JP6953799B2 - Antenna device - Google Patents

Description

The present invention relates to an antenna device including two antennas.

Conventionally, as disclosed in Patent Document 1, there is an antenna device including a first antenna (hereinafter, first antenna) and a second antenna (hereinafter, second antenna).

Japanese Patent No. 4952668

Generally, if the first antenna and the second antenna are too close to each other, the radio waves radiated from the first antenna induce a current in the second antenna, which deteriorates the performance as the second antenna. In order to ensure non-interference between antennas (so-called isolation), it is necessary to arrange the antennas at a certain distance from each other.

The present invention has been made based on this circumstance, and an object of the present invention is to provide an antenna device capable of improving isolation between antennas.

The first antenna device for achieving the purpose is a linear conductor arranged along a device axis (Ax) which is a predetermined straight line for transmitting or receiving radio waves of a predetermined frequency. The first antenna (1), the second antenna (2) which is a linear conductor arranged along the device axis at a predetermined distance from the first antenna for transmitting or receiving radio waves, and the first antenna. The first resonance element is provided with at least one resonance structure (3, 3A, 3B) arranged between the antenna and the second antenna, and the resonance structure is a linearly formed conductor member. (31) and the second resonance element (32) are provided, the first resonance element includes a point located in the middle from one end to the other end as the center of the first resonance element, and the second resonance element is from one end. A point located in the middle to the other end is provided as the center of the second resonance element, and the first resonance element is a device center point at which the distances from the first antenna and the second antenna are equal on the device axis. predetermined distance than the position where the first antenna side, the center of the first resonator element is located, and are arranged in a posture perpendicular to the device axis, the second resonance element, by the device center point The center of the second resonance element is located at a position on the side of the second antenna at a separation distance, and the first resonance element is arranged around the device axis in a posture rotated by a predetermined angle larger than 0 °. Each of the first resonance element and the second resonance element is characterized in that the length from the center to each end is set to the resonance length, which is the length of resonance at the frequency.
The second antenna device for achieving the above object is a dipole antenna arranged along a device axis (Ax) which is a predetermined straight line for transmitting or receiving radio waves of a predetermined frequency. The first antenna (1), the second antenna (2), which is a dipole antenna different from the first antenna for transmitting or receiving radio waves and is arranged along the device axis, and the first antenna. The first antenna and the second antenna each include at least one resonance structure (3, 3A, 3B) arranged between the antenna and the second antenna, and the feeding points of the first antenna and the second antenna are spaced apart from each other on the device axis. Arranged so as to have (Lx), the resonance structure includes a first resonance element (31) and a second resonance element (32) which are linearly formed conductor members, and the first resonance element is A point located in the middle from one end to the other end is provided as the center of the first resonance element, and the second resonance element is provided with a point located in the middle from one end to the other end as the center of the second resonance element. , The first resonance element is on the device axis at a predetermined separation distance from the device center point (C), which is a point where the distances from the feeding points of the first antenna and the second antenna are equal to each other, on the first antenna side. The center of the first resonance element is located at the position and is arranged in a posture perpendicular to the device axis, and the second resonance element is located at a position on the second antenna side at a distance from the center point of the device. The center of the two resonance elements is located, and the first resonance element is arranged around the device axis in a posture rotated by a predetermined angle larger than 0 °, and both the first resonance element and the second resonance element are arranged. The length from the center to each end is set to the resonance length, which is the length of resonance at the frequency.

When radio waves are radiated from the first antenna in the above configuration, the electric field radiated from the first antenna also propagates in the direction in which the first resonance element, the second resonance element, and the second antenna are lined up. Here, since the length from the center to the end of the first resonant element having the above configuration is electrically set to a length corresponding to a half wavelength, the portion from the center to one end of the first resonant element (hereinafter). , The first first half), resonance is generated by the electric field propagating from the first antenna, and resonance is also generated in the part from the center to the other end (hereinafter, the first second half).

However, since the first second half is located on the opposite side of the device axis from the first first half, the phase of the current exciting to the first second half is 180 ° out of phase with the current exciting to the first first half. It becomes a thing. Therefore, the electric field radiated from the first first half and the electric field radiated from the first second half cancel each other out, and the first resonance element as a whole operates so as to cancel the electric field propagating from the first antenna. That is, the first resonance element functions as a member that prevents the electric field radiated from the first antenna from propagating to the second antenna.

