Patent Description:
A technology of embedding an antenna apparatus in the roof of a vehicle to eliminate the protrusion of the antenna apparatus from the roof in order not to impair the aesthetic appearance of the vehicle has been developed.

For example, Patent Literature (hereinafter, referred to as "PTL") <NUM> discloses providing a recess in a roof (in other words, a recessed antenna accommodating portion), accommodating an antenna apparatus in the antenna accommodating portion, and closing the antenna accommodating portion with an accommodating lid being a part of the roof. With such a configuration, it is possible to eliminate a portion protruding outside the vehicle body to prevent the design of the vehicle from being impaired and the antenna from being broken.

PTL <NUM>
<CIT> <CIT> relates to an antenna device and mounting method. <CIT> relates to a terminal device. <CIT> relates to an antenna that is specially adapted for a portable electronic device. <CIT> relates to an antenna module.

However, with respect to the antenna apparatus disclosed in PTL <NUM>, for example, the possibility that the performance (or characteristics) of the antenna apparatus may be deteriorated when the antenna apparatus is embedded in a vehicle roof has not been studied comprehensively.

The present disclosure provides, for example, a technique capable of suppressing deterioration in performance or characteristics of an antenna apparatus embedded in an exterior of a mobile entity.

A mobile entity according to the invention is defined in claim <NUM>.

According to an aspect of the present disclosure, when the antenna apparatus is embedded in the exterior of the mobile entity, it is possible to suppress a decrease in performance or characteristics of the antenna apparatus.

Additional benefits and advantages of the disclosed exemplary embodiments will become apparent from the specification and drawings.

Hereinafter, an embodiment will be described in detail with appropriate reference to the drawings. However, any unnecessarily detailed description may be omitted. For example, any detailed description of well-known matters and redundant descriptions on substantially the same configurations may be omitted. This is to avoid the unnecessary redundancy of the following description and to facilitate understanding of those skilled in the art.

It is to be noted that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this disclosure, and are not intended to limit the claimed subject.

Hereinafter, an embodiment of the present disclosure will be described with reference to <FIG>.

<FIG> illustrate an example of a configuration of a vehicle roof embedded antenna apparatus according to an embodiment of the present disclosure. <FIG> is a perspective view and <FIG> is an XZ sectional view. In <FIG>, the X direction is a front-rear longitudinal direction of a vehicle (+X is front and -X is rear), the Y direction is a left-right direction along the width of the vehicle, and the Z direction is the vertical height direction of the vehicle. The vehicle in the present specification is an example of a mobile entity (or mobility) and may include an automobile, train, or small electric vehicle. Non-limiting examples of the small electric vehicle include two-wheeled standing electric scooter, electric wagon, electric cart, or electric baby cart.

As seen in <FIG>, vehicle roof embedded antenna apparatus <NUM> is used in a state of being embedded in recess <NUM> in vehicle roof <NUM>. Vehicle roof <NUM> may be a painted conductive metal or may be made of metal. Recess <NUM> in vehicle roof <NUM> illustrates a recess formed by a plurality of flat surfaces, but may also be formed by a combination of curved surfaces or of flat and curved surfaces. Recess <NUM> does not have to be a conductive metal.

Patch antenna elements <NUM>-k (k = <NUM>, <NUM>, <NUM>, or <NUM>) are disposed on the front surface of dielectric substrates <NUM>-k (k = <NUM>, <NUM>, <NUM>, or <NUM>), and GND (not illustrated) is formed on the back surface. Each of patch antenna elements <NUM>-k (k = <NUM>, <NUM>, <NUM>, or <NUM>) is a square conductor, one side of which is a half wavelength of an effective wavelength considering the wavelength shortening according to the dielectric constant of, for example, dielectric substrate <NUM>-k (k = <NUM>, <NUM>, <NUM>, or <NUM>). The GND is a square conductor, one side of which is larger than the half wavelength of the free space wavelength.

The patch antenna is a type of planar antenna and is also called a microstrip antenna.

