ANTENNA DEVICE

Abstract

Antenna device (U) for transmitting and receiving electromagnetic waves through an externally arranged cover element (B), the antenna device comprising: a first (2a) and a second (2b) antenna section which are arranged adjacent to each other along a direction orthogonal to a predetermined direction in which the electromagnetic waves (Fx1, Fx2) are transmitted, and which respectively transmit the electromagnetic waves (Fx1, Fx2); a first (5a) and a second (5b) dielectric lens which are arranged in the predetermined direction in front of the first and second antenna sections (2a, 2b), respectively, and which respectively narrow the beams of the electromagnetic waves (Fx1, Fx2) transmitted from the first and second antenna sections (2a, 2b) and transmit the beams of the electromagnetic waves (Fx1, Fx2) to the outside, wherein an outer end surface of the first dielectric lens (5a) projects further forward in the predetermined direction than an outer end surface of the second dielectric lens (5b), so that a distance (D1) between the cover element (B) and the outer end surface of the first dielectric lens (5a) in the predetermined direction is shorter than a distance (D2) between the cover element (B) and the outer end surface of the second dielectric lens (5b) in the predetermined direction.

Description

Technical area

[0001] The present disclosure relates to an antenna device. State of the art

[0002] Radar antenna devices are known that detect the position of an object (hereinafter also referred to as “target”) without contact using electromagnetic waves in the frequency bands of millimeter waves and microwaves.

[0003] This type of antenna device generally has a configuration in which the antenna device is mounted in a cover member such as a bumper of a vehicle in view of protection from an external flying object or in view of maintaining the aesthetics of a mounting object (such as a vehicle body), and transmits and receives electromagnetic waves through the cover member (for example, see PTL 1).

[0004] PTL2 discloses a millimeter-wave radar-equipped headlight comprising a millimeter-wave radar that detects an object in front of a vehicle and an illumination unit that illuminates an area in front of the vehicle. The illumination unit integrates an antenna module of the millimeter-wave radar. The illumination unit includes a projection lens, a light source, a reflector, and a diaphragm. The antenna module includes a millimeter-wave waveguide and a millimeter-wave reflector mirror. The reflection surface of the millimeter-wave reflector mirror is formed by a spheroidal surface whose first focal point is located near the opening of the millimeter-wave waveguide and whose second focal point is located in front of the rear focal point. Citation listPatent literature PTL 1 Japanese Patent Application Laid-Open No. JP 2009-103457 A PTL 2 Published US patent application US 2011 / 0279304A1 SummaryTechnical problem

[0005] High-frequency electromagnetic waves such as millimeter waves generally have the ability to penetrate an insulator (such as a resin material forming a bumper), but the transmittance of the electromagnetic waves varies depending on the dielectric constant of the insulator, the thickness of the insulator, the angle of incidence to the insulator, and the like. Therefore, a portion of the electromagnetic waves transmitted from the antenna device is reflected by an inner surface of the cover member, which may degrade the output or reception characteristics of the antenna device.

[0006] Fig. Figure 1 is a diagram showing the behavior of an electromagnetic wave reflected by a covering element.

[0007] Fig. 1 shows a state in which a part of the electromagnetic wave F transmitted from the antenna device 100 is reflected by the cover member B, and further, the reflected wave is reflected again by a front end surface of the antenna device 100 (e.g., a front end surface of a dielectric lens).

[0008] In such a state, a part (dotted line in Fig. 1) (hereinafter also referred to as “direct transmission wave Fa”) of the electromagnetic wave F transmitted from the antenna device 100 is not reflected by the cover member B and transmitted to an outside space in front of the antenna device 100, while the other part (alternating long and short dashed line in Fig. 1) (hereinafter also referred to as "re-reflected wave Fb") is reflected by the cover member B, then re-reflected by the front end surface of the antenna device 100, and transmitted to the outside space in front of the antenna device 100. As assumed, if the phase of the direct transmission wave Fa and the phase of the re-reflected wave Fb are in opposite phase relationship, at this time, both cancel each other out, and an output gain of the antenna device 100 decreases. Such a decrease in the output gain of the antenna device 100 may cause, for example, a deterioration in the detection performance of object detection.

[0009] In this connection, the distance between the front end surface of the antenna device 100 and an inner surface of the cover member B is set, for example, to a distance that is an even multiple of λ / 4 (where λ denotes a free-space wavelength of the electromagnetic waves transmitted and received by the antenna device 100; hereinafter, the same), whereby the phase of the direct transmission wave Fa and the phase of the re-reflected wave Fb are made in phase, and a state in which the direct transmission wave Fa is canceled out by the re-reflected wave Fb can be suppressed.

[0010] However, when the antenna device 100 is actually used, the distance between the antenna device 100 and the cover member B changes due to vibrations or the like of a vehicle equipped with the antenna device 100. Therefore, in the antenna device 100 according to the related art, even if the antenna device 100 is installed such that the distance between the front end surface of the antenna device 100 and the inner surface of the cover member B is set to the distance of an even multiple of λ / 4, a decrease in the output gain of the antenna device 100 is an unavoidable problem due to vibrations of the vehicle or the like.

[0011] The present disclosure has been made in view of the problems described above, and an object thereof is to provide a more suitable antenna device for transmitting and receiving electromagnetic waves through a cover member. Solution to the problem

[0012] The present disclosure, which primarily solves the above-mentioned problems, is an antenna device according to claim 1. Preferred embodiments are shown in the subclaims. Beneficial effects

[0013] The antenna device according to the present disclosure can be suitably used for transmitting and receiving electromagnetic waves through the cover member. Brief description of the drawings Fig. Figure 1 is a diagram showing the behavior of an electromagnetic wave reflected by a cover element; Fig. 2 shows a state in which an antenna device according to Embodiment 1 is mounted in the cover member; Fig. 3 is a side sectional view showing a configuration of the antenna device according to Embodiment 1; Fig. 4 is a plan view of the antenna device according to Embodiment 1; Fig. 5 is a diagram of the antenna device according to Embodiment 1 as seen from the rear; Fig. 6 shows a behavior of electromagnetic waves when the antenna device according to Embodiment 1 is in operation; Fig. 7 shows a behavior of electromagnetic waves when an antenna device according to a comparative example is in operation; Fig. 8 is a graph showing the amplitudes of the re-reflected waves Fb1 and Fb2 in the antenna device according to Embodiment 1 with respect to the position of the antenna device; Fig. 9A shows a simulation result of checking the radar performance of the antenna device according to Embodiment 1; Fig. 9B shows a simulation result of checking the radar performance of the antenna device according to the comparative example; Fig. 10 is a plan view of an antenna device according to Embodiment 2; Fig. 11 is a diagram of the antenna device according to Embodiment 2 as seen from the rear; Fig. 12 shows a simulation result of checking the radar performance of the antenna device according to Embodiment 2; Fig. 13A shows a comparison of the reception gains of the antenna device according to the comparative example, the antenna device according to Embodiment 1, and the antenna device according to Embodiment 2; Fig. 13B shows a comparison of the reception gains of the antenna device according to the comparative example, the antenna device according to Embodiment 1, and the antenna device according to Embodiment 2; Fig. 14 is a plan view of an antenna device according to Embodiment 3; Fig. 15 is a graph showing the amplitudes of the re-reflected waves in the antenna device according to Embodiment 3 with respect to the position of the antenna device; Fig. 16 is a plan view of an antenna device according to Embodiment 4; Fig. 17 is a diagram of an antenna device according to Embodiment 5 as seen from the rear; Fig. 18A is a graph showing an output characteristic depending on a radiation direction of the antenna device according to Embodiment 5; Fig. 18B is a graph showing an output characteristic depending on the radiation direction of the antenna device according to Embodiment 2; and Fig. 19 shows an example of an antenna device according to Embodiment 6. Description of embodiments

