JP2016208411A - Antenna apparatus and Doppler sensor including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna device capable of increasing the degree of freedom in adjusting directivity and a Doppler sensor including the same.SOLUTION: An antenna device 1 includes an antenna unit 2 and a directivity adjusting unit 5. The antenna unit 2 includes a feeding antenna element 3 and a parasitic antenna element 4. The feeding antenna element 3 includes a first dielectric substrate 31, a first conductor layer 32, a ground layer, and a feeding point. The parasitic antenna element 4 includes a second dielectric substrate 41 and a second conductor layer 42. The second conductor layer 42 is configured to resonate at a wavelength of electromagnetic wave radiated from the feeding antenna element 3. The directivity adjusting unit 5 keeps a distance between the feeding antenna element 3 and the parasitic antenna element 4 at a predetermined distance and changes the angle formed by a first center line of the feeding antenna element 3 and a second center line of the parasitic antenna element 4 while keeping a position of an intersection point between the first center line and the second center line.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an antenna device and a Doppler sensor including the antenna device, and more particularly to an antenna device capable of adjusting directivity and a Doppler sensor including the antenna device.

  Conventionally, this type of antenna device includes a ground plate, a flat radiating element, and a flat waveguide element, while maintaining the surface of the radiating element and the surface of the waveguide element in parallel, There is known a flat patch antenna having crossing angle adjusting means capable of adjusting a crossing angle between a straight line connecting the center of the radiating element and the center of the waveguide element and a perpendicular to the ground plate (Patent Document 1).

  As a Doppler sensor, a configuration including an oscillator, a transmission antenna, a reception antenna, a mixer, and a signal processing circuit is known (Patent Document 2).

Japanese Examined Patent Publication No. 7-93532 JP 2010-223623 A

  In the field of antenna devices, it is desired to develop an antenna device with a high degree of freedom in adjusting directivity.

  An object of the present invention is to provide an antenna device capable of increasing the degree of freedom of directivity adjustment and a Doppler sensor including the antenna device.

  The antenna device of the present invention includes an antenna unit and a directivity adjusting unit that adjusts the directivity of electromagnetic waves radiated from the antenna unit. The antenna unit includes a feeding antenna element and a parasitic antenna element. The feeding antenna element includes a first dielectric substrate, a first conductor layer formed on a surface of the first dielectric substrate, a ground layer formed on a back surface of the first dielectric substrate, a feeding point, , And is configured to radiate electric signals as electromagnetic waves to the space. The parasitic antenna element includes a second dielectric substrate and a second conductor layer formed on a surface of the second dielectric substrate, and the second conductor layer is radiated from the feeder antenna element. It is configured to resonate at the wavelength of the electromagnetic wave. The directivity adjusting unit maintains a predetermined distance between the feeding antenna element and the parasitic antenna element, and the first center line along the thickness direction of the feeding antenna element and the parasitic antenna element. While maintaining the position of the intersection with the second center line along the thickness direction, the angle formed by the first center line and the second center line can be changed.

  The Doppler sensor of the present invention includes a transmitting antenna that transmits electromagnetic waves, a receiving antenna that captures electromagnetic waves transmitted from the transmitting antenna and reflected by an object, a frequency of the electromagnetic waves transmitted from the transmitting antenna, and reception by the receiving antenna. A mixer that outputs an output signal having a frequency corresponding to a difference from the frequency of the electromagnetic wave, and a signal processing device that detects an object based on the output signal of the mixer. It is configured.

  In the antenna device of the present invention, the degree of freedom in adjusting directivity can be increased.

  In the Doppler sensor of the present invention, the degree of freedom in adjusting the directivity of the transmission antenna can be increased.

