Antenna device, vehicle, and signal processing method

Abstract

The objective is to improve the gain of an antenna while suppressing the degradation of the signal-to-noise ratio of signals received or transmitted by an antenna mounted on the roof of a vehicle. [Solution] The antenna device is installed on the roof of the vehicle. An opening is provided in the sheet metal that makes up the roof. The antenna device comprises a first antenna provided at a position that overlaps with the opening in a plan view of the roof, and a second antenna provided at a position that does not overlap with the opening in a plan view of the roof.

Description

Technical Field

[0001] The present invention relates to an antenna device, a vehicle, and a signal processing method.

Background Art

[0002] Patent Document 1 discloses an antenna installed on the roof of a vehicle. By the way, when an antenna is installed on the roof of a vehicle, the distance between the sheet metal (conductor) constituting the roof and the antenna element is close, and the gain of the antenna decreases.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Therefore, it is conceivable to provide an opening in the sheet metal constituting the roof and install an antenna above this opening to suppress a decrease in gain. However, if an opening is provided in the sheet metal constituting the roof, there is a possibility that the opening functions as a slot antenna. Then, there is a possibility that the antenna installed on the roof and the opening functioning as a slot antenna are coupled or resonate. As a result, there has been a problem that the noise of the electrical signal generated in vehicle equipment or the like provided in the vehicle acts on the antenna through the opening, and the signal-to-noise ratio (SN ratio) of the signal transmitted and received by the antenna deteriorates. An aspect of the disclosed embodiment is to improve the gain of the antenna while suppressing the deterioration of the signal-to-noise ratio of the signal received or transmitted in the antenna installed on the roof of the vehicle.

Means for Solving the Problems

[0005] Embodiments of the disclosure are exemplified by an antenna device installed on the roof of a vehicle. In this device, an opening is provided in the sheet metal that makes up the roof. The antenna device comprises a first antenna provided at a position that overlaps with the opening in a plan view of the roof, and a second antenna provided at a position that does not overlap with the opening in a plan view of the roof. [Effects of the Invention]

[0006] The first antenna, positioned in a location that overlaps with the opening in a plan view of the roof, has a higher gain than the second antenna, but is more susceptible to noise. On the other hand, the second antenna, positioned in a location that does not overlap with the opening in a plan view of the roof, has a lower gain than the first antenna, but is less susceptible to noise. By using such a first and second antenna in combination, this antenna device can improve antenna gain while suppressing the degradation of the signal-to-noise ratio of received or transmitted signals, even when installed on the roof of a vehicle. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a projection view illustrating the structure of the antenna device according to the first embodiment. [Figure 2] Figure 2 illustrates the configuration of a signal processing method for signals transmitted and received via the antenna device of the first embodiment, and a control device that performs the signal processing method. [Figure 3] Figure 3 is a projection view illustrating the structure of the antenna device according to the second embodiment. [Figure 4] Figure 4 is a projection view illustrating the structure of the antenna device according to the second embodiment. [Figure 5] Figure 5 illustrates the configuration of a control device that implements the control method for the antenna system of the second embodiment. [Figure 6] Figure 6 illustrates the configuration of an antenna system that implements the signal processing method of the third embodiment. [Figure 7] Figure 7 illustrates the structure of an antenna device in a comparative example. [Modes for carrying out the invention]

[0008] The antenna device 1 will be described below with reference to the drawings.

[0009] <Comparative Example> Referring to Figure 7, an antenna device 301 according to a comparative example will be described. Figure 7 is a diagram illustrating the structure of the comparative example antenna device 301. The antenna device 301 is mounted on the roof 2 of the vehicle C1 illustrated in Figure 7. Vehicle C1 is a typical automobile. The roof 2 is the outer panel of the roof portion of vehicle C1 and is a metal outer panel (also called "sheet metal"). At least a part of the roof 2 may be curved. The antenna device 301 is a shark fin antenna, having an antenna element (also simply called "element") 312 inside a cover that has an external appearance resembling a shark's dorsal fin. The antenna device 301 may further include a circuit board containing an amplifier, etc. The cover of the antenna device 301 is to be bonded to the roof 2. The element 312 is, for example, a linear conductor. Element 312 may be an inverted L-shaped antenna formed by bending the element of a quarter-wavelength monopole antenna at a 90-degree angle, or it may be an inverted F-shaped antenna fed from the midpoint, a helical coil, a plate antenna, etc.

