Antenna array for high-frequency equipment

Abstract

To provide an antenna array for a high frequency device that can track and suppress grating lobes at any beam angle to reduce power consumption while maintaining sidelobe suppression performance, while also compensating for gain that tends to deteriorate due to lower power consumption.SOLUTION: A receiving antenna array 107 is constructed on the basis of a base design with on-elements 11a grouped adjacently, and an on-element 11c provided separately from the on-element 11a and arranged at a specific interval in a specific direction. The antenna array 107 has fewer on-elements 11a and 11c than the base design by increasing the number of elements set as off-elements 11ab and 11cb compared to the base design. Furthermore, the grouping is extended to the off-elements 11b adjacent to the on-elements 11a.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to an antenna array for a high-frequency device.

Background Art

[0002] The technology development of phased array antennas for high-frequency devices has been in progress (for example, see Patent Document 1). According to the phased array antenna described in Patent Document 1, individual array elements (hereinafter, on-elements) are arranged two-dimensionally and grouped as square sub-arrays of eight units, for example, 4×2 or 8×1 of the individual array elements. Then, a plurality of square sub-arrays are tiled so as to reduce the periodicity of the phase center, thereby reducing grating lobes.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technology described in Patent Document 1, in order to suppress grating lobes, the periodicity of the phase center is reduced. However, the grating lobes themselves still remain (about -10 dBc), and the beam scanning range with suppressed side lobes and grating lobes is limited to about ±10°. In addition, due to the reduction of the periodicity of the phase center, the phase centers will all shift irregularly from the element coordinates, complicating the calculation of phase values and the calculation of tapering. That is, when the off-grid increases in both the vertical and horizontal directions of the phase center position, the interval between adjacent on-elements changes from the ideal distance of 0.5λ, and the premise is lost, so the calculation of phase values becomes complicated.

[0005] The inventors have also discovered that grouping adjacent individual array elements vertically or horizontally to reduce the number of phase shifters and simplify the system generates grating lobes during the same vertical or horizontal scan as the grouping. In addition, in a prior application, the inventors proposed a technique that can cancel grating lobes by forming a null filter using pairs of single elements arranged at specific intervals.

[0006] On the other hand, in scanning radar sensors, for example, there is a particular need to further reduce the number of phase shifters electrically connected to the elements of the phased array in order to reduce costs and simplify the system. Furthermore, there is a need for sidelobe suppression technology to suppress unwanted ambient noise. In addition, since there is a need for lower power consumption in the technical field related to this application, it is desirable to increase the number of non-operating off-elements, but increasing the number of off-elements tends to reduce the transmission and reception capability of the phased array, so it is desirable to compensate for that capability.

[0007] The object of the present invention is to provide an antenna array for high-frequency equipment that can track and suppress grating lobes at any beam angle, thereby maintaining side lobe suppression performance while reducing power consumption, and compensating for the gain that tends to degrade as a result of such reduced power consumption. [Means for solving the problem]

[0008] The invention described in claim 1 relates to an antenna array having elements that are electrically switched on or off by a phase shifter. The antenna array is configured based on a base design in which active elements are configured to be grouped adjacently along a specific direction in the vertical or horizontal direction in a two-dimensional array and controlled by the same phase shifter, as well as single-on elements that are provided separately from the active elements and arranged at specific intervals in a specific direction.

[0009] The antenna array operates with a reduced number of active elements or single-on elements compared to the base design by increasing the number of elements set as off-elements that are not electrically connected to the phase shifter. The element control unit controls the off-elements adjacent to the active elements. They are grouped as active elements and operated while connected. According to the invention described in claim 1, at any beam angle, it becomes possible to reduce power consumption while maintaining side lobe suppression performance by tracking and suppressing the grating lobe, and to compensate for the gain that tends to degrade as a result of such reduction in power consumption. [Brief explanation of the drawing]

[0010] [Figure 1] System configuration diagram of a radar device showing a schematic representation of one embodiment. [Figure 2] An electrical configuration diagram schematically showing the transmitting unit in one embodiment. [Figure 3] An electrical configuration diagram schematically showing the receiving unit of one embodiment. [Figure 4] A schematic diagram (base design) showing the arrangement of elements constituting a receiving antenna array in one embodiment. [Figure 5] Diagram illustrating the arrangement dimensions of the elements constituting the receiving antenna array in one embodiment. [Figure 6] Diagram illustrating the first stage in configuring the optimized arrangement in one embodiment. [Figure 7] Diagram illustrating the second stage in configuring the optimized arrangement in one embodiment. [Figure 8] A schematic diagram showing the optimized arrangement of elements in one embodiment. [Figure 9] Comparison of beam pattern simulation results in the front direction of the H-plane in one embodiment (Stage 1 vs. Stage 2) [Figure 10] Comparison of grating lobe suppression simulation results when the beam is directed in the E-plane 17.5° direction in one embodiment (64CH all ON vs. 40CH ON (low power consumption operation)). [Figure 11]This figure shows a comparison of the characteristics of the element arrangement configuration in one embodiment with those of the base design (Base design (64CH) vs. the present invention (40CH)). [Modes for carrying out the invention]

[0011] The following describes an embodiment in which a high-frequency antenna array is applied to the radar device 1, with reference to the drawings. The radar device 1 is mounted at a predetermined location on a vehicle and is used as a long-range radar (LRR) that scans a predetermined range of approximately 10 m to several hundred m, or as a short-range radar.