FIG. 1A is a schematic perspective view of a main part viewed from the front side of the antenna device according to the embodiment. FIG. 1B is a schematic perspective view of a main part viewed from the back side of the antenna device according to the embodiment. FIG. 2 is a schematic side view of a main part of the antenna device according to the embodiment. FIG. 3 is a schematic side view of a movable body and a feeding antenna element in the antenna device of the embodiment. FIG. 4A is a schematic perspective view seen from the back side of the movable body and the parasitic antenna element in the antenna device of the embodiment. FIG. 4B is an enlarged view of a main part of FIG. 4A. FIG. 5A is a schematic front view of a feeding antenna element in the embodiment. FIG. 5B is a schematic side view of the feeding antenna element in the embodiment. FIG. 6A is a schematic front view of a parasitic antenna element according to the embodiment. FIG. 6B is a schematic side view of the parasitic antenna element according to the embodiment. FIG. 7A is a schematic cross-sectional view of a feeding antenna element. FIG. 7B is a schematic front view of the feeding antenna element. FIG. 7C is a directivity characteristic diagram of the feeding antenna element. FIG. 8A is a schematic cross-sectional view illustrating a first example of a relative positional relationship between a feeding antenna element and a parasitic antenna element. FIG. 8B is a schematic front view illustrating a first example of a relative positional relationship between the feeding antenna element and the parasitic antenna element. FIG. 8C is a directivity characteristic diagram of the antenna unit in the first example. FIG. 9A is a schematic cross-sectional view showing a second example of the relative positional relationship between the feeding antenna element and the parasitic antenna element. FIG. 9B is a schematic front view showing a second example of the relative positional relationship between the feeding antenna element and the parasitic antenna element. FIG. 9C is a directional characteristic diagram of the antenna unit in the second example. FIG. 10A is a schematic cross-sectional view illustrating a third example of the relative positional relationship between the feeding antenna element and the parasitic antenna element. FIG. 10B is a schematic front view showing a third example of the relative positional relationship between the feeding antenna element and the parasitic antenna element. FIG. 10C is a directivity characteristic diagram of the antenna unit in the third example. FIG. 11A is a schematic cross-sectional view showing a fourth example of the relative positional relationship between the feeding antenna element and the parasitic antenna element. FIG. 11B is a schematic front view showing a fourth example of the relative positional relationship between the feeding antenna element and the parasitic antenna element. FIG. 11C is a directivity characteristic diagram of the antenna unit in the fourth example. FIG. 12A is a schematic cross-sectional view illustrating a fifth example of the relative positional relationship between the feeding antenna element and the parasitic antenna element. FIG. 12B is a schematic front view showing a fifth example of the relative positional relationship between the feeding antenna element and the parasitic antenna element. FIG. 12C is a directivity characteristic diagram of the antenna unit in the fifth example. FIG. 13A is a schematic cross-sectional view illustrating a sixth example of the relative positional relationship between the feeding antenna element and the parasitic antenna element. FIG. 13B is a schematic front view illustrating a sixth example of the relative positional relationship between the feeding antenna element and the parasitic antenna element. FIG. 13C is a directivity characteristic diagram of the antenna unit in the sixth example. FIG. 14A is a schematic cross-sectional view illustrating a seventh example of the relative positional relationship between the feeding antenna element and the parasitic antenna element. FIG. 14B is a schematic front view showing a seventh example of the relative positional relationship between the feeding antenna element and the parasitic antenna element. FIG. 14C is a directivity characteristic diagram of the antenna unit in the seventh example. FIG. 15A is a schematic cross-sectional view illustrating an eighth example of the relative positional relationship between the feeding antenna element and the parasitic antenna element. FIG. 15B is a schematic front view showing an eighth example of the relative positional relationship between the feeding antenna element and the parasitic antenna element. FIG. 15C is a directivity characteristic diagram of the antenna unit in the eighth example. FIG. 16A is a schematic cross-sectional view showing a ninth example of the relative positional relationship between the feeding antenna element and the parasitic antenna element. FIG. 16B is a schematic front view illustrating a ninth example of a relative positional relationship between the feeding antenna element and the parasitic antenna element. FIG. 16C is a directional characteristic diagram of the antenna unit in the ninth example. FIG. 17A is a schematic front view of a first modification of the second conductor layer in the embodiment. FIG. 17B is a schematic front view of a second modification of the second conductor layer in the embodiment. FIG. 17C is a schematic front view of a third modification of the second conductor layer in the embodiment. FIG. 17D is a schematic front view of a fourth modification of the second conductor layer in the embodiment. FIG. 17E is a schematic front view of a fifth modification of the second conductor layer in the embodiment. FIG. 17F is a schematic front view of a sixth modification of the second conductor layer in the embodiment. FIG. 18A is an operation explanatory diagram in the case where the longitudinal direction of the second conductor layer is the same as the polarization direction of the electromagnetic wave incident on the second conductor layer. FIG. 18B is an operation explanatory diagram in the case where the short side direction of the second conductor layer is the same as the polarization direction of the electromagnetic wave incident on the second conductor layer. FIG. 18C is an explanatory diagram of the direction of the current flowing through the second conductor layer according to the polarization direction of the electromagnetic wave incident on the second conductor layer. FIG. 18D is an explanatory diagram of the direction of the current flowing through the second conductor layer according to the polarization direction of the electromagnetic wave incident on the second conductor layer. FIG. 19 is a circuit block diagram of the Doppler sensor in the embodiment.

