Vehicle Antenna Module

Abstract

The vehicle-mounted antenna module comprises: a plate-like component, fixed to the body of the vehicle, at least a portion of which is plate-like; and multiple antennas, arranged on the plate-like component, any multiple of the multiple antennas arranged on the plate-like component constitute a first diversity antenna for receiving RF (Radio Frequency) signals in a first frequency band, and at least any two of the multiple antennas constituting the first diversity antenna are respectively arranged in two areas that are not adjacent to each other when a plane possessed by the plate-like component is divided into four quadrants around the center of the plane.

Description

Technical Field

[0001] The present disclosure relates to a vehicle-mounted antenna module.

[0002] This application claims the benefit of priority based on Japanese patent application No. 2020-97808, filed on June 4, 2020, the disclosure of which is incorporated herein in its entirety. Background Art

[0003] Japanese Patent Application Laid-Open No. 2009-224908 (Patent Document 1) discloses a terrestrial digital television receiving system as follows. That is, the receiving system includes one or two antennas consisting of a first antenna and a second antenna for receiving terrestrial digital television signals, a first amplifier consisting of a first bandpass filter and a first amplifier circuit connected to the first antenna, a second amplifier consisting of a second bandpass filter and a second amplifier circuit connected to the second antenna, and a synthesis processing unit for synthesizing the signals amplified by the first amplifier and the second amplifier, wherein the first bandpass filter of the first amplifier has at least one characteristic of a wider bandwidth and a flatter out-of-band attenuation characteristic than the second bandpass filter, the first amplifier is an amplifier with high receiving sensitivity, the second bandpass filter of the second amplifier has at least one characteristic of a narrower bandwidth and a steeper out-of-band attenuation characteristic than the first bandpass filter, the second amplifier has a greater interference wave removal function than the first amplifier, the second amplifier circuit connected to the second bandpass filter is an amplifier circuit with a bypass switch or an amplifier circuit subjected to gain control, and the second amplifier is an amplifier with a higher interference wave removal function with a wider dynamic range than the first amplifier.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2009-224908 Summary of the invention

[0007] The vehicle-mounted antenna module disclosed in the present invention comprises: a plate-like component, fixed to the body of the vehicle, at least a portion of which is plate-like; and multiple antennas, arranged on the plate-like component, any multiple of the multiple antennas arranged on the plate-like component constitute a first diversity antenna for receiving RF (Radio Frequency) signals of a first frequency band, and at least any two of the multiple antennas constituting the first diversity antenna are respectively arranged in two areas that are not adjacent to each other when the plane of the plate-like component is divided into four quadrants around the center of the plane.

[0008] The vehicle-mounted antenna module disclosed in the present invention comprises: a plate-shaped component, which is fixed to the body of the vehicle and at least a part of which is plate-shaped; and a plurality of antennas, which are arranged on the plate-shaped component, and the plurality of antennas are arranged in an opening portion of a roof plate of the vehicle when viewed from above, and any plurality of the plurality of antennas constitute a first diversity antenna for receiving an RF signal of a first frequency band, and at least any two of the plurality of antennas constituting the first diversity antenna are respectively arranged in two areas that are not adjacent to each other when the opening portion is divided into four quadrants around the center of the opening portion when viewed from above.

[0009] One aspect of the present disclosure can be implemented not only as a vehicle-mounted antenna module having such a characteristic processing unit, but also as a method having the characteristic processing as steps, or as a program for causing a computer to execute the steps. In addition, one aspect of the present disclosure can be implemented as a semiconductor integrated circuit that implements a part or all of the vehicle-mounted antenna module, or can be implemented as a system including the vehicle-mounted antenna module. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic perspective view of a vehicle according to an embodiment of the present disclosure.

[0011] Figure 2 It is a cross-sectional view of a roof module according to an embodiment of the present disclosure.

[0012] Figure 3 It is an exploded perspective view of a roof module according to an embodiment of the present disclosure.

[0013] Figure 4 It is a plan view showing an example of the structure of the vehicle-mounted antenna module according to the embodiment of the present disclosure.

[0014] Figure 5 It is a plan view showing another example of the structure of the vehicle-mounted antenna module according to the embodiment of the present disclosure.

[0015] Figure 6 It is a diagram showing an example of the configuration of a circuit unit according to an embodiment of the present disclosure.

[0016] Figure 7 It is a diagram showing the directivity of the antenna involved in the embodiment of the present disclosure.

[0017] Figure 8 Graph showing directivity of the antenna according to the embodiment of the present disclosure.

[0018] Fig. 9 Graph showing directivity of the antenna according to the embodiment of the present disclosure.

[0019] Fig.10Graph showing directivity of the antenna according to the embodiment of the present disclosure.

[0020] Fig.11 This is a flowchart that defines an example of an operation procedure when a circuit unit in the vehicle-mounted antenna module according to an embodiment of the present disclosure selectively transmits an RF signal to a vehicle-mounted device. DETAILED DESCRIPTION

[0021] Conventionally, a reception system including a plurality of antennas and adopting a diversity method has been proposed.

[0022] [Problems to be Solved by the Present Disclosure]

[0023] In the technology described in Patent Document 1, it is not easy to precisely arrange the antennas constituting the diversity antenna on the vehicle. For example, the intervals between the antennas constituting the diversity antenna may deviate from the designed values, making it difficult to receive RF signals with high sensitivity.

[0024] The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide a vehicle-mounted antenna module capable of receiving RF signals with higher sensitivity.

[0025] [Effects of the present disclosure]

[0026] According to the present disclosure, it is possible to receive RF signals with higher sensitivity.

[0027] [Description of Embodiments of the Present Disclosure]

[0028] First, the contents of the embodiments of the present disclosure will be listed and described.

[0029] (1) An embodiment of the present disclosure relates to a vehicle-mounted antenna module comprising: a plate-shaped member fixed to a vehicle body, at least a portion of which is plate-shaped; and a plurality of antennas disposed on the plate-shaped member, wherein any plurality of the plurality of antennas disposed on the plate-shaped member constitute a first diversity antenna for receiving an RF signal in a first frequency band, and at least any two of the plurality of antennas constituting the first diversity antenna are respectively disposed in two areas that are not adjacent to each other when a plane of the plate-shaped member is divided into four quadrants around the center of the plane.