[0012] As illustrated in Figure 1, the vehicle radar system 1 comprises a control circuit 2, a signal generation unit 3, a transmission unit 4, a reception unit 5, a signal processing unit 6, a receiving antenna array 107, and a transmitting antenna array 207. The receiving antenna array 107 of the radar system 1 calculates the distance to the target T, the angle of presence, etc., by combining the signals from the channels of each receiving RX, for example, by having multiple channels of receiving RX.

[0013] The control circuit 2 is configured to function as an element control unit according to the present invention by executing a predetermined control logic, and performs various controls on the signal generation unit 3, the transmission unit 4, and the reception unit 5. At this time, it controls the frequency, amplification, phase value φ, etc., related to the radar device 1.

[0014] The signal generation unit 3, although not shown, includes, for example, a PLL and a frequency multiplier, and generates local signals to be output to the transmitting unit 4 and local signals to be output to the receiving unit 5. At this time, the same PLL supplies local signals to the mixer 8 of the receiving RX's channel. The local signals represent, for example, signals in the 77 GHz band.

[0015] The transmitting unit 4 is a variable gain amplifier 11, as shown in Figure 2. (Equivalent to a variable gain section)It includes a variable gain amplifier 11, a phase shifter 12, and an amplifier 13, and is connected to the transmission antenna array 207 through the pad 10. The variable gain amplifier 11 is configured to be able to adjust the amplification degree based on the control of the control circuit 2 and inputs the TX signal of the signal generation unit 3. The phase shifter 12 shifts the output phase of the variable gain amplifier 11 and can change its phase value φ based on the control of the control circuit 2. The amplifier 13 is a so-called power amplifier and amplifies the output signal of the phase shifter 12.

[0016] An element of the transmission antenna array 207 is electrically connected to the phase shifter 12 through the amplifier 13. The transmission antenna array 207 is composed of a phased array antenna with on-elements connected adjacent to each other in pairs and a single on-element connected separately, and can output the radar towards the target T. The radar wave reflected by the target T is input to the receiving antenna array 107.

[0017] The receiving unit 5 shown in FIG. 1 is connected to the receiving antenna array 107 through the pad 20 shown in FIG. 3. The receiving unit 5 has the same form for each of the plurality of receiving RX channels. As shown in FIG. 3, each receiving unit 5 includes a variable gain amplifier 14 (Equivalent to a variable gain section) a phase shifter 15, and an amplifier 16. The phase shifter 15 is electrically connected to the receiving antenna array 107 through the variable gain amplifier 14.

[0018] When the receiving unit 5 receives a signal from the receiving antenna array 107, the variable gain amplifier 14 amplifies the signal received from the receiving antenna array 107, and the phase shifter 15 shifts the amplified signal of the variable gain amplifier 14 by the phase value φ. Then the amplifier 16 amplifies the phase-shifted signal of the phase shifter 15 and outputs it to the mixer 8 for each receiving RX channel. [[ID=​​On the other hand, when the signal generation unit 3 outputs a local signal to the receiving unit 5, the LO amplifier 9 amplifies the local signal and outputs it to the mixer 8. The mixer 8 mixes the output of amplifier 16 and the output of LO amplifier 9 and outputs it as an IF signal to the signal processing unit 6. The signal processing unit 6 shown in Figure 1 is composed of a processor or predetermined electronic control logic, similar to the control circuit 2.

[0020] The signal processing unit 6 processes the IF signal processed by the mixer 8 using an IF filter (not shown), then performs A / D conversion, and subsequently uses the FFT result to perform signal processing such as digital beamforming (DBF), thereby measuring the distance to the target T, the relative velocity to the target T, and the angle of presence of the target T.

[0021] The control circuit 2 can control the beam scanning angle of the transmitting antenna array 207 and the receiving antenna array 107 by controlling the phase value φtx of the phase shifter 12 of the transmitting unit 4 and the phase value φrx of the phase shifter 15 of the receiving unit 5 for each receiving channel. The control circuit 2 controls the phase shifters 12 and 15 By turning the power supply between the element and each element on or off, the phase shifters 12 and 15 are switched on and off for each element It is configured to be electrically configurable to be on or off.

[0022] In this case, a narrow virtual beam is formed within the sector region, allowing for the identification of the scanned target T with higher resolution. Because the field of view can be narrowed to the sector region, the computational load can be reduced compared to conventional MIMO radar. The hybrid method can be considered an efficient scanning technique that mitigates the trade-off between reduced scan time and high resolution capability. Furthermore, it is possible to apply multi-signal classification (MUSIC), which provides higher separation capabilities than the aforementioned DBF, to multiple targets T.

