TW202504165A - Antenna components, antenna arrays and antenna modules - Google Patents

Abstract

To provide an antenna element, an antenna array, and an antenna module capable of achieving miniaturization and a wider bandwidth with a simple structure. An antenna element according to one aspect of the present technology is provided with: a first conductor layer having a planar element shape; a second conductor layer; a dielectric layer; a first interlayer connection part; and a second interlayer connection part. The second conductor layer is connected to a ground potential. The dielectric layer is provided between the first conductor layer and the second conductor layer. The first interlayer connection part penetrates the dielectric layer, and connects the first conductor layer to a power supply part. The second interlayer connection part penetrates the dielectric layer, and connects the first conductor layer and the second conductor layer.

Description

Antenna components, antenna arrays and antenna modules

The present technology relates to an antenna element, an antenna array and an antenna module capable of transmitting or receiving electromagnetic waves such as millimeter waves.

Antennas used in high-frequency areas are generally pattern antennas formed of conductive materials on electronic substrates because they can miniaturize components according to the length of the wavelength. In particular, in recent years, small antennas in the millimeter wave area used in cellular or radar applications have required antenna structures that are cheaper, smaller, and have high gain and high directivity in a limited space. As an antenna structure with high mass production and the most widely used directional antenna, patch antennas are widely known as planar antennas (for example, refer to Patent Document 1). [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2022-51890

[The problem the invention is trying to solve]

However, the fractional bandwidth that a single chip antenna can cover is only a few percent. To achieve broadband, a more complex structure is required, such as an array structure that uses multiple components or a resonant structure that configures components across the stack. However, this is limited by space and cost.

In view of the above situation, the purpose of this technology is to provide an antenna element, antenna array and antenna module that can achieve miniaturization and broadband with a simple structure. [Technical means to solve the problem]

An antenna element of one form of the present technology includes: a first conductor layer in the shape of a planar element, a second conductor layer, a dielectric layer, a first interlayer connection portion, and a second interlayer connection portion. The second conductor layer is connected to the ground potential. The dielectric layer is disposed between the first conductor layer and the second conductor layer. The first interlayer connection portion penetrates the dielectric layer to connect the first conductor layer to the feeding portion. The second interlayer connection portion penetrates the dielectric layer to connect the first conductor layer to the second conductor layer.

The first conductor layer of the antenna element functions as a radiation element, the second conductor layer functions as a ground conductor plate, and a ring antenna is formed by the first inter-layer connection portion, the first conductor layer, and the second inter-layer connection portion. Thus, miniaturization and broadband can be achieved with a simple structure.

The first conductive layer is typically formed in a smaller area than the second conductive layer. This allows stable resonance in the intended frequency band to be achieved.

The loop length formed by the first inter-layer connection portion, the first conductive layer, and the second inter-layer connection portion can be less than one wavelength of the radio wave, for example, a length equivalent to half a wavelength. This can further miniaturize the antenna element.

The planar shape of the first conductive layer may be a rectangle having long sides and short sides.

The first conductive layer has a first region connected to the first inter-layer connecting portion and a second region connected to the second inter-layer connecting portion, and the first region and the second region can be arranged separately from the peripheral portion of the first conductive layer. Thereby, the directivity of the radio wave can be expanded.

The first region and the second region may be arranged along a direction parallel to the long side, or may be arranged along a direction intersecting the direction parallel to the long side.

It is feasible that the aforementioned dielectric layer is a dielectric substrate composed of a dielectric material, the aforementioned first conductive layer is a metal layer formed on the first main surface of the aforementioned dielectric substrate, and the aforementioned second conductive layer is a metal layer formed on the second main surface of the aforementioned dielectric substrate which is opposite to the aforementioned first main surface.

The second conductive layer may have an opening portion formed with a larger opening diameter than the first inter-layer connecting portion. Thereby, the electrical insulation structure between the first inter-layer connecting portion and the second conductive layer can be simplified.

The first inter-layer connection portion and the second inter-layer connection portion may be through-hole electroplating or buried via holes provided in the dielectric layer.

An antenna array of one form of the present technology includes a plurality of antenna elements. Each of the plurality of antenna elements includes: a first conductor layer in the shape of a planar element; a second conductor layer connected to a ground potential; a dielectric layer disposed between the first conductor layer and the second conductor layer; a first inter-layer connection portion penetrating the dielectric layer to connect the first conductor layer to a feeder portion; and a second inter-layer connection portion penetrating the dielectric layer to connect the first conductor layer to the second conductor layer. The first conductor layer of each of the plurality of antenna elements is arranged on a surface of the dielectric layer.

It is feasible that at least one of the plurality of antenna elements is a transmitting antenna element, and at least one of the others is a receiving antenna element.

The plurality of antenna elements may be arranged in a matrix along a first axis and a second axis orthogonal to each other on the surface.

It is feasible that the aforementioned first conductive layer has a rectangular planar shape including a long side parallel to the aforementioned first axis and a short side parallel to the aforementioned second axis, and the mutually opposing short sides of the two aforementioned first conductive layers arranged along the aforementioned first axis have a notch portion that partially expands the interval between the aforementioned two first conductive layers.

The second conductor layer of each of the plurality of antenna elements may be formed by a common conductor layer.

An antenna module of one form of the present technology includes a plurality of antenna elements and a signal processing circuit. Each of the plurality of antenna elements includes: a first conductor layer in the shape of a planar element; a second conductor layer connected to a ground potential; a dielectric layer disposed between the first conductor layer and the second conductor layer; a first inter-layer connection portion penetrating the dielectric layer to connect the first conductor layer to a feeder portion; and a second inter-layer connection portion penetrating the dielectric layer to connect the first conductor layer to the second conductor layer. The signal processing circuit is connected to the plurality of antenna elements.

Hereinafter, the implementation of the present technology will be described with reference to the drawings.

<First Implementation Form> Figure 1 is a perspective view of the antenna element 100 of the first implementation form of the present technology, and Figure 2 is a side sectional view thereof. Furthermore, in the figure, the X-axis, Y-axis, and Z-axis represent three mutually orthogonal axial directions, which correspond to the longitudinal direction (front-back direction), transverse direction (width direction), and thickness direction (height direction) of the antenna element 100, respectively.

[Basic structure of antenna element] The antenna element 100 of this embodiment is configured as a millimeter wave antenna for transmission, reception, or transceiver. The antenna element 100 includes: a dielectric layer 10, a first conductive layer 21, a second conductive layer 22, a first inter-layer connecting portion 31, and a second inter-layer connecting portion 32. The antenna element 100 is configured by a dielectric multi-layer substrate (double-sided wiring substrate).

The dielectric layer 10 is disposed between the first conductive layer 21 and the second conductive layer 22. The dielectric layer 10 is a dielectric substrate having rigidity, which is equivalent to an insulating layer constituting the above-mentioned dielectric multilayer substrate. The planar shape of the dielectric layer 10 is rectangular, and the lengths in the longitudinal direction (X-axis direction) and the lateral direction (Y-axis direction) are formed to be, for example, about 5 mm. The thickness (Z-axis direction) of the dielectric layer 10 is set according to the dielectric constant of the dielectric material constituting the dielectric layer 10 and the wavelength of the radio wave used, and is, for example, 0.65 mm in the present embodiment using the radio wave of the 60 GHz band.

As dielectric materials constituting the dielectric layer 10, for example, insulating organic materials such as FR4, BT resin, polytetrafluoroethylene, and insulating inorganic materials such as ceramics can be cited. The dielectric constant of the dielectric layer 10 is not particularly limited and can be arbitrarily set according to the frequency of the radio waves transmitted or received by the antenna element 100. For example, in the case of transmitting and receiving electromagnetic waves in the 60 GHz band, a material with a dielectric constant of, for example, 3.6 is used as the dielectric substrate 10.

The first conductive layer 21 corresponds to a conductive layer formed on one surface side of the dielectric multilayer substrate, and in this embodiment is a metal layer formed on the first main surface 10a (the upper surface in FIG. 1 and FIG. 2 ) of the dielectric layer 10. The first conductive layer 21 is configured as a radiating element of the antenna element 100.

The first conductor layer 21 is formed with a smaller area than the second conductor layer 22, and is formed into a plane pattern of a plane shape, such as a rectangular plane element shape. The plane element shape refers to, for example, the plane shape (patch shape) of the conductor portion forming the radiating element such as a patch antenna. The size (length of each side) of the first conductor layer 21 is not particularly limited and can be arbitrarily set according to the frequency band of the radio wave used. In this embodiment, the length of the long side 21L along the X-axis direction is about 1.6 mm, and the length of the short side 21S along the Y-axis direction is about 1.0 mm.