Similarly, in the second resonance element, resonance occurs in the portion from the center to one end (hereinafter, the second first half portion). Further, in the portion from the center to the other end of the second resonance element (hereinafter, the second latter half portion), resonance occurs in which the current phase is inverted from that of the second first half portion. Therefore, the electric field radiated from the second first half and the electric field radiated from the second second half cancel each other out, and the second resonant element is also the electric field radiated from the first antenna like the first resonant element. It functions as a member that inhibits propagation.

Further, since the second resonance element is arranged in a posture in which the first resonance element is rotated by a predetermined angle in the top view, the electric field from the first antenna to the second antenna has a path of two non-overlapping members. It will be blocked. As a result, the isolation between the first antenna and the second antenna can be improved.

In the above, the effects of the above configuration have been described by taking the case where radio waves are radiated from the first antenna as an example. However, since the above configuration is configured to have symmetry around the center point of the device, the first When radio waves are radiated from two antennas, they work in the same way, and the same effect can be obtained.

Further, the third antenna device for achieving the above object is a linear conductor arranged along the device axis (Ax) which is a predetermined straight line for transmitting or receiving radio waves of a predetermined frequency. A first antenna (1) and a second antenna (2) which is a linear conductor arranged along the device axis at a predetermined distance from the first antenna for transmitting or receiving radio waves. , At least one resonance structure (3) arranged between the first antenna and the second antenna, and the resonance structure is a first resonance element (a first resonance element) which is a conductor member formed in a cross shape. 31) and the second resonance element (32) are provided, and the first resonance element has a predetermined separation distance from the device center point, which is a point on the device axis where the distances from each of the first antenna and the second antenna are equal. The center of the first resonance element is located at a point on the first antenna side and is arranged in a posture perpendicular to the device axis, and the second resonance element is separated from the center point of the device and is on the second antenna side. The center of the second resonance element is located at the point where the second resonance element is formed, and the second resonance element is arranged in a posture perpendicular to the device axis. Both the first resonance element and the second resonance element have a length from the center to each end. Is set to a resonance length, which is a length that resonates with a frequency.
Further, the fourth antenna device for achieving the above object is a dipole antenna arranged along the device axis (Ax) which is a predetermined straight line for transmitting or receiving radio waves of a predetermined frequency. The first antenna (1), the second antenna (2), which is a dipole antenna different from the first antenna for transmitting or receiving radio waves and is arranged along the device axis, and the first antenna. The first antenna and the second antenna each include at least one resonance structure (3, 3A, 3B) arranged between the antenna and the second antenna, and the feeding points of the first antenna and the second antenna are spaced apart from each other on the device axis. Arranged so as to have (Lx), the resonance structure includes a first resonance element (31) and a second resonance element (32) which are conductor members formed in a cross shape, and the first resonance element is On the device axis, the center of the first resonance element is located at a predetermined separation distance from the device center point, which is the point where the distances from the first antenna and the second antenna are equal, and on the side of the first antenna. In addition, the second resonance element is arranged in a posture orthogonal to the device axis, the center of the second resonance element is located at a point on the side of the second antenna at a distance from the center point of the device, and the device axis. Both the first resonance element and the second resonance element are arranged in a posture orthogonal to the antenna, and the length from the center to each end is set to the resonance length which is the length of resonance at the frequency. It is characterized by that.

Even when the first resonance element has a cross shape, the portion from the center to each end operates in the same manner as the first first half portion and the first second half portion described above, so that the first resonance element is the first antenna. It functions as a member that hinders the propagation of the electric field from the antenna to the second antenna. Further, the second resonance element also operates in the same manner as the first resonance element. Therefore, according to the third and fourth antenna devices , the same effect as that of the first and second antenna devices can be obtained.

The reference numerals in parentheses described in the claims indicate, as one embodiment, the correspondence with the specific means described in the embodiments described later, and limit the technical scope of the present invention. is not it.