[0023] The following describes the element arrangement of the base design 7a of the receiving antenna array 107 used in such a radar device 1. As shown in Figure 4, the receiving antenna array 107 is used as a phased array antenna and is composed of on-elements 11a and 11c that are electrically connected to the receiving unit 5, and off-elements 11b that are not electrically connected to the receiving unit 5. Off-elements 11b are elements that are electrically disconnected from the receiving unit 5 and are therefore turned off. In Figures 4 and 5, the areas with filled rectangular frames indicate the elements 11a that are grouped together, and the isolated on-elements 11c are shown with hatching. Off-elements 11b are shown with solid lines and do not have hatching inside.

[0024] On-element 11a is a grouping on-element, equivalent to an effective element, and on-element 11c is a single on-element, equivalent to an effective element. The on-elements 11c are provided in pairs spaced apart in the Y direction, which is a specific direction, and this pair of on-elements 11c corresponds to a pair of single on-elements. Off-element 11b is equivalent to a dummy element. The electrical line lengths from each on-element 11a, 11c to the mixer 17 of the receiving unit 5 should be configured as equal-length paths so that they are in equal phase.

[0025] As shown in Figure 4, each element 11a to 11c of the receiving antenna array 107 has a rectangular metal surface. The outer frame of the receiving antenna array 107 is rectangular, and the rectangular elements 11a to 11c are arranged in the grid-like vertex regions within the outer frame of the receiving antenna array 107. In this embodiment, as shown in Figure 4, the on-elements 11a and 11c are arranged in a predetermined two-dimensional region divided into 16 rows and 12 columns, but the embodiment is not limited to this. Furthermore, the outer frames of the receiving antenna array 107 and the transmitting antenna array 207 have the same shape. Note that Figure 5 shows an excerpt of the receiving antenna array 107 shown in Figure 4.

[0026] The transmitting antenna array 207 shown in Figure 1 is also used as a phased array antenna and is composed of on-elements electrically connected to the transmitting unit 4 and off-elements not electrically connected to the transmitting unit 4. The electrical line lengths from the output of the phase shifter 12 of the transmitting unit 4 to each on-element should be configured to be equal in length so that they are in equal phase.

[0027] Each element of the transmitting antenna array 207 also has a rectangular metal surface. The outer frame of the transmitting antenna array 207 is rectangular, and rectangular on-elements or off-elements are arranged in the grid-like vertex regions within the outer frame of the transmitting antenna array 207. It is desirable that the on-elements of the transmitting antenna array 207 be arranged to complement the arrangement of the on-elements 11a and 11c of the receiving antenna array 107, but this explanation is omitted as it is not related to the features of the present invention.

[0028] The elements 11a to 11c of the receiving antenna array 107 are each configured such that the distance between the centers of adjacent elements 11a to 11c is set to half the radar wavelength λ, and each element 11a to 11c is configured in a rectangular shape. The elements of the transmitting antenna array 207 are similar, but are not shown here. The diagram shows each element 11a to 11c configured in a rectangular shape, but they may also be configured in a hexagonal or octagonal shape. The transmitting antenna array 207 and the receiving antenna array 107 are arranged along the XY plane, and transmit beams in the +Z axis direction or receive beams from the +Z axis direction, which is perpendicular to the XY plane.

[0029] In this embodiment, the receiving antenna array 107 is simply shown in Figures 3 and 4, but dummy elements (not shown) may be separately placed on the outermost edge of the two-dimensional array of the receiving antenna array 107. Dummy elements, as referred to here, are elements that are not connected to the receiving unit 5, similar to the off-elements 11b. By placing dummy elements on the outermost edge of the two-dimensional array, the quality of the received signal using the receiving antenna array 107 can be improved. Similarly, dummy elements may be separately placed on the transmitting antenna array 207.

[0030] In this configuration, the number of on-elements 11a and 11c that require phase shift control is reduced by devising a two-dimensional arrangement of on-elements 11a and 11c and off-elements 11b, thereby simplifying phase shift control. In the following description, as shown in Figure 4, the columns of the receiving antenna array 107 are referred to as columns X1 to X12, and the rows of the receiving antenna array 107 are referred to as rows Y1 to Y16. When indicating the arrangement area of ​​elements 11a to 11c, it is represented by a two-dimensional arrangement of coordinates (X,Y).

[0031] As shown in Figure 4, for example, in column X2, if the on-element 11a of row Y2 and the on-element 11a of row Y3 are electrically connected and grouped, the negative sign used to connect them, such as "Y2-Y3", indicates that the on-elements 11a are grouped in a specific direction, and that these on-elements 11a have their phase values ​​controlled by the same phase shifter 15.

[0032] The on-elements 11a and 11c of the base design 7a of the receiving antenna array 107 shown in Figure 4 are connected to the receiving unit 5 by a transmission line using a printed circuit board. This allows the beam to be received with directionality by combining and receiving energy from a desired angle via the on-elements 11a and 11c of the receiving antenna array 107.

[0033] <Detailed description of the arrangement structure of on-elements 11a and 11c in the base design 7a of the receiving antenna array 107> Next, referring to Figure 4, the placement of the on-elements 11a and 11c in the base design 7a will be explained in detail. As shown in Figure 4, the receiving antenna array 107 has its center of all rows located between row Y8 and row Y9, and its center of all columns located between column X6 and column X7. The on-elements 11a and 11c of the base design 7a are arranged symmetrically above and below the center of these rows, and symmetrically left and right with respect to the center of the columns. Furthermore, the on-elements 11a and 11c are arranged point-symmetrically with respect to the center of the receiving antenna array 107.