[0030] In this way, by configuring the antennas constituting the first diversity antenna to be respectively arranged in two areas that are not adjacent to each other when the plane of the plate-shaped member is divided into four quadrants, a plurality of antennas including the antennas pre-configured at desired positions on the plate-shaped member can be collectively mounted on the vehicle, so that, compared with, for example, the case where the antennas are individually configured on the vehicle, the antennas can be mounted on the vehicle with high accuracy in a manner that makes the spacing between them the same as the design value. Furthermore, the spacing between the two antennas constituting the first diversity antenna can be ensured in the limited configuration space on the plate-shaped member, and the correlation between the two antennas can be reduced. Therefore, the RF signal can be received with higher sensitivity.

[0031] (2) Preferably, two of the plurality of antennas constituting the first diversity antenna are provided on the plate-shaped member so as to sandwich the other antenna that receives an RF signal in a frequency band higher than the first frequency band.

[0032] Through such a structure, the antenna for receiving high-frequency RF signals can be set at a position close to the center of the plate-like component. Therefore, even if obstacles to the RF signals are set around the plate-like component, high-frequency RF signals that are generally difficult to diffract can be received with higher sensitivity.

[0033] (3) Preferably, any multiple of the multiple antennas arranged on the plate-like component constitute a second diversity antenna for receiving RF signals in a second frequency band higher than the first frequency band, and at least any two of the multiple antennas constituting the second diversity antenna are respectively arranged in two areas that are not adjacent to each other when the plane of the plate-like component is divided into four quadrants.

[0034] With such a configuration, RF signals of two frequency bands can be received with higher sensitivity using a diversity antenna.

[0035] (4) Preferably, the plurality of antennas constituting the first diversity antenna receive RF signals in a frequency band of fifth-generation mobile communications below 6 GHz or in a frequency band of mobile communications of a generation prior to the fifth-generation mobile communications.

[0036] Through such a structure, RF signals in the fifth-generation mobile communication frequency band below 6 GHz or the mobile communication frequency band of generations before the fifth-generation mobile communication, which are generally sent from a distant base station and incident on the vehicle antenna module from a low elevation angle, can be received with higher sensitivity.

[0037] (5) The vehicle-mounted antenna module involved in the embodiment of the present disclosure comprises: a plate-like component fixed to the body of the vehicle, at least a portion of which is plate-like; and a plurality of antennas arranged on the plate-like component, wherein the plurality of antennas are arranged in an opening portion of a roof panel of the vehicle when viewed from above, and any plurality of the plurality of antennas constitute a first diversity antenna for receiving an RF signal in a first frequency band, and at least any two of the plurality of antennas constituting the first diversity antenna are respectively arranged in two areas that are not adjacent to each other when the opening portion is divided into four quadrants around the center of the opening portion when viewed from above.

[0038] In this way, by configuring the antennas constituting the first diversity antenna to be respectively arranged in two areas that are not adjacent to each other when the opening of the top plate is divided into four quadrants in a plan view, a plurality of antennas including the antennas pre-arranged at desired positions on the plate-shaped member can be mounted on the vehicle in a concentrated manner, so that, compared with, for example, the case where the antennas are individually arranged on the vehicle, the antennas can be mounted on the vehicle with high accuracy in a manner that makes the spacing between them the same as the design value. Furthermore, the spacing between the two antennas constituting the first diversity antenna can be ensured in the limited arrangement space on the plate-shaped member, and the correlation between the two antennas can be reduced. Therefore, the RF signal can be received with higher sensitivity.

[0039] The following is an explanation of the embodiments of the present disclosure using the accompanying drawings. It should be noted that the same or equivalent parts in the drawings are marked with the same reference numerals, and their description is not repeated. In addition, at least a part of the embodiments described below can be arbitrarily combined.

[0040] [Structure and basic movements]

[0041] Figure 1 2 is a schematic perspective view of a vehicle according to an embodiment of the present disclosure. Figure 1 The vehicle 10 includes a vehicle body 12 and a roof module 20 .

[0042] The vehicle body 12 is a part that forms the outer shape of the vehicle 10. The vehicle body 12 may be a monocoque or a vehicle body mounted on a ladder frame. The vehicle body 12 is formed of, for example, a metal plate. The vehicle body 12 has an opening 13 at the roof portion of the vehicle 10. For example, the shape of the opening 13 is a square shape. The roof module 20 is embedded in the opening 13 of the vehicle body 12.

[0043] Figure 2 It is a cross-sectional view of a roof module according to an embodiment of the present disclosure. Figure 2 yes Figure 1 Section view along line AA. Figure 3 : is an exploded perspective view of a roof module according to an embodiment of the present disclosure. Figure 2 and Figure 3The roof module 20 includes a vehicle roof 22 , a radio wave shielding portion 30 , conductive elastic members 40 , 45 , and a vehicle-mounted antenna module 50 .

[0044] [Vehicle roof]

[0045] For example, the vehicle roof panel 22 is formed of resin. The shape of the vehicle roof panel 22 is a square plate. More specifically, the vehicle roof panel 22 has a shape corresponding to the opening 13 in a manner that can block the opening 13 of the vehicle body 12. The vehicle roof panel 22 is fixed to the vehicle body 12 by, for example, screwing in a state of being embedded in the opening 13.

[0046] The vehicle roof panel 22 has a square antenna opening 22h in the center portion in a plan view. The vehicle-mounted antenna module 50 is embedded in the antenna opening 22h. The antenna opening 22h is an example of an opening.

[0047] [Radio wave shielding part]

[0048] The radio wave shielding part 30 is fixed to the surface of the vehicle roof panel 22 on the vehicle cabin side. The shape of the radio wave shielding part 30 is a square plate. For example, the radio wave shielding part 30 has the same shape as the vehicle roof panel 22 in a plan view in a manner that can cover the entire surface of the vehicle roof panel 22 on the vehicle cabin side. It should be noted that the size of the main surface of the radio wave shielding part 30 can also be larger than the surface of the vehicle roof panel 22 on the vehicle cabin side, and can also be smaller than it.

[0049] The radio wave shielding part 30 has a square antenna opening 30h in the center portion when viewed from above. More specifically, the radio wave shielding part 30 has an antenna opening 30h at a position overlapping the antenna opening 22h when fixed to the vehicle cabin side surface of the vehicle roof panel 22. The vehicle-mounted antenna module 50 is embedded in the antenna opening 30h.

