seventh feeder 21132, one end of the sixth feeder 21131 is electrically connected to one end of the third feeder 2112, the other end of the sixth feeder 21131 is electrically connected to one end of the seventh feeder 21132, and the other end of the seventh feeder 21132 is electrically connected to one end of the first feeder 212.

[0056] See also Figure 3 , Figure 3 The equivalent circuit diagram of a serpentine feed unit provided by an embodiment of the present invention is shown in FIG. Figure 3 As shown, the equivalent circuit includes a first equivalent capacitor C1, a first equivalent inductor L1, a second equivalent capacitor C2 and a second equivalent inductor L2, wherein the first equivalent capacitor C1 is connected in parallel with the first equivalent inductor L1, and the second equivalent capacitor C2 is connected in parallel with the second equivalent inductor L2.

[0057] In this embodiment, by properly setting the feed parameters of the serpentine feeder unit 211, a first equivalent capacitance C1, a first equivalent inductance L1, a second equivalent capacitance C2, and a second equivalent inductance L2 that meet design requirements can be obtained. This allows the propagation phase difference between two adjacent transmit array elements 22 to change with changes in the frequency of the current signal fed by the feed network 21, thereby causing the phase offset to vary with frequency. Consequently, when the frequency difference is large, the ratio of the propagation phase difference between adjacent antenna elements in the waveguide to the propagation phase difference between adjacent antenna elements in free space is sufficiently large. Consequently, when the transmit antenna array 200 performs frequency scanning within a specific bandwidth, it can achieve a large antenna beam deflection angle, thereby enabling wide vertical angle scanning and effectively detecting target heights.

[0058] See also Figure 4 , Figure 4 The following is a schematic diagram of a simulation of an antenna beam during a frequency scanning process provided by an embodiment of the present invention. Figure 4 As shown in the figure, during frequency scanning within a certain frequency range, the maximum radiation direction of the antenna beam output by the transmitting antenna array points at different vertical angles at different frequencies. Furthermore, when the difference between the two scanning frequencies is large, the deflection angle of the antenna beam is large enough to effectively obtain target height information.

[0059] See also Figure 5 , Figure 5 Schematic diagram of target height detection provided by an embodiment of the present invention. Figure 5 As shown, assuming that a human target is scanned, by sequentially feeding current signals with increasing or decreasing frequencies into the transmitting antenna array to perform frequency scanning, the maximum radiation direction of the antenna beam output by the transmitting antenna array can be deflected in a larger range of vertical pointing angles, effectively obtaining the height information of the human target, thereby effectively identifying the target type.

[0060] Finally, it should be noted that the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. These embodiments do not serve as additional limitations on the content of the present invention. The purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of the present invention. In addition, under the concept of the present invention, the above-mentioned technical features can continue to be combined with each other, and there are many other variations of the different aspects of the present invention as described above, all of which are considered to be within the scope of the description of the present invention. Furthermore, it is obvious to those skilled in the art that improvements or modifications can be made based on the above description, and all such improvements and modifications should fall within the scope of protection of the claims appended to the present invention.

[0061] The embodiment of the present invention further provides a millimeter wave radar, comprising the transmitting antenna system described above. The millimeter wave radar of this embodiment also has the above advantages, which will not be described in detail here.

Claims

1. A transmitting antenna array, characterized in that: include: A feeding network, comprising a plurality of serpentine feed units and a plurality of first feed lines, each of the serpentine feed units being electrically connected between two adjacent first feed lines; each of the serpentine feed units comprising a first bend, a third feed line, and a second bend, the first bend and the second bend being symmetrical about the center of the third feed line, one end of the first bend being electrically connected to one end of one of the first feed lines, and the other end being electrically connected to one end of the third feed line, one end of the second bend being electrically connected to the other end of the third feed line, and the other end being electrically connected to one end of another of the first feed lines; a plurality of transmitting array elements, corresponding one-to-one to the plurality of first feed lines, each of the transmitting array elements being electrically connected to a corresponding first feed line; The feeding network can feed current signals with frequencies that increase or decrease sequentially, so that the maximum radiation directions of the antenna beams output by the multiple transmitting array elements are directed to corresponding angles in the vertical direction in sequence, thereby achieving scanning in the vertical direction.

2. The transmitting antenna array according to claim 1, wherein: The equivalent circuit of the serpentine feed unit includes an equivalent capacitor and an equivalent inductor, and the transfer function of the equivalent circuit is as follows: Wherein, F(f, L, C) is the phase offset, f is the frequency of the current signal flowing through the serpentine feed unit, L is the equivalent inductance, C is the equivalent capacitance, A is the amplitude of the current signal, and Φ(f, L, C) is the phase difference between two adjacent transmitting array elements.

3. The transmitting antenna array according to claim 1, wherein: The feeding network further includes an impedance matching unit, one end of which is used to feed a current signal, and the other end of which is electrically connected to the first feeder.

4. The transmitting antenna array according to claim 3, wherein: The impedance matching unit includes a second feeder and an impedance matching branch. One end of the second feeder is used to feed a current signal, and the other end is electrically connected to the first feeder. The impedance matching branch is provided on the second feeder.

5. The transmitting antenna array according to claim 1, wherein: A first coupling slot is provided between the first bending portion and the third feeder, and a second coupling slot is provided between the second bending portion and the third feeder. The lengths of the first coupling slot and the second coupling slot are both less than 0.25 times the waveguide wavelength.

6. The transmitting antenna array according to claim 1, wherein: The first bending portion includes a fourth feeder and a fifth feeder, one end of the fourth feeder is electrically connected to one end of the first feeder, the other end of the fourth feeder is electrically connected to one end of the fifth feeder, and the other end of the fifth feeder is electrically connected to one end of the third feeder.

7. The transmitting antenna array according to claim 1, wherein: The second bending portion includes a sixth feeder and a seventh feeder, one end of the sixth feeder is electrically connected to one end of the third feeder, the other end of the sixth feeder is electrically connected to one end of the seventh feeder, and the other end of the seventh feeder is electrically connected to one end of the first feeder.

8. A transmitting antenna system, characterized in that: include: dielectric substrate; as well as The transmitting antenna array according to any one of claims 1 to 7, wherein the transmitting antenna array is arranged on the dielectric substrate.

9. A millimeter wave radar, characterized in that: Comprising the transmitting antenna system as claimed in claim 8.

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