[0034] Specifically, in the base design 7a, the on-element 11a in the left half region shown in the diagram is: Coordinates (X1, Y3-Y4) and coordinates (X1, Y13-Y14), Coordinates (X2, Y2-Y3) and coordinates (X2, Y14-Y15), Coordinates (X2, Y5-Y6) and coordinates (X2, Y11-Y12), Coordinates (X2, Y8-Y9), Coordinates (X3, Y4-Y5) and coordinates (X3, Y12-Y13), Coordinates (X3, Y7-Y8) and coordinates (X3, Y9-Y10), They are located in a symmetrical arrangement, both vertically and horizontally.

[0035] Furthermore, the on-element 11a is, Coordinates (X4, Y1-Y2) and coordinates (X4, Y15-Y16), Coordinates (X4, Y3-Y4) and coordinates (X4, Y13-Y14), Coordinates (X4, Y6-Y7) and coordinates (X4, Y10-Y11), Coordinates (X5, Y4-Y5) and coordinates (X5, Y12-Y13), Coordinates (X5, Y6-Y7) and coordinates (X5, Y10-Y11), Coordinates (X5,Y8-Y9), Coordinates (X6, Y2-Y3) and coordinates (X6, Y14-Y15), Coordinates (X6, Y7-Y8) and coordinates (X6, Y9-Y10), They are located in a symmetrical arrangement, both vertically and horizontally.

[0036] Furthermore, in the base design 7a, the on-element 11a in the right half region shown in the diagram is Coordinates (X12, Y3-Y4) and coordinates (X12, Y13-Y14), Coordinates (X11, Y2-Y3) and coordinates (X11, Y14-Y15), Coordinates (X11, Y5-Y6) and coordinates (X11, Y11-Y12), Coordinates (X11, Y8-Y9), Coordinates (X10, Y4-Y5) and coordinates (X10, Y12-Y13), Coordinates (X10, Y7-Y8) and coordinates (X10, Y9-Y10), They are located in a symmetrical arrangement, both vertically and horizontally.

[0037] Furthermore, the on-element 11a is, Coordinates (X9, Y1-Y2) and coordinates (X9, Y15-Y16), Coordinates (X9, Y3-Y4) and coordinates (X9, Y13-Y14), Coordinates (X9, Y6-Y7) and coordinates (X9, Y10-Y11), Coordinates (X8, Y4-Y5) and coordinates (X8, Y12-Y13), Coordinates (X8, Y6-Y7) and coordinates (X8, Y10-Y11), Coordinates (X8, Y8-Y9), Coordinates (X7, Y2-Y3) and coordinates (X7, Y14-Y15), Coordinates (X7, Y7-Y8) and coordinates (X7, Y9-Y10), They are located in a symmetrical arrangement, both vertically and horizontally.

[0038] The grouping direction of the on-element 11a is configured with the Y direction as a specific direction, and there is no grouping in the X direction. Therefore, effective elements are arranged at a λ / 2 pitch in the X direction, and grating lobes GL do not occur in principle. In this embodiment, the X direction corresponds to the second direction, the transverse direction, and the Y direction corresponds to the first direction, the vertical direction.

[0039] The transmission line has a branch point at the point where the transmission line connected to the pair of on-elements 11a is routed in the inner layer of the PCB multilayer board, and the phase center of the grouped pair of on-elements 11a is located in the center of the coordinates of the two grouped elements, and the phase value to be set corresponds to the average of the phase values ​​of the two elements before grouping. The transmission line is constructed using the wiring configured on the printed circuit board, and in this case, it is desirable that the electrical line lengths of the transmission line connecting the IC pad and the pair of on-elements 11a be equal in length to each other or have a relationship of p × λ (where p is an integer) to ensure equiphase.

[0040] As illustrated in Figure 4, the on-elements 11c are arranged in pairs with a specific spacing within the receiving antenna array 107. A single on-element 11c is equivalent to two single on-elements, which are arranged in isolation, spaced apart in the same Y direction as the grouped on-elements 11a, and are arranged symmetrically with respect to the center of the row.

[0041] On-elements 11c are provided in pairs at coordinates (X6, Y5) and (X6, Y12). On-elements 11c are also provided in pairs at coordinates (X7, Y5) and (X7, Y12). The distance d1 between the centers of the on-elements 11c in row Y5 and row Y12 is 3.5λ. These on-elements 11c, spaced 3.5λ apart at specific intervals, act as steerable null filters capable of generating nulls at the generation angle θ1 of the first grating lobe GL. See Figure 10 for the generation angle θ1 of the grating lobe GL.

[0042] Furthermore, on-elements 11c are provided in pairs at coordinates (X5, Y1) and (X5, Y16). Similarly, on-elements 11c are provided in pairs at coordinates (X8, Y1) and (X8, Y16). The distance d2 between the centers of the on-elements 11c in row Y1 and row Y16 is 7.5λ. These on-elements 11c, separated by 7.5λ, act as a second null filter that generates nulls.