[0014] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In this description and the accompanying drawings, components having substantially the same functions are assigned the same reference numerals, thus omitting redundant description. (Embodiment 1)[Configuration of the antenna device]

[0015] The following describes an example of the configuration of an antenna device according to Embodiment 1 with reference to the Fig. 2-8. Note that the antenna device according to the present embodiment is applied to a vehicle-mounted radar device.

[0016] To clarify the positional relationships of the configurations, the attached drawings show a common orthogonal coordinate system (X, Y, Z) based on a forward direction (i.e., a target direction of object detection) in which the antenna device transmits an electromagnetic wave to the outside of its own antenna device (hereinafter referred to as the "device exterior"). In the following description, it is assumed that a plus direction of the X-axis represents the forward direction in which the antenna device transmits an electromagnetic wave to the device exterior (hereinafter abbreviated as the "forward direction"), a plus direction of the Y-axis represents a lateral left direction of the antenna device, and a plus direction of the Z-axis represents an upward direction of the antenna device (hereinafter abbreviated as the "upward direction").

[0017] Fig. 2 shows a state in which the antenna device U according to the present embodiment is mounted in the cover member B (here, a bumper member of the vehicle C).

[0018] The antenna device U according to the embodiment is attached to, for example, the cover member B of the vehicle C and transmits and receives electromagnetic waves through the cover member B.

[0019] The cover element B has, for example, a thin plate shape extending in a direction perpendicular to the ground, as in Fig. 2 is shown. Fig. 2 shows a state in which the plus Z direction of the antenna device U is directed in an upward direction (direction perpendicular to the ground) of the vehicle C and the plus X direction of the antenna device U is directed in a traveling direction (direction horizontal to the ground) of the vehicle C.

[0020] Fig. 3 is a side sectional view showing a configuration of the antenna device U according to the present embodiment. Fig. 4 is a plan view of the antenna device U according to the embodiment. Fig. 5 is a diagram of the antenna device U according to the embodiment as seen from the rear.

[0021] The antenna device U according to the embodiment includes a circuit board 1, a first antenna section 2a, a second antenna section 2b, a signal processing IC 3, a housing 4, a first dielectric lens 5a, a second dielectric lens 5b, and a bracket 6.

[0022] The printed circuit board 1 is a board on which the first antenna section 2a, the second antenna section 2b, the signal processing IC 3, and the like are mounted. The first antenna section 2a, the second antenna section 2b, the signal processing IC 3, and the like are mounted on a board surface of the printed circuit board 1, and wiring (not shown) for electrically connecting the components is formed in a pattern.

[0023] The printed circuit board 1 is arranged such that the extension direction of the printed circuit board surface is parallel to a front-to-back direction. In other words, the printed circuit board 1 is arranged such that the extension direction of the printed circuit board surface intersects the extension direction of the cover element B (here, approximately the ±Z direction).

[0024] The configuration of the circuit board 1 is not particularly limited in the invention, and for example, a printed circuit board (PCB), a multilayer board, or a semiconductor board with a built-in signal processing IC 3 is used as the circuit board 1.

[0025] The first antenna section 2a is arranged on the circuit board 1 and transmits the electromagnetic wave Fx1 forward. Furthermore, the first antenna section 2a receives reflected waves from the front, which are the electromagnetic waves Fx1 and Fx2 transmitted by the first antenna section 2a and the second antenna section 2b, and reflected and returned by a target.

[0026] The second antenna section 2b is arranged on the circuit board 1 in the minus Y direction adjacent to the first antenna section 2a and transmits the electromagnetic wave Fx2 forward. Furthermore, the second antenna section 2b receives reflected waves from the front, which are the electromagnetic waves Fx1 and Fx2 transmitted from the first antenna section 2a and the second antenna section 2b, and reflected and returned by the target.

[0027] For example, a longitudinal array antenna directional toward the surface of the printed circuit board 1 is used as the first antenna section 2a and the second antenna section 2b. The first antenna section 2a and the second antenna section 2b are arranged in a front portion of the printed circuit board 1, transmit electromagnetic waves Fx1 and Fx2 toward a front end face of the printed circuit board 1 and parallel to the surface of the printed circuit board 1, and receive reflected waves from the direction of the front end face of the printed circuit board 1 parallel to the surface of the printed circuit board 1. The longitudinal array antenna includes a plurality of strip conductors arranged so that their longitudinal directions are parallel to each other, and transmits and receives electromagnetic waves along a direction in which the strip conductors are arranged.

[0028] The first antenna section 2a consists, for example, of three longitudinally radiating array antennas (hereinafter also referred to as "antenna elements") arranged adjacently along the ±Y direction. Similarly, the second antenna section 2b consists of three longitudinally radiating array antennas arranged adjacently along the ±Y direction. The first antenna section 2a and the second antenna section 2b are then each configured as a phased array antenna by means of the plurality of antenna elements arranged adjacently along the ±Y direction.

[0029] The first antenna section 2a and the second antenna section 2b are typically configured to perform the same function. That is, the first antenna section 2a and the second antenna section 2b transmit electromagnetic waves Fx1 and Fx2 with the same frequency and phase to the front of the device exterior. Furthermore, the first antenna section 2a and the second antenna section 2b receive reflected waves, which are the electromagnetic waves Fx1 and Fx2 reflected and returned by the target.

[0030] The signal processing IC 3 transmits a drive signal of a high frequency (e.g., a millimeter wave frequency band) to the first antenna section 2a and the second antenna section 2b, and causes the first antenna section 2a and the second antenna section 2b to transmit electromagnetic waves Fx1 and Fx2 (e.g., pulse compression electromagnetic waves consisting of pulse trains or frequency-modulated continuous electromagnetic waves).

[0031] The signal processing IC 3 detects a reception signal with respect to the reflected waves from each of the first antenna section 2a and the second antenna section 2b, performs object detection processing (e.g., detection processing and frequency analysis processing) on ​​the reception signal, and determines the distance to the target (e.g., a vehicle or a person), a direction in which the target is located, and in addition, a reflection intensity, a speed of the target, and the like.