[0010] An opening A1 is formed in the roof 2 along the direction in which the element 312 extends. In other words, a portion of the sheet metal of the roof 2 is cut out. Furthermore, the opening A1 is provided along the element 312 so as to surround it when viewed from above ("top" in Figure 7) to below ("bottom" in Figure 7) the roof 2 in the direction normal to the surface of the roof 2. That is, the opening A1 is formed in the area of ​​the sheet metal of the roof 2 that includes the orthogonal projection of the element 312 on the roof 2 and its surroundings. The position and size of the opening A1 are preferably centered on the portion directly below the element 312 and including the surrounding portion, but it is sufficient if 90% or more of the orthogonal projection of the element 4 is included in the opening A1 when viewed from above. For example, if the element 312 is an inverted L-shaped antenna, the end on the feed point side or the tip end furthest from the feed point may be located outside the opening 21. In Figure 7, the shape of the aperture A1 is rectangular, and its longer side is aligned with the direction in which the linear element 312 extends. Note that the shape of the aperture A1 is not limited to a rectangle; it may also be an oval shape such as an ellipse or oblong, and the orientation of the aperture A1 is such that its longitudinal direction is aligned with the element 312. If element 312 is an inverted L-shaped antenna, the end of element 312 on the feed point side is insulated and positioned around the edge of the aperture A1. If element 312 is an inverted F-shaped antenna, the end of element 312 on the ground side is positioned around the edge of the aperture A1. Also, if element 4 is an inverted F-shaped antenna, the feed line can be connected to the middle part (feed point) of element 4 by passing through the aperture A1.

[0011] The opening A1 in the roof 2 may be closed by the roof cover 323. The roof cover 323 is formed flush with the surface of the roof 2, for example, using a filler that easily transmits radio waves. The material of the roof cover 323 is preferably a dielectric material with radio wave transparency, such as resin.

[0012] As in this comparative example, by providing an opening A1 in the roof 2 directly below the element 312, the decrease in the gain of the antenna device 301 can be suppressed even when the element 312 is placed relatively close to the roof 2. In other words, the performance of the antenna device 301 installed on the roof 2 of the vehicle C1 can be improved. Furthermore, the weight of the roof 2 (and consequently the weight of the vehicle C1) can be reduced.

[0013] However, it is assumed that the roof 2 of vehicle C1, which includes aperture A1, acts as a slot antenna. For example, when vehicle equipment such as a motor for driving mounted on vehicle C1 operates and generates noise, the antenna device 301 installed on the roof 2 and aperture A1, which functions as a slot antenna, may couple or resonate. As a result, it cannot be ruled out that noise generated by vehicle equipment such as the motor may act on the antenna device 301 via aperture A1, potentially worsening the signal-to-noise ratio (SNR) of the transmitted and received signals of the antenna device 301.

[0014] <First Embodiment> An antenna device 1 and an antenna system 10 according to the first embodiment will be described with reference to Figures 1 and 2. Figure 1 is a projection view illustrating the structure of the antenna device 1 of the first embodiment. However, Figure 1 also illustrates a part of the roof 2 of the vehicle on which the antenna device 1 is mounted. In Figure 1, part D1 is a front view of the antenna device 1, and part D2 is a plan view. In part D1 of Figure 1, the direction to the right with respect to the plane of the paper (Figure 1) is the X-axis direction of the coordinate axes, and the direction upward is the Y-axis direction. The Y-axis direction is also the vertically upward direction. Furthermore, following the right-hand rule, the direction that extends forward from the plane of the paper is the Z-axis direction. On the other hand, in part D2, the direction that extends forward from the plane of the paper is the Y-axis direction, and the direction downward with respect to the plane of the paper (Figure 1) is the Z-axis direction. Therefore, part D2 (plan view) is a plan view of the roof 2 when viewed from above (positive Y-axis direction in part D2) in the direction normal to the surface of the roof 2, looking downward (negative Y-axis direction in part D2). Note that the direction of the coordinate axes is the same in Figures 3 and 4.

[0015] The antenna device 1 has a flat chassis 11 and a pair of antenna elements 12A and 12B attached to the chassis 11. The pair of antenna elements 12A and 12B are also collectively referred to as the antenna element 12. The antenna elements 12A and 12B are each an antenna of a type called a plate-shaped inverted L-shaped antenna, having a structure in which the middle of an element of a plate-shaped monopole antenna is bent at 90 degrees and a cross-section in the shape of an inverted L. That is, the antenna device 1 has a configuration in which two antenna devices 301 illustrated in FIG. 7 are arranged in parallel. The antenna elements 12A and 12B are each an example of a first antenna and a second antenna.