[0043] On-elements 11c are provided in pairs at coordinates (X3, Y2) and (X3, Y15). Similarly, on-elements 11c are provided in pairs at coordinates (X10, Y2) and (X10, Y15). Since the row-to-row or column-to-column distance between adjacent elements 11a to 11c is 0.5λ, the distance d3 between the centers of the on-elements 11c in row Y3 and row Y15 is 6.5λ. These on-elements 11c, separated by 6.5λ, act as a third null filter that generates nulls.

[0044] Thus, the on-elements 11c are single elements spaced apart, but the Y-direction distances d1 to d3 between the centers of these on-elements 11c are set to a specific interval of (0.5+m)λ (where m is an integer). That is, the on-elements 11c are arranged symmetrically from the center of the receiving antenna array 107 at intervals of (0.5+m)λ (where m=1, 2, ...).

[0045] Furthermore, it has been confirmed that intentionally setting m to 3 or greater is desirable in order to increase the density of on-elements 11a and 11c in the central part. By setting m to 3 or greater, the effective elements in the central part of the receiving antenna array 107 can be made denser, making it possible to take measures to suppress side lobes. Figure 4 shows examples of m=3, 6, and 7. In addition, in order to change the characteristics of the null filter, it is desirable to provide multiple sets of on-elements 11c in the receiving antenna array 107 that satisfy the condition of having different m values. Since the grating lobe GL has an angular width, it is possible to suppress the grating lobe GL, which has an angular width, by stacking null filters with different attenuation characteristics near the generation angle of the grating lobe GL.

[0046] Figure 5 shows an excerpt of the element arrangement in columns X6 and X7. The on-elements 11a of adjacent rows Y7-Y8 in the Y direction are controlled so that the phase value φ from the phase shifter 12 of the transmitting TX and the phase shifter 15 of the receiving RX are the same. The phase center of the on-elements 11a of rows Y7-Y8 is at an intermediate position between rows Y7 and Y8. Since the same signal is applied to the on-elements 11a of rows Y9-Y10, the phase center of the on-elements 11a of rows Y9-Y10 is at an intermediate position between rows Y9 and Y10.

[0047] Since the inter-element distances for rows Y7-Y8 and Y9-Y10 are λ / 2, the phase center spacing d of the on-element 11a in rows Y7-Y8 and Y9-Y10 is twice λ / 2, which is λ. When the theoretical grating lobe angle GL is calculated when the main beam angle is changed, the resulting grating lobe angle GL is equivalent to that when the relationship between the phase center spacing d and the radar wavelength λ is designed with d=1λ, which in principle could lead to the generation of a strong grating lobe GL.

[0048] This phenomenon is caused by the drawback of designing the phase shifter 15 to group adjacent elements in the Y direction in order to reduce the number of phase shifters 15. However, as mentioned above, by inserting a single on-element 11c, the λ periodicity of the phase center spacing d can be disrupted. It has been confirmed that this can reduce the grating lobe GL by several dB. Furthermore, it has been confirmed that the on-element 11c has attenuation characteristics as a steerable null filter and can track and suppress the grating lobe GL.

[0049] According to the configuration of the base design 7a of the receiving antenna array 107 in this embodiment, a single on-element 11c is positioned spaced apart from a pair of adjacent on-elements 11a along the Y direction. This reduces the uniformity of the phase center spacing when the on-elements 11a are grouped, allowing for tracking and suppression of the grating lobe GL. By designing the on-element 11a density to be higher in the center and lower at the four corners, a smaller number of phase shifters 15 can be used, and side lobe performance can be kept low. From the perspective of tapering, the design that eliminates on-elements 11a and 11c at the four corners is also effective. This is because, due to the distance from the center of the receiving antenna array 107, a large amount of attenuation would be required in the internal variable gain amplifier 14 to achieve tapering.

[0050] Thus, the receiving antenna array 107 is configured based on the base design 7a, but the inventors have further attempted to reduce the number of phase shifters 15 connected to the on-elements 11a and 11c. Reducing the number of phase shifters 15 connected to the on-elements 11a and 11c in the aforementioned arrangement will reduce the number of operating phase shifters 15, thereby lowering power consumption.

[0051] The inventors applied Monte Carlo element failure analysis as the first step to the base design 7a of such a large-scale receiving antenna array 107. This allowed them to learn the arrangement of on-elements 11a and 11c that are strongly related to performance at major beam angles. They also performed computer simulations to optimize the effective element arrangement by extracting on-elements 11a and 11c that show little performance degradation even when the electrical connection to the elements is turned off.

[0052] Furthermore, if such on-elements 11a and 11c are derived and the number of on-elements 11a and 11c is reduced compared to the base design 7a, there is concern that various characteristics such as gain will deteriorate. Therefore, as a second step, the inventors have taken the off-element 11b adjacent to the on-elements 11a and 11c that were deemed effective in the first step. In contrast Extend and group on elements 11a and 11c Operate in this state (hereinafter, the phrase "extended and grouped" means "operate in a grouped state"). The simulation is being conducted with this in mind.