Furthermore, the planar shape of the first conductive layer 21 is not limited to a rectangle, and may be a polygon other than a rectangle, a circle, an ellipse, or a combination of these shapes. Furthermore, at least a portion of the rectangle (e.g., a side or a vertex) may be deformed into any shape.

The second conductor layer 22 corresponds to a conductor layer formed on the other surface side of the above-mentioned dielectric multi-layer substrate, and in the present embodiment, is a metal layer formed on the second main surface 10b (the lower surface in FIG. 1 and FIG. 2 ) of the dielectric layer 10 which is opposite to the first main surface 10a. The second conductor layer 22 is configured as a ground conductor plate of the antenna element 100. The second conductor layer 22 is formed over the entire back surface 10b of the dielectric layer 10 by being electrically connected to the ground potential G, but it is of course not limited to this.

The metal constituting the first conductive layer 21 and the second conductive layer 22 is not particularly limited, and examples thereof include copper and aluminum. The thickness of the first conductive layer 21 and the second conductive layer 22 is not particularly limited, and they may be formed to have the same thickness or different thicknesses.

The first interlayer connection portion 31 penetrates the dielectric layer 10 along the thickness direction (Z-axis direction) thereof and connects the first conductive layer 21 to the feeding portion F. The first interlayer connection portion 31 is a cylindrical conductive body electrically connected to the first conductive layer 21, and in the present embodiment is formed by a through-hole electroplating or a buried conductive hole filled with a conductive material provided in the dielectric layer 10. The second conductive layer 22 has an opening portion 22a formed with an opening diameter larger than the outer diameter of the first interlayer connection portion 31. The first interlayer connection portion 31 is electrically insulated from the second conductive layer 22 by being received in the opening portion 22a without contacting the peripheral portion of the opening portion 22a. The annular region between the opening 22a and the first inter-layer connecting portion 31 may also be filled with the same material as the dielectric layer 10 or a different dielectric material.

The second interlayer connection portion 32 penetrates the dielectric layer 10 along the thickness direction (Z-axis direction) thereof, and electrically connects the first conductive layer 21 and the second conductive layer 22. The second interlayer connection portion 32 is a cylindrical conductive body similar to the first interlayer connection portion 31, and in this embodiment, is formed by a through-hole electroplating or buried via filled with a conductive material provided in the dielectric layer 10. The second interlayer connection portion 32 is formed with the same diameter and height as the first interlayer connection portion 31.

The first interlayer connection portion 31 and the second interlayer connection portion 32 are connected vertically relative to the first conductive layer 21. Therefore, the length (height) of the first interlayer connection portion 31 and the second interlayer connection portion 32 is equivalent to the thickness (0.65 mm) of the dielectric layer 10. As shown in FIG. 1 , the first conductive layer 21 has a first region 211 connected to the first interlayer connection portion 31 and a second region 212 connected to the second interlayer connection portion 32. The first region 211 and the second region 212 are both in the plane of the first conductive layer 21 and are arranged separately from the peripheral portion of the first conductive layer 21.

In the present embodiment, the first region 211 and the second region 212 are arranged in a direction parallel to the long side 21L (X-axis direction) at positions symmetrical with respect to the center of the first conductive layer 21. However, the present invention is not limited thereto, and the first region 211 and the second region 212 may be arranged in a direction intersecting the direction parallel to the long side 21L (X-axis direction) as described later (see FIG. 38 ).

The antenna element 100 of the present embodiment constructed as described above is configured as a ring antenna having an axis parallel to the width direction (Y-axis direction) by the first conductive layer 21, the first inter-layer connecting portion 31, and the second inter-layer connecting portion 32.

The antenna element 100 of this embodiment sets the length of each side (long side 21L, short side 21S) of the first conductor layer 21 so that the frequency band of the radio wave used is 60 GHz (for example, 57 GHz to 64 GHz). That is, since the first conductor layer 21 is formed into a planar element shape with a length and width larger than the axial diameter and arrangement interval of the interlayer connecting parts 31 and 32, the current density is concentrated on the periphery of the first conductor layer 21. Therefore, the fractional frequency band can be increased by setting the length of each side of the first conductor layer 21.

Furthermore, the loop length formed by the first interlayer connection portion 31, the second interlayer connection portion 32, and the first conductive layer 21 (including the effective length due to wavelength shortening caused by the dielectric constant of the dielectric layer 10) is set to be less than 1 wavelength of the radio wave used, and more preferably, to be equal to half the wavelength of the radio wave. In this embodiment, the above-mentioned effective length is set to 2.477 mm, which is equal to half the wavelength of a 60 GHz radio wave.

The antenna element 100 according to this embodiment has a plurality of resonant frequencies including a resonant frequency corresponding to the loop length and a resonant frequency corresponding to the perimeter of the first conductor layer 21, so that the fractional band (the value obtained by dividing the bandwidth by the center frequency) that can be covered by a single element can be increased.

FIG3 shows an example of simulation results of the voltage standing wave ratio (VSWR) of the antenna element 100. FIG4 shows the simulation results of the radiation characteristics of the azimuth plane (XZ plane) at 60 GHz of the antenna element 100, and FIG5 shows the simulation results of the radiation characteristics of the elevation plane (YZ plane) at 60 GHz of the antenna element 100. In FIG4 and FIG5, the 0ﾟ direction (upward direction) is equivalent to the top surface direction (+Z direction).

As shown in Figure 3, the frequency band where the VSWR ratio is less than 1.5 is 59 GHz to 67 GHz, and the fractional band is 12.7%. Also, as shown in Figures 4 and 5, a directional characteristic with a wide range and good balance in the top direction is obtained.

As described above, according to this embodiment, although it is a single-element structure, an antenna characteristic with wide-band resonance can be obtained.

[Comparative Example] Next, the radiation characteristics of the antenna element 100 of this embodiment will be described by comparing it with the antenna structures of Comparative Examples 1 and 2 described below.

(Comparative Example 1) Figure 6 is a perspective view of the antenna element 101 of Comparative Example 1, and Figure 7 is a side cross-sectional view thereof. The antenna element 101 shows a representative structure of a back-fed chip antenna.

That is, the antenna element 101 includes: a dielectric layer 110; a first conductive layer 121 as a radiation element formed on the surface of the dielectric layer 110, a second conductive layer 122 as a ground conductive plate formed on the back of the dielectric layer 110, and an interlayer connection portion 131 that penetrates the dielectric layer 110 and connects the first conductive layer 121 to a feeding point. The interlayer connection portion 131 is electrically insulated from the second conductive layer 122. Here, the shape of the first conductive layer 121 is set to be a rectangle with a long side of 1.2 mm and a short side of 1.0 mm.

FIG8 is a simulation result showing an example of the voltage-sense-wave ratio (VSWR) of the antenna element 101. FIG9 is a simulation result showing the radiation characteristics of the azimuth plane (XZ plane) at 60 GHz of the antenna element 101, and FIG10 is a simulation result showing the radiation characteristics of the elevation plane (YZ plane) at 60 GHz of the antenna element 101. In FIG9 and FIG10, the 0ﾟ direction (upward direction) is equivalent to the top direction (+Z direction).

As shown in FIG8 , in the antenna element 101 of Comparative Example 1, the frequency band in which the VSWR ratio is 1.5 or less is 57 GHz to 61 GHz, and the fractional frequency band is 6.7%. In contrast, the antenna element 100 according to the present embodiment has a fractional frequency band of 12.7% as described above (see FIG3 ), and the fractional frequency band can be increased by about 2 times compared to Comparative Example 1. Thus, a wider frequency band can be achieved compared to the antenna element 101 of Comparative Example 1.

Furthermore, regarding the antenna directivity, it is substantially the same as the antenna element 101 of Comparative Example 1 shown in Figures 9 and 10. Based on this, according to this embodiment, it is possible to have the antenna directivity equivalent to that of the patch antenna structure and to expand the frequency band.

(Comparative Example 2) Figure 11 is a perspective view of the antenna element 102 of Comparative Example 2, and Figure 12 is a side view thereof. The antenna element 102 includes an antenna structure 123 formed in a vertical ring shape relative to a ground conductor plate 124. One end of the antenna structure is connected to a feeding point, and the other end is connected to the ground conductor plate 124. The loop length is set to be equivalent to the half-wavelength of a 60 GHz radio wave.

FIG13 is a simulation result showing an example of the voltage-sense-wave ratio (VSWR) of the antenna element 102. FIG14 is a simulation result showing the radiation characteristics of the azimuth plane (XZ plane) at 60 GHz of the antenna element 102, and FIG15 is a simulation result showing the radiation characteristics of the elevation plane (YZ plane) at 60 GHz of the antenna element 102. In FIG14 and FIG15, the 0ﾟ direction (upward direction) is equivalent to the top direction (+Z direction).