[0050] The radio wave shielding portion 30 has radio wave shielding properties. More specifically, the radio wave shielding portion 30 has shielding properties with respect to radio waves of a certain frequency. For example, the radio wave shielding portion 30 is formed by a frequency selective film (FSS: Frequency Selective Surface). The frequency selective film includes a base film formed of a resin or the like and a unit element formed on the base film of a metal foil or the like. The frequency selective film has the property of shielding radio waves of one or more frequency bands and transmitting radio waves of other frequency bands according to the frequency characteristics of the unit element.

[0051] For example, the radio wave shielding portion 30 has shielding properties against radio waves of frequencies used by multiple devices such as smartphones, mobile phones, and personal computers in the cabin of the vehicle 10 to communicate with each other. Specifically, the radio wave shielding portion 30 has shielding properties against radio waves in the frequency bands of Wi-Fi (registered trademark) communication and Bluetooth (registered trademark) communication. Alternatively, the radio wave shielding portion 30 has shielding properties against radio waves of frequencies used to provide contactless power supply to devices in the cabin. With such a structure, it is possible to suppress the propagation of radio waves output by devices on the cabin side to the outside of the vehicle.

[0052] It should be noted that the radio wave shielding part 30 may also have shielding properties against radio waves of all frequencies. In this case, the radio wave shielding part 30 is formed of metals such as aluminum and iron. In addition, the radio wave shielding part 30 may also include a sheet-like member having heat insulation and sound insulation properties.

[0053] [Conductive elastic member]

[0054] The conductive elastic members 40 and 45 have conductivity and elasticity. For example, the conductive elastic members 40 and 45 are rubber containing conductive fillers such as conductive carbon and metal powder.

[0055] The conductive elastic members 40 , 45 are provided along the edge of the vehicle roof panel 22 .

[0056] The conductive elastic member 40 is provided along the outer periphery of the vehicle roof panel 22. More specifically, the conductive elastic member 40 is provided between the outer periphery of the vehicle roof panel 22 and the edge of the opening 13 of the vehicle 10. For example, the conductive elastic member 40 is fixed therebetween by being sandwiched between the outer periphery of the vehicle roof panel 22 and the edge of the opening 13.

[0057] The conductive elastic member 45 is provided along the edge of the antenna opening 22h of the vehicle roof panel 22. More specifically, the conductive elastic member 40 is provided between the edges of the antenna opening 22h and the antenna opening 30h and the outer peripheral surface of the vehicle-mounted antenna module 50. For example, the conductive elastic member 45 is fixed between the edges of the antenna opening 22h and the antenna opening 30h and the outer peripheral surface of the vehicle-mounted antenna module 50 by being sandwiched therebetween.

[0058] [Vehicle Antenna Module]

[0059] The vehicle-mounted antenna module 50 includes a plate-shaped member 51 , a plurality of antennas 52 , a circuit unit 53 , and a housing 54 .

[0060] The plate-like member 51 is a member at least part of which is plate-like. For example, the shape of the plate-like member 51 is a square plate. A conductor layer 51a serving as a ground is formed of metal foil or the like on one main surface (for example, the surface on the vehicle compartment side) of the plate-like member 51. The conductor layer 51a has radio wave shielding properties.

[0061] The antenna 52 and the circuit unit 53 are provided on the plate-shaped member 51. For example, the antenna 52 and the circuit unit 53 are formed on the vehicle outer side surface of the plate-shaped member 51. The arrangement of the antenna 52 and the circuit unit 53 on the plate-shaped member 51 will be described later.

[0062] The housing 54 is formed of, for example, resin. The housing 54 covers the top, bottom, and surrounding of the plate-like member 51 and the antenna 52. More specifically, the housing 54 includes a flat bottom 54a and a main body 54b having a rectangular parallelepiped shape. The plate-like member 51 is fixed to the vehicle outer side surface of the bottom 54a. The main body 54b is fixed to the bottom 54a in a manner covering the plate-like member 51 when the plate-like member 51 is fixed to the bottom 54a. The bottom 54a protrudes outward from the main body 54b in a plan view when the main body 54b is fixed to the bottom 54a.

[0063] For example, the antenna opening 30h of the radio wave shielding portion 30 and the antenna opening 22h of the vehicle roof panel 22 have shapes substantially the same as the main body 54b of the housing 54 of the vehicle antenna module 50 in a plan view and are smaller than the bottom 54a of the housing 54.

[0064] The roof module 20 is manufactured by embedding the main body 54b of the shell 54 of the vehicle-mounted antenna module 50 from the vehicle compartment side to the antenna opening 30h and the antenna opening 22h. In more detail, the vehicle-mounted antenna module 50 is fixed to the radio wave shielding part 30 in a state of being embedded in the antenna opening 30h of the radio wave shielding part 30. For example, a conductive elastic member 45 is provided on the outer peripheral surface of the main body 54b of the shell 54 of the vehicle-mounted antenna module 50. In addition, a frame-shaped bracket is fixed to the outer peripheral portion of the shell 54 by screw fastening or the like. In addition, the edge of the antenna opening 30h of the radio wave shielding part 30 is sandwiched between the outer peripheral portion of the shell 54 and the bracket.

[0065] In addition, the vehicle-mounted antenna module 50 is embedded and fixed in the antenna opening 22h of the vehicle roof panel 22. More specifically, the main body 54b of the housing 54 of the vehicle-mounted antenna module 50 and the conductive elastic member 45 are embedded in the antenna opening 22h, and the radio wave shielding portion 30 is fixed to the vehicle cabin side surface of the vehicle roof panel 22. The roof panel module 20 manufactured in this way is fixed to the vehicle body 12 by, for example, screwing the vehicle roof panel 22 to the vehicle body 12.

[0066] The plate-shaped member 51 is fixed to the vehicle body 12 of the vehicle 10. More specifically, the roof module 20 is fixed to the vehicle body 12 by screwing the vehicle roof panel 22 to the vehicle body 12 in a state where the plate-shaped member 51 is fixed to the bottom portion 54a of the housing 54.

[0067] Figure 4 1 is a plan view showing an example of the structure of a vehicle-mounted antenna module according to an embodiment of the present disclosure. Figure 4 The vehicle-mounted antenna module 50 includes antennas 52a, 52b, 52c, 52d, 52e, 52f, and 52g as antennas 52. Each antenna 52 is connected to a circuit unit 53 via a transmission line (not shown). The antenna 52 is provided in an antenna opening 22h of the vehicle roof 22 in a plan view. For example, the antenna 52 and the circuit unit 53 are provided on the vehicle outer side surface of the plate-shaped member 51.