[0032] The signal processing IC 3 estimates the direction of the target by a method such as scanning the transmission directions of the electromagnetic waves Fx1 and Fx2 transmitted from the antenna sections (first antenna section 2a and second antenna section 2b) or detecting the reception phase difference between reflected wave signals received by the respective antenna elements arranged in a group of the antenna sections (first antenna section 2a and second antenna section 2b).

[0033] Since the processing by the signal processing IC 3 is the same as that of a conventional configuration, a detailed description thereof will be omitted here. The signal processing IC 3 is mainly composed of a known microcomputer including, for example, a CPU, a ROM, and a RAM, and further includes a drive circuit for generating a high-frequency drive signal to be transmitted to the first antenna section 2a and the second antenna section 2b, a detection circuit for performing reception processing of reflected wave signals from the first antenna section 2a and the second antenna section 2b, and the like. However, it goes without saying that part of the signal processing IC 3 can also be implemented using only a dedicated hardware circuit without a CPU or the like.

[0034] The housing 4 houses the circuit board 1 and supports the first dielectric lens 5a and the second dielectric lens 5b in front of the circuit board 1. The housing 4 typically houses the circuit board 1 in a substantially sealed state.

[0035] Window sections 4a and 4b through which the first antenna section 2a and the second antenna section 2b transmit and receive electromagnetic waves are formed on a front surface of the housing 4, respectively, and the first dielectric lens 5a and the second dielectric lens 5b are fixed to the window sections 4a and 4b (see Fig. 3).

[0036] For example, a metal material or a resin material is used as the raw material for the housing 4. When the resin material is used for the housing 4, a product integrally formed from the same resin material can be used for the housing 4 and the dielectric lens (first dielectric lens 5a or second dielectric lens 5b).

[0037] The first dielectric lens 5a is supported in front of the first antenna section 2a, narrows a beam of the electromagnetic wave Fx1 transmitted from the first antenna section 2a, and transmits it to a front portion of the device exterior. The first dielectric lens 5a then focuses the reflected waves, which are the electromagnetic waves Fx1 and Fx2 transmitted to the device exterior and reflected and returned by the target, onto the first antenna section 2a.

[0038] The second dielectric lens 5b is supported in front of the second antenna section 2b, narrows a beam of the electromagnetic wave Fx2 transmitted from the second antenna section 2b, and transmits it to a front portion of the device exterior. The second dielectric lens 5b then focuses the reflected waves, which are the electromagnetic waves Fx1 and Fx2 transmitted to the device exterior and reflected and reverberated by the target, onto the second antenna section 2b.

[0039] A front end surface of the first dielectric lens 5a (corresponding to an "outer end surface" of the invention) and a front end surface of the second dielectric lens 5b (corresponding to the "outer end surface" of the invention) both face the cover member B. In other words, the antenna device U is fixed to the cover member B such that a direction (±Y direction) in which the first antenna portion 2a and the second antenna portion 2b are adjacent to each other is parallel to the extending direction of the cover member B.

[0040] For example, a semi-cylindrical or parabolic cylindrical lens having a convex shape in the plus X direction and extending along the ±Y direction is used as the first dielectric lens 5a and the second dielectric lens 5b. The semi-cylindrical or parabolic cylindrical lens has substantially the same lateral cross-sectional shape (also called a semicircular cylindrical shape; hereinafter, it will be generally referred to as a semi-cylindrical lens) at any point in the ±Y direction. Therefore, when electromagnetic waves transmitted from the plurality of antenna elements arranged along the ±Y direction are reflected from the target and arrive at the antenna elements, the electromagnetic waves can be prevented from traveling in different directivity directions from each other (the same applies to the first antenna section 2a or the second antenna section 2b).This makes it possible to suppress any impairment of the accuracy of object detection due to mutual interference or due to a change in the phase difference.

[0041] The front end face of the first dielectric lens 5a projects further forward than the front end face of the second dielectric lens 5b (see Fig. 4). In other words, the distance D1 between the front end surface of the first dielectric lens 5a and an inner surface of the cover member B (hereinafter referred to as "first inter-end surface distance") is shorter than the distance D2 between the front end surface of the second dielectric lens 5b and the inner surface of the cover member B (hereinafter referred to as "second inter-end surface distance").

[0042] The difference between a forward protrusion amount of the front end surface of the first dielectric lens 5a and a forward protrusion amount of the front end surface of the second dielectric lens 5b is typically set to approximately λ / 4×(2m-1), where λ denotes a free-space wavelength of the electromagnetic waves Fx1 and Fx2, and m denotes any positive integer. In other words, the difference between the first end-face distance D1 and the second end-face distance D2 is set to approximately λ / 4×(2m-1), where λ denotes a free-space wavelength of the electromagnetic waves Fx1 and Fx2, and m denotes any positive integer. Here, "approximately" includes a tolerance range (e.g., approximately 1 mm) due to a manufacturing error (hereinafter, the same applies).

[0043] The adjustment of the difference between the forward projection amount of the front end surface of the first dielectric lens 5a and the forward projection amount of the front end surface of the second dielectric lens 5b is performed, for example, by adjusting the lens thickness of each of the first dielectric lens 5a and the second dielectric lens 5b, the arrangement positions, the relative dielectric constants, or the aperture diameters.

[0044] By this, it is possible to cause “a re-reflected wave generated when the electromagnetic wave Fx1 transmitted from the first antenna section 2a is reflected by the cover member B, is reflected again by the first dielectric lens 5a, and travels to the device exterior” and “a reflected wave generated when the electromagnetic wave Fx2 transmitted from the second antenna section 2b is reflected by the cover member B, is reflected again by the second dielectric lens 5b, and travels to the device exterior” to cancel each other out (as will be explained later with reference to Fig. 6).

[0045] For example, in order to prevent the phase of the direct transmission wave and the phase of the re-reflected wave from being in the opposite phase relationship when the electromagnetic waves Fx1 and Fx2 are transmitted, the first end face distance D1 and the second end face distance D2 are set to satisfy the following expressions 1 and 2, respectively: λ / 4×2i−β <D1<λ / 4×2i+β and λ / 4×2j−β <D2<λ / 4×2j+β where i and j denote arbitrary positive integers and β denotes a tolerance distance of λ / 8.

[0046] Raw materials constituting the first dielectric lens 5a and the second dielectric lens 5b may be any, using, for example, acrylic resin, tetrafluoroethylene resin, polystyrene resin, polycarbonate resin, polybutylene terephthalate resin, polyphenylene resin, polypropylene resin, syndiotactic polystyrene resin, or ABS resin.

[0047] The holder 6 holds the housing 4 and fixes the housing 4 to the cover element B in a front region of the housing 4. The holder 6 fixes the housing 4 to the cover element B, for example by means of a fastening element, such as a double-sided adhesive tape or a screw.

[0048] The holder 6 fixes the housing 4 to the cover element B in such a way that, for example, the transmission directions of the electromagnetic waves Fx1 and Fx2 are a direction horizontal to the ground. [Behavior of the electromagnetic wave during operation of the antenna device]

[0049] Next, the behavior of electromagnetic waves during operation of the antenna device U according to the present embodiment will be described with reference to FIG. Fig. 6 and Fig. 7 described.