As shown in FIG13 , in the antenna element 102 of Comparative Example 2, the frequency band in which the VSWR ratio is 1.5 or less is 58 GHz to 60 GHz, and the fractional frequency band is 6.6%. In contrast, the antenna element 100 according to the present embodiment has a fractional frequency band of 12.7% (see FIG3 ) as described above, and the fractional frequency band can be increased by about 2 times compared to Comparative Example 2. Thus, a wider frequency band can be achieved compared to the antenna element 101 of Comparative Example 1.

In addition, regarding directivity, unlike Comparative Example 1, it has a figure-8 characteristic like a dipole antenna, which is not suitable for a directional antenna structure toward the radiation plane (ceiling) used in the millimeter wave region. Based on this situation, according to this embodiment, compared with the representative ring antenna structure, a directional characteristic with a wide range and good balance toward the ceiling direction can be achieved, and a wider bandwidth can be sought.

Fig. 16 is a simulation result comparing the antenna characteristics and directivity of the antenna element 100 of the present embodiment and the antenna element 101 of Comparative Example 1. Here, each element is formed with the same size at a resonance frequency of 60 GHz, and the antenna characteristics and directivity up to 50 to 65 GHz are measured at 5 GHz intervals.

As shown in FIG. 16 , the antenna element 100 of the present embodiment obtains the same directional characteristics as the antenna element 101 of Comparative Example 1. On the other hand, according to the present embodiment, the antenna gain in the top direction in the range of 55 GHz to 65 GHz is higher than that of Comparative Example 1. Until now, in order to increase the bandwidth and gain of the antenna, a method has been used such as setting the antenna element to an array shape requiring multiple elements, or increasing the number of layers of the multilayer substrate and adding a reflection and broadband pattern in the middle, but according to the present embodiment, broadbandization can be achieved by a cheap and simple method.

<Second Implementation> Figure 17 is a perspective view of the antenna module 300 of the second implementation of the present technology, Figure 18 is a plan view thereof, and Figure 19 is a block diagram showing the circuit structure of the antenna module 300. In addition, in the figure, the same symbols are given to the parts corresponding to the first implementation described above, and their descriptions are omitted.

The antenna module 300 of this embodiment includes an antenna array 200 and a signal processing circuit 301 ( FIG. 19 ). The antenna array 200 and the signal processing circuit 301 are formed or mounted on a common dielectric multi-layer substrate 1 .

[Antenna array] The antenna array 200 has a plurality of antenna elements 100. The plurality of antenna elements 100 include a transmitting antenna Tx and three receiving antennas Rx1, Rx2, and Rx3. Each antenna element 100 has the same structure and is configured in the same manner as the antenna element described in the first embodiment. The number of transmitting antennas is not limited to one, but may be two or more. In addition, the number of receiving antennas is not limited to three, but may be two or four or more.

The first conductor layers 21 of each antenna element 100 are independently arranged on the first main surface 10a of the dielectric layer 10. Each first conductor layer 21 is formed into the same planar element shape, and in the present embodiment, is formed into a substantially rectangular shape having long sides in the X-axis direction and short sides in the Y-axis direction. As shown in FIG. 18 , the antenna elements 100 are arranged in a matrix along the X-axis direction and the Y-axis direction on the first main surface 10a of the dielectric layer 10.

On the other hand, the second conductor layer 22 of each antenna element 100 is formed of a common conductor layer connected to the ground potential. In the second conductor layer 22, by providing an opening 22a in the formation area of the first inter-layer connection portion 31 of each antenna element 100, the second conductor layer 22 and each first inter-layer connection portion 31 are electrically insulated. The first inter-layer connection portion 31 of each antenna element 100 is connected to the signal processing circuit 301 via a signal transmission line (not shown) formed on the second main surface 10b of the dielectric layer 10. As the signal transmission line, various signal lines such as a microstrip line, a stripline line, and a coplanar waveguide line can be used.

[Signal processing circuit] The signal processing circuit 301 is a millimeter wave radar IC that generates a millimeter wave signal to be transmitted to the transmitting antenna Tx, processes the millimeter wave signal received by the receiving antennas Rx1 to Rx3, and calculates the arrival angle, which is equivalent to the feeding part. On the dielectric multilayer substrate 1, as shown in FIG. 19, there are further mounted: a voltage regulator 302 for adjusting the voltage supplied to the signal processing circuit 301, a memory 303 for storing driving parameters of the signal processing circuit 301, and a connector 304 for electrically connecting the signal processing circuit, the voltage regulator 302, and the memory 303 to an external device not shown in the figure.

The antenna module 300 of this embodiment is configured as a MIMO (Multi Input Multi Output) radar antenna. According to this embodiment, since the transmitting and receiving antennas are mounted on the same substrate, the same effects as those of the first embodiment described above are obtained, and the antenna device can be made smaller and thinner.

[Improvement of Isolation Characteristics] As described above, the first conductor layer 21 of each antenna element 100 constituting the antenna array 200 has a rectangular plane shape having a long side parallel to the X-axis direction and a short side parallel to the Y-axis direction. Therefore, when the antenna elements 100 are arranged on the first main surface 10a of the square-shaped dielectric layer 10, the interval between the antenna elements 100 adjacent to each other along the X-axis direction becomes smaller than the interval between the antenna elements 100 adjacent to each other along the Y-axis direction.

Therefore, in the present embodiment, a notch 210 for partially expanding the interval between the two first conductive layers 21 is provided on the short sides 21s facing each other of the two first conductive layers 21 arranged along the X-axis direction. Thus, the isolation characteristics between two antenna elements 100 adjacent to each other along the X-axis direction (between the transmitting antenna Tx and the receiving antenna Rx1, and between the two receiving antennas Rx2 and Rx3) can be improved compared to the antenna array 200 without the notch 210 as shown in FIG. 20, for example.

The shape of the notch 210 is not particularly limited, and in this embodiment, it is formed into an arc shape. In addition, as shown in FIG. 27 , the notch 210 may be formed into a triangle, a rectangle, or a trapezoid. By providing the notch 210 at a portion of the short side 21S of the first conductive layer 21, it is possible to prevent the perimeter of the first conductive layer 21 from changing significantly. In this way, broadband can be ensured and the isolation characteristics can be improved.

FIG21 shows the simulation result of the isolation characteristic of the receiving antenna Rx1 relative to the transmitting antenna Tx. The solid line in the figure shows the characteristic when there is a notch 210 (hereinafter, also referred to as isolation treatment), and the dotted line shows the characteristic when there is no notch 210 (hereinafter, also referred to as no isolation treatment). As shown in the figure, in the case of isolation treatment, an improvement of about 1 dB can be seen compared to the case of no isolation treatment.

Figure 22 shows the simulation results of the isolation characteristics of the receiving antenna Rx2 relative to the transmitting antenna Tx. The solid line in the figure represents the characteristics when the isolation is processed, and the dotted line represents the characteristics when the isolation is not processed. As shown in the figure, in the experiment, there is no significant difference between the case with isolation processing and the case without isolation processing. This is believed to be due to the fact that the transmitting antenna Tx and the receiving antenna Rx2 are located at a diagonal position with respect to each other, and the physical distance is relatively large.

FIG23 shows the simulation results of the isolation characteristics of the receiving antenna Rx3 relative to the transmitting antenna Tx. The solid line in the figure represents the characteristics when the isolation treatment is applied, and the dotted line represents the characteristics when the isolation treatment is not applied. As shown in the figure, a significant improvement can be seen in the frequency band of 60 GHz to 64 GHz compared to the case without the isolation treatment. This is believed to be because although the transmitting antenna Tx and the receiving antenna Rx3 are not affected by the formation of the notch 210 because the long sides of the first conductive layer 21 face each other, the current density in the peripheral portion of the first conductive layer 21 is high, so the shape effect of the notch 210 achieves a function like a filter at a specific frequency.

Figure 24 shows the simulation results of the isolation characteristics between the receiving antenna Rx2 and the receiving antenna Rx3. The solid line in the figure shows the characteristics when the isolation processing is performed, and the dotted line shows the characteristics when the isolation processing is not performed. As shown in the figure, in the case of the isolation processing, an improvement of about 2 dB can be seen compared to the case of the non-isolation processing.

FIG25 shows the simulation result of the isolation characteristics between the receiving antenna Rx1 and the receiving antenna Rx3. The solid line in the figure represents the characteristics when the isolation is processed, and the dotted line represents the characteristics when the isolation is not processed. As shown in the figure, in the experiment, there is no significant difference between the case where the isolation is processed and the case where the isolation is not processed. This is believed to be due to the fact that the receiving antenna Rx1 and the receiving antenna Rx3 are located at a diagonal position with respect to each other, and the physical distance is relatively large.