[0068] Here, in various countries including Japan, various communication services are allocated to different frequency bands. For example, AM broadcasting is allocated to 526.5kHz to 1606.5kHz, FM broadcasting is allocated to 76MHz to 108MHz, television broadcasting is allocated to 470MHz to 710MHz, satellite broadcasting is allocated to 2.3GHz, keyless entry is allocated to 315MHz and 433MHz, GPS (Global Positioning System) is allocated to 1.5GHz, fifth-generation mobile communication is allocated to the 3.5GHz band below 6GHz, fifth-generation mobile communication in the millimeter wave band is allocated to the 28GHz band, remote engine starter is allocated to 920MHz, fourth-generation mobile communication, which is the generation before fifth-generation mobile communication, is allocated to 0.8GHz, 1.5GHz, 1.7GHz and 2GHz, ITS (Intelligent Transport Systems) wireless is allocated to 760MHz and 5.9GHz, and ETC (Electronic Toll Collection system) is allocated to 5.8GHz. Hereinafter, the frequency band of the fifth generation mobile communication below 6 GHz is also referred to as "Sub6", and the mobile communication of the generation before the fifth generation mobile communication is also referred to as "TEL".

[0069] The antenna 52 is provided corresponding to different communication services. The antenna 52 can receive RF signals of a frequency band to which the corresponding communication service is allocated. For example, the antennas 52a and 52b correspond to TEL, the antennas 52c and 52d correspond to Sub6, the antenna 52e corresponds to ITS wireless in the 760MHz frequency band, the antenna 52f corresponds to ITS wireless in the 5.9GHz frequency band, and the antenna 52g corresponds to GPS.

[0070] Hereinafter, antenna 52a is also referred to as TEL antenna 52a, antenna 52b is also referred to as TEL antenna 52b, antenna 52c is also referred to as Sub6 antenna 52c, antenna 52d is also referred to as Sub6 antenna 52d, antenna 52e is also referred to as ITS760MHz antenna 52e, antenna 52f is also referred to as ITS5.9GHz antenna 52f, and antenna 52g is also referred to as GPS antenna 52g.

[0071] The circuit unit 53 transmits the RF signal received by the antenna 52 to, for example, a vehicle-mounted device (not shown) provided in the vehicle 10 for each communication service.

[0072] Any number of antennas 52 constitute a diversity antenna for receiving RF signals in the same frequency band. For example, TEL antenna 52a and TEL antenna 52b constitute a diversity antenna for receiving RF signals in the 2 GHz frequency band of TEL. In addition, for example, Sub6 antenna 52c and Sub6 antenna 52d constitute a diversity antenna for receiving RF signals in the Sub6, i.e., 3.5 GHz frequency band. The diversity antenna constituted by TEL antenna 52a and TEL antenna 52b is an example of a first diversity antenna. The diversity antenna constituted by Sub6 antenna 52c and Sub6 antenna 52d is an example of a second diversity antenna.

[0073] The 3.5 GHz frequency band of the RF signal received by the Sub6 antenna 52c and the Sub6 antenna 52d is a higher frequency band than the 2 GHz frequency band of the RF signal received by the TEL antenna 52a and the TEL antenna 52b.

[0074] The RF signal received by the diversity antenna is selectively transmitted to the vehicle-mounted device by the circuit unit 53. In more detail, when the signal strength g1 of the RF signal s1 received by a certain antenna constituting the diversity antenna is greater than a specified value, the circuit unit 53 selects the RF signal s1 and transmits it to the corresponding vehicle-mounted device. On the other hand, when the signal strength g1 is below the above-mentioned specified value and the signal strength g2 of the RF signal s2 received by the other antenna constituting the diversity antenna is greater than the above-mentioned specified value, the circuit unit 53 selects the RF signal s2 and transmits it to the corresponding vehicle-mounted device. On the other hand, when the RF signals received by the multiple antennas constituting the diversity antenna are below the above-mentioned specified value, the circuit unit 53 selects the RF signal with the highest signal strength among the RF signals received by the multiple antennas constituting the diversity antenna, and transmits the selected RF signal to the corresponding vehicle-mounted device.

[0075] The TEL antenna 52a and the TEL antenna 52b are respectively arranged in two areas that are not adjacent to each other when the plane of the plate-shaped member 51 is divided into four quadrants around the center O of the plane. In addition, the TEL antenna 52a and the TEL antenna 52b are respectively arranged in two areas that are not adjacent to each other when the antenna opening 22h is divided into four quadrants around the center of the antenna opening 22h in a plan view. In more detail, the TEL antenna 52a and the TEL antenna 52b are respectively arranged in areas Rg3 and Rg1 that are not adjacent to each other when the plane of the plate-shaped member 51 is divided by straight lines L1 and L2 that pass through the center O and are orthogonal to each other. For example, the straight line L1 is a straight line parallel to the first side of the rectangular plate-shaped member 51, and the straight line L2 is a straight line parallel to the second side of the rectangular plate-shaped member 51. For example, the straight line L1 is a straight line parallel to a first side of the rectangular antenna opening 22h, and the straight line L2 is a straight line parallel to a second side of the rectangular antenna opening 22h.

[0076] For example, the TEL antenna 52a and the TEL antenna 52b are provided at positions on the diagonal line D1 of the plate-shaped member 51. Specifically, for example, the center of the TEL antenna 52a and the center of the TEL antenna 52b are located on the diagonal line D1 of the plate-shaped member 51. In addition, for example, the TEL antenna 52a and the TEL antenna 52b are provided at mutually opposing corner portions on the surface of the plate-shaped member 51 on the vehicle outer side so that the interval between them on the plate-shaped member 51 becomes the largest.

[0077] The Sub6 antenna 52c and the Sub6 antenna 52d are respectively provided in two areas that are not adjacent to each other when the plane of the plate-shaped member 51 is divided into four quadrants around the center O of the plane. In addition, the Sub6 antenna 52c and the Sub6 antenna 52d are respectively provided in two areas that are not adjacent to each other when the antenna opening 22h is divided into four quadrants around the center of the antenna opening 22h in a plan view. More specifically, the Sub6 antenna 52c and the Sub6 antenna 52d are respectively provided in areas Rg3 and Rg1 that are not adjacent to each other when the plane of the plate-shaped member 51 is divided by straight lines L1 and L2.