For example, when the radio wave used is <NUM>, it is sufficient that one side of patch antenna element <NUM>-k (k = <NUM>, <NUM>, <NUM>, or <NUM>) is about <NUM>, and one side of the GND is about <NUM> or longer, and preferably about <NUM>.

Dielectric substrates <NUM>-k (k = <NUM>, <NUM>, <NUM>, or <NUM>) are, for example, arranged side by side on an inclined portion of recess <NUM> in vehicle roof <NUM> to surround the bottom center of recess <NUM> in vehicle roof <NUM> (in other words, radially around the bottom center). The inclined portion of recess <NUM> in vehicle roof <NUM> has tilt (inclination) angle α, for example, in the elevation direction with respect to the horizontal plane (XY plane) in which the bottom of recess <NUM> in vehicle roof <NUM> is located. Tilt angle α is <NUM> degrees as a non-limiting example. The patch antenna in individual dielectric substrate <NUM>-k (k = <NUM>, <NUM>, <NUM>, or <NUM>) may correspond to a sector antenna. In other words, four sector antennas may be configured by four patch antennas. Note that, the distance between patch antenna elements <NUM> forming the sector antennas facing each other in the inclined portion of recess <NUM> in vehicle roof <NUM> is, for example, about <NUM>. This distance is determined by a positional relationship between the elements including a below-described parasitic element in an attempt to obtain a desired directivity.

Feed points <NUM>-k (k = <NUM>, <NUM>, <NUM>, or <NUM>) are provided at positions where matching with radio circuitry can be obtained.

Parasitic element <NUM> is a conductor disposed at a substantially central axis of the four sector antennas (for example, disposed substantially equidistantly from two of the sector antennas facing each other). The center of parasitic element <NUM> is disposed at a position higher than horizontal plane <NUM> in which the centers of patch antenna elements <NUM>-k (k = <NUM>, <NUM>, <NUM>, or <NUM>) are located. Further, parasitic element <NUM> is disposed at a predetermined distance from the bottom surface of recess <NUM> in vehicle roof <NUM> without making contact with the bottom surface, and its length is set shorter than the half wavelength. Note that, parasitic element <NUM> may be integrated with a resin cover (not illustrated) covering recess <NUM> in vehicle roof <NUM>, or may be fixed at somewhere in recess <NUM> in vehicle roof <NUM>, for example, to the bottom at a predetermined distance from the bottom.

A description will be given below of an example of the operation of vehicle roof embedded antenna apparatus <NUM> configured as described above as compared with the operations of compared antenna apparatuses described in <FIG> and <FIG>.

<FIG> illustrate a configuration of vehicle roof embedded antenna apparatus <NUM> to be compared with vehicle roof embedded antenna apparatus <NUM> according to an embodiment of the present disclosure. <FIG> are a perspective view and a sectional view of vehicle roof embedded antenna apparatus <NUM>.

A difference between vehicle roof embedded antenna apparatus <NUM> illustrated in <FIG> and vehicle roof embedded antenna apparatus <NUM> illustrated in <FIG> is whether parasitic element <NUM> is present or absent. For example, vehicle roof embedded antenna apparatus <NUM> of <FIG> is provided with parasitic element <NUM>, whereas vehicle roof embedded antenna apparatus <NUM> of <FIG> is not provided with any parasitic element.

<FIG> illustrate four sector antennas composed of four sectors as in <FIG>. The configuration of each of the sectors is the same, and thus, a description focusing on the sectors on the forward side will be given with reference to <FIG>. Patch antenna element <NUM>-<NUM> is disposed on the front surface of dielectric substrate <NUM>-<NUM>, GND (not illustrated) is formed on the back surface, and feed point <NUM>-<NUM> is also provided. Dielectric substrate <NUM>-<NUM> is disposed along recess <NUM> in vehicle roof <NUM>, for example, at tilt (inclination) angle α = <NUM> degrees in the elevation direction with respect to the horizontal plane (XY plane). The dielectric substrates are arranged radially, forming the four sector antennas.