[0016] Therefore, when the antenna elements 12A and 12B are each attached to the roof 2 of the vehicle, they have a portion extending vertically upward (Y-axis direction) from the upper surface of the chassis 11 and a portion extending horizontally in parallel with the chassis 11 after being bent at 90 degrees. The flat chassis 11 is a dielectric (insulator) such as resin, and the antenna elements 12A and 12B are insulated from each other and electrically separated. Although omitted in FIG. 1, the antenna elements 12A and 12B each have an independent feeding point and can be independently connected to a cable.

[0017] However, similar to the antenna device 301, the antenna device 1 may be a shark fin antenna in which the antenna elements 12A and 12B are provided inside a cover having a shape like a shark's dorsal fin. Also, the antenna elements 12A and 12B may be an inverted F-shaped antenna fed from a midpoint, a helical coil, a plate-shaped antenna, or the like. However, in each of the following embodiments, the antenna device 1 is illustrated as having inverted L-shaped antenna elements 12A and 12B or the like.

[0018] The roof 2 is a part of the vehicle body and is a sheet metal made of metal. In this embodiment, an opening A1 is formed in the metal roof 2 of the vehicle. That is, the vehicle has a vehicle body in which an opening is provided in the sheet metal constituting the roof 2. The opening A1 is also referred to as an opening portion. Note that a dielectric such as resin is fitted into the opening A1. In the partial view D1 (front view), the opening A1 is illustrated by a dotted line. Also, above the opening A1 (vertically upward), the roof 2 pedestals 3A and 3B made of the same material as the roof 2 are provided and fixed to the roof 2.

[0019] The chassis 11 of the antenna device 1 is fixed to the roof 2 via the pedestals 3A and 3B. As a result of the chassis 11 being fixed to the pedestals 3A and 3B and the roof 2, the antenna device 1 is mounted on the roof 2. Among the antenna device 1, the arrangement position of the antenna element 12A is directly above the portion of the roof 2 where there is no metal material due to the opening A1 in a plan view with respect to the roof 2.

[0020] Therefore, when transmitting and receiving electromagnetic waves from the feeding point of the antenna element 12A, the gain of the antenna (for example, the sensitivity during reception) is improved as compared with the case where there is no opening A1. On the other hand, when transmitting and receiving electromagnetic waves from the feeding point of the antenna element 12A, the noise becomes larger as compared with the case where there is no opening A1.

[0021] On the other hand, the arrangement position of the antenna element 12B is vertically above the portion where the metal material exists, which is outside the opening A1 of the roof 2 in a plan view with respect to the roof 2. Therefore, when transmitting and receiving electromagnetic waves from the feeding point of the antenna element 12B, the gain of the antenna (for example, the sensitivity during reception) is smaller than that of the antenna element 12A, but the noise is suppressed.

[0022] Figure 2 illustrates the configuration of a signal processing method for signals transmitted and received via the antenna device 1 of this embodiment, and a control device that performs the signal processing method. This control device includes antenna elements 12A and 12B, a switching means 6 acting as a switch interposed between the transceiver and the transceiver, and a control unit 5 as an example of a controller that controls the switching means 6.

[0023] As shown in Figure 1, there is an opening A1 directly below the antenna element 12A, and there is no metal material of the roof 2. On the other hand, directly below the antenna element 12B, there is space away from the opening A1, and the metal material of the roof 2 is present. In this embodiment, the antenna device 1, the control unit 5, and the switching means 6 are referred to as the antenna system 10. The antenna system 10 is an antenna device 1 with additional components and is also an example of an antenna device.

[0024] The switching means 6 is a semiconductor switch, relay, etc. The switching means 6 connects either the terminal connected to the feed point of antenna element 12A or the terminal connected to the feed point of antenna element 12B to the transceiver. In other words, the switching means 6 selects the received signal from either antenna element 12A as the first antenna or antenna element 12B as the second antenna and connects it to the transceiver. The switching means 6 also causes the transmission signal from the transceiver to be radiated as an electromagnetic wave from either antenna element 12A or antenna element 12B.