[0078] For example, the Sub6 antenna 52c and the Sub6 antenna 52d are provided at positions on the diagonal line D1 of the plate-shaped member 51. Specifically, for example, the center of the Sub6 antenna 52c and the center of the Sub6 antenna 52d exist on the diagonal line D1 of the plate-shaped member 51.

[0079] For example, TEL antennas 52a and 52b are provided on the plate-shaped member 51 via antenna 52 for receiving RF signals in a frequency band higher than 2 GHz. In the example shown in the figure, TEL antennas 52a and 52b are provided on the plate-shaped member 51 via Sub6 antennas 52c and 52d.

[0080] Figure 5 FIG. 2 is a plan view showing another example of the structure of the vehicle-mounted antenna module according to the embodiment of the present disclosure. Figure 5 , the TEL antenna 52a and the TEL antenna 52b are respectively arranged in regions Rg3 and Rg1 that are not adjacent to each other when the plane possessed by the plate-like member 51 is divided by straight lines L1 and L2. For example, the TEL antenna 52a and the TEL antenna 52b are arranged at positions on the diagonal D1 of the plate-like member 51. In addition, the Sub6 antenna 52c and the Sub6 antenna 52d are respectively arranged in regions Rg2 and Rg4 that are not adjacent to each other when the plane possessed by the plate-like member 51 is divided by straight lines L1 and L2. For example, the Sub6 antenna 52c and the Sub6 antenna 52d are arranged at positions on the diagonal D2 of the plate-like member 51. Specifically, for example, the center of the Sub6 antenna 52c and the center of the Sub6 antenna 52d exist on the diagonal D2 of the plate-like member 51. For example, the Sub6 antenna 52c and the Sub6 antenna 52d are provided at mutually opposing corner portions on the surface of the plate-like member 51 on the vehicle outer side so that the interval between them on the plate-like member 51 becomes the largest.

[0081] For example, the TEL antenna 52a and the TEL antenna 52b are provided on the plate-shaped member 51 so as to sandwich the antenna 52 that receives the RF signal in a frequency band higher than the 2 GHz band. Figure 5 In the example shown, the TEL antenna 52a and the TEL antenna 52b are provided on the diagonal line D1 of the plate-shaped member 51 so as to sandwich the ITS 5.9 GHz antenna 52f. Figure 5 In the illustrated example, the Sub6 antenna 52c and the Sub6 antenna 52d are provided at positions on a diagonal line D2 different from the diagonal line D1 of the plate-shaped member 51 so as to sandwich the ITS5.9 GHz antenna 52f.

[0082] Figure 6 1 is a diagram showing an example of the configuration of a circuit unit according to an embodiment of the present disclosure. Figure 6 The circuit unit 53 includes receiving units 61a, 61b, 61c, 61d, 61e, 61f, 61g and selecting units 62a, 62b. Hereinafter, the receiving units 61a, 61b, 61c, 61d, 61e, 61f, 61g are each referred to as a receiving unit 61, and the selecting units 62a, 62b are each referred to as a selecting unit 62.

[0083] Each of the receiving units 61 is connected to a corresponding antenna 52. More specifically, the receiving unit 61a is connected to the TEL antenna 52a, the receiving unit 61b is connected to the TEL antenna 52b, the receiving unit 61c is connected to the Sub6 antenna 52c, the receiving unit 61d is connected to the Sub6 antenna 52d, the receiving unit 61e is connected to the ITS760MHz antenna 52e, the receiving unit 61f is connected to the ITS5.9GHz antenna 52f, and the receiving unit 61g is connected to the GPS antenna 52g.

[0084] For example, the receiving unit 61 has a bandpass filter and an amplifier circuit, and performs filtering and amplification on the RF signal received by the corresponding antenna 52. The receiving units 61a and 61b output the amplified RF signal to the selecting unit 62a. The receiving units 61c and 61d output the amplified RF signal to the selecting unit 62b. The receiving units 61e, 61f, and 61g transmit the amplified RF signal to the corresponding vehicle-mounted device.

[0085] The selection unit 62 selectively transmits each RF signal received by the two antennas 52 constituting the diversity antenna to the vehicle-mounted device. More specifically, the selection unit 62 selects one of the RF signals received from the two receiving units 61 and transmits it to the vehicle-mounted device. Specifically, for example, when the signal strength ga of the RF signal sa received from the receiving unit 61a is greater than the threshold Th1, the selection unit 62a selects the RF signal sa and transmits it to the corresponding vehicle-mounted device. On the other hand, when the signal strength ga of the RF signal sa received from the receiving unit 61a is less than the threshold Th1 and the signal strength gb of the RF signal sb received from the receiving unit 61b is greater than the threshold Th1, the selection unit 62a selects the RF signal sb and transmits it to the corresponding vehicle-mounted device. On the other hand, when the signal strength ga of the RF signal sa is less than the threshold Th1 and the signal strength gb of the RF signal sb is less than the threshold Th1, the selection unit 62a selects the RF signal with the higher signal strength between the RF signal sa and the RF signal sb, and transmits the selected RF signal to the corresponding vehicle-mounted device.

[0086] In addition, for example, when the signal strength gc of the RF signal sc received from the receiving unit 61c is greater than the threshold value Th2, the selecting unit 62b selects the RF signal sc and transmits it to the corresponding vehicle-mounted device. On the other hand, when the signal strength gc of the RF signal sc received from the receiving unit 61c is less than the threshold value Th2 and the signal strength gd of the RF signal sd received from the receiving unit 61d is greater than the threshold value Th2, the selecting unit 62b selects the RF signal sd and transmits it to the corresponding vehicle-mounted device. On the other hand, when the signal strength gc of the RF signal sc is less than the threshold value Th2 and the signal strength gd of the RF signal sd is less than the threshold value Th2, the selecting unit 62b selects the RF signal with the higher signal strength between the RF signal sc and the RF signal sd, and transmits the selected RF signal to the corresponding vehicle-mounted device.