[0050] Fig. 6 shows the behavior of electromagnetic waves when the antenna device U according to the present embodiment is operated.

[0051] Fig. Figure 7 shows the behavior of electromagnetic waves during operation of the antenna device Ua according to a comparative example. The antenna device Ua according to the comparative example differs from the antenna device U according to the present embodiment in that the first inter-face distance D1 and the second inter-face distance D2 are the same.

[0052] As in the Fig. 6 and Fig. 7, in the antenna devices U and Ua, the electromagnetic wave Fx1 transmitted forward from the first antenna section 2a and the electromagnetic wave Fx2 transmitted forward from the second antenna section 2b reach the cover member B substantially in phase.

[0053] At this time, most of the electromagnetic wave Fx1 transmitted from the first antenna section 2a (hereinafter referred to as "direct transmission wave Fa1") passes through the cover member B unchanged, but a part Fb1 (hereinafter referred to as "re-reflected wave Fb1") of the electromagnetic wave Fx1 is reflected by the cover member B, then returns to the first dielectric lens 5a side, is reflected again by the first dielectric lens 5a, and is transmitted to the device exterior.

[0054] In addition, most of the electromagnetic wave Fx2 transmitted from the second antenna section 2b (hereinafter referred to as "direct transmission wave Fa2") passes through the cover member B unchanged, but a part Fb2 (hereinafter referred to as "re-reflected wave Fb2") of the electromagnetic wave Fx2 is reflected by the cover member B, then returns to the second dielectric lens 5b side, is reflected again by the second dielectric lens 5b, and is transmitted to the device exterior.

[0055] Assuming that the distances (first inter-face distance D1 and second inter-face distance D2) between the front end surfaces of the antenna devices U and Ua and the inner surface of the cover member B are adjusted so that the direct transmission waves Fa1 and Fa2 and the re-reflected waves Fb1 and Fb2 are in phase, the influence of the re-reflected waves Fb1 and Fb2 on the output gains of the antenna devices U and Ua is small. However, in reality, the distances between the antenna devices U and Ua and the cover member B change due to vibrations or the like of the vehicles equipped with the antenna devices U and Ua.

[0056] If at this time, as shown in the antenna device Ua according to the comparative example (see Fig. 7), the first end face distance D1 and the second end face distance D2 are equal, as above with reference to Fig. 1, the re-reflected waves Fb1 and Fb2 act to cancel the direct transmission waves Fa1 and Fa2 and cause a reduction in the output gain of the antenna device Ua.

[0057] In this regard, in the antenna device U according to the embodiment, the difference between the first end-face distance D1 and the second end-face distance D2 is set to approximately λ / 4×(2m-1). Therefore, the phase of the re-reflected wave Fb1 generated due to the electromagnetic wave Fx1 transmitted from the first antenna section 2a and the phase of the re-reflected wave Fb2 generated due to the electromagnetic wave Fx2 transmitted from the second antenna section 2b are in the opposite phase relationship and cancel each other out. Therefore, in the antenna device U according to the embodiment, the amount of re-reflected waves Fb1 and Fb2 superimposed on the direct passing waves Fa1 and Fa2 can be reduced.This makes it possible to suppress the situation where the output gains of the electromagnetic waves Fx1 and Fx2 are reduced due to the positional shift of the antenna device U.

[0058] Fig. Fig. 8 is a graph showing the amplitudes of the re-reflected waves Fb1 and Fb2 in the antenna device U according to the present embodiment with respect to the position of the antenna device U. In Fig. 8, the horizontal axis represents the position of the antenna device U from the cover member B, and the vertical axis represents an amplitude of the reflected wave Fb1 generated due to the electromagnetic wave Fx1 transmitted from the first antenna section 2a, an amplitude of the reflected wave Fb2 generated due to the electromagnetic wave Fx2 transmitted from the second antenna section 2b, and an amplitude of the combined component Fb-all of the re-reflected wave Fb1 and the re-reflected wave Fb2.

[0059] As in Fig. As shown in Fig. 8, in the antenna device U according to the embodiment, because the difference between the first inter-face distance D1 and the second inter-face distance D2 is set to approximately λ / 4×(2m-1) (see Expression 1 above), the re-reflected wave Fb1 and the re-reflected wave Fb2 are in the opposite phase relationship regardless of the position of the antenna device U. Therefore, the combined component Fb-all of the re-reflected wave Fb1 and the re-reflected wave Fb2 becomes zero regardless of the position of the antenna device U.

[0060] Even if the difference between the first end-face distance D1 and the second end-face distance D2 is not exactly equal to about λ / 4×(2m-1), when the first end-face distance D1 and the second end-face distance D2 are different, it is possible to cause the re-reflected wave Fb1 and the re-reflected wave Fb2 to attenuate each other, and it is possible to reduce the amount of the re-reflected waves Fb1 and Fb2 superimposed on the direct through waves Fa1 and Fa2 compared to the case where the first end-face distance D1 and the second end-face distance D2 are the same.

[0061] By setting the first end-face distance D1 and the second end-face distance D2 to be different from each other, either the first antenna section 2a or the second antenna section 2b can ensure high output gain and reception gain, thereby improving robustness against the positional shift of the antenna device U.

[0062] The Fig. 9A and Fig. 9B shows simulation results of checking the radar performance of the antenna device U according to the present embodiment and the antenna device Ua according to the comparative example.

[0063] In the simulation, the first antenna section 2a and the second antenna section 2b each transmit an electromagnetic wave, and the radio wave intensity (i.e., the reception gain) of the reflection waves from a predetermined target received at each of the first antenna section 2a and the second antenna section 2b is calculated. In the simulation, the reception gain is calculated for each distance between the cover member B and the antenna devices U and Ua while changing the distances between the inner surface of the cover member B and the front end surfaces of the antenna devices U and Ua (i.e., the first end-face distance D1 and the second end-face distance D2). The sampling points of the simulation results are connected to draw the graph lines.

[0064] The lines in Fig. 9A shows the simulation results of the antenna device U according to the embodiment and illustrates the following: dashed line: reception gain at the first antenna section 2a; alternating long and short dashed line: reception gain at the second antenna section 2b; and Solid line: sum of reception gain at the first antenna section 2a and reception gain at the second antenna section 2b.

[0065] The lines in Fig. 9B shows the simulation results of the antenna device Ua according to the comparative example and illustrates the following: dashed line: reception gain at the first antenna section 2a; alternating long and short dashed line: reception gain at the second antenna section 2b; and Solid line: sum of reception gain at the first antenna section 2a and reception gain at the second antenna section 2b.

[0066] As in Fig. 9B, in the antenna device Ua according to the comparative example, a region where the radio wave intensity decreases appears (position at 5 mm and position at 7 mm in Fig. 9B), at multiple positions depending on the distance between the cover member B and the front end surface of the antenna device Ua. That is, in the antenna device Ua according to the comparative example, the output gain of the antenna device Ua is reduced by a slight positional shift of the antenna device Ua, and thereby the reception gain at the antenna device Ua is reduced. That is, in the antenna device Ua according to the comparative example, the accuracy of object detection is significantly deteriorated by the positional shift of the antenna device Ua.