[0025] The control unit 5 includes, for example, a Central Processing Unit (CPU) and memory. 5 may also be called an Electronic Control Unit (ECU). Control unit 5 is a memo. The control unit 5 executes the computer program and provides the functions of the control unit 5. The control unit 5 acquires vehicle information from an in-vehicle network such as a CAN bus, and instructs the switching means 6 to switch the connection state according to the acquired vehicle information. If the control unit 5 can determine from the vehicle information that a specific vehicle device is operating, for example, it connects the transceiver to the antenna element 12B. Here, the specific vehicle device is, for example, a motor that generates the driving force to move the vehicle. The specific vehicle device is not limited to a motor for driving, as long as it is expected to be a source of noise. For example, the specific vehicle device may be an engine with a spark plug, because noise may be generated by the ignition of the spark plug when the engine is running.

[0026] For example, when a specific vehicle device is operating, the control unit 5 switches the switching means 6 to output the received signal from the antenna element 12B to the transceiver. In this case, the control unit 5 also supplies the signal power of the transmitted signal from the transceiver to the antenna element 12B and transmits the transmitted signal as electromagnetic waves radiated from the antenna element 12B. When vehicle devices such as the driving motor are operating, a large amount of noise such as inverter noise (also called electromagnetic noise) is generated. In this embodiment, noise in electrical signals, that is, random or unpredictable fluctuations of electrical signals, is referred to as noise. When such noise is generated, the signal-to-noise ratio (SNR) of the antenna element 12A, which has no shielding directly below its mounting position, deteriorates. Therefore, the control unit 5 uses the antenna element 12B, which can suppress the deterioration of the SNR.

[0027] On the other hand, if vehicle information indicates that certain vehicle equipment, such as the drive motor, is not operating, the control unit 5 connects the transceiver to the antenna element 12A. That is, the control unit 5 switches the switching means 6 to output the received signal from the antenna element 12A to the transceiver. In this case, the control unit 5 transmits the transmission signal from the transceiver using electromagnetic waves radiated from the antenna element 12A. Through this control, the control unit 5 can perform high-quality transmission and reception using the high-gain antenna element 12A when the drive motor and other equipment are not operating and the generation of noise such as inverter noise is low.

[0028] As described above, in this embodiment, an opening A1 is provided in the sheet metal constituting the roof 2 of the vehicle. The antenna device 1 of this embodiment includes an antenna element 12A provided at a position overlapping with the opening A1 in a plan view of the roof 2, and an antenna element 12B provided at a position not overlapping with the opening A1. Therefore, the antenna device 1 can be provided by combining an antenna element 12A, which has high gain but may degrade the signal-to-noise ratio, and an antenna element 12B, which has low gain but is less likely to degrade the signal-to-noise ratio. As a result, with this combination, when the antenna device 1 is installed on the roof 2 of a vehicle, the degradation of the signal-to-noise ratio of the received or transmitted signal can be suppressed while improving the gain of the antenna device 1.

[0029] Furthermore, the antenna system 10 includes a switching means 6 that acts as a switch to select and output the signal of either antenna element 12A or antenna element 12B to the antenna device 1, and a control unit 5 that controls the switching means 6. The control unit 5 switches and controls the switching means 6 according to whether or not a specific vehicle device is operating, based on vehicle information acquired from an in-vehicle network such as the vehicle's CAN bus.

[0030] In other words, when a specific vehicle device is operating, the control unit 5 selects antenna element 12B, which does not have an opening A1 directly below it and is located on the metal sheet metal of the roof 2, and connects it to the transceiver. In this case, the metal sheet metal of the roof 2 directly below antenna element 12B allows the control unit 5 to suppress noise from specific vehicle devices, such as the motor, from degrading the signal-to-noise ratio of the signals transmitted and received from the antenna device 1.

[0031] On the other hand, when no specific vehicle equipment is operating, the control unit 5 selects antenna element 12A, which has an opening A1 directly below it and no metal sheet metal on the roof 2, and connects it to the transceiver. As a result, when there is little possibility of noise generation from specific vehicle equipment, such as a motor, the antenna system 10 can perform high-quality transmission and reception using antenna element 12A, which has no metal sheet metal on the roof 2 directly below it and has high gain.