FIG26 shows the simulation result of the isolation characteristics between the receiving antenna Rx1 and the receiving antenna Rx2. The solid line in the figure represents the characteristics when the isolation processing is performed, and the dotted line represents the characteristics when the isolation processing is not performed. As shown in the figure, a significant improvement can be seen in the frequency band of 60 GHz to 64 GHz compared with the case without the isolation processing. This is similar to the result shown in FIG23, and it is believed that the function of a filter in a specific frequency is obtained by the shape effect of the notch 210.

<Third embodiment> [Another configuration example of antenna element] Next, another configuration example of the antenna element of the present technology is described. In each figure, the same symbol is given to the part corresponding to Figure 1, and its detailed description is omitted.

The antenna element 151 shown in FIG28 is different from the antenna element 100 shown in FIG1 in that the first conductor layer 21 as a radiating element and the second conductor layer 22 as a ground conductor plate are formed with the same area. Here, the length of each side of the first conductor layer 21 and the second conductor layer 22 is set to 3 mm respectively.

FIG29 shows the simulation results of the voltage-stationary-wave ratio (VSWR) characteristics of the antenna element 151 and the radiation characteristics of the azimuth plane (XZ plane) and elevation plane (YZ plane) at 60 GHz. As shown in the figure, since the area of the first conductor layer 21 is too large, the resonance state changes, and it is difficult to establish an antenna for the 60 GHz band. Therefore, the first conductor layer 21 needs to be formed with an area at least smaller than the second conductor layer 22, and it is better to optimize the perimeter of the first conductor layer 21 according to the frequency band used.

The antenna element 152 shown in FIG30 is different from the antenna element 100 shown in FIG1 in that, when viewed from the Z-axis direction, the peripheral portion (long side and short side) of the first conductor layer 21 as a radiating element is formed into a strip shape in which the peripheral portion (long side and short side) of the first inter-layer connecting portion 31 (first region 211) and the outer peripheral portion of the second inter-layer connecting portion 32 (second region 212) are connected. Here, the length of the short side of the first conductor layer 21 is set to 0.3 mm, and the length of the long side is set to 1.1 mm.

FIG31 shows the simulation results of the voltage-sense-wave ratio (VSWR) characteristics of the antenna element 152 and the radiation characteristics in the azimuth plane (XZ plane) and elevation plane (YZ plane) at 60 GHz. As shown in the figure, although resonance occurs in the 60 GHz band, the radiation characteristics of the antenna maintain the directivity of the loop antenna.

On the other hand, the antenna element 153 shown in FIG32 is different from the antenna element 152 shown in FIG30 in that, when viewed from the Z-axis direction, it is formed in a strip shape located at the outer periphery of the first interlayer connecting portion 31 (first region 211) and the second interlayer connecting portion 32 (second region 212) on the inner side of the periphery (long side and short side) of the first conductor layer 21 as a radiating element. Here, the length of the short side of the first conductor layer 21 is set to 0.5 mm, and the length of the long side is set to 1.3 mm.

FIG33 shows the simulation results of the voltage-situation-wave-ratio (VSWR) characteristics and the radiation characteristics in the azimuth plane (XZ plane) and elevation plane (YZ plane) at 60 GHz of the antenna element 153. As shown in the figure, the frequency band starts to expand with the 60 GHz frequency band as the center, and the radiation characteristics toward the top surface of the antenna also become larger.

Furthermore, the antenna element 154 shown in FIG. 34 is different from the antenna element 153 shown in FIG. 32 in that the length of the short side of the first conductor layer 21 as a radiating element is set to 1.0 mm and the length of the long side is set to 1.3 mm.

FIG35 shows the simulation results of the voltage-situation-wave-ratio (VSWR) characteristics of the antenna element 154 and the radiation characteristics in the azimuth plane (XZ plane) and elevation plane (YZ plane) at 60 GHz. As shown in the figure, it can be seen that as the frequency band is further expanded, the radiation pattern of the antenna is continuously optimized toward the top plane direction.

Furthermore, the antenna element 155 shown in FIG. 36 is different from the antenna element 154 shown in FIG. 34 in that the length of the short side of the first conductor layer 21 as a radiating element is set to 0.5 mm and the length of the long side is set to 1.6 mm.

Figure 37 shows the voltage-stationary-wave ratio (VSWR) characteristics of the antenna element 155 and the simulation results of the radiation characteristics in the azimuth plane (XZ plane) and elevation plane (YZ plane) at 60 GHz. As shown in the figure, complex resonance is also generated in the Y-axis direction, and the frequency band is further expanded, and the radiation pattern of the antenna becomes stronger toward the top surface.

Furthermore, the two antenna elements 156 shown in FIG38 are different from the antenna element 100 shown in FIG1 in that the first interlayer connection portion 31 and the second interlayer connection portion 32 connected to the first conductive layer 21 as a radiating element are arranged in a direction intersecting the direction parallel to the long side (X-axis direction). Here, an example is shown in which the second interlayer connection portion 32 is arranged at a corner portion of the first conductive layer 21.

FIG39 shows the simulation results of the voltage-stationary-wave ratio (VSWR) characteristics and the radiation characteristics in the azimuth plane (XZ plane) and elevation plane (YZ plane) at 60 GHz of the antenna element 156. As shown in the figure, since the same simulation results as the VSWR characteristics (FIG. 3) and radiation characteristics (FIG. 4 and FIG. 5) of the antenna element 100 shown in FIG1 are obtained, the same effects as those of the first embodiment are obtained in this configuration example.

<Fourth Implementation Form> [Another Example of Improving Isolation Characteristics] Next, the fourth implementation form of the present technology is described. In the fourth implementation form, another example of improving the isolation characteristics described in the second implementation form is described.

Here, in the second embodiment described above, a method for improving the isolation characteristics by providing the notch portion 210 on the short sides facing each other in the X-axis direction in each first conductive layer 21 is described. On the other hand, in the fourth embodiment, in addition to the notch portion 210, improvements based on other viewpoints are further applied to further improve the isolation characteristics.

In the description here, first, an example corresponding to the second embodiment described above is given and described. Fig. 40 is a diagram showing an example of an antenna module 300 corresponding to the second embodiment described above.

As shown in Fig. 40, the antenna module 300 (antenna array 200) has a plurality of antenna elements 100, including a transmitting antenna Tx and three receiving antennas Rx1, Rx2, and Rx3. The first conductive layer 21 of each of the transmitting antenna Tx and the receiving antennas Rx1, Rx2, and Rx has a notch 210 on the short sides facing each other in the X-axis direction.

The shape of the antenna module 300 in the plane direction is set to be a rectangle. In this example, the length in the X-axis direction is set to be 5.0 mm, and the width in the Y-axis direction is set to be 5.0 mm.

Furthermore, in the Y-axis direction, the distance between the center position of the receiving antenna Rx1 and the center position of the receiving antenna Rx2, and the distance between the center position of the receiving antenna Rx1 and the center position of the receiving antenna Rx3 are set to 2.5 mm. Furthermore, in the X-axis direction, the distance between the center position of the receiving antenna Rx2 and the center position of the receiving antenna Rx3, and the distance between the center position of the receiving antenna Rx1 and the center position of the receiving antenna Rx3 are set to 2.5 mm.

In the XY direction (plane direction), the distance D between the center position of the transmitting antenna Tx and the center positions of the three receiving antennas Rx1, Rx3, and Rx3 is set to 2 mm. Furthermore, the center positions of the three receiving antennas Rx1, Rx3, and Rx3 in the plane direction are the midpoint position between the center position of the receiving antenna Rx1 and the center position of the receiving antenna Rx2 in the Y-axis direction, and the midpoint position between the center position of the receiving antenna Rx2 and the center position of the receiving antenna Rx3 in the X-axis direction.

Fig. 41 is a graph showing the isolation characteristic of the antenna module 300 shown in Fig. 40. In Fig. 41, the horizontal axis represents the frequency [GHz] of the radio wave used in the antenna element 100, and the vertical axis represents the isolation characteristic [dB]. In addition, the value [dB] of the vertical axis means that the lower the isolation characteristic, the higher the value.

41, the three curves respectively represent the isolation characteristics of the receiving antenna Rx1 relative to the transmitting antenna Tx (Tx→Rx1), the isolation characteristics of the receiving antenna Rx2 relative to the transmitting antenna Tx (Tx→Rx2), and the isolation characteristics of the receiving antenna Rx3 relative to the transmitting antenna Tx (Tx→Rx3).

In addition, at the upper right of FIG. 41 , an image (in the form of thermal imaging) is shown for visualizing the effect of the transmitting antenna Tx on the receiving antennas Rx1 , Rx2 , and Rx3 .

As described above in the second embodiment, in the form shown in FIG. 40 , since the notch portion 210 is provided in the first conductive layer 21 , the isolation characteristic is improved compared to the form without the notch portion 210 .