It is a figure which showed the schematic structure of the antenna device 10 in an embodiment. It is a top view of the resonance structure 3. It is a figure which showed the operation of the upper element 31 when the radio wave is radiated from the 1st antenna 1. It represents the operation of the lower element 32 when the radio wave is radiated from the first antenna 1. It is a figure which shows the electric field distribution when the radio wave is radiated from the 1st antenna 1. It is a figure which shows the passing characteristic of an embodiment. It is a figure which shows the directivity in the horizontal plane of an embodiment. It is a figure which shows the directivity in the vertical plane of an embodiment. It is a figure which shows the electric field distribution in the 1st comparative structure. It is a figure which shows the result of having analyzed the passing characteristic of the 1st comparative structure. It is a figure which shows the schematic structure of the antenna device 10q as a 2nd comparative structure. It is a figure which shows the result of having analyzed the passing characteristic of the 2nd comparative structure. It is a figure which shows the structure of the hexastar parasite element 5 included in the 3rd comparative structure. It is a figure which shows the result of having analyzed the passing characteristic of the 3rd comparative structure. It is a figure which shows the structure of the octastard parasitic element 6 included in the 4th comparative structure. It is a figure which shows the result of having analyzed the passing characteristic of the 4th comparative structure. It is a figure which showed the schematic structure of the antenna device 10 of the modification 1. It is a figure which shows the structure of the 1st resonance structure 3A and the 2nd resonance structure 3B. It is a figure which shows the result of having analyzed the passing characteristic of the antenna device 10 of the modification 1. It is a figure which shows the schematic structure of the antenna device 10 of the modification 2. It is a figure which shows the positional relationship of the upper element 31, the lower element 32, and the linear parasitic element 7 in the modification 2. It is a figure which shows the result of having analyzed the passing characteristic in a certain setting of the modification 2. It is a figure which shows the result of having analyzed the passing characteristic in a certain setting of the modification 2. It is a figure which shows an example of the use state of the antenna device 10 of the modification 2. It is a figure which shows the positional relationship of the upper element 31, the lower element 32, and the linear parasitic element 7 in the modification 3. It is a figure which shows the result of having analyzed the passing characteristic of the antenna device 10 of the modification 3. It is a figure which shows the schematic structure of the antenna device 10 of the modification 4. It is a figure which shows the result of having analyzed the passing characteristic of the antenna device 10 of the modification 4. It is a figure which shows the schematic structure of the antenna device 10 of the modification 5. It is a figure which shows the result of having analyzed the passing characteristic of the antenna device 10 of the modification 5. It is a figure for demonstrating the structure of the modification 6.

[Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the antenna device 10 according to the present embodiment has a first antenna 1 for transmitting a radio wave having a predetermined frequency (hereinafter, a target radio wave) and a second antenna 2 for receiving the target radio wave. And a resonance structure 3 for improving the isolation between the first antenna 1 and the second antenna 2. Each member included in the antenna device 10 is held in a housing or the like by using a holding member (not shown).

The radio wave to be transmitted and received by the antenna device 10 (that is, the target radio wave) may be appropriately designed. Here, as an example, it is assumed that the target radio wave is set to a radio wave of 760 MHz used for vehicle-to-vehicle communication. Of course, the target radio wave may be appropriately designed, and as another embodiment, it may be a radio wave of, for example, 300 MHz, 900 MHz, 5.9 GHz, or the like. Further, the antenna device 10 may be configured to be able to transmit and receive radio waves in a predetermined range. Here, as an example, it is assumed that the antenna device 10 also transmits and receives radio waves in a predetermined range (for example, 755 to 765 MHz) determined with reference to the target frequency.

Hereinafter, the frequency to be transmitted / received (here, 760 MHz) will be referred to as a target frequency. Further, λ in the following term refers to the wavelength of the target radio wave. For example, 0.5λ refers to a half wavelength of the target radio wave, and 2λ refers to twice the wavelength of the target radio wave. Further, a frequency band to be transmitted / received (here, 755 to 765 MHz) determined based on the target frequency is described as the target frequency band.

The first antenna 1 and the second antenna 2 are realized as dipole antennas, respectively. That is, the first antenna 1 and the second antenna 2 are realized by using a linear conductor (hereinafter, a linear element) having a length electrically corresponding to 0.5λ. The electrical length here is an effective length in consideration of the fringed electric field, the wavelength shortening effect of the dielectric, and the like. If the wavelength of the target radio wave is shortened by a support member (not shown), the length may be half of the shortened wavelength.