<FIG> illustrate a configuration of vehicle roof protruding antenna apparatus <NUM> to be compared with vehicle roof embedded antenna apparatus <NUM> according to an embodiment of the present disclosure. <FIG> are a perspective view and a sectional view of vehicle roof protruding antenna apparatus <NUM>. Vehicle roof protruding antenna apparatus <NUM> has a configuration of four sector antennas along protrusion <NUM> from vehicle roof <NUM>. Vehicle roof embedded antenna apparatus <NUM> illustrated in <FIG> is an example in which antenna apparatus <NUM> is below the surface of vehicle roof <NUM> (in other words, not protruding from the roof surface). In contrast, regarding vehicle roof protruding antenna apparatus <NUM> illustrated in <FIG>, antenna apparatus <NUM> is formed in a shape protruding on the surface of vehicle roof <NUM>. Therefore, in vehicle roof protruding antenna apparatus <NUM> illustrated in <FIG>, since antenna apparatus <NUM> protrudes from vehicle roof <NUM>, the appearance of the vehicle is impaired.

<FIG> illustrate four sector antennas composed of four sectors as in <FIG>. The configuration of each of the sectors may be the same, and thus, a description focusing on the sectors on the forward side will be given with reference to <FIG>. Patch antenna element <NUM>-<NUM> is disposed on the front surface of dielectric substrate <NUM>-<NUM>, GND (not illustrated) is formed on the back surface, and feed point <NUM>-<NUM> is also provided. Dielectric substrate <NUM>-<NUM> is disposed along protrusion <NUM> on vehicle roof <NUM>, for example, at tilt (inclination) angle α = <NUM> degrees in the elevation direction with respect to the horizontal plane (XY plane). The dielectric substrates are arranged radially, forming the four sector antennas.

<FIG> illustrate exemplary radiation patterns of antenna apparatuses <NUM>, <NUM>, and <NUM> described in <FIG>. <FIG> illustrates the radiation patterns of the antenna apparatuses in the XZ plane, and <FIG> illustrates the radiation patterns of the antenna apparatuses in the XY plane. In <FIG>, the operation gains (sensitivities) are indicated in dBi.

Solid line <NUM> described in <FIG> indicates the radiation pattern of patch antenna elements <NUM> of vehicle roof embedded antenna apparatus <NUM> described in <FIG>. Dashed line <NUM> in <FIG> indicates the radiation pattern of patch antenna elements <NUM> of vehicle roof embedded antenna apparatus <NUM> described in <FIG>. One-dot chain line <NUM> in <FIG> indicates the radiation pattern of patch antenna elements <NUM> of vehicle roof protruding antenna apparatus <NUM> described in <FIG>.

Each of the radiation patterns indicates the characteristics exhibited during when the GND (not illustrated) is connected to vehicle roof <NUM>, recess <NUM> or protrusion <NUM>.

First, attention is paid to the gains in the +X direction (e.g., the forward direction of the vehicle) (Z = <NUM>) in <FIG>. The highest gain of the gains is of vehicle roof protruding antenna apparatus <NUM> described in <FIG> (one-dot chain line <NUM>). This is because vehicle roof protruding antenna apparatus <NUM> protrudes from vehicle roof <NUM> and the influence of vehicle roof <NUM> is thus relatively small. The lowest gain of the gains is of vehicle roof embedded antenna apparatus <NUM> having no parasitic element <NUM> described in <FIG> (dashed line <NUM>). This is because vehicle roof embedded antenna apparatus <NUM> is embedded in the vehicle roof and has no parasitic element, and the influence of vehicle roof <NUM> is thus the largest.

Vehicle roof embedded antenna apparatus <NUM> described in <FIG> having parasitic element <NUM> (solid line <NUM>) has a lower gain in the +X direction as compared to vehicle roof protruding antenna apparatus <NUM> (dashed line <NUM>), but has a higher gain in the +X direction as compared to vehicle roof embedded antenna apparatus <NUM> having no parasitic element <NUM> (dashed line <NUM>). The reason for this is that parasitic element <NUM> provided in vehicle roof embedded antenna apparatus <NUM> described in <FIG> operates as a waveguide element. Note that, since parasitic element <NUM> is present substantially equidistantly as seen from all four patch antenna elements <NUM>-k (k = <NUM>, <NUM>, <NUM>, or <NUM>), parasitic element <NUM> operates similarly as the waveguide element for these four patch antenna elements.