  Each figure described in the following embodiment is a schematic diagram, and the ratio of each size and thickness of each component does not necessarily reflect an actual dimensional ratio.

  Below, the antenna apparatus 1 of this embodiment is demonstrated based on FIGS.

  The antenna device 1 includes an antenna unit 2 and a directivity adjustment unit 5 that adjusts the directivity of electromagnetic waves radiated from the antenna unit 2. The antenna unit 2 includes a feeding antenna element 3 and a parasitic antenna element 4. As shown in FIGS. 5A and 5B, the feed antenna element 3 includes a first dielectric substrate 31, a first conductor layer 32 formed on the surface 311 of the first dielectric substrate 31, and the first dielectric substrate 31. A ground layer 33 formed on the back surface 312 and a feeding point 34 are provided. The feeding antenna element 3 is configured to radiate an electric signal as an electromagnetic wave into the space. The parasitic antenna element 4 includes a second dielectric substrate 41 and a second conductor layer 42 formed on the surface 411 of the second dielectric substrate 41 as shown in FIGS. 6A and 6B. The second conductor layer 42 is configured to resonate at the wavelength of the electromagnetic wave radiated from the feed antenna element 3. The directivity adjusting unit 5 includes a first center line 30 (see FIG. 8A) along the thickness direction of the feeding antenna element 3 and a second center line 40 (see FIG. 8A) along the thickness direction of the parasitic antenna element 4. The angle θ (see FIG. 8A) formed by can be changed. The directivity adjusting unit 5 maintains a predetermined distance L1 (see FIG. 3) between the feeding antenna element 3 and the parasitic antenna element 4, and the position of the intersection of the first center line 30 and the second center line 40. The angle θ formed by the first center line 30 and the second center line 40 can be changed while maintaining the above. In the antenna device 1 having the above configuration, the degree of freedom in adjusting the directivity can be increased. “Directivity of electromagnetic waves radiated from the antenna unit 2” means the relationship between the radiation direction and the radiation intensity of the electromagnetic waves radiated from the antenna unit 2. 7A, 7B, 8A, 8B, 9A, 9B, 10A, 10B, 11A, 11B, 12A, 12B, 13A, 13B, 14A, 14B, 15A, 15B, 16A, and 16B are orthogonal to the lower right. A coordinate system is shown. The orthogonal coordinate system defines an x-axis and a y-axis that are orthogonal to each other on the surface of the first conductor layer 32 with the center point of the surface of the first conductor layer 32 as an origin, and is orthogonal to the surface of the first conductor layer 32 The z axis is defined. 7C, 8C, 9C, 10C, 11C, 12C, 13C, 14C, and 15C, the directional characteristics of the antenna unit 2 in the xz plane including the x axis and the z axis in the orthogonal coordinate system are displayed in polar coordinates. FIG. 16C shows the directivity of the antenna unit 2 in a plane including one diagonal line of the first conductor layer 32 (a diagonal line along the direction in which the feeding antenna element 3 and the parasitic antenna element 4 are arranged in front view) and the z axis. The characteristics are displayed in polar coordinates.

  Each component of the antenna device 1 will be described in more detail below.

  The electromagnetic wave radiated from the antenna unit 2 is a composite wave of the electromagnetic wave radiated from the feeding antenna element 3 and the electromagnetic wave re-radiated from the parasitic antenna element 4. Therefore, in the antenna device 1, the radiation intensity of the electromagnetic wave radiated from the antenna unit 2 is maximized by changing the relative positional relationship between the feeding antenna element 3 and the parasitic antenna element 4 by the directivity adjusting unit 5. It becomes possible to adjust the radiation direction.

  The electromagnetic wave radiated from the feeding antenna element 3 is, for example, a radio wave having a frequency of 24 GHz.