[0053] The following sections describe the simulation conditions and results for the first and second stages. <Explanation of the simulation conditions and results for the first stage> In the first stage, element failure analysis is performed using the Monte Carlo method to extract on-elements 11a and 11c whose characteristics do not deteriorate significantly even if they are turned off. In this simulation, constraints are set to maintain the characteristics of the grating lobe GL and side lobe suppression effect of the base design 7a described above (maintaining upper and lower pairs of null filters and having multiple null filters), and under these constraints, the conditions in which the characteristics are optimized are searched for while randomly reducing the on-elements 11a and 11c in the base design 7a of the receiving antenna array 107.

[0054] Furthermore, the inventor performs a coherency test in this simulation method to verify the accuracy of gain degradation that depends on the number of elements turned on in the receiving antenna array 107. In this test method, for example, in Figure 4, the initial state is one in which all on elements of the receiving antenna array 107 are electrically turned off, and a total of 64 channels, including single on elements, are turned on sequentially, with pairs of on elements considered as one unit. Then, the relative gain when the elements are turned on sequentially can be obtained. At this time, if the relative phases are aligned when the elements are turned on sequentially, ideally the theoretical value of 20log can be obtained. 10 An array gain of N (N=64) can be obtained. Using this method, we have been able to confirm that the trends of the theoretical and measured values ​​are in agreement.

[0055] One of the constraints of the simulation method in the first stage is to maintain performance that suppresses grating lobes (GL) while reducing the number of element channels activated by applying E-plane 17.5°V as the maximum beam angle in the same direction as grouping. This is because it is assumed that this will be performed within a practical range when applied to a typical vehicle radar. In addition, simulations were also performed applying the maximum beam angle up to an H-plane 60°H angle to verify whether a wide FoV can be secured.

[0056] The second constraint is that when setting an isolated single on-element 11c to OFF relative to the base design 7a, the single on-elements 11c that are provided in pairs in the Y direction must be reduced as a pair. This is because on-elements 11c function as a null filter when provided in pairs at specific intervals. In fact, the inventors have confirmed through repeated Monte Carlo calculations that on-elements 11c with low scores that cannot exist as a pair lose the suppression effect of the grating lobe GL.

[0057] Under the aforementioned constraints, the inventor performs element failure analysis using the Monte Carlo method, randomly reducing the arrangement of on-elements 11a and 11c in the base design 7a and performing beam analysis. This allows the inventor to accumulate, learn, and score the arrangements of on-elements 11a and 11c that can be turned off while minimizing performance degradation, and then perform simulations. This allows the inventor to extract on-elements 11a and 11c that can be turned off and derive an arrangement of on-elements 11a and 11c that appropriately maintains various characteristics even when the number of channels in the phase shifter 15 is reduced.

[0058] Figure 6 shows the results after the first stage of simulation. Here, the simulation results are shown in which the number of channels of the phase shifter 15 used has been optimized from 64 channels to 40 channels. In Figure 6, the base design 7a of the receiving antenna array 107 is shown on the left, and the optimization results of the receiving antenna array 107 after the first stage of simulation are shown on the right.

[0059] In the simulation results shown on the right side of Figure 6, the off-elements 11ab and 11cb, indicated by thick white rectangular borders, represent elements that have been turned off, respectively, from the on-elements 11a and 11c in the base design 7a. Here, the element that has been turned off from the paired on-element 11a is shown as off-element 11ab, and the element that has been turned off from the single on-element 11c is shown as off-element 11cb.

[0060] As shown in arrangement 7b in the right diagram of Figure 6, compared to the base design 7a, we can derive on elements 11a and 11c that can be turned off, and by turning off these on elements 11a and 11c and operating them, we can significantly reduce the number of on elements 11a and 11c that need to be operated.

[0061] This arrangement 7b results in a larger number of on-elements 11a connected in the Y direction being thinned out. Furthermore, it has been found that the single on-elements 11c at coordinates (X3, Y2) and (X3, Y15) can be turned off as a pair. Additionally, the elements at coordinates (X8, Y1) and (X8, Y16) can be turned off as a pair, as can the elements at coordinates (X10, Y2) and (X10, Y15). Even when these on-elements 11a and 11c are turned off, the number of phase shifters 15 can be reduced while maintaining various characteristics as much as possible. Moreover, in the first stage simulation, it has been confirmed that the side lobes can be further reduced by introducing randomness in the arrangement of the off-elements 11b.

[0062] <Explanation of the simulation conditions and results for the second stage> By performing the first stage simulation, on-elements 11a and 11c that can be switched off while appropriately maintaining various characteristics can be derived, and power consumption can be reduced by decreasing the number of channels of the phase shifter 15 that are operated. However, in this case, the number of on-elements 11a and 11c that are operated will be reduced compared to the base design 7a, so there is a concern about degradation of gain.

[0063] Therefore, in the second stage, the inventors perform simulations to compensate for the gain by extending the on-elements 11a and 11c to the adjacent off-elements 11b, 11ab, and 11ca, while satisfying other predetermined constraints. The first constraint in this case is that an on-element 11a paired in the Y direction extends only one more off-element 11b, 11ab, or 11ca in the same direction, i.e., adjacent in the Y direction. In other words, the constraint is that when an on-element 11a is extended in the Y direction, the number of groupings in the Y direction must be 3.