[0032] (modified version) In the first embodiment described above, an antenna device 1 was illustrated in which a pair of antenna elements 12A and 12B are mounted on a single chassis 11. However, the configuration of the antenna device 1 is not limited to this configuration. For example, the antenna device 1 may consist of a pair of antenna elements The antennas 12A and 12B may be attached to a pair of chassis 11A and 11B, respectively, resulting in two independent antenna devices 1A and 1B. In short, it is sufficient for each antenna device 1A and 1B to be mounted in two locations: directly above the opening A1 of the roof 2, and on the upper side of the metal sheet metal of the roof 2, spaced apart from the opening A1. With such independent and separated antenna devices 1A and 1B, the antenna device 1 can be mounted more flexibly than in the example in Figure 1.

[0033] <Second Embodiment> Referring to Figures 3 to 5, the antenna device 1 and antenna system 10 according to the second embodiment will be described. Figures 3 and 4 are projection views illustrating the structure of the antenna device 1 of the second embodiment. However, Figures 3 and 4 also illustrate a part of the roof 2 of the vehicle on which the antenna device 1 is mounted and the antenna system 10. In Figures 3 and 4, partial figure D1 is a front view of the antenna device 1, partial figure D2 is a plan view, and partial figure D3 is a right side view. Also, in Figures 3 and 4, the definition of the coordinate axes is the same as in Figure 1. Therefore, in partial figure D3, the left direction toward the plane of the paper is the Y-axis direction, which is the vertically upward direction. That is, in partial figure D3, the right direction of the roof 2 (negative Y-axis direction) is the direction of the vehicle interior.

[0034] In the first embodiment described above, the antenna device 1 had a pair of antenna elements 12A and 12B. Antenna element 12A was positioned to overlap with the opening A1 in a plan view of the roof 2, while antenna element 12B was positioned not to overlap with the opening A1. In this embodiment, the antenna device 1 has a single antenna element 12. The shape of the antenna element 12 is similar to that of antenna elements 12A and 12B in Figure 1, with an inverted L-shaped cross-section. However, as described in the first embodiment, the antenna element 12 is not limited to an inverted L-shaped antenna.

[0035] On the other hand, in this embodiment, a shutter 7 capable of closing the opening A1 of the vehicle's roof 2, and a motor 8A and gear 8B acting as a manipulator to drive the shutter 7 are provided on the vehicle. In this embodiment, the antenna device 1, shutter 7, motor 8A, gear 8B, and control unit 5 in Figure 6 are referred to as the antenna system 10. The antenna system 10 is an antenna device 1 with additional components and is also an example of an antenna device. Furthermore, the motor 8A and gear 8B are referred to as the shutter drive unit 8.

[0036] Figure 3 illustrates a state in which the shutter 7 does not close the opening A1. That is, as illustrated in partial figure D3 (right side view), the shutter 7 is able to swing or rotate around an axis 8C that extends along the longitudinal edge of the opening A1 (arrow AR). Here, swinging or rotating means reciprocating movement in an arc-shaped path around the axis.

[0037] In other words, the shutter 7 is a plate-shaped structure that closes the opening A1, has a rectangular shape in plan view, and has a rotatable shaft 8C on one of its longitudinal sides. Therefore, in the state shown in Figure 3, where the shutter 7 does not close the opening A1, the two shorter sides of the rectangular shape hang down into the vehicle's interior. That is, when the motor 8A drives the gear 8B and lowers the shutter 7 into the vehicle's interior, the opening A1 is not closed by the shutter 7.

[0038] Figure 4 illustrates the state in which the shutter 7 is closing the opening A1. Motor 8A drives gear 8B, moving the plate-shaped surface of the shutter 7 so that it is parallel to the sheet metal of the roof 2, thereby closing the opening A1. In Figure 4, the shutter 7 appears to be parallel to the sheet metal of the roof 2, and there appears to be a gap between the shutter 7 and the roof 2. However, in reality, the shutter 7 is installed so that it is parallel to the sheet metal of the roof 2, there is no gap between the shutter 7 and the roof 2, and the shutter 7 closes the opening A1.

[0039] Figure 5 illustrates the configuration of a control device that implements the control method for the antenna system 10 of this embodiment. This control device includes a shutter drive unit 8 that swings or rotates the shutter 7 around an axis 8C, and a control unit 5 that controls the shutter drive unit 8. The configuration of the control unit 5 is the same as in the first embodiment.

[0040] The shutter drive unit 8 includes a motor 8A and a gear 8B as illustrated in Figures 3 and 4. The control unit 5 inputs a control signal to the motor 8A that specifies the rotation angle of the motor 8A's rotation axis, making it possible to position the motor 8A's rotation axis at any angle. The motor 8A may be a servo motor or a stepping motor.