  The planar shape of the first dielectric substrate 31 in the feed antenna element 3 shown in FIGS. 5A and 5B is a square shape. The first dielectric substrate 31 is a substrate formed of a dielectric material. The first dielectric substrate 31 is, for example, a glass epoxy resin substrate. The glass epoxy resin substrate preferably satisfies, for example, the FR-4.0 grade according to the UL746E standard. As an example, the first dielectric substrate 31 has a plane size of 4 mm × 4 mm, a thickness of 1 mm, and a relative dielectric constant of 4.2.

  The planar shape of the first conductor layer 32 is a square shape. The first conductor layer 32 is a metal foil formed of copper. In short, the first conductor layer 32 is formed of a conductor. As an example, the first conductor layer 32 has a planar size of 2.7 mm × 2.7 mm.

  The planar shape of the ground layer 33 is a square shape. The ground layer 33 is a metal foil formed of copper. In short, the ground layer 33 is formed of a conductor.

  As an example, the feed antenna element 3 is formed of a glass cloth / epoxy resin copper-clad laminate satisfying the FR-4.0 grade.

  The first center line 30 of the feed antenna element 3 passes through the center point of the front surface 311 of the first dielectric substrate 31, the center point of the back surface 312, and the center point of the surface of the first conductor layer 32.

  The feeding antenna element 3 can electrically connect the inner conductor of the connector 8 provided at the tip of the high-frequency coaxial cable 7 for feeding to the feeding antenna element 3 to the first conductor layer 32, and the outer conductor of the connector 8. 81 is configured to be electrically connected to the ground layer 33. In the feeding antenna element 3, a hole 333 into which the inner conductor of the connector 8 can be inserted is formed at the center of the first dielectric substrate 31. The hole 333 passes through the first dielectric substrate 31 in the thickness direction. In the high-frequency coaxial cable 7, the exposed core wire is electrically connected to the inner conductor of the connector 8, and the coaxial outer conductor is electrically connected to the outer conductor 81 of the connector 8.

  The feeding point 34 is, for example, a part of the first conductor layer 32 exposed by the hole 333 of the first dielectric substrate 31. More specifically, the feeding point 34 is a point where the inner conductor of the connector 8 is connected to the first conductor layer 32 in the feeding antenna element 3.

  The connector 8 is preferably a high frequency coaxial connector. As the high-frequency coaxial connector, for example, an SMA connector can be adopted. The SMA connector preferably satisfies or conforms to standards such as JIS C5411 and MIL-PRF-39012. The connector 8 is not limited to an SMA connector, and an appropriate high-frequency coaxial connector may be used according to the frequency of electromagnetic waves radiated from the antenna unit 2.

  The planar shape of the second dielectric substrate 41 in the parasitic antenna element 4 shown in FIGS. 6A and 6B is a square shape. The second dielectric substrate 41 is a substrate formed of a dielectric material. The second dielectric substrate 41 is, for example, a glass epoxy resin substrate. For example, the glass epoxy resin substrate preferably satisfies the FR-4.0 grade. As an example, the second dielectric substrate 41 has a plane size of 4 mm × 4 mm, a thickness of 1 mm, and a relative dielectric constant of 4.2.

  The planar shape of the second conductor layer 42 is a square shape. The second center line of the parasitic antenna element 4 passes through the center point of the front surface 411 of the second dielectric substrate 41, the center point of the back surface 412, and the center point of the surface of the second conductor layer 42. As an example, the second conductor layer 42 has a planar size of 2.7 mm × 2.7 mm.

  As an example, the parasitic antenna element 4 is formed of a glass cloth / epoxy resin copper-clad laminate satisfying the FR-4.0 grade.

  The parasitic antenna element 4 is disposed in front of the feeding antenna element 3. The planar size of the second conductor layer 42 in the parasitic antenna element 4 is set so as to resonate at the wavelength of the electromagnetic wave radiated from the feeder antenna element 3. More specifically, the length of one side of the second conductor layer 42 having a square planar shape is set to a length that resonates at the wavelength of the electromagnetic wave radiated from the feeding antenna element 3.

  In the parasitic antenna element 4, the second conductor layer 42 is configured to resonate at the wavelength of the electromagnetic wave radiated from the feeding antenna element 3. Therefore, in the parasitic antenna element 4, a current flows through the second conductor layer 42 due to the electromagnetic wave radiated from the feed antenna element 3, and the electromagnetic wave is radiated from the second conductor layer 42.