[0087] For example, the selection unit 62 includes a comparison circuit for comparing the signal strength of the RF signal received from the corresponding receiving unit 61 with a threshold value or the signal strength of the RF signal received from the other corresponding receiving unit 61, and a switch for switching the RF signal to be transmitted to the corresponding vehicle-mounted device among the RF signals received from the two receiving units 61. The selection unit 62 compares the signal strength of the RF signal received from the corresponding receiving unit 61 with the threshold value regularly or irregularly. And, based on the comparison result, the selection unit 62 selects one of the RF signals received from the two receiving units 61 and transmits it to the corresponding vehicle-mounted device.

[0088] Figure 7 It is a diagram showing the directivity of the antenna involved in the embodiment of the present disclosure. Figure 7 Shows Figure 4 The directivity of the TEL antenna 52 a in the vehicle-mounted antenna module 50 with respect to the RF signal of a vertically polarized wave incident from a direction at an elevation angle of 40° is shown. Figure 8 Graph showing directivity of the antenna according to the embodiment of the present disclosure. Figure 8 Shows Figure 4 The directivity of the TEL antenna 52 b in the vehicle-mounted antenna module 50 with respect to the RF signal of a vertically polarized wave incident from a direction at an elevation angle of 40° is shown.

[0089] Reference Figure 7 and Figure 8, the TEL antenna 52a and the TEL antenna 52b have different directivities due to the influence of the installation position on the plate-shaped member 51. Specifically, for example, the directivity of the TEL antenna 52a has a null point in the direction of an azimuth angle of about 240°. That is, the receiving sensitivity of the TEL antenna 52a to the RF signal incident from the direction of an azimuth angle of about 240° is low. On the other hand, the TEL antenna 52b does not have a null point in the direction of an azimuth angle of about 240°. In addition, the receiving sensitivity of the TEL antenna 52b to the RF signal incident from the direction of an azimuth angle of about 240° is higher than the receiving sensitivity of the TEL antenna 52a to the RF signal incident from the direction of an azimuth angle of about 240°.

[0090] Fig. 9 Graph showing directivity of the antenna according to the embodiment of the present disclosure. Fig. 9 Shows Figure 4 The directivity of the Sub6 antenna 52c in the vehicle-mounted antenna module 50 with respect to the RF signal of a vertically polarized wave incident from a direction at an elevation angle of 40°. Fig.10 Graph showing directivity of the antenna according to the embodiment of the present disclosure. Fig.10 Shows Figure 4 The directivity of the Sub6 antenna 52d in the vehicle-mounted antenna module 50 with respect to the RF signal of a vertically polarized wave incident from a direction at an elevation angle of 40°.

[0091] Reference Fig. 9 and Fig.10 , the Sub6 antenna 52c and the Sub6 antenna 52d have different directivities due to the influence of the installation position on the plate-shaped member 51. Specifically, for example, the directivity of the Sub6 antenna 52c has a zero point in the direction of an azimuth angle of approximately 140° and in the direction of an azimuth angle of approximately 290°. That is, the receiving sensitivity of the Sub6 antenna 52c to the RF signal incident from the direction of an azimuth angle of approximately 140° and the RF signal incident from the direction of an azimuth angle of approximately 290° is low. On the other hand, the Sub6 antenna 52d does not have a zero point in the direction of an azimuth angle of approximately 140° and in the direction of an azimuth angle of approximately 290°. In addition, the receiving sensitivity of the Sub6 antenna 52d to the RF signal incident from the direction of an azimuth angle of approximately 140° is higher than the receiving sensitivity of the Sub6 antenna 52c to the RF signal incident from the direction of an azimuth angle of approximately 140°. In addition, the receiving sensitivity of the Sub6 antenna 52d to the RF signal incident from the direction of the azimuth angle of approximately 290° is higher than the receiving sensitivity of the Sub6 antenna 52c to the RF signal incident from the direction of the azimuth angle of approximately 290°.

[0092] The signal strength ga of the RF signal sa output from the receiving unit 61a and the signal strength gb of the RF signal sb output from the receiving unit 61b may differ from each other due to the difference in directivity of the TEL antenna 52a and the TEL antenna 52b as described above. In addition, the signal strength gc of the RF signal sc output from the receiving unit 61c and the signal strength gd of the RF signal sd output from the receiving unit 61d may differ from each other due to the difference in directivity of the Sub6 antenna 52c and the Sub6 antenna 52d as described above.

[0093] The selection unit 62 compares the signal strength ga of the RF signal sa received from the receiving unit 61a and the signal strength gb of the RF signal sb received from the receiving unit 61b with the threshold value Th1, and transmits the RF signal sa and the RF signal sb to the vehicle-mounted device corresponding to the direction based on the comparison result. In addition, the selection unit 62 compares the signal strength gc of the RF signal sc received from the receiving unit 61c and the signal strength gd of the RF signal sd received from the receiving unit 61d with the threshold value Th2, and transmits the RF signal sc and the RF signal sd to the vehicle-mounted device corresponding to the direction based on the comparison result.

[0094] Thus, for example, even if the signal strength of the RF signal of one of the TEL antennas 52a and 52b decreases, by sending the RF signal of the other to the corresponding vehicle-mounted device, it is possible to suppress the decrease in the signal strength of the RF signal received by the vehicle-mounted device. Also, for example, even if the signal strength of the RF signal of one of the Sub6 antenna 52c and the Sub6 antenna 52d decreases, by sending the RF signal of the other to the corresponding vehicle-mounted device, it is possible to suppress the decrease in the signal strength of the RF signal received by the vehicle-mounted device.

[0095] [Flow of Action]

[0096] The vehicle-mounted antenna module 50 according to the embodiment of the present disclosure includes a computer including a memory, and a CPU or other computing unit in the computer reads and executes a program including a part or all of the steps of the following flowchart and sequence from the memory. The program can be installed from the outside. The program is circulated in a state stored in a recording medium.

[0097] Fig.11 This is a flowchart that defines an example of an operation procedure when a circuit unit in the vehicle-mounted antenna module according to an embodiment of the present disclosure selectively transmits an RF signal to a vehicle-mounted device. Fig.11 The diagram shows an operation sequence when the circuit unit 53 selects one of the RF signals received from the receiving units 51c and 51d and transmits the selected signal to the vehicle-mounted device.

[0098] Reference Fig.11First, the circuit unit 53 waits for the selection timing according to the specified period (No in step S102), and at the selection timing (Yes in step S102), compares the signal strength gc of the RF signal sc received from the receiving unit 61c with the specified threshold Th2 (step S104).