[0041] Antenna device 1 is mounted on the roof 2 directly above opening A1, as shown in Figures 3 and 4. Antenna device 1 inputs the received signal to the transceiver. Antenna device 1 is also powered by the transceiver and radiates the transmitted signal.

[0042] The control unit 5, as in Figure 2, acquires vehicle information from an in-vehicle network such as a CAN bus, and controls the shutter drive unit 8 according to the acquired vehicle information. For example, if the control unit 5 can determine from the vehicle information that a specific vehicle device is operating, it drives the shutter 7 to close the opening A1. The specific vehicle device is, as in the first embodiment, a motor for driving, an engine, etc. When the motor for driving, etc. is operating, a large amount of noise such as inverter noise is generated. Therefore, if there is no shielding directly below the mounting position, the signal-to-noise ratio of the antenna device 1 deteriorates, so the control unit 5 closes the opening A1 with the shutter 7 to suppress the deterioration of the signal-to-noise ratio. In this case, the gain of the antenna device 1 decreases.

[0043] On the other hand, if vehicle information indicates that a specific vehicle device is not operating, the control unit 5 opens the shutter 7 to increase the gain of the antenna device 1 because there is less noise inside the vehicle.

[0044] As described above, the antenna system 10 of this embodiment has a shutter 7 capable of closing an opening A1 formed directly below the antenna device 1 mounted on the roof 2 of the vehicle. When a specific vehicle device is operating, the control unit 5 drives the shutter 7 to close the opening A1. In this way, by closing the opening A1, the control unit 5 suppresses the deterioration of the signal-to-noise ratio of the signals transmitted and received through the antenna device 1 when there is a high possibility that noise will be generated by a specific vehicle device.

[0045] On the other hand, if a specific vehicle device is not operating, the control unit 5 opens the shutter 7 to increase the gain of the antenna device 1. In this way, the control unit 5 improves the quality of the transmitted and received signals by increasing the gain of the antenna device 1 when there is little possibility of noise being generated by a specific vehicle device.

[0046] (modified version) In this embodiment, the shutter drive unit 8 has a motor 8A and a gear 8B as illustrated in Figures 3 and 4. The shutter 7 is also pivotable or rotatable around an axis 8C that extends along the longitudinal edge of the opening A1. The motor 8A and gear 8B drive the shutter 7, moving it so that two of its rectangular sides hang down into the vehicle's interior and the plate-like surface of the shutter 7 is parallel to the sheet metal of the roof 2. However, the opening and closing of the opening A1 by the shutter 7 is not limited to this mechanism. For example, the shutter drive unit 8 may move the shutter 7 horizontally while maintaining its parallel position to the sheet metal of the roof 2. For example, the shutter 7 may slide on a rail parallel to the sheet metal of the roof 2. The shutter 7 may also have wheels that rotate on the rail, or bearings for sliding. The shutter drive unit 8 may also open and close the opening A1 by reciprocating the shutter 7 on the rail.

[0047] <Third Embodiment> Referring to Figure 6, the antenna system 10 according to the third embodiment will be described. Figure 6 is a diagram illustrating the configuration of the antenna system 10 that performs the signal processing method of the third embodiment. In this embodiment, the antenna system 10 has an antenna device 1 similar to that of the second embodiment. Also, similar to the second embodiment, the antenna device 1 of this embodiment is mounted directly above the opening A1 of the roof 2 of the vehicle. Therefore, similar to Figures 3 and 4, the antenna element 12 of the antenna device 1 is included in the range of the opening A1 in a plan view relative to the roof 2.

[0048] In this embodiment, the antenna system 10 further uses aperture A1 as a slot antenna. The antenna system 10 includes an adjustment unit 9A that adjusts the signal acquired by aperture A1, a subtractor 9B that subtracts the signal adjusted by the adjustment unit 9A from the signal received by the antenna device 1, and a control unit 5 that controls the adjustment unit 9A. The configuration of the control unit 5 is the same as in the first embodiment.

[0049] The adjustment unit 9A adjusts the amplitude and phase of the signal (noise N2) from aperture A1 and generates the adjusted signal (alpha*N2). Here, alpha is a complex number coefficient that adjusts the amplitude and phase. The subtractor 9B subtracts the adjusted signal (alpha*N2) from the received signal (S1+N1) received by the antenna device 1. The adjustment unit 9A is, for example, a Digital Signal Processor (DSP).