  FIG. 7C shows the result of simulating the directivity (radiation pattern) in the case of the single feeding antenna element 3 shown in FIGS. 7A and 7B using the FDTD method (Finite-Difference Time-Domain method). The “FDTD method” is called a time domain difference method or a finite difference time domain method. 8C, 9C, 10C, 11C, 12C, 13C, 14C, 15C, and 16C are results of simulating the directivity characteristics of the antenna unit 2 using the FDTD method. In the following description, the wavelength in a vacuum of the electromagnetic wave radiated from the feeding antenna element 3 is λ.

  In the first example (FIGS. 8A and 8B), the angle θ formed by the first center line 30 of the feed antenna element 3 and the second center line 40 of the parasitic antenna element 4 is 15 °, and the predetermined distance L1 is 3 mm (0. 24λ), and the directivity as shown in FIG. 8C was obtained.

  In the second example (FIGS. 9A and 9B), the angle θ is 30 °, the predetermined distance L1 is 3 mm (0.24λ), and the directivity as shown in FIG. 9C was obtained.

  In the third example (FIGS. 10A and 10B), the angle θ is 45 °, the predetermined distance L1 is 3 mm (0.24λ), and the directivity as shown in FIG. 10C was obtained.

  In the fourth example (FIGS. 11A and 11B), the angle θ is 45 °, the predetermined distance L1 is 2 mm (0.16λ), and the directivity as shown in FIG. 11C was obtained.

  In the fifth example (FIGS. 12A and 12B), the angle θ is 45 °, the predetermined distance L1 is 4 mm (0.32λ), and the directivity as shown in FIG. 12C was obtained.

  In the sixth example (FIGS. 13A and 13B), the angle θ is 45 °, the predetermined distance L1 is 5 mm (0.40λ), and the directivity as shown in FIG. 13C was obtained.

  In the seventh example (FIGS. 14A and 14B), the angle θ is 45 °, the predetermined distance L1 is 6 mm (0.48λ), and the directivity as shown in FIG. 14C was obtained.

  In the eighth example (FIGS. 15A and 15B), the angle θ is 45 °, the predetermined distance L1 is 7 mm (0.56λ), and the directivity as shown in FIG. 15C was obtained.

  In the ninth example (FIGS. 16A and 16B), the angle θ is 45 °, the predetermined distance L1 is 3 mm (0.24λ), and the directivity as shown in FIG. 16C was obtained.

  From the results of FIGS. 7C, 8C, 9C, 10C, 11C, 12C, 13C, 14C, and 16C, in the antenna unit 2, the directivity is changed by changing the relative positional relationship between the feeding antenna element 3 and the parasitic antenna element 4. It is assumed that the characteristics can be adjusted.

  From the results of FIGS. 8C, 9C, 10C, and 16C, it can be seen that the directivity can be adjusted by changing the angle θ while keeping the predetermined distance L1 constant. More specifically, in the antenna unit 2, the radiation intensity in the direction from the feeding antenna element 3 to the parasitic antenna element 4 can be increased. In short, the antenna unit 2 can form a main lobe in the direction of the parasitic antenna element 4 with the feeding antenna element 3 as a reference position. In the antenna unit 2, the directivity can be increased as the angle θ is decreased. Therefore, in the antenna device 1, it is possible to obtain desired directivity characteristics by moving the parasitic antenna element 4 in a direction in which the radiation intensity of the antenna unit 2 is desired to be increased with the feeding antenna element 3 as a reference position.

  8C to 16C, it is preferable that the predetermined distance L1 is not less than 0.15 times and not more than 0.4 times the wavelength of the electromagnetic wave radiated from the feeding antenna element 3 in vacuum. Thereby, in the antenna device 1, it is possible to increase the radiation intensity in the direction from the feeding antenna element 3 to the parasitic antenna element 4.

  The second conductor layer 42 in the parasitic antenna element 4 is preferably formed in a planar shape having n-fold rotational symmetry (n ≧ 3). As a result, the antenna device 1 can adjust the directivity regardless of the polarization direction of the electromagnetic wave radiated from the feeding antenna element 3. “N-fold rotational symmetry” means a property that coincides with the first figure when the figure is rotated around the rotation axis by 1 / n of 360 degrees.