[0099] Next, when the signal strength gc of the RF signal sc is greater than the threshold value Th2 (Yes in step S106), the circuit unit 53 sets the RF signal to be transmitted to the vehicle-mounted device as the RF signal sc, and starts transmitting the RF signal sc to the vehicle-mounted device (step S108). Next, the circuit unit 53 waits for a new selection timing (step S102).

[0100] On the other hand, when the signal strength gc of the RF signal sc is equal to or less than the threshold Th2 (No in step S106), the circuit unit 53 compares the signal strength gd of the RF signal sd received from the receiving unit 61d with the threshold Th2 (step S110).

[0101] Next, when the signal strength gd of the RF signal sd is greater than the threshold value Th2 (Yes in step S112), the circuit unit 53 sets the RF signal to be transmitted to the vehicle-mounted device as the RF signal sd, and starts transmitting the RF signal sd to the vehicle-mounted device (step S114). Next, the circuit unit 53 waits for a new selection timing (step S102).

[0102] On the other hand, when the signal strength gd of the RF signal sd is less than the threshold value Th2 (No in step S112), the circuit unit 53 compares the signal strength gc of the RF signal sc received from the receiving unit 61c with the signal strength gd of the RF signal sd received from the receiving unit 61d (step S116).

[0103] Next, when the signal strength gc of the RF signal sc is greater than the signal strength gd of the RF signal sd (Yes in step S118), the circuit unit 53 sets the RF signal to be transmitted to the vehicle-mounted device to the RF signal sc and starts transmitting the RF signal sc to the vehicle-mounted device (step S120). Next, the circuit unit 53 waits for a new selection timing (step S102).

[0104] On the other hand, when the signal strength gc of the RF signal sc is less than the signal strength gd of the RF signal sd (No in step S118), the circuit unit 53 sets the RF signal to be transmitted to the vehicle-mounted device to the RF signal sd and starts transmitting the RF signal sd to the vehicle-mounted device (step S122). Then, the circuit unit 53 waits for a new selection timing (step S102).

[0105] It should be noted that, in the vehicle-mounted antenna module 50 involved in the embodiment of the present disclosure, a structure is provided with TEL antennas 52a, 52b, Sub6 antennas 52c, 52d, ITS760MHz antenna 52e, ITS5.9GHz antenna 52f and GPS antenna 52g as antennas 52, but the present invention is not limited thereto. The vehicle-mounted antenna module 50 may also be provided with an antenna 52 corresponding to other communication services other than the above-mentioned in addition to or in place of the antenna 52 corresponding to the above-mentioned communication service.

[0106] In addition, in the vehicle-mounted antenna module 50 involved in the embodiment of the present disclosure, the TEL antenna 52a and the TEL antenna 52b are provided on the plate-shaped member 51 in a manner of being sandwiched between the Sub6 antennas 52c, 52d or the ITS5.9GHz antenna 52f, but the present invention is not limited thereto. The TEL antenna 52a and the TEL antenna 52b may be provided on the plate-shaped member 51 in a manner of not sandwiching other antennas 52 therebetween, or may be provided on the plate-shaped member 51 in a manner of sandwiching other antennas 52 other than the Sub6 antennas 52c, 52d and the ITS5.9GHz antenna 52f.

[0107] In addition, the vehicle-mounted antenna module 50 according to the embodiment of the present disclosure is configured to include TEL antennas 52a and 52b and Sub6 antennas 52c and 52d constituting diversity antennas, but the present invention is not limited thereto. The vehicle-mounted antenna module 50 may also include one or more diversity antennas.

[0108] In addition, the vehicle-mounted antenna module 50 according to the embodiment of the present disclosure is assumed to be a configuration including a diversity antenna composed of two antennas, but the present invention is not limited thereto. The vehicle-mounted antenna module 50 may be a diversity antenna composed of three or more antennas.

[0109] In addition, the vehicle-mounted antenna module 50 according to the embodiment of the present disclosure is configured to include TEL antennas 52a and 52b for receiving RF signals in the TEL frequency band and Sub6 antennas 52c and 52d for receiving RF signals in the Sub6 frequency band as diversity antennas, but the present invention is not limited thereto. The vehicle-mounted antenna module 50 may also include a diversity antenna for receiving RF signals in other frequency bands.

[0110] In addition, in the circuit unit 53 of the vehicle-mounted antenna module 50 according to the embodiment of the present disclosure, the selector 62 is configured to selectively send the RF signals received from the two receiving units 61 to the vehicle-mounted device, but the present invention is not limited thereto. The selector 62 may also be configured to synthesize the RF signals received from the two receiving units 61 and send the synthesized signals to the vehicle-mounted device.

[0111] In addition, although the vehicle-mounted antenna module 50 according to the embodiment of the present disclosure is configured to include the circuit unit 53 , the present invention is not limited thereto. A part or all of the circuit unit 53 may be provided outside the vehicle-mounted antenna module 50 .

[0112] Technology capable of receiving RF signals with higher sensitivity is desired. For example, when the antenna 52 in the vehicle-mounted antenna module 50 receives an RF signal incident on the vehicle-mounted antenna module 50 from a low elevation angle, the receiving sensitivity is sometimes reduced relative to the RF signal incident from a part of the azimuth direction due to the influence of the RF signal reflected at the body 12 of the vehicle 10. That is, the directivity of the antenna 52 sometimes has a null point in a part of the azimuth direction. Therefore, in order to solve such a problem, the use of a diversity antenna can be considered. However, it is not easy to configure the antennas constituting the diversity antenna on the vehicle 10 with high precision. For example, the spacing between the antennas constituting the diversity antenna sometimes deviates from the design value.

[0113] In contrast, in the vehicle-mounted antenna module 50 according to the embodiment of the present disclosure, a plate-shaped member 51 is fixed to the vehicle body 12 of the vehicle 10, and at least a portion thereof is plate-shaped. A plurality of antennas 52 are provided on the plate-shaped member 51. TEL antennas 52a and 52b among the plurality of antennas 52 are first diversity antennas that receive RF signals in a first frequency band. The TEL antennas 52a and 52b are respectively provided in two areas that are not adjacent to each other when a plane of the plate-shaped member 51 is divided into four quadrants around the center of the plane.