[0067] On the other hand, Fig. 9A, in the antenna device U according to the embodiment, even if the distance between the cover member B and the front end face of the antenna device U is changed, the sum of the reception gain of the first antenna section 2a and the reception gain of the second antenna section 2b is substantially a constant reception gain (solid line in Fig. 9A). That is, the antenna device U according to the embodiment can suppress the situation where the accuracy of object detection is excessively deteriorated even when the antenna device U is shifted, unlike the antenna device Ua according to the comparative example. [Effects]

[0068] As described above, the antenna device U according to the embodiment includes first and second antenna sections 2a and 2b that are adjacently arranged along the direction orthogonal to the front side and respectively transmit electromagnetic waves Fx1 and Fx2 forward, and first and second dielectric lenses 5a and 5b that are arranged in front of the first and second antenna sections 2a and 2b and respectively narrow the beams of the electromagnetic waves Fx1 and Fx2 transmitted from the first and second antenna sections 2a and 2b to transmit them to the device exterior, wherein the front end surface (outer end surface) of the first dielectric lens 5a protrudes further forward than the front end surface (outer end surface) of the second dielectric lens 5b.

[0069] Thus, according to the antenna device U according to the embodiment, when electromagnetic waves Fx1 and Fx2 are transmitted to the device exterior, it is possible to cause “a re-reflected wave Fb1 generated when the electromagnetic wave Fx1 transmitted from the first antenna section 2a is reflected by the cover member B, is re-reflected by the first dielectric lens 5a, and travels to the device exterior” and “a re-reflected wave Fb2 generated when the electromagnetic wave Fx2 transmitted from the second antenna section 2b is reflected by the cover member B, is re-reflected by the second dielectric lens 5b, and travels to the device exterior” to cancel each other out.Thereby, even if the distance between the antenna device U and the cover member B changes due to vibration during driving or the like, it is possible to suppress the situation in which the output gain and the input gain are reduced due to the above-described re-reflected waves Fb1 and Fb2.

[0070] Specifically, in the antenna device U according to the embodiment, the difference between the forward projection amount of the front end surface of the first dielectric lens 5a and the forward projection amount of the front end surface of the second dielectric lens 5b (or the difference between the distance between the front end surface of the first dielectric lens 5a and the cover member B and the distance between the front end surface of the second dielectric lens 5b and the cover member B) is set to approximately λ / 4×(2m-1). This allows the re-reflected wave Fb1 and the re-reflected wave Fb2 to cancel each other more effectively. (Embodiment 2)

[0071] Next, an antenna device U according to Embodiment 2 will be described with reference to FIG. Fig. 10 to 12. The antenna device U according to the present invention differs from Embodiment 1 in the configurations of the first dielectric lens 5a and the second dielectric lens 5b. The description of the configurations similar to Embodiment 1 will be omitted (hereinafter, the same applies to other embodiments).

[0072] Fig. 10 is a plan view of the antenna device U according to the present embodiment. Fig. 11 is a diagram of the antenna device U according to the present embodiment as seen from the rear.

[0073] The first dielectric lens 5a according to the embodiment is formed from a lens having a semi-cylindrical shape at a front end portion. On the other hand, the second dielectric lens 5b according to the embodiment is formed from a lens having a dome or paraboloid of revolution shape at the front end portion.

[0074] The semi-cylindrical dielectric lens narrows the beam only in the ±Z direction, while the dome or paraboloidal dielectric lens narrows the beam in both the ±Z and ±Y directions. Therefore, the dome or paraboloidal dielectric lens is more useful than the semi-cylindrical dielectric lens because it can further narrow the beam of an electromagnetic wave.

[0075] Also in the antenna device U according to the embodiment, it is desirable that the difference between the forward projection amount of the front end surface of the first dielectric lens 5a and the forward projection amount of the front end surface of the second dielectric lens 5b (ie, the difference between the first end surface distance D1 and the second end surface distance D2) is approximately λ / 4×(2m-1) so that the re-reflected wave Fb1 and the re-reflected wave Fb2 cancel each other. Fig. 10 indicates an aspect in which the forward protrusion amount of the front end surface of the first dielectric lens 5a is larger by λ / 4 than the forward protrusion amount of the front end surface of the second dielectric lens 5b.

[0076] However, when lenses having different shapes are used for the first dielectric lens 5a and the second dielectric lens 5b as in the embodiment, the difference between the first inter-end face distance D1 and the second inter-end face distance D2 is set to approximately λ / 4×(2m-1) based on the average protrusion positions of the respective lenses.For example, since the front end surface of the dome-shaped dielectric lens has a shape recessed in different directions compared with the front end surface of the semi-cylindrical dielectric lens, even if the distance from a tip of the front end surface of the dome-shaped dielectric lens is equal to the distance from a tip of the front end surface of the semi-cylindrical dielectric lens, the average protrusion position of the front end surface of the dome-shaped dielectric lens is a position closer to the base end side than the average protrusion position of the front end surface of the semi-cylindrical dielectric lens (see the reference position of D2 in ). Fig. 10).

[0077] Fig. Fig. 12 shows a simulation result of checking the radar performance of the antenna device U according to the present embodiment in the same manner as Fig. 9A.

[0078] The lines in Fig. 12 represent the following: dashed line: reception gain at the first antenna section 2a; alternating long and short dashed line: reception gain at the second antenna section 2b; and Solid line: sum of reception gain at the first antenna section 2a and reception gain at the second antenna section 2b.

[0079] As in Fig. 12, also in the antenna device U according to the embodiment, even if the distance between the cover member B and the antenna device U changes, the total reception gain of the first antenna section 2a and the second antenna section 2b is substantially a constant reception gain (solid line in Fig. 12A). That is, the antenna device U according to the embodiment can also suppress, in the same manner as the antenna device U according to Embodiment 1, the situation in which the accuracy of object detection is excessively deteriorated even if the antenna device U is displaced.

[0080] The Fig. 13A and Fig. 13B show a comparison of the reception gains of the antenna device Ua according to the comparative example (see Fig. 7), the antenna device U according to Embodiment 1 and the antenna device U according to Embodiment 2.

[0081] Fig. 13A shows reception gains (here, combined gains obtained by summing the reception gain of the first antenna section 2a and the reception gain of the second antenna section 2b) when the distances between the cover member B and the front end surfaces of the antenna devices U and Ua are changed, for each of the distances. Fig. Fig. 13B shows amounts of change in the combined gains when the distances between the cover member B and the front end surfaces of the antenna devices U and Ua are changed.

[0082] The lines in Fig. 13A represent the following: dashed line: reception gain at the antenna device Ua according to the comparative example; alternating long and short dashed line: reception gain at the antenna device U according to embodiment 1; and Solid line: Reception gain at the antenna device U according to Embodiment 2.