  When the planar shape of the second conductor layer 42 is a rectangle as shown in FIG. 18A, the second conductor layer 42 has two-fold rotational symmetry. In FIG. 18A, the length of the long side of the rectangle is set to a length that resonates at the wavelength of the electromagnetic wave radiated from the feeding antenna element 3. Therefore, when an electromagnetic wave in the polarization direction indicated by the white arrow in FIG. 18A (the same direction as the longitudinal direction of the second conductor layer 42) is incident on the second conductor layer 42, the second conductor layer 42 has an alternate long and short dash line. Current flows in the direction indicated by the arrow. Thereby, in the antenna device 1, the directivity can be adjusted. On the other hand, when an electromagnetic wave in the polarization direction indicated by the white arrow in FIG. 18B (the same direction as the short direction of the second conductor layer 42) is incident on the second conductor layer 42, the second conductor layer 42 includes: Almost no current flows. For this reason, in the antenna apparatus 1, the direction which wants to raise radiation intensity cannot be controlled.

  Further, when the planar shape of the second conductor layer 42 is an equilateral triangular frame as shown in FIG. 18C, the second conductor layer 42 has a three-fold rotational symmetry. In FIG. 18C, the length of one side of the equilateral triangle frame is set to a length that resonates at the wavelength of the electromagnetic wave radiated from the feeding antenna element 3. Therefore, when an electromagnetic wave having a polarization direction parallel to one side of the equilateral triangular frame is incident on the second conductor layer 42 as shown by a white arrow in FIG. 18C, the second conductor layer 42 is indicated by a one-dot chain line arrow. As shown, current flows in the direction along each of the three sides. Thereby, in the antenna device 1, the directivity can be adjusted. When the electromagnetic wave in the polarization direction indicated by the white arrow shown in FIG. 18D (the direction orthogonal to one of the three sides in front view) is incident on the second conductor layer 42, the second conductor layer A current flows through 42 in the direction along each of the two sides (slanted sides) as indicated by the dashed-dotted arrows. Thereby, in the antenna device 1, the directivity can be adjusted.

  The 2nd conductor layer 42 should just be formed in the planar shape which has n times rotational symmetry (n> = 3), and is not restricted to a square. For example, the second conductor layer 42 may be formed in any one of the planar shapes of FIGS. 17A, 17B, 17C, 17D, 17E, and 17F.

  The planar shape of the second conductor layer 42 shown in FIG. 17A is a regular triangle, and has three-fold rotational symmetry. The second conductor layer 42 shown in FIG. 17B has a circular planar shape. The second conductor layer 42 shown in FIG. 17C has a + -shape in plan view and has four-fold rotational symmetry. The second conductor layer 42 shown in FIG. 17D has a regular triangular frame shape and has three-fold rotational symmetry. The second conductor layer 42 shown in FIG. 17E has a regular pentagonal planar shape and has five-fold rotational symmetry. The second conductor layer 42 shown in FIG. 17F has a regular hexagonal planar shape and has 6-fold rotational symmetry.

  As an example, the directivity adjusting unit 5 includes a hemispherical shell-shaped dome 51 and a movable body 52 configured to be rotatable along a spherical surface 512 inside the dome 51, as shown in FIGS. 1A and 1B. Prepare. The dome 51 and the movable body 52 are formed of a dielectric material. In the antenna unit 2, the feeding antenna element 3 is arranged at the center of the dome 51 where the distance from the spherical surface 511 in the dome 51 is constant (predetermined distance L <b> 1), and the parasitic antenna element 4 is arranged on the movable body 52. Thereby, in the antenna device 1, the directivity of the antenna unit 2 can be adjusted by moving the parasitic antenna element 4 without changing the position of the feed antenna element 3. Can be easily adjusted.

  The movable body 52 has a spherical cap-shaped first movable portion 521 and a spherical cap-shaped second movable portion 522 connected by a shaft portion 523 (see FIGS. 4A and 4B). The inner spherical surface of the first movable part 521 preferably has the same radius as the outer spherical surface 511 of the dome 51. It is preferable that the outer spherical surface of the second movable portion 522 has the same radius as the inner spherical surface 512 of the dome 51.