[0064] The second constraint is that when an isolated single on-element 11c is extended, it can only be extended by one point in the direction orthogonal to the Y direction, i.e., in the X direction. This stems from the fact that the base design 7a has single on-elements 11c paired together. The reason for pairing the single on-elements 11c in the first place is to form a null filter and reduce the sidelobe level. In this case, even if extended in the X direction, the distance between the paired single on-elements 11c can be maintained, and the function as a null filter can be preserved. Moreover, by extending the on-elements 11c laterally, the number of elements that can function effectively can be increased, thereby increasing the gain.

[0065] Under these constraints, the inventor performed simulations by conducting element failure analysis using the Monte Carlo method. The right side of Figure 7 and Figure 8 show the optimized element arrangement results as optimized arrangement 7c. The left side of Figure 7 shows the optimized arrangement 7b from the first stage of simulation, and the right side of Figure 7 shows the optimized arrangement 7c from the second stage of simulation.

[0066] The inventors used the Monte Carlo method to perform numerous trials and optimize the arrangement of on-elements 11a and 11c, resulting in the optimized arrangement 7c of on-elements 11a, 11c, 11ac, and 11cc shown in the right-hand figure of Figure 7.

[0067] In the right-hand diagram of Figure 7, elements that have been expanded in the X or Y direction after the second-stage simulation, in particular, from the arrangement 7b of the first-stage simulation results shown in the left-hand diagram of Figure 7, are labeled as on-elements 11ac and 11cc, with hatching in a black frame and arrows indicating the direction of expansion. In Figures 7 and 8, on-element 11ac represents an element that has been expanded in the Y direction from on-element 11a, and on-element 11cc represents an element that has been expanded in the X direction from on-element 11c.

[0068] Figure 8 shows the results for these on-elements 11a, 11c, 11ac, and 11cc with a modified representation. The optimized configuration 7c shown in Figure 8 has the same configuration as the optimized configuration 7c shown on the right side of Figure 7, but for ease of understanding, on-elements 11a and 11ac are shown with black outlines, and on-elements 11c and 11cc are shown with hatching over the black outlines. The extended on-element 11cc is located at coordinates (X6, Y1) and (X6, Y16). In this optimized configuration 7c as well, on-elements 11c and 11cc remain as a pair, separated at a specific interval in the Y direction.

[0069] Let's compare the base design 7a shown in Figure 4 with the optimized configuration 7c shown in Figure 8. In the optimized configuration 7c, on-elements 11c and 11cc remain as a pair at coordinates (X6,Y5) and (X6,Y12), and further remain as a pair at coordinates (X7,Y5) and (X7,Y12).

[0070] Furthermore, in the optimized configuration 7c, on-elements 11c and 11cc remain as pairs at coordinates (X5,Y1), (X5,Y16), and (X6,Y11). However, on-element 11c does not remain as a pair at coordinates (X8,Y1) and (X8,Y16), nor at coordinates (X10,Y2) and (X10,Y15). Moreover, in the optimized configuration 7c, on-element 11c does not remain as a pair at coordinates (X3,X2) and (X3,X15). It is particularly desirable to retain two or more pairs of on-element 11c. By doing so, the suppression effect of the grating lobe GL by the null filter can be maintained.

[0071] Figure 9 shows the comparison of characteristics in the H-plane centered on Boresight after the first and second stage simulations. As shown in Figure 9, it has been confirmed that the peak characteristic P of Boresight can be improved by approximately 1.8 dB. As shown in Figure 10, it has been confirmed that the grating lobe GL appears near a predetermined angle θ1 when the E-plane is 17.5°V. When the base design 7a is adopted, at the angle θ1 shown, the grating lobe GL is suppressed by the action of null filters, single on-elements 11c and 11cc, which are spaced apart by a specific interval of 3.5λ. As shown in Figure 10, even when the optimized arrangement 7c is adopted, the level of this grating lobe GL is almost identical to the characteristics of the base design 7a.

[0072] Figure 11 shows a comparison of characteristics between the case where base design 7a is adopted and the case where optimized arrangement 7c is adopted. As shown in Figure 11, it can be confirmed that equivalent characteristics are obtained for both the beam width and directivity gain of the H-plane and E-plane centered on Boresight. Furthermore, it has been confirmed that almost equivalent characteristics are obtained for both the beam width and directivity gain of the H-plane and E-plane at 60°H, and also for both the beam width and directivity gain of the H-plane and E-plane at 17.5°V.

[0073] When the base design 7a is adopted for the receiving antenna array 107, it is possible to operate by providing 64 phase shifters 15 for 64 channels, i.e., 64 units. Even with this base design 7a, the number of operating phase shifters 15 can be reduced by 67% to 33% compared to conventional technology. Furthermore, by applying the Monte Carlo simulation methods of the first and second stages described above and optimizing the number of operating phase shifters 15 to 40 channels, it is possible to reduce the number by approximately 20% compared to conventional methods.

[0074] If the control circuit 2 controls the receiving antenna array 107 to operate with 40 channels in the optimized configuration 7c, rather than operating with 64 channels, the number of phase shifters 15 that need to be installed can be reduced, thus eliminating waste.