On the other hand, further improvement of the isolation characteristic is expected. Therefore, in the fourth embodiment, the isolation characteristic is further improved.

Fig. 42 is a perspective view of the antenna module 400 of the fourth embodiment. Fig. 43 is a plan view of the antenna module 400 of the fourth embodiment. In the description of the fourth embodiment, the differences from the above-mentioned second embodiment (and Figs. 40 and 41) are mainly described.

Typically, in the fourth embodiment, in order to improve the isolation characteristics of the receiving antennas Rx1, Rx2, and Rx3 relative to the transmitting antenna Tx, the following three methods (A) to (C) are mainly used. (A) A notch 210 is provided for each first conductive layer 21 (same as the second embodiment described above). (B) The distance between the transmitting antenna Tx and the receiving antennas Rx1, Rx2, and Rx3 is increased in the plane direction (XY direction). (C) A shielding layer 41 is provided to shield the electric field from the transmitting antenna Tx to the receiving antennas Rx1, Rx2, and Rx3. (c) By providing a third inter-layer connection portion 42 connecting the shielding layer 41 and the second conductive layer 22, the shielding layer 41 is lowered to the ground potential.

As shown in Figures 42 and 43, the antenna module 400 (antenna array) has a plurality of antenna elements 100, including a transmitting antenna Tx and three receiving antennas Rx1, Rx2, and Rx3. The first conductive layer 21 of each of the transmitting antenna Tx and the receiving antennas Rx1, Rx2, and Rx has a notch 210 on the short sides facing each other in the X-axis direction.

The shape of the antenna module 400 in the plane direction is set to be a rectangle that is long in the X-axis direction. In this example, the length in the X-axis direction (the direction parallel to the long side of the first conductive layer 21) is set to 12.5 mm, and the width in the Y-axis direction (the direction parallel to the short side of the first conductive layer 21) is set to 7.5 mm (5 mm×5 mm in FIG. 40). Furthermore, the specific numerical values described in the fourth embodiment are only examples and can be appropriately changed.

Furthermore, in the Y-axis direction, the distance between the center position of the receiving antenna Rx1 and the center position of the receiving antenna Rx2, and the distance between the center position of the receiving antenna Rx1 and the center position of the receiving antenna Rx3 are set to 2.5 mm. Furthermore, in the X-axis direction, the distance between the center position of the receiving antenna Rx2 and the center position of the receiving antenna Rx3, and the distance between the center position of the receiving antenna Rx1 and the center position of the receiving antenna Rx3 are set to 2.5 mm.

In the XY direction (plane direction), the distance D between the center position of the transmitting antenna Tx and the center positions of the three receiving antennas Rx1, Rx3, and Rx3 is set to 5 mm. Furthermore, the center positions of the three receiving antennas Rx1, Rx3, and Rx3 in the plane direction are the midpoint position between the center position of the receiving antenna Rx1 and the center position of the receiving antenna Rx2 in the Y-axis direction, and the midpoint position between the center position of the receiving antenna Rx2 and the center position of the receiving antenna Rx3 in the X-axis direction.

Here, the relative position relationship of the three receiving antennas Rx1, Rx2, and Rx3 is the same as that of the example shown in FIG40 (and the second embodiment). On the other hand, the distance D between the center position of the transmitting antenna Tx and the center position of the three receiving antennas Rx1, Rx3, and Rx3 is 2 mm in the example shown in FIG40, while it is 5 mm in the example here, which is longer than that of the example shown in FIG40.

Comparing the fourth embodiment with the example shown in FIG. 40 (and the second embodiment), the relative position relationship of the three receiving antennas Rx1, Rx2, and R3 is fixed, and the three receiving antennas Rx1, Rx2, and R3 move in the direction away from the transmitting antenna Tx in the X-axis direction. Furthermore, the relative position relationship of the three receiving antennas Rx1, Rx2, and R3 is fixed, and the relative position relationship of the three receiving antennas Rx1, Rx2, and R3 is roughly determined due to the use of MIMO in this technology.

In this way, by making the center positions of the three receiving antennas Rx1, Rx3, and Rx3 far away from the center position of the transmitting antenna Tx, the isolation characteristics of the receiving antennas Rx1, Rx3, and Rx3 relative to the transmitting antenna Tx can be improved.

Typically, the distance D in the XY direction (plane direction) between the center position of the transmitting antenna Tx and the center positions of the three receiving antennas Rx1, Rx3, and Rx4 is set to be greater than half the wavelength (1/2λ) of the radio wave used. Furthermore, according to experimental results, it can be seen that by setting the distance D to be greater than half the wavelength (1/2λ), the isolation characteristics of the receiving antennas Rx1, Rx3, and Rx4 relative to the transmitting antenna Tx are improved.

On the other hand, it is believed that the greater the distance D, the better the isolation characteristics of the receiving antennas Rx1, Rx3, and Rx4 relative to the transmitting antenna Tx. However, according to experimental results, the improvement tends to reach a limit when the distance D is greater than a certain distance. Furthermore, of course, there is also the problem that the larger the antenna module 400 is, the larger the distance D is. If the antenna module 400 is enlarged, there is also the following problem: transmission loss occurs between the millimeter wave radar IC301 and the receiving antenna Tx, the receiving antennas Rx1, Rx2, and Rx2, and the overall performance of the system is deteriorated.

Therefore, typically, the distance D between the center position of the transmitting antenna Tx and the center positions of the three receiving antennas Rx1, Rx3, and Rx4 in the XY direction (plane direction) is set to be at least 1.5 times (1.5λ) the half wavelength of the radio wave used. In this way, the isolation characteristics can be appropriately improved without increasing the size of the antenna module 400.

In addition, the antenna module 400 (antenna array) has a shielding layer 41, which is disposed between the first conductive layer 21 of the transmitting antenna Tx and the first conductive layer 21 of the receiving antennas Rx1, Rx2, and Rx3 on the surface 10a of the dielectric layer 10. The shielding layer 41 can shield unnecessary electric fields (radio waves) that directly enter the receiving antennas Rx1, Rx2, and Rx3 from the transmitting antenna Tx.

The shielding layer 41 is formed in a ring shape (and in a strip shape) on the surface 10a of the dielectric layer 10 so as to surround the first conductive layer 21 of the transmitting antenna Tx. In this example, the shielding layer 41 is formed in a rectangular ring shape, but the shape may be another shape such as an elliptical ring shape.

The shielding layer 41 is typically a metal layer formed on the surface 10a of the dielectric layer 10. Examples of the metal material used for the shielding layer 41 include copper and aluminum, but the material is not particularly limited. The material may be the same as that of the first conductive layer 21 and the second conductive layer, or a different material. The thickness of the shielding layer 41 is not particularly limited, and may be the same as that of the first conductive layer 21 and the second conductive layer 22, or a different thickness.

In this example, the length of the outer periphery of the shielding layer 41 is set to 3.5 mm × 3.5 mm (X axis × Y axis), and the width of the shielding layer 41 (the width of the tape) is set to 0.25 mm. In addition, in the Y axis direction, the distance between the inner periphery of the shielding layer 41 and the long side of the first conductive layer 21 of the transmitting antenna Tx is set to 1 mm. In addition, in the X axis direction, the distance between the inner periphery of the shielding layer 41 and the short side of the first conductive layer 21 of the transmitting antenna Tx is set to 0.6 mm.

In addition, the antenna module 400 (antenna array) has a plurality of third interlayer connecting portions 42. The third interlayer connecting portions 42 penetrate the dielectric layer 10 along the thickness direction (Z-axis direction) thereof and electrically connect the shielding layer 41 and the second conductive layer 22. The third interlayer connecting portions 42 are cylindrical conductive bodies similar to the first interlayer connecting portions 31 and the second interlayer connecting portions 32, and are formed by buried conductive holes provided in the dielectric layer 10 by through-hole electroplating or filled with conductive materials.

Since the third interlayer connection portion 42 is vertically connected to the shielding layer 41 and the second conductive layer 22, the length (height) of the third interlayer connection portion 42 is equal to the thickness (0.65 mm) of the dielectric layer 10. The diameter of the third interlayer connection portion 42 is, for example, set to be the same size as the width (band width) of the shielding layer 41. The diameter of the third interlayer connection portion 42 can be the same as the first interlayer connection portion 31 and the second interlayer connection portion 32, or can be different diameters.

The plurality of third inter-layer connection parts 42 are arranged at a predetermined interval (0.8 mm) along the circumference of the shielding layer 41. In the example here, the plurality of third inter-layer connection parts 42 are not arranged over the entire circumference of the shielding layer 41, but are arranged for a portion of the entire circumference of the shielding layer 41. Specifically, the plurality of third inter-layer connection parts 42 are arranged at a portion corresponding to one side along the Y-axis direction (one side between the transmitting antenna Tx and the receiving antenna Rx) and at a portion corresponding to two sides along the X-axis direction among the four sides of the rectangle of the shielding layer 41. Furthermore, the plurality of third inter-layer connection parts 42 may be arranged over the entire circumference of the shielding layer 41.