  In the dome 51, a plurality of slits 513 configured to be able to move the shaft portion 523 of the movable body 52 are formed at equal intervals in the circumferential direction. As a result, the directivity adjusting unit 5 rotates the movable body 52 along the dome 51 to maintain the distance between the feeding antenna element 3 and the parasitic antenna element 4 at the predetermined distance L1 while maintaining the parasitic antenna element 4. Can be moved. In the antenna device 1, the movable body 52 can be held at the position after the movable body 52 is moved by appropriately designing the width of the slit 513. The antenna device 1 may further include a member for positioning the movable body 52 in order to prevent a relative displacement between the dome 51 and the movable body 52 after being rotated along the dome 51.

  The antenna device 1 preferably includes a case that houses the antenna unit 2 and the directivity adjusting unit 5. The case is composed of a base and a cover. For example, the base and the cover may be coupled by a plurality of screws or the like.

  The base is preferably configured to hold the antenna unit 2 and the directivity adjusting unit 5. The base preferably includes, for example, a disc-shaped base body, and includes a first holding part that holds the feeding antenna element 3 on a first surface of the base body, and a second holding part that holds the dome 51. . The second holding part can be constituted by, for example, two annular ribs arranged concentrically. It is preferable that the base has a plurality of protrusions that keep the plurality of slits 513 of the dome 51 at a predetermined width between the two annular ribs. The base is preferably configured so that the second surface of the base body can be installed on the wall surface or the like with the indoor wall surface side of the building.

  The base is preferably made of a conductive material. A metal is preferable as the conductive material. As the metal, for example, aluminum or zinc alloy is preferable. When the conductive material is aluminum, the base can be formed by, for example, an aluminum die casting method.

  The cover is a radome that protects the antenna unit 2 and the directivity adjusting unit 5. The cover is formed of a material that transmits electromagnetic waves radiated from the antenna unit 2. More specifically, the cover is made of a material that transmits electromagnetic waves of 24 GHz. The cover preferably has a transmittance for electromagnetic waves of 24 GHz of 60% or more, more preferably 70% or more, and still more preferably 80% or more.

  As a material for the cover, for example, polycarbonate, fluorine resin, polyphenylene oxide, or the like can be used. The cover is preferably made of a molded article made of a material obtained by adding a white pigment to polycarbonate, for example. As the white pigment, an inorganic pigment is preferable. Examples of white pigments that can be used include titanium dioxide and zinc white (zinc oxide).

  FIG. 19 is a circuit block diagram of the Doppler sensor 9 including the antenna device 1.

  The Doppler sensor 9 includes a transmission antenna 91 that transmits electromagnetic waves, a reception antenna 92 that captures electromagnetic waves transmitted from the transmission antenna 91 and reflected by an object, and an oscillator 93. The Doppler sensor 9 includes a mixer 94 that outputs an output signal having a frequency corresponding to the difference between the frequency of the electromagnetic wave transmitted from the transmitting antenna 91 and the frequency of the electromagnetic wave received by the receiving antenna 92, and an object based on the output signal of the mixer 94. And a signal processing device 95 for detecting. The transmission antenna 91 is configured by the antenna device 1. As a result, the Doppler sensor 9 can increase the degree of freedom in adjusting the directivity of the transmission antenna 91. The object is, for example, a person.

  In the Doppler sensor 9, a transmission signal (electric signal) output from the oscillator 93 from the transmission antenna 91 is transmitted as an electromagnetic wave (radiated to space). The mixer 94 outputs an output signal having a frequency difference between the frequency of the transmission signal output from the oscillator 93 and the frequency of the reception signal received by the reception antenna 92 and converted into an electrical signal.

  The signal processing device 95 can be realized, for example, by causing a computer (for example, a microcomputer) to execute a predetermined program. For example, the predetermined program may be stored in a memory of a computer. The signal processing device 95 includes an amplifier circuit that amplifies the output signal output from the mixer 94, and an A / D converter that converts the output signal amplified by the amplifier circuit into a digital output signal and outputs the digital output signal. Is preferred.

  The materials, numerical values, and the like described in the embodiments are merely preferred examples and are not intended to be limiting. Furthermore, the present invention can be appropriately modified in configuration without departing from the scope of its technical idea.