[0075] According to the simulation results of the first stage, operating with 40 channels increases the loss by several dB compared to 64-channel operation. However, by performing the simulation results of the second stage and expanding the elements, the gain can be compensated for, and as mentioned above, characteristics that are not inferior to those obtained when using base design 7a can be obtained. Furthermore, in the aforementioned coherency test, a good agreement trend was obtained between the measured values ​​and the theoretically calculated values. As a result, the degradation of the main lobe can be minimized, and a wide FoV can be maintained.

[0076] <Summary of this embodiment> According to this embodiment, the optimized arrangement 7c of the receiving antenna array 107 is based on a base design 7a in which on-elements 11a and 11c are set to suppress grating lobes GL. Therefore, even if the number of off-elements 11b is increased in the first stage and the number of on-elements 11a is expanded in the second stage, the suppression function of grating lobes GL, which is already suppressible in the base design 7a, can be maintained, and the directional gain can be compensated. The receiving antenna array 107 can further suppress sidelobe levels by adding randomness to the turning off of elements.

[0077] While the base design 7a requires 64 phase shifters 15, the antenna array 7 configuration of this embodiment can operate using only 40 phase shifters 15, thus reducing the number of phase shifters 15 that need to be actively operated. If the receiving antenna array 7 is not operated with 64 channels but with 40 channels using the optimized arrangement 7c, the number of phase shifters 15 to be installed can be reduced, eliminating waste. This allows for lower power consumption and simplifies system control.

[0078] According to this embodiment, since the on-element 11c extends the grouping to adjacent elements in a direction orthogonal to the specific direction while maintaining a specific interval in that specific direction, the phase center does not change in the Y direction in principle, the specific interval between the pair of on-elements 11c can be maintained, and the suppression function of the grating lobe GL by the base design 7a can be maintained.

[0079] According to this embodiment, the on-elements 11c and 11cc are arranged at specific intervals in a specific direction, and multiple pairs are configured in that specific direction to form a null filter. Multiple null filters can be combined, enabling the suppression characteristics of the grating lobe GL to be adapted to a wide range of angles. The characteristics of the grating lobe GL suppression function based on the base design 7a can be retained.

[0080] As a result, the control circuit 2 controls the on-connection and off-connection of each element 11a to 11c of the receiving antenna array 107 as shown in the optimized arrangement 7c, thereby operating the receiving antenna array 107 and obtaining the radar characteristics shown in the simulation described above. The control circuit 2 controls the on-connection and off-connection of each element 11a to 11c as shown in the simulation results described above, and may switch between settings as in the base design 7a or as in the optimized arrangement 7c depending on changes in the environment in which it is located.

[0081] (Other embodiments) The embodiments described above are not limited to those described above, and for example, the following modifications or extensions are possible. In the embodiment described above, a configuration in which the on-elements 11a are expanded to three along a specific direction and grouped is shown, but it is not limited to three; they may be expanded to four or more and grouped. Although a configuration in which the on-elements 11a are expanded in the vertical direction (Y direction) has been described, it is not limited to this. The on-elements 11a may also be expanded and grouped in a direction orthogonal to the specific direction. It is not necessary to expand and group the on-elements 11a in a straight line; they may be grouped in an L-shape, or expanded and grouped in a box shape of 2x2 or more. By expanding the on-elements 11a to four in a 2x2 configuration, the gain performance in the Y direction can be improved.

[0082] Furthermore, since it has been found that extending the elements in the Y direction is advantageous, the optimized arrangement 7c shown in the above embodiment has more advantageous characteristics. This is because the optimized arrangement 7c in the above embodiment extends the on-element 11a to the off-element 11b adjacent in the Y direction and groups them with respect to the base design 7a, and by extending in the Y direction, the horizontal scanning performance is not adversely affected, and a good balance of performance can be achieved.

[0083] This disclosure is described in accordance with the embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the equivalence. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and concept of this disclosure. [Explanation of Symbols]

[0084] In the drawing, 2 is the control circuit, 107 is the receiving antenna array (antenna array), 7a is the base design, 11a, 11c, 11ac, and 11cc are on-elements (11a is the active element, 11c is the single on-element), and 11b, 11ab, and 11cb are off-elements.

Claims

1. An antenna array (7) comprising elements (11a to 11c, 11ab, 11cb) that are electrically connected on or off with respect to a phase shifter (15) by a variable gain unit, Based on a base design (7a), the effective elements (11a) are configured by being grouped adjacently along a specific vertical or horizontal direction in a two-dimensional array and controlled by the same phase shifter, and the single-on elements (11c) are provided separately from the effective elements and arranged at specific intervals in the specific direction. An antenna array for a high-frequency device, configured such that the number of elements set as off-elements (11ab, 11cb) that are not electrically connected to the phase shifter is increased compared to the base design (7a), thereby reducing the number of effective elements (11a) or single-on elements (11c) compared to the base design, and operating with the off-elements adjacent to the effective elements grouped together and connected as effective elements.

2. The antenna array for a high-frequency device according to claim 1, wherein the single on-element is grouped with adjacent elements in a direction orthogonal to the specific direction while maintaining the specific spacing in the specific direction.

3. The antenna array for a high-frequency device according to claim 1 or 2, wherein the single on-elements are arranged in the specific direction at specific intervals, and a null filter is formed by arranging multiple pairs in the specific direction.

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