Here, the shielding layer 41 is connected to the second conductive layer 22 via a plurality of third inter-layer connecting portions 42. Since the second conductive layer 22 is grounded, the shielding layer 41 is also set to the ground potential accordingly. In this way, since the shielding layer 41 is set to the ground potential, the electric field (radio wave) from the transmitting antenna Tx to the receiving antennas Rx1, Rx2, and Rx3 can be appropriately shielded.

FIG44 is a graph showing the isolation characteristic of the antenna module 400. In FIG44, the horizontal axis represents the frequency [GHz] of the radio wave used in the antenna element 100, and the vertical axis represents the isolation characteristic [dB]. In addition, the value [dB] of the vertical axis means that the lower the isolation characteristic, the higher the value.

44, the three curves respectively represent the isolation characteristics of the receiving antenna Rx1 relative to the transmitting antenna Tx (Tx→Rx1), the isolation characteristics of the receiving antenna Rx2 relative to the transmitting antenna Tx (Tx→Rx2), and the isolation characteristics of the receiving antenna Rx3 relative to the transmitting antenna Tx (Tx→Rx3).

In addition, at the upper right of FIG. 44 , an image (in the form of thermal imaging) is shown for visualizing the effect of the transmitting antenna Tx on the receiving antennas Rx1 , Rx2 , and Rx3 .

Comparing FIG. 44 (the fourth embodiment) with FIG. 41 (the second embodiment), the curves Tx→Rx1, Tx→Rx2, and Tx→Rx3 all tend to fall downward. That is, in the fourth embodiment of the combination of the (A) "notch 210", (B) "distance D", and (C) "shielding layer 42", the isolation characteristic is further improved compared to the second embodiment of the (A) "notch" alone.

In addition, in the three curves of Fig. 44, the values representing the isolation characteristics are set to approximately 30 [dB] or less. In this way, by setting the values representing the isolation characteristics to 30 [dB] or less, a sufficient isolation characteristic can be obtained.

[Function, etc.] As described above, in the fourth embodiment, a shielding layer 41 (metal layer) is provided between the first conductor layer 21 of the transmitting antenna Tx and the first conductor layer 21 of the receiving antennas Rx1, Rx2, and Rx3 on the surface 10a of the dielectric layer 10 to shield the electric field from the transmitting antenna Tx to the receiving antennas Rx1, Rx2, and Rx3. In this way, the isolation characteristics of the receiving antennas Rx1, Rx2, and Rx3 relative to the transmitting antenna Tx can be further improved.

Furthermore, in the fourth embodiment, the shielding layer 41 is formed in a ring shape on the surface 10a of the dielectric layer 10 so as to surround the first conductive layer 21 of the transmitting antenna Tx. This can further improve the isolation characteristics of the receiving antennas Rx1, Rx2, and Rx3 relative to the transmitting antenna Tx.

In the fourth embodiment, a third interlayer connection portion 42 is provided that penetrates the dielectric layer 10 and connects the shielding layer 41 and the second conductive layer 22. Thus, the shielding layer 41 can be grounded, and thus the electric field (radio wave) from the transmission antenna Tx to the reception antennas Rx1, Rx2, and Rx3 can be appropriately shielded.

Furthermore, in the fourth embodiment, the third inter-layer connection portion 42 is formed as a through-hole electroplating or buried via provided in the dielectric layer 10. Thus, the shielding layer 41 and the second conductive layer 22 can be properly connected.

Furthermore, in the fourth embodiment, when the wavelength of the radio wave used is set to λ and the distance in the plane direction between the center position of the transmitting antenna Tx and the center position of the front receiving antennas Rx1, Rx2, and Rx3 is set to D, it is set to 0.5λ≦D≦1.5λ. By setting the distance D to a length of half a wavelength (1/2λ) or more, the isolation characteristics of the receiving antennas Rx1, Rx3, and Rx3 relative to the transmitting antenna Tx can be further improved. Furthermore, by setting the distance D to 1.5 times (1.5λ) or less of the wavelength of the radio wave used, the isolation characteristics can be appropriately improved without enlarging the antenna module 400.

<Various variations of the fourth embodiment> Next, various variations of the fourth embodiment will be described.

In the fourth embodiment described above, a case of using a combination of (A) "notch 210", (B) "distance D", and (C) "shielding layer 42". On the other hand, the combination of (A) "notch 210", (B) "distance D", and (C) "shielding layer 42" may be any of the following combinations. 1. The form of only (A) "notch 210" (second embodiment) 2. The form of only (B) "distance D" 3. The form of only (C) "shielding layer 42" 4. The form of the combination of (A) "notch 210" and (B) "distance D" 5. The form of the combination of (A) "notch 210" and (C) "shielding layer 42" 6. The form of the combination of (B) "distance D" and (C) "shielding layer 42" 7. The form of the combination of (A) "notch 210", (B) "distance D" and (C) "shielding layer 42" (fourth embodiment)

Here, in the case of the form including the above-mentioned "shielding layer 42" (C), that is, in the above-mentioned 4 forms 3.5.6.7., (c) "third inter-layer connection part 42" can be provided, and on the other hand, (c) "third inter-layer connection part 42" can be omitted. Therefore, the above-mentioned 4 forms 3.5.6.7. can be divided into two according to the presence or absence of (c) "third inter-layer connection part 42", but any form can be used. Furthermore, in the above-mentioned 4th embodiment, the combination of 7. (A) "notch part 210", (B) and (C) and the form including (c) are representatively described.

Here, a representative example is given to explain the combination of (A) "notch 210" and (B) "distance D" in 4. above.

Fig. 45 is a perspective view of an antenna module 500 of a variation of the fourth embodiment. In the antenna module 500 shown in Fig. 45, the shielding portion 41 and the third inter-layer connecting portion 42 are omitted compared to the antenna module 400 shown in Fig. 42. Other aspects are the same as those of Fig. 42.

Furthermore, in the antenna module 500, the first conductive layer 21 of each of the transmitting antenna Tx and the receiving antennas Rx1, Rx2, Rx is provided with a notch 210 on the short sides facing each other in the X-axis direction. In addition, in the XY direction (plane direction), the distance D between the center position of the transmitting antenna Tx and the center positions of the three receiving antennas Rx1, Rx3, Rx3 is set to 5 mm. That is, the distance D satisfies the condition of 0.5λ≦D≦1.5λ.

Fig. 46 is a graph showing the isolation characteristic of the antenna module 500. In Fig. 46, the horizontal axis represents the frequency [GHz] of the radio wave used in the antenna element 100, and the vertical axis represents the isolation characteristic [dB]. In addition, the value [dB] of the vertical axis means that the lower the isolation characteristic, the higher the value.

46, the three curves respectively represent the isolation characteristics of the receiving antenna Rx1 relative to the transmitting antenna Tx (Tx→Rx1), the isolation characteristics of the receiving antenna Rx2 relative to the transmitting antenna Tx (Tx→Rx2), and the isolation characteristics of the receiving antenna Rx3 relative to the transmitting antenna Tx (Tx→Rx3).

In addition, at the upper right of FIG. 46 , an image (in the form of thermal imaging) is shown for visualizing the effect of the transmitting antenna Tx on the receiving antennas Rx1, Rx2, and Rx3.

Comparing FIG. 46 (variation of the fourth embodiment) with FIG. 41 (second embodiment), the curves of Tx→Rx1, Tx→Rx2, and Tx→Rx3 are generally inclined downward. That is, in the variation of the fourth embodiment of the combination of (A) "notch 210" and (B) "distance D", the isolation characteristic is further improved compared to the second embodiment of the (A) "notch" alone.

In the above description, the shielding layer 41 is described as completely surrounding the first conductive layer 21 of the transmitting antenna Tx. On the other hand, the shielding layer 41 may be formed to partially surround the first conductive layer 21 of the transmitting antenna Tx. Typically, the shielding layer 41 only needs to be formed to be interposed between the first conductive layer 21 of the transmitting antenna Tx and the first conductive layer 21 of the receiving antennas Rx1, Rx2, and Rx3.

In the above description, the shielding layer 41 surrounds the transmitting antenna Tx side, but the shielding layer 42 may be formed to surround (partially or entirely) the receiving antennas Rx1, Rx2, and Rx3. In this case, the shielding layer 41 may be formed to surround the three receiving antennas Rx1, Rx2, and Rx3 collectively or individually.

Furthermore, when the shielding layer 41 is disposed on the side of the receiving antennas Rx1, Rx2, and Rx3, typically, a third inter-layer connecting portion 42 is disposed on the shielding layer 41 to set the shielding layer 41 to a ground potential.