Next, attention is paid to the gains in the horizontal plane (XY plane) illustrated in <FIG>. Here, +X is the forward direction of the vehicle, and Y indicates the width direction of the vehicle. Vehicle roof embedded antenna apparatus <NUM> having parasitic element <NUM> described in <FIG> (solid line <NUM>) has the narrowest half-value angle. This can be compensated for by increasing the number of sectors. For example, although the number of sectors of vehicle roof embedded antenna apparatus <NUM> described in <FIG> is <NUM>, compensation is possible by increasing the number of sectors to <NUM>, <NUM>, <NUM> or the like.

<FIG> illustrates vehicle roof embedded antenna apparatus <NUM> illustrated in <FIG> as mounted in vehicle <NUM>. One aspect in which vehicle roof embedded antenna apparatus <NUM> is attached to vehicle roof <NUM> is illustrated. It can be seen that vehicle roof embedded antenna apparatus <NUM> does not protrude from vehicle roof <NUM>.

As described above, in the present embodiment, vehicle roof embedded antenna apparatus <NUM> is embedded in recess <NUM> in vehicle roof <NUM>. The four sector antennas are configured to be disposed along recess <NUM> in vehicle roof <NUM> at tilt (inclination) angle α = <NUM> degrees in the elevation direction with respect to the horizontal plane (XY plane) and arranged radially. Parasitic element <NUM> is disposed substantially at the central axis of the four sector antennas.

As described with reference to <FIG>, with such a configuration, it is possible to prevent the appearance of the vehicle from being impaired, because there is no protrusion from the vehicle roof, and it is also possible to suppress the gain reduction in the horizontal plane even when the antenna apparatus is embedded in the vehicle roof.

The embodiment has been described above as an example of the art disclosed in the present application. However, the art in the present disclosure is not limited to this example, and can be applied to embodiments in which changes, substitutions, additions, omissions, and the like are made. It is also possible to combine constituent elements described in the above embodiment into a new embodiment.

Here, other embodiments will be exemplified below.

The embodiment has been described in relation to the case where the patch antennas configured with dielectric substrates <NUM>-k (k = <NUM>, <NUM>, <NUM>, or <NUM>) are used as an example of the antenna elements. Each of the antenna elements only has to transmit and receive electromagnetic waves at a desired frequency. For example, the antenna element may be a linear antenna, a loop antenna, or the like, or may also be a combination thereof. Thus, the antenna element is not limited to the patch antenna configured with a dielectric substrate. The patch antenna configured with the dielectric substrate has a merit of allowing easy and inexpensive realization of the antenna apparatus.

The embodiment has been described in relation to the case where tilt angle α is <NUM> degrees by way of example. Tilt angle α may be any angle as long as a desired radiation directivity is obtained. Therefore, tilt angle α is not limited to <NUM> degrees. Tilt angle α may be made larger as long as the parasitic element does not protrude from the vehicle roof. A larger tilt angle is desirable also in terms of suppressing a decrease in the horizontal plane gain.

The embodiment has been described in relation to the case where the number of sectors is <NUM>. The number of sectors may be any number as long as communication can be established with a base station or an access point that emits radio waves to be received. Therefore, the number of sectors may be smaller or larger than <NUM>, and is not limited to <NUM>. Moreover, the spacing in an array is not limited. While it is desirable to increase the number of sectors in order to increase the coverage ratio in the horizontal plane, the sector configuration does not need to be employed and the number of antennas may be one when the aim is to cover a specific direction in the horizontal plane (embodiment not covered by the appended claims).