[0083] As in the Fig. 13A and Fig. As shown in FIG. 13B, in the antenna device U according to Embodiment 1 and the antenna device U according to Embodiment 2, even when the antenna device U is shifted, the change amounts of the reception gain are reduced compared to the antenna device Ua according to the comparative example. That is, the antenna device U according to Embodiment 1 and the antenna device U according to Embodiment 2 can reduce the change amounts of the output gain even when the antenna device U is shifted, unlike the antenna device Ua according to the comparative example. This makes it possible to suppress the situation where the accuracy of object detection deteriorates excessively.

[0084] As described above, like the antenna device U according to the present embodiment, even if the lens shape of the first dielectric lens 5a and the lens shape of the second dielectric lens 5b are different from each other, it is possible to suppress the situation in which the output gain and the reception gain are reduced due to the re-reflected waves Fb1 and Fb2 by setting the first dielectric lens 5a and the second dielectric lens 5b so that the first end-face distance D1 and the second end-face distance D2 are different from each other.

[0085] However, in the antenna device U according to the present embodiment, since the amount of change in the reception gain when the distance between the cover member B and the antenna device U changes is larger than that of the antenna device U according to Embodiment 1, the antenna device U according to Embodiment 1 is more suitable. (Embodiment 3)

[0086] Next, the antenna device U according to Embodiment 3 will be described with reference to the Fig. 14 and Fig. 15. The antenna device U according to the present embodiment differs from Embodiment 1 in that it includes a third antenna section 2c and a third dielectric lens 5c.

[0087] Fig. 14 is a plan view of the antenna device U according to the present embodiment.

[0088] Fig. Fig. 15 is a graph showing the amplitude of a re-reflected wave in the antenna device U according to the present embodiment with respect to the position of the antenna device U (the position in the X-axis direction). The lines in Fig. 15 represent the following: Fb1: amplitude of a re-reflected wave due to an electromagnetic wave Fx1 transmitted from the first antenna section 2a; Fb2: amplitude of a re-reflected wave due to an electromagnetic wave Fx2 transmitted from the second antenna section 2b; Fb3: amplitude of a re-reflected wave due to an electromagnetic wave Fx3 transmitted from the third antenna section 2c; and Fb-all: Combination of re-reflected wave Fb1, re-reflected wave Fb2 and re-reflected wave Fb3.

[0089] The third antenna section 2c is arranged on the circuit board 1 on the minus-Y direction side, adjacent to the second antenna section 2b. It transmits the electromagnetic wave Fx3 forward and receives reflected waves from the front, which are electromagnetic waves Fx1, Fx2, and Fx3 reflected and returned by the target. The third antenna section 2c consists of three longitudinally radiating array antennas arranged along the ±Y direction, like the first antenna section 2a and the second antenna section 2b.

[0090] The third antenna section 2c is configured to perform the same function as the first antenna section 2a and the second antenna section 2b. That is, the first antenna section 2a, the second antenna section 2b, and the third antenna section 2c transmit electromagnetic waves Fx1, Fx2, and Fx3 with the same frequency and phase to the front of the device exterior. The first antenna section 2a, the second antenna section 2b, and the third antenna section 2c then each receive reflected waves, which are the electromagnetic waves Fx1, Fx2, and Fx3 reflected and returned by the target.

[0091] The third dielectric lens 5c is supported in front of the third antenna section 2c, narrows a beam of the electromagnetic wave Fx3 transmitted from the third antenna section 2c, and transmits it to a front area of ​​the device exterior. The third dielectric lens 5c then focuses the reflected waves, which are the electromagnetic waves Fx1, Fx2, and Fx3 transmitted to the device exterior and reflected from the target, onto the third antenna section 2c.

[0092] In the antenna device U according to the present embodiment, adjusting the protrusion amount of the front end surface of each of the first dielectric lens 5a, the second dielectric lens 5b, and the third dielectric lens 5c provides an extinction effect of the re-reflected waves Fb1, Fb2, and Fb3 generated when the electromagnetic waves Fx1, Fx2, and Fx3 are reflected by the cover member B and re-reflected by the front end surfaces of each of the first dielectric lens 5a, the second dielectric lens 5b, and the third dielectric lens 5c.

[0093] Specifically, the protrusion amounts of the front end surfaces of the first dielectric lens 5a, the second dielectric lens 5b, and the third dielectric lens 5c differ from each other by, for example, approximately λ / 6. For example, the protrusion amount of the front end surface of the second dielectric lens 5b is λ / 6 larger than the protrusion amount of the front end surface of the third dielectric lens 5c, and the protrusion amount of the front end surface of the first dielectric lens 5a is 2×λ / 6 larger than the protrusion amount of the front end surface of the third dielectric lens 5c.In other words, the distance D2 with respect to the cover element B arranged in front of the front end face of the second dielectric lens 5b is smaller by λ / 6 than the distance D3 with respect to the cover element B arranged in front of the front end face of the third dielectric lens 5c, and the distance D1 with respect to the cover element B arranged in front of the front end face of the first dielectric lens 5a is smaller by 2×λ / 6 than the distance D3 with respect to the cover element B arranged in front of the front end face of the third dielectric lens 5c.

[0094] This allows a reflected wave Fb1 due to the electromagnetic wave Fx1 transmitted from the first antenna section 2a, a reflected wave Fb2 due to the electromagnetic wave Fx2 transmitted from the second antenna section 2b, and a reflected wave Fb3 due to the electromagnetic wave Fx3 transmitted from the third antenna section 2c to act to cancel each other out, regardless of the position of the antenna device U, as shown in Fig. 15 is shown.

[0095] In the above embodiment, the aspect is shown in which three sets each comprising an antenna section and a dielectric lens are adjacently arranged along the ±Y direction, however, the present invention is also applicable to an antenna device U comprising n (n is an arbitrary positive integer) antenna sections adjacently arranged along the ±Y direction and transmitting electromagnetic waves forward, and n dielectric lenses respectively arranged in front of the n antenna sections, narrowing beams of the electromagnetic waves transmitted from the n respective antenna sections and transmitting them to the device exterior.

[0096] In this case, the forward protrusion amounts of the front end surfaces of the n dielectric lenses may be set to differ from each other by approximately λ×(2m-1) / (n×2). In other words, the distances with respect to the cover member B arranged in front of the front end surfaces of the n dielectric lenses may be set to differ from each other by approximately λ×(2m-1) / (n×2). For example, in an aspect where four sets each comprising an antenna portion and a dielectric lens are arranged, the forward protrusion amounts of the front end surfaces of the four dielectric lenses are set to differ by approximately λ / 8. Furthermore, in an aspect where five sets each comprising an antenna portion and a dielectric lens are arranged, the forward protrusion amounts of the front end surfaces of the five dielectric lenses are set to differ by approximately λ / 10.

[0097] In other words, the outer end surfaces of the other n-1 dielectric lenses each protrude relative to the outer end surface of one of the n dielectric lenses by approximately λ×k×(2m-1) / (n×2) (k denotes any integer between 1 and n-1) in the predetermined direction, and the forward protrusion amounts of the outer end surfaces of the other n-1 dielectric lenses in the predetermined direction relative to the outer end surface of one of the n dielectric lenses are different.