[0050] The control unit 5 processes the signal (S1 + N1 - alpha * N2) input from the subtractor 9B to the transceiver. The complex coefficient alpha is calculated to reduce the noise component, and an instruction is given to the adjustment unit 9A. Section 5 can, for example, be processed as an adaptive filter.

[0051] The adaptive filter receives a signal (S1 + N1 - alpha * N2) that is fed back to the control unit 5. The amplitude and phase of the noise N2 are adjusted by the coefficient alpha to minimize them. In this case, When the noise (N1) in the received signal (S1+N1) obtained by antenna device 1 cancels out with the adjusted signal (alpha*N2), the feedback signal (S1+N1-alpha*N2) becomes minimal and approaches signal S1.

[0052] More specifically, the control unit 5 incorporates an adaptive algorithm, and according to this adaptive algorithm, the coefficients of the adaptive filter (F) are adjusted so that the signal (S1 + N1 - alpha * N2) approaches its minimum. Adjust the filter parameter (also called the filter parameter) to determine the coefficient alpha. Various methods have been proposed for Gorism (for example, see Japanese Patent Publication No. 11-259078, by Isao Nakanishi, IEICE "Forest of Knowledge" Group 1, Chapter 3 (https: / / www.ieice-hbkb.org / files / 01 / 01gun_09hen_03m.pdf (accessed March 22, 2024))).

[0053] However, the processing of the control unit 5 is not limited to adaptive algorithms. For example, the complex coefficient alpha for canceling noise (N1) using the signal (noise N2) acquired from aperture A1 may be determined experimentally or empirically. For example, an anechoic chamber where electromagnetic waves do not reach. In this case, it is desirable that the coefficient alpha be determined such that the received signal received by the antenna device 1 is minimized when a specific vehicle device mounted on the vehicle is in operation. Then, the control unit 5, The noise (N1) may be canceled by a coefficient alpha determined experimentally or empirically.

[0054] As described above, in this embodiment, the antenna system 10 is formed directly below the antenna device 1 mounted on the roof 2 of the vehicle, and acquires noise (N2) from an aperture A1 that encloses the antenna element 12 in a plan view relative to the roof 2. The antenna system 10 then adjusts the amplitude and phase of the noise (N2), and uses the adjusted signal (alpha*N2) to antenna The noise (N1) in the received signal (S1+N1) received by device 1 is canceled. In this way, the antenna system 10 increases the gain (sensitivity) of the antenna device 1 by the aperture A1 of the roof 2, and the noise (N1) mixed into the received signal (S1+N1) is suppressed due to the effect of aperture A1. [Explanation of Symbols]

[0055] 1. Antenna equipment 2 Roof 3A, 3B pedestal 5. Control Unit 6. Switching means 7 shutters 8. Shutter drive unit 8A motor 8B Gear 8C axis 9A adjustment part 9B Subtractor 11 Chassis 12, 12A, 12B antenna elements

Claims

1. An antenna device installed on the roof of a vehicle, An opening is provided in the sheet metal that constitutes the roof. A first antenna is provided in a position that overlaps with the opening in a plan view of the roof, The roof comprises a second antenna located in a position that does not overlap with the opening in a plan view of the roof. Antenna device.

2. A switch that selects and outputs the signal from either the first antenna or the second antenna, The system further includes a control unit that controls the aforementioned switch, The control unit, based on information acquired from the vehicle, selects the signal received by the second antenna when a specific vehicle device is operating, and selects the signal received by the first antenna when the specific vehicle device is not operating, and controls the switch to output the selected signal, as described in claim 1. Antenna device.

3. The specific vehicle equipment is a motor that generates a driving force for moving the vehicle, as described in claim 2. Antenna device.

4. A vehicle body in which an opening is provided in the sheet metal that makes up the roof, An antenna device comprising a first antenna provided at a position overlapping with the opening in a plan view of the roof, and a second antenna provided at a position not overlapping with the opening in a plan view of the roof, has vehicle.

5. A controller mounted on a vehicle in which an opening is provided in the sheet metal that makes up the roof, based on information acquired from the vehicle, When a specific vehicle device is not operating, the system selects the signal received by the first antenna, which is located in a position overlapping with the opening in a plan view of the roof. When the aforementioned specific vehicle equipment is operating, the signal received by the second antenna, which is located in a position that does not overlap with the opening in a plan view of the roof, is selected. A signal processing method that outputs the selected signal.

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