The embodiment has been described in relation to the case where the number of parasitic elements <NUM> is one, and parasitic element <NUM> is disposed at the central axis of the array of the sector antennas. While in terms of suppressing the gain reduction in the horizontal plane, it is preferable that parasitic element <NUM> be disposed at a position higher than the horizontal plane in which the antenna elements are located, the number of parasitic elements and the position of the arranged parasitic element in the horizontal plane only have to be a position for suppressing the gain reduction in the horizontal plane that could be caused due to the vehicle roof (embodiment not covered by the appended claims). Therefore, the number of parasitic elements is not limited to <NUM>, and the arrangement is not limited to the central axis of the array of sector antennas (embodiment not covered by the appended claims). However, the configuration in which a single parasitic element is disposed at the central axis of the array of the sector antennas allows obtainment of the effect that is the same between the elements of the sector antennas in terms of suppressing the gain reduction in the horizontal plane. Thus, the configuration in which a single parasitic element is disposed at the central axis of the array of the sector antennas can be one effective candidate for a simple configuration.

The present disclosure can be realized by software, hardware, or software in cooperation with hardware.

Each functional block used in the description of each embodiment described above can be partly or entirely realized by an LSI such as an integrated circuit, and each process described in the each embodiment may be controlled partly or entirely by the same LSI or a combination of LSIs. The LSI may be individually formed as chips, or one chip may be formed so as to include a part or all of the functional blocks. The LSI may include a data input and output coupled thereto. The LSI herein may be referred to as an IC, a system LSI, a super LSI, or an ultra LSI depending on a difference in the degree of integration.

However, the technique of implementing an integrated circuit is not limited to the LSI and may be realized by using a dedicated circuit, a general-purpose processor, or a special-purpose processor. In addition, a FPGA (Field Programmable Gate Array) that can be programmed after the manufacture of the LSI or a reconfigurable processor in which the connections and the settings of circuit cells disposed inside the LSI can be reconfigured may be used. The present disclosure can be realized as digital processing or analogue processing.

If future integrated circuit technology replaces LSIs as a result of the advancement of semiconductor technology or other derivative technology, the functional blocks could be integrated using the future integrated circuit technology. Biotechnology can also be applied.

The present disclosure can be realized by any kind of apparatus, device or system having a function of communication, which is referred to as a communication apparatus. Some non-limiting examples of such a communication apparatus include a phone (e.g., cellular (cell) phone, smart phone), a tablet, a personal computer (PC) (e.g., laptop, desktop, netbook), a camera (e.g., digital still/video camera), a digital player (digital audio/video player), a wearable device (e.g., wearable camera, smart watch, tracking device), a game console, a digital book reader, a telehealth/telemedicine (remote health and medicine) device, and a vehicle providing communication functionality (e.g., automotive, airplane, ship), and various combinations thereof.

The communication apparatus is not limited to be portable or movable, and may also include any kind of apparatus, device or system being non-portable or stationary, such as a smart home device (e.g., an appliance, lighting, smart meter, control panel), a vending machine, and any other "things" in a network of an "Internet of Things (IoT)".

The communication apparatus also may include an infrastructure facility, such as, e.g., a base station, an access point, and any other apparatus, device or system that communicates with or controls apparatuses such as those in the above non-limiting examples.

It should be noted that, since the above-mentioned embodiments are for exemplifying the art in the present disclosure, various modifications, substitutions, additions, omissions, and the like can be performed within the scope of claims.

Claim 1:
A mobile entity, comprising:
a recess (<NUM>) in an exterior of the mobile entity (<NUM>); and
an antenna apparatus (<NUM>), comprising: a plurality of the antenna elements (<NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>) disposed
in the recess to surround a bottom center of the recess (<NUM>) to form a sector configuration,
characterized in that the mobile entity further comprises a parasitic element (<NUM>) whose center is disposed in the recess (<NUM>) at a position higher than a horizontal plane (<NUM>) in which
the centers of the antenna element (<NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>) of the plurality of antenna element are located, and the parasitic element (<NUM>) is disposed at a central axis of the sector configuration.