[0098] As described above, the number of sets each comprising an antenna section and a dielectric lens is arbitrary, and the forward projection amounts of the front end surfaces of the respective dielectric lenses can be adjusted according to the number of sets. This allows re-reflected waves to cancel each other out, regardless of the position of the antenna device U. (Embodiment 4)

[0099] Next, an antenna device U according to Embodiment 4 will be described with reference to Fig. 16. The antenna device U according to the present embodiment differs from Embodiment 2 in that only the first antenna section 2a serves as a receiving antenna.

[0100] Fig. 16 is a plan view of the antenna device U according to the present embodiment.

[0101] The second antenna section 2b transmits the electromagnetic wave Fx2 to the outside of the device via the second dielectric lens 5b. However, the second antenna section 2b according to the present embodiment only transmits the electromagnetic wave Fx2 but does not perform reception processing. The electromagnetic wave Fx2 transmitted to the outside of the device is reflected by the target and detected by the first antenna section 2a. That is, the second antenna section 2b serves as an auxiliary antenna to increase the output gain of the electromagnetic wave at the first antenna section 2a.

[0102] As described above, the antenna device U according to the embodiment also allows, when electromagnetic waves Fx1 and Fx2 are transmitted to the device exterior, a “re-reflected wave Fb1 generated when the electromagnetic wave Fx1 transmitted from the first antenna section 2a is reflected by the cover member B, is reflected again by the first dielectric lens 5a, and travels to the device exterior” and a “re-reflected wave Fb2 generated when the electromagnetic wave Fx2 transmitted from the second antenna section 2b is reflected by the cover member B, is reflected again by the second dielectric lens 5b, and travels to the device exterior” to act to cancel each other. (Embodiment 5)

[0103] Next, an antenna device U according to Embodiment 5 will be described with reference to FIG. Fig. 17, Fig. 18A and Fig. 18B. The antenna device U according to the present embodiment differs from Embodiment 2 in that dielectric lenses with different lens diameters are used for the first dielectric lens 5a and the second dielectric lens 5b.

[0104] Fig. 17 is a diagram of the antenna device U according to the present embodiment as seen from the rear.

[0105] Fig. 18A is a graph showing an output characteristic of the antenna device U according to the present embodiment, and Fig. 18B is a graph showing an output characteristic of the antenna device U according to Embodiment 2.

[0106] The lines in the Fig. 18A and Fig. 18B represent the following: dashed line: output gain at the first antenna section 2a; alternating long and short dashed line: output gain at the second antenna section 2b; and solid line: sum of the output gain at the first antenna section 2a and the output gain at the second antenna section 2b.

[0107] In the Fig. 18A and Fig. 18B, the horizontal axis represents a radiation angle and the vertical axis represents the output gain. In the Fig. 18A and Fig. 18B illustrates a position with a radiation angle of 90 degrees as a direction for transmitting an electromagnetic wave from the antenna section (first antenna section 2a or second antenna section 2b). A range from about 60 degrees to 120 degrees corresponds to a main lobe of the electromagnetic wave transmitted from the antenna section (first antenna section 2a or second antenna section 2b), and ranges from about 0 degrees to 60 degrees and from about 120 degrees to 180 degrees correspond to side lobes of the electromagnetic wave transmitted from the antenna section (first antenna section 2a or second antenna section 2b).

[0108] In the Fig. 18A and Fig. Figure 18B shows the magnitude of the difference between the output gain of the main lobe and the output gain of the side lobes (width of the gap in the Fig. 18A and Fig. 18B) of the combined gain (solid line) represents a sidelobe level for the entire antenna device U.

[0109] In general, the output gain of a dielectric lens varies depending on the dielectric lens's emission direction. The output characteristic of the dielectric lens as a function of the emission direction depends on the lens diameter of the dielectric lens. Therefore, when two dielectric lenses are used, it is possible to shift the emission directions in which the respective output gains are reduced by using dielectric lenses with different lens diameters.

[0110] In the present embodiment, from this point of view, a dielectric lens with a larger lens diameter than the first dielectric lens 5a is used as the second dielectric lens 5b (for example, the lens diameter Lb of the second dielectric lens 5b is 15 mm, and the lens diameter La of the first dielectric lens 5a is 10 mm). In the embodiment, a semi-cylindrical lens is used as the first dielectric lens 5a, and a dome-shaped lens is used as the second dielectric lens 5b. Lenses of the same shape can be used for the first dielectric lens 5a and the second dielectric lens 5b.

[0111] As in Fig. As shown in Fig. 18B, the first antenna section 2a and the second antenna section 2b have the same output characteristics when the lens diameter of the first dielectric lens 5a and the lens diameter of the second dielectric lens 5b are the same. Thus, when the lens diameter of the first dielectric lens 5a and the lens diameter of the second dielectric lens 5b are the same, a radiation angle at which the intensity of the side lobes of the electromagnetic wave transmitted from the first antenna section 2a increases overlaps with a radiation angle at which the intensity of the side lobes of the electromagnetic wave transmitted from the second antenna section 2b increases. For this reason, a radiation angle at which the intensity of the side lobes is abnormally large with respect to the intensity of the main lobe appears as a combined gain.This creates the risk of creating a situation where a reflected wave (e.g., a wave reflected from the ground) generated due to the side lobes is mistakenly detected as a wave reflected from the target.

[0112] On the other hand, if, as Fig. 18A, the lens diameter of the first dielectric lens 5a and the lens diameter of the second dielectric lens 5b are different, so the radiation angle at which the intensity of the side lobes of the electromagnetic wave transmitted from the first antenna section 2a increases is shifted from the radiation angle at which the intensity of the side lobes of the electromagnetic wave transmitted from the second antenna section 2b increases. Consequently, as a combined gain, the intensity of the side lobes is relatively small relative to the intensity of the main lobe for each direction. This also reduces the risk of false detection due to the side lobes.

[0113] As described above, according to the antenna device U according to the embodiment, it is possible to suppress the occurrence of false detection due to the side lobes. (Embodiment 6)

[0114] In the above embodiments, the radar device has been described as the application target of the antenna device U, but the antenna device U according to the present invention can also be used for communication applications.

[0115] Fig. 19 shows an example of an antenna device U according to Embodiment 6.

[0116] Fig. 19 shows a state in which electromagnetic waves are transmitted and received between the antenna device U mounted on one vehicle Ca and the antenna device U mounted on another vehicle Cb, and communication is performed (so-called vehicle-to-vehicle communication). In the antenna device U according to the present embodiment, a signal processing IC for communication (not shown) may be mounted instead of the object detection signal processing IC 3 described above.

[0117] Since the antenna device U according to the present invention can prevent the situation where phases are canceled by multiple reflection with the cover member (bumper) and the output gain is reduced when electromagnetic waves are transmitted through the cover member B, the antenna device U can be suitably used for an aspect to communicate with another antenna device as in the embodiment. (Other embodiments)

[0118] The present invention is not limited to the above embodiments, and various modifications are possible. For example, it goes without saying that various combinations of the aspects illustrated in the embodiments can be used.