Here, in the case where the shielding layer 41 is set on the side of the receiving antennas Rx1, Rx2, and Rx3, according to the experimental results, when the shielding layer 41 is not set to the ground potential, the shielding layer 41 will have a bad effect on the isolation characteristics. This is because if the ungrounded shielding layer 41 is set near the receiving antennas Rx1, Rx2, and Rx3, the shielding layer 41 becomes an intermediary for the electric field (radio wave) from the transmitting antenna Tx to the receiving antennas Rx1, Rx2, and Rx3. Therefore, in the case where the shielding layer 41 is set on the side of the receiving antennas Rx1, Rx2, and Rx3, typically, the third inter-layer connection portion 42 is set on the shielding layer 41, and the shielding layer 41 is set to the ground potential.

Furthermore, the present technology can also adopt the following structure. (1) An antenna element, which includes: a first conductor layer in the shape of a planar element; a second conductor layer connected to the ground potential; a dielectric layer disposed between the first conductor layer and the second conductor layer; a first inter-layer connection portion penetrating the dielectric layer to connect the first conductor layer to the feeder portion; and a second inter-layer connection portion penetrating the dielectric layer to connect the first conductor layer to the second conductor layer. (2) An antenna element as described in (1), wherein the first conductor layer is formed with a smaller area than the second conductor layer. (3) An antenna element as described in (2) above, wherein the length of the loop formed by the first interlayer connection portion, the first conductive layer, and the second interlayer connection portion is less than 1 wavelength of the radio wave used. (4) An antenna element as described in (3) above, wherein the length of the loop is equal to half the wavelength of the radio wave used. (5) An antenna element as described in any one of (2) to (4) above, wherein the planar shape of the first conductive layer is a rectangle having long sides and short sides. (6) An antenna element as described in (5) above, wherein the first conductive layer has a first region connected to the first inter-layer connection portion, and a second region connected to the second inter-layer connection portion, and the first region and the second region are arranged separately from the peripheral portion of the first conductive layer. (7) An antenna element as described in (6) above, wherein the first region and the second region are arranged along a direction parallel to the long side. (8) An antenna element as described in (6) or (7) above, wherein the first region and the second region are arranged along a direction intersecting the direction parallel to the long side. (9) An antenna element as described in any one of (1) to (8) above, wherein the dielectric layer is a dielectric substrate made of a dielectric material, the first conductor layer is a metal layer formed on the first main surface of the dielectric substrate, and the second conductor layer is a metal layer formed on the second main surface of the dielectric substrate on the opposite side to the first main surface. (10) An antenna element as described in any one of (1) to (9) above, wherein the second conductor layer has an opening portion formed with an opening diameter larger than the outer diameter of the first inter-layer connection portion. (11) An antenna element as described in any one of (1) to (10) above, wherein the first inter-layer connection portion and the second inter-layer connection portion are provided in through-hole electroplating or buried via holes of the dielectric layer. (12) An antenna array comprises a plurality of antenna elements, each of which comprises: a first conductor layer in the shape of a planar element; a second conductor layer connected to a ground potential; a dielectric layer disposed between the first conductor layer and the second conductor layer; a first inter-layer connection portion penetrating the dielectric layer and connecting the first conductor layer to a feeder portion; and a second inter-layer connection portion penetrating the dielectric layer and connecting the first conductor layer to the second conductor layer; The first conductor layer of each of the plurality of antenna elements is arranged on a surface of the dielectric layer. (13) An antenna array as described in (12) above, wherein at least one of the plurality of antenna elements is a transmitting antenna element, and at least one of the other antenna elements is a receiving antenna element. (14) An antenna array as described in (13) above, wherein the plurality of antenna elements are arranged in a matrix along the first and second axes that are orthogonal to each other on the surface. (15) An antenna array as described in (14) above, wherein the first conductor layer has a rectangular planar shape having a long side parallel to the first axis and a short side parallel to the second axis, and the short sides of the two first conductor layers arranged along the first axis that face each other have a notch that partially expands the interval between the two first conductor layers. (16) An antenna array as described in any one of (12) to (15), wherein the aforementioned second conductor layer of each of the plurality of antenna elements is formed by a common conductor layer. (17) An antenna array as described in any one of (13) to (16), further comprising: a shielding layer disposed on the aforementioned surface of the aforementioned dielectric layer between the aforementioned first conductor layer of the aforementioned transmitting antenna element and the aforementioned first conductor layer of the aforementioned receiving antenna element, shielding the electric field from the aforementioned transmitting antenna element to the aforementioned receiving antenna. (18) An antenna array as described in (17), wherein the aforementioned shielding layer is formed in a ring shape on the aforementioned surface of the aforementioned dielectric layer so as to surround the aforementioned first conductor layer of the aforementioned transmitting antenna element. (19) The antenna array as described in (17) or (18) further comprises: A third inter-layer connection portion which penetrates the dielectric layer and connects the shielding layer to the second conductive layer. (20) The antenna array as described in (19), wherein the third inter-layer connection portion is provided in a through-hole electroplating or buried through-hole of the dielectric layer. (21) The antenna array as described in any one of (17) to (20), wherein the shielding layer is a metal layer formed on the aforementioned surface of the dielectric layer. (22) An antenna array as in any one of (13) to (21) above, wherein the plurality of antenna elements include one transmitting antenna element and a plurality of receiving antenna elements, and when the wavelength of the radio wave used is λ and the distance in the plane direction between the center position of the one transmitting antenna element and the center position of the plurality of receiving antenna elements is D, 0.5λ≦D. (23) An antenna array as in (22) above, wherein D≦1.5λ. (24) An antenna module comprises a plurality of antenna elements and a signal processing circuit, wherein each of the plurality of antenna elements comprises: a first conductive layer in the shape of a planar element; a second conductive layer connected to a ground potential; a dielectric layer disposed between the first conductive layer and the second conductive layer; a first inter-layer connection portion penetrating the dielectric layer and connecting the first conductive layer to a feeding portion; and a second inter-layer connection portion penetrating the dielectric layer and connecting the first conductive layer to the second conductive layer; the signal processing circuit is connected to the plurality of antenna elements.

1: Dielectric multilayer substrate 10, 110: Dielectric layer 10a: 1st main surface/front surface 10b: 2nd main surface/back surface 21, 121: 1st conductor layer 21L: Long side 21S: Short side 22, 122: 2nd conductor layer 22a: Opening 31: 1st interlayer connection part/interlayer connection part 32: 2nd interlayer connection part/interlayer connection part 41: Shielding layer 42: 3rd interlayer connection part 100, 101, 102, 151~156: Antenna element 101: Antenna element 123: Antenna structure 124: Ground conductor plate 131: Interlayer connection 200: Antenna array 210: Notch 211: Area 1 212: Area 2 300, 400, 500: Antenna module 301: Signal processing circuit 302: Voltage regulator 303: Memory 304: Connector F: Feeder G: Ground potential Rx1, Rx2, Rx3: Receiving antenna Tx: Transmitting antenna X, Y, Z: Axes