  For example, the first dielectric substrate 31 and the second dielectric substrate 41 are not limited to glass epoxy resin substrates, and are formed of, for example, a fluororesin substrate (for example, a polytetrafluoroethylene resin substrate) or a ceramic substrate. May be. Moreover, the 1st conductor layer 32, the ground layer 33, and the 2nd conductor layer 42 may be formed using a copper paste, a silver paste, etc., for example.

  In the antenna device 1, the second movable portion 522 may also serve as the second dielectric substrate 41.

  In addition, the feeding antenna element 3 may be provided with a feeding microstrip line continuous to the first conductor layer 32, and the inner conductor of the connector 8 may be connected to the microstrip line by soldering or the like.

  In addition, when the antenna device 1 does not include a case, the dome 51 is placed in, for example, a wall or ceiling of a building, a mounting portion in a device in which the antenna device 1 is installed, You may make it fix to a wall etc.

  The Doppler sensor may be a two-frequency (multi-frequency) type Doppler sensor, an FMCW (Frequency Modulated Continuous Wave) type Doppler sensor, or the like.

  Further, the frequency of the electromagnetic wave radiated from the feeding antenna element 3 is not limited to 24 GHz, and may be, for example, 2.4 GHz. In this case, when the frequency of the electromagnetic wave is 2.4 GHz, the feeding antenna element 3 sets the plane size of the first conductor layer 32 to 10 times (that is, 27 mm × 27 mm) compared to the case where the frequency is 24 GHz. Is preferred.

DESCRIPTION OF SYMBOLS 1 Antenna apparatus 2 Antenna unit 3 Feeding antenna element 30 1st center line 31 1st dielectric substrate 32 1st conductor layer 33 Ground layer 4 Parasitic antenna element 40 2nd center line 41 2nd dielectric substrate 42 2nd conductor layer DESCRIPTION OF SYMBOLS 5 Directionality adjustment part 51 Dome 52 Movable body 512 Spherical surface L1 Predetermined distance (theta) Angle 9 Doppler sensor 91 Transmission antenna 92 Reception antenna 93 Oscillator 94 Mixer 95 Signal processing apparatus

Claims (5)

An antenna unit, and a directivity adjustment unit that adjusts the directivity of electromagnetic waves radiated from the antenna unit,
The antenna unit includes a feeding antenna element and a parasitic antenna element,
The feeding antenna element includes a first dielectric substrate, a first conductor layer formed on a surface of the first dielectric substrate, a ground layer formed on a back surface of the first dielectric substrate, a feeding point, And configured to radiate electric signals as electromagnetic waves into space,
The parasitic antenna element includes a second dielectric substrate and a second conductor layer formed on a surface of the second dielectric substrate, and the second conductor layer is radiated from the feeder antenna element. Configured to resonate at the wavelength of the electromagnetic wave,
The directivity adjusting unit maintains a predetermined distance between the feeding antenna element and the parasitic antenna element, and the first center line along the thickness direction of the feeding antenna element and the parasitic antenna element. The angle between the first center line and the second center line can be changed while maintaining the position of the intersection with the second center line along the thickness direction.
An antenna device characterized by that. The predetermined distance is not less than 0.15 times and not more than 0.4 times the wavelength of the electromagnetic wave in vacuum.
The antenna device according to claim 1. The second conductor layer in the parasitic antenna element is formed in a planar shape having n-fold rotational symmetry (n ≧ 3).
The antenna device according to claim 1 or 2, wherein The directivity adjusting unit includes a hemispherical dome, and a movable body configured to be rotatable along a spherical surface inside the dome.
The dome and the movable body are formed of a dielectric,
In the antenna unit, the feeding antenna element is arranged at the center of the dome where the distance from the spherical surface in the dome is constant, and the parasitic antenna element is arranged in the movable body.
The antenna apparatus according to any one of claims 1 to 3, wherein A transmitting antenna for transmitting electromagnetic waves, a receiving antenna for capturing electromagnetic waves transmitted from the transmitting antenna and reflected by an object, an oscillator, a frequency of electromagnetic waves transmitted from the transmitting antenna, and a frequency of electromagnetic waves received by the receiving antenna And a mixer that outputs an output signal having a frequency corresponding to the difference between and a signal processing device that detects an object based on the output signal of the mixer,
The transmitting antenna is configured by the antenna device according to any one of claims 1 to 4.
Doppler sensor characterized by that.

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