[0114] In this way, by providing the TEL antennas 52a and 52b constituting the first diversity antenna in two areas that are not adjacent to each other when the plane of the plate-shaped member 51 is divided into four quadrants, a plurality of antennas including the TEL antennas 52a and 52b pre-arranged at desired positions on the plate-shaped member 51 can be mounted on the vehicle 10 in a concentrated manner, so that the mutual intervals can be made the same as the designed values, compared with, for example, the case where the TEL antennas 52a and 52b are individually arranged on the vehicle 10. Furthermore, the intervals between the TEL antennas 52a and 52b can be ensured within the limited arrangement space on the plate-shaped member 51, and the correlation between the TEL antennas 52a and 52b can be reduced.

[0115] In addition, in the vehicle-mounted antenna module 50 involved in the embodiment of the present disclosure, the plate-shaped member 51 is fixed to the body 12 of the vehicle 10, and at least a part of it is plate-shaped. A plurality of antennas 52 are provided on the plate-shaped member 51. The plurality of antennas 52 are provided in the antenna opening 22h of the vehicle roof 22 in a plan view. The TEL antennas 52a and 52b among the plurality of antennas 52 are first diversity antennas that receive RF signals in a first frequency band. The TEL antennas 52a and 52b are provided in two areas that are not adjacent to each other when the antenna opening 22h is divided into four quadrants around the center of the antenna opening 22h in a plan view.

[0116] In this way, by configuring the TEL antennas 52a and 52b constituting the first diversity antenna to be respectively arranged in two areas that are not adjacent to each other when the antenna opening 22h is divided into four quadrants in a plan view, a plurality of antennas including the TEL antennas 52a and 52b pre-arranged at desired positions on the plate-shaped member 51 can be collectively mounted on the vehicle 10, so that, for example, the TEL antennas 52a and 52b can be mounted on the vehicle 10 with high accuracy in a manner that the intervals between them are the same as the designed values, compared to, for example, the case where the TEL antennas 52a and 52b are individually arranged on the vehicle 10. Furthermore, the intervals between the TEL antennas 52a and 52b can be ensured within the limited arrangement space on the plate-shaped member 51, and the correlation between the TEL antennas 52a and 52b can be reduced. Therefore, the RF signal can be received with higher sensitivity.

[0117] Therefore, in the vehicle-mounted antenna module 50 according to the embodiment of the present disclosure, it is possible to receive RF signals with higher sensitivity.

[0118] The above embodiments should be considered as illustrative in all aspects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0119] The above description includes the following additional features.

[0120] [Note 1]

[0121] A vehicle-mounted antenna module, comprising:

[0122] a plate-like member fixed to the body of the vehicle, at least a portion of which is plate-like; and

[0123] A plurality of antennas are arranged on the plate-like member,

[0124] Any plurality of the plurality of antennas provided on the plate-shaped member constitute a first diversity antenna for receiving RF signals in a first frequency band,

[0125] At least two of the plurality of antennas constituting the first diversity antenna are respectively disposed in two areas that are not adjacent to each other when the plane of the plate-like member is divided into four quadrants.

[0126] The shape of the plate-like member is a square shape,

[0127] At least any two of the plurality of antennas constituting the first diversity antenna are provided at mutually opposing corner portions of one surface of the plate-like member.

[0128] Description of Reference Numerals

[0129] 10 Vehicles

[0130] 12 Body

[0131] 13 Opening

[0132] 20 Top plate module

[0133] 22 Vehicle roof

[0134] 22h Antenna opening

[0135] 30 Radio wave shielding part

[0136] 30h Antenna opening

[0137] 40 Conductive elastic member

[0138] 45. Conductive elastic member

[0139] 50 Vehicle Antenna Module

[0140] 51 Plate-like components

[0141] 51a Conductor layer

[0142] 52 Antenna

[0143] 52a, 52b TEL antenna

[0144] 52c, 52d Sub6 Antenna

[0145] 52e ITS760MHz Antenna

[0146] 52f ITS5.9GHz Antenna

[0147] 52g GPS Antenna

[0148] 53 Circuit Department

[0149] 54 Shell

[0150] 54a Bottom

[0151] 54b Main body

[0152] 61 Receiving Department

[0153] 62 Select Department.

Claims

1. A vehicle-mounted antenna module, comprising: a plate-like member fixed to the body of the vehicle, at least a portion of which is plate-like; and A plurality of antennas are arranged on the plate-like member, Any plurality of the plurality of antennas provided on the plate-shaped member constitute a first diversity antenna for receiving RF (Radio Frequency) signals in a first frequency band. At least any two of the plurality of antennas constituting the first diversity antenna are provided in two areas that are not adjacent to each other when a plane of the plate-like member is divided into four quadrants around the center of the plane.

2. The vehicle-mounted antenna module according to claim 1, Two of the plurality of antennas constituting the first diversity antenna are provided on the plate-shaped member so as to sandwich the other antenna that receives an RF signal in a frequency band higher than the first frequency band.

3. The vehicle-mounted antenna module according to claim 1 or 2, Any plurality of the plurality of antennas provided on the plate-shaped member constitute a second diversity antenna for receiving RF signals in a second frequency band higher than the first frequency band, At least any two of the plurality of antennas constituting the second diversity antenna are respectively provided in two areas that are not adjacent to each other when the plane is divided into four quadrants around the center of the plane.

4. The vehicle-mounted antenna module according to claim 1 or 2, The plurality of antennas constituting the first diversity antenna receive RF signals in a frequency band of fifth-generation mobile communications below 6 GHz or in a frequency band of mobile communications of a generation prior to the fifth-generation mobile communications.

5. The vehicle-mounted antenna module according to claim 3, The plurality of antennas constituting the first diversity antenna receive RF signals in a frequency band of fifth-generation mobile communications below 6 GHz or in a frequency band of mobile communications of a generation prior to the fifth-generation mobile communications.

6. A vehicle-mounted antenna module, comprising: a plate-like member fixed to the body of the vehicle, at least a portion of which is plate-like; and A plurality of antennas are arranged on the plate-like member, The plurality of antennas are disposed in an opening portion of a roof panel of the vehicle in a plan view. Any number of the plurality of antennas constitute a first diversity antenna for receiving RF signals in a first frequency band, At least any two of the plurality of antennas constituting the first diversity antenna are respectively provided in two areas that are not adjacent to each other when the opening is divided into four quadrants around the center of the opening in a plan view.

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