[0119] In the above embodiments, the semi-cylindrical lens or the dome-shaped lens is shown as an example of the shapes of the first dielectric lens 5a and the second dielectric lens 5b. However, as the shapes of the first dielectric lens 5a and the second dielectric lens 5b, a double-sided convex lens, a spherical lens, a Fresnel lens, or a combination thereof, or a concave lens and a combination thereof, or the like can be used. In addition to these, as the first dielectric lens 5a and the second dielectric lens 5b, their back surfaces may be convex in the minus X direction. The first dielectric lens 5a and the second dielectric lens 5b may be integrally formed.

[0120] In the above embodiments, the longitudinal array antenna is shown as an example of the first antenna section 2a and the second antenna section 2b. However, the first antenna section 2a and the second antenna section 2b may be any of those formed by a conductor pattern formed on the circuit board 1, and in addition to the longitudinal array antenna, an antenna such as a Yagi array antenna, a Fermi antenna, a post-wall waveguide antenna (substrate-integrated waveguide antenna), or a post-wall horn antenna (substrate-integrated horn antenna) may also be used.

[0121] In the above embodiments, as an example of the positional relationship between the antenna device U and the cover member B, the aspect in which the cover member B extends along the direction (±Y direction) in which the first antenna portion 2a and the second antenna portion 2b of the antenna device U are adjacent to each other is illustrated. However, the antenna device U may be mounted so as to be inclined toward the cover member B. In other words, the direction (±Y direction) in which the first antenna portion 2a and the second antenna portion 2b of the antenna device U are adjacent to each other may be inclined toward the extending direction of the cover member B.In the aspect, the first inter-end surface distance D1 may be set based on the distance between the cover member B in front of the first dielectric lens 5a and the front end surface of the first dielectric lens 5a, and the second inter-end surface distance D2 may be set based on the distance between the cover member B in front of the second dielectric lens 5b and the front end surface of the second dielectric lens 5b.

[0122] Although various embodiments have been described in the foregoing, it is to be understood that various changes in form and details may be made without departing from the spirit and scope of the invention(s) claimed herein or hereinafter. Industrial applicability

[0123] With the antenna device according to the present disclosure, it is possible to ensure a high output gain even when electromagnetic waves are transmitted and received through the cover member. List of reference symbols U Antenna device B Cover element C vehicle 1 circuit board 2a first antenna section 2b second antenna section 2c third antenna section 3 Signal processing IC 4 housings 4a, 4b window section 5a first dielectric lens 5b second dielectric lens 5c third dielectric lens 6 Bracket

Claims

[1] Antenna device (U) for transmitting and receiving electromagnetic waves through an externally arranged cover element (B), the antenna device comprising: a first (2a) and a second (2b) antenna section which are arranged adjacent to each other along a direction orthogonal to a predetermined direction in which the electromagnetic waves (Fx1, Fx2) are transmitted, and which respectively transmit the electromagnetic waves (Fx1, Fx2); a first (5a) and a second (5b) dielectric lens which are arranged in the predetermined direction in front of the first and second antenna sections (2a, 2b), respectively, and which respectively narrow the beams of the electromagnetic waves (Fx1, Fx2) transmitted from the first and second antenna sections (2a, 2b) and transmit the beams of the electromagnetic waves (Fx1, Fx2) to the outside, wherein an outer end surface of the first dielectric lens (5a) projects further forward in the predetermined direction than an outer end surface of the second dielectric lens (5b), so that a distance (D1) between the cover element (B) and the outer end surface of the first dielectric lens (5a) in the predetermined direction is shorter than a distance (D2) between the cover element (B) and the outer end surface of the second dielectric lens (5b) in the predetermined direction. [2] The antenna device (U) according to claim 1, wherein the outer end surfaces of the first and second dielectric lenses (5a, 5b) each have a semi-cylindrical shape convex in the predetermined direction or a parabolic cylindrical shape convex in the predetermined direction. [3] The antenna device (U) according to claim 1, wherein one of the first and second dielectric lenses (5a, 5b) has an outer end surface having a semi-cylindrical shape convex in the predetermined direction or a parabolic cylindrical shape convex in the predetermined direction, and the other has an outer end surface having a dome shape convex in the predetermined direction or a paraboloid of revolution convex in the predetermined direction. [4] The antenna device (U) according to any one of claims 1 to 3, wherein a difference between a protrusion amount of the outer end surface of the first dielectric lens (5a) in the predetermined direction and a protrusion amount of the outer end surface of the second dielectric lens (5b) in the predetermined direction is approximately λ / 4×(2m-1), where λ denotes a free space wavelength of the electromagnetic waves and m denotes an arbitrary positive integer. [5] The antenna device (U) according to any one of claims 1 to 4, wherein a difference between a distance between the outer end surface of the first dielectric lens (5a) and a surface of the cover member (B) facing the first dielectric lens (5a) and a distance between the outer end surface of the second dielectric lens (5b) and a surface of the cover member facing the second dielectric lens (5b) is approximately λ / 4×(2m-1), where λ denotes a free-space wavelength of the electromagnetic waves and m denotes an arbitrary positive integer. [6] The antenna device (U) according to any one of claims 1 to 5, wherein a lens diameter of the first dielectric lens (5a) and a lens diameter of the second dielectric lens (b) are different from each other. [7] Antenna device (U) according to one of claims 1 to 6, wherein the first and the second antenna section (2a, 2b) each consist of a longitudinally radiating group antenna arranged on a circuit board (1). [8] The antenna device (U) according to claim 7, wherein at least one of the first antenna section (2a) or the second antenna section (2b) consists of a plurality of longitudinally radiating array antennas arranged in an array along the direction orthogonal to the predetermined direction. [9] Antenna device (U) according to one of claims 1 to 8, comprising: n antenna sections comprising the first and second antenna sections (2a, 2b) are arranged adjacent to each other along the direction orthogonal to the predetermined direction and each transmits the electromagnetic waves, where n is any positive integer; n dielectric lenses comprising the first and second dielectric lenses (5a, 5b) are arranged in the predetermined direction in front of the n antenna sections, respectively, and each narrows the beams of the electromagnetic waves transmitted from the n antenna sections and transmits the beams of the electromagnetic waves to the outside of the device (U), wherein the outer end surfaces of the other n-1 dielectric lenses protrude relative to the outer end surface of one of the n dielectric lenses by approximately λ×k×(2m-1) / (n×2) in the predetermined direction, where λ denotes a free-space wavelength of the electromagnetic waves, k denotes any integer between 1 and n-1, and m denotes any integer, and Projection amounts of the outer end surfaces of the other n-1 dielectric lenses in the predetermined direction with respect to the outer end surface of one of the n dielectric lenses are different from each other. [10] The antenna device (U) according to any one of claims 1 to 9, wherein at least one of the first antenna section (2a) or the second antenna section (2b) receives the electromagnetic wave from the predetermined direction returned after reflection by an object. [11] Radar device comprising the antenna device (U) according to any one of claims 1 to 10.

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