FIG. 1 is a perspective view of an antenna element of the first embodiment of the present technology. FIG. 2 is a side sectional view of the antenna element. FIG. 3 is a simulation result showing an example of the voltage-to-wave ratio of the antenna element. FIG. 4 is a simulation result showing the radiation characteristics of the antenna element in the azimuth plane at 60 GHz. FIG. 5 is a simulation result showing the radiation characteristics of the antenna element in the elevation plane at 60 GHz. FIG. 6 is a perspective view of the antenna element of Comparative Example 1. FIG. 7 is a side sectional view of the antenna element of Comparative Example 1. FIG. 8 is a simulation result showing an example of the voltage-to-wave ratio of the antenna element of Comparative Example 1. FIG. 9 shows the simulation result of the radiation characteristic of the antenna element of Comparative Example 1 in the azimuth plane at 60 GHz. FIG. 10 shows the simulation result of the radiation characteristic of the antenna element of Comparative Example 1 in the elevation plane at 60 GHz. FIG. 11 is a perspective view of the antenna element of Comparative Example 2. FIG. 12 is a side view of the antenna element of Comparative Example 2. FIG. 13 shows the simulation result of an example of the voltage-to-wave ratio of the antenna element of Comparative Example 2. FIG. 14 shows the simulation result of the radiation characteristic of the antenna element of Comparative Example 2 in the azimuth plane at 60 GHz. FIG. 15 shows the simulation result of the radiation characteristic of the antenna element of Comparative Example 2 in the elevation plane at 60 GHz. FIG. 16 is a simulation result comparing the antenna characteristics and directivity of the antenna element shown in FIG. 1 and the antenna element of Comparative Example 1 shown in FIG. 6. FIG. 17 is a perspective view of the antenna module of the second embodiment of the present technology. FIG. 18 is a plan view of the antenna module. FIG. 19 is a block diagram showing the circuit structure of the antenna module. FIG. 20 is a perspective view showing the structure of the antenna module without isolation treatment, which is the same as FIG. 17. FIG. 21 is a simulation result showing the isolation characteristics of a receiving antenna relative to a transmitting antenna in the antenna module. FIG. 22 is a simulation result showing the isolation characteristics of another receiving antenna relative to a transmitting antenna in the antenna module. FIG. 23 is a simulation result showing the isolation characteristic of another receiving antenna relative to the transmitting antenna in the above antenna module. FIG. 24 is a simulation result showing an example of the isolation characteristic between receiving antennas in the above antenna module. FIG. 25 is a simulation result showing another example of the isolation characteristic between receiving antennas in the above antenna module. FIG. 26 is a simulation result showing another example of the isolation characteristic between receiving antennas in the above antenna module. FIG. 27 is an explanatory diagram showing another configuration example of the above isolation processing. FIG. 28 is a three-dimensional diagram showing another configuration example of the antenna element shown in FIG. 1. FIG. 29 shows the simulation results of the voltage station wave ratio (VSWR) characteristics of the antenna element shown in FIG. 28 and the radiation characteristics of the azimuth plane and elevation plane at 60 GHz. FIG. 30 shows a three-dimensional diagram of another configuration example of the antenna element shown in FIG. 1. FIG. 31 shows the simulation results of the voltage station wave ratio (VSWR) characteristics of the antenna element shown in FIG. 30 and the radiation characteristics of the azimuth plane and elevation plane at 60 GHz. FIG. 32 shows a three-dimensional diagram of another configuration example of the antenna element shown in FIG. 1. FIG. 33 shows the simulation results of the voltage station wave ratio (VSWR) characteristics of the antenna element shown in FIG. 32 and the radiation characteristics of the azimuth plane and elevation plane at 60 GHz. FIG. 34 is a three-dimensional diagram showing another configuration example of the antenna element shown in FIG. 1. FIG. 35 is a three-dimensional diagram showing the voltage-to-sound ratio (VSWR) characteristic of the antenna element shown in FIG. 34, and the simulation results of the radiation characteristics in the azimuth plane and the elevation plane at 60 GHz. FIG. 36 is a three-dimensional diagram showing another configuration example of the antenna element shown in FIG. 1. FIG. 37 is a three-dimensional diagram showing the voltage-to-sound ratio (VSWR) characteristic of the antenna element shown in FIG. 36, and the simulation results of the radiation characteristics in the azimuth plane and the elevation plane at 60 GHz. FIG. 38 is a three-dimensional diagram showing another configuration example of the antenna element shown in FIG. 1. FIG. 39 shows the simulation results of the voltage station wave ratio (VSWR) characteristics of the antenna element shown in FIG. 38 and the radiation characteristics in the azimuth plane and elevation plane at 60 GHz. FIG. 40 shows an example of an antenna module corresponding to the second embodiment. FIG. 41 shows the isolation characteristics of the antenna module shown in FIG. 40. FIG. 42 shows a three-dimensional image of the antenna module of the fourth embodiment. FIG. 43 shows a plan view of the antenna module of the fourth embodiment. FIG. 44 shows the isolation characteristics of the antenna module of the fourth embodiment. FIG. 45 shows a three-dimensional image of the antenna module of a variation of the fourth embodiment. FIG. 46 is a diagram showing the isolation characteristics of the antenna module of a variation of the fourth embodiment.

10: Dielectric layer

10a: 1st main surface/surface

21: 1st conductor layer

21L: Long side

21S: Short side

22: Second conductor layer

22a: Opening

31: 1st inter-layer connection/inter-layer connection

32: Second inter-layer connection/inter-layer connection

100: Antenna components

211: Area 1

212: Area 2

X,Y,Z: axis

Claims (24)

An antenna element, comprising: a first conductor layer in the shape of a planar element; a second conductor layer connected to a ground potential; a dielectric layer disposed between the first conductor layer and the second conductor layer; a first inter-layer connection portion penetrating the dielectric layer to connect the first conductor layer to a feeding portion; and a second inter-layer connection portion penetrating the dielectric layer to connect the first conductor layer to the second conductor layer. The antenna element of claim 1, wherein the first conductor layer is formed with a smaller area than the second conductor layer. The antenna element of claim 2, wherein the loop length formed by the first inter-layer connection portion, the first conductive layer, and the second inter-layer connection portion is less than 1 wavelength of the radio wave used. The antenna element of claim 3, wherein the aforementioned loop length is equal to half the wavelength of the radio wave used. The antenna element of claim 2, wherein the plane shape of the first conductor layer is a rectangle with long sides and short sides. The antenna element as claimed in claim 5, wherein the first conductive layer has a first region connected to the first inter-layer connecting portion and a second region connected to the second inter-layer connecting portion, and the first region and the second region are arranged separately from the peripheral portion of the first conductive layer. The antenna element of claim 6, wherein the first region and the second region are arranged in a direction parallel to the long side. The antenna element of claim 6, wherein the first region and the second region are arranged along a direction intersecting the direction parallel to the long side. The antenna element of claim 1, wherein the dielectric layer is a dielectric substrate made of a dielectric material, the first conductor layer is a metal layer formed on the first main surface of the dielectric substrate, and the second conductor layer is a metal layer formed on the second main surface of the dielectric substrate opposite to the first main surface. The antenna element of claim 1, wherein the second conductor layer has an opening portion formed with an opening diameter larger than the outer diameter of the connecting portion between the first layers. The antenna element of claim 1, wherein the first inter-layer connection portion and the second inter-layer connection portion are disposed in the through-hole electroplating or buried through-hole of the dielectric layer. An antenna array includes a plurality of antenna elements, each of which includes: a first conductor layer in the shape of a planar element; a second conductor layer connected to a ground potential; a dielectric layer disposed between the first conductor layer and the second conductor layer; a first inter-layer connection portion penetrating the dielectric layer to connect the first conductor layer to a feeder portion; and a second inter-layer connection portion penetrating the dielectric layer to connect the first conductor layer to the second conductor layer; The first conductor layer of each of the plurality of antenna elements is arranged on a surface of the dielectric layer. The antenna array of claim 12, wherein at least one of the plurality of antenna elements is a transmitting antenna element, and at least one of the others is a receiving antenna element. The antenna array of claim 13, wherein the plurality of antenna elements are arranged in a matrix along the mutually orthogonal first and second axes on the surface. The antenna array of claim 14, wherein the first conductor layer has a rectangular plane shape including a long side parallel to the first axis and a short side parallel to the second axis, and the short sides of the two first conductor layers arranged along the first axis facing each other have a notch portion that partially expands the interval between the two first conductor layers. The antenna array of claim 12, wherein the aforementioned second conductor layer of each of the aforementioned plurality of antenna elements is formed by a common conductor layer. The antenna array of claim 13 further comprises: A shielding layer, which is disposed on the aforementioned surface of the aforementioned dielectric layer, between the aforementioned first conductive layer of the aforementioned transmitting antenna element and the aforementioned first conductive layer of the aforementioned receiving antenna element, shielding the electric field from the aforementioned transmitting antenna element to the aforementioned receiving antenna. The antenna array of claim 17, wherein the shielding layer is formed in a ring shape on the aforementioned surface of the dielectric layer so as to surround the first conductive layer of the transmitting antenna element. The antenna array of claim 17 further comprises: A third inter-layer connection portion, which penetrates the aforementioned dielectric layer and connects the aforementioned shielding layer and the aforementioned second conductive layer. The antenna array of claim 19, wherein the third inter-layer connection is provided in the through-hole electroplating or buried through-hole of the dielectric layer. The antenna array of claim 17, wherein the shielding layer is a metal layer formed on the surface of the dielectric layer. The antenna array of claim 13, wherein the aforementioned plurality of antenna elements include one transmitting antenna element and a plurality of receiving antenna elements, and when the wavelength of the radio wave used is set to λ and the distance in the plane direction between the center position of the aforementioned one transmitting antenna element and the center position of the aforementioned plurality of receiving antenna elements is set to D, 0.5λ≦D. For example, the antenna array of claim 22, wherein D≦1.5λ. An antenna module includes a plurality of antenna elements and a signal processing circuit, wherein each of the plurality of antenna elements includes: A first conductor layer in the shape of a planar element; A second conductor layer connected to a ground potential; A dielectric layer disposed between the first conductor layer and the second conductor layer; A first inter-layer connection portion penetrating the dielectric layer to connect the first conductor layer to a feeder portion; and A second inter-layer connection portion penetrating the dielectric layer to connect the first conductor layer to the second conductor layer; The signal processing circuit is connected to the plurality of antenna elements.