The first antenna 1 is connected to a radio (not shown) via a coaxial cable, for example, and converts an electric signal input from the radio into radio waves and radiates it into space. Further, the second antenna 2 is also connected to a radio (not shown), and the signal received by the second antenna 2 is sequentially output to the radio. The radio device performs predetermined signal processing on the signal input from the second antenna 2 and supplies high-frequency power according to the transmission signal to the first antenna 1. The first antenna 1 and the second antenna 2 include a feeding point which is an electrical connection point with the coaxial cable. In addition to the coaxial cable, the first antenna 1 and the radio may be connected via a well-known matching circuit, filter circuit, or the like. The same applies to the second antenna 2.

The first antenna 1 and the second antenna 2 are arranged at predetermined intervals Lx in a posture along the straight line Ax. In other words, in the second antenna 2, the linear element of the second antenna 2 is arranged on the extension line of the linear element included in the first antenna 1. The straight line Ax corresponds to a line (that is, a center line) connecting the center of the first antenna 1 and the center of the second antenna 2, and represents the central axis of the antenna device 10.

Hereinafter, the straight line Ax will also be referred to as a device axis Ax. The alternate long and short dash line in FIG. 1 represents the device axis Ax. The point C shown in FIG. 1 represents a point on the device axis Ax where the distances between the first antenna 1 and the second antenna 2 are equal (hereinafter, the device center point). The plane that passes through the device center point C and is orthogonal to the device axis Ax is hereinafter referred to as a reference plane Pc.

The distance (hereinafter, antenna distance) Lx between the first antenna 1 and the second antenna 2 may be appropriately designed. Here, as an example, it is assumed that the antenna spacing Lx is set to 2λ. In general, the smaller the antenna spacing Lx, the more the isolation tends to deteriorate (in other words, the degree of interference becomes stronger).

Hereinafter, for convenience, the configuration of the antenna device 10 (particularly the resonance structure 3) will be described using a right-handed three-dimensional coordinate system having X, Y, and Z axes orthogonal to each other. The Z-axis is an axis parallel to the device axis Ax and whose positive direction is the direction from the second antenna 2 to the first antenna 1. The X-axis is an axis orthogonal to the Z-axis in an arbitrary direction, and the Y-axis is an axis orthogonal to each of the X-axis and the Z-axis. The X-axis may be, for example, an axis in a direction parallel to the upper element 31 described later. The origin of the three-dimensional coordinate system may be set, for example, at the device center point C. In the following description, the positions of each member will be described with the Z-axis positive direction as the upper side of the antenna device 10, but in the actual usage posture, the Z-axis positive direction is always oriented toward the zenith. You don't have to be. It may be used in a posture in which the positive direction of the Z axis faces downward, laterally, or the like.

The resonance structure 3 includes an upper element 31 and a lower element 32 which are linear conductor members having a predetermined length. The upper element 31 and the lower element 32 are formed in the same shape. The upper element 31 is located at a position where the center of the upper element 31 is on the first antenna 1 side by a predetermined separation distance α from the device center point C on the device axis Ax, and is arranged in a posture parallel to the X axis. Has been done. That is, the center of the upper element 31 is located on the device axis Ax, and the upper element 31 is arranged in a posture orthogonal to the device axis Ax. The center of the upper element 31 is a point located in the middle from one end to the other end of the upper element 31. The upper element 31 corresponds to the first resonant element according to the claim.

Further, the lower element 32 is located at a position where the center of the lower element 32 is on the second antenna 2 side by a predetermined separation distance α from the device center point C on the device axis Ax, and is parallel to the Y axis. It is arranged in a good posture. In such a configuration, the upper element 31 is rotated 90 ° clockwise with the device axis Ax as the rotation axis at a position on the second antenna 2 side by a predetermined separation distance α from the device center point C, and is on the lower side. It corresponds to the configuration in which the element 32 is arranged.

The center of the lower element 32 is a point located in the middle from one end to the other end of the lower element 32. Further, here, as an example, the rotation direction with the device axis Ax as the rotation axis is clockwise, but as another aspect, the rotation direction may be counterclockwise. The lower element 32 corresponds to the second resonant element according to claim. Hereinafter, when the upper element 31 and the lower element 32 are not distinguished, they are also described as a resonance element.

FIG. 2 is a diagram (so-called plan view) schematically showing the configuration of the resonance structure 3 as viewed from the positive direction of the Z axis. As described above, since the lower element 32 is arranged in a posture in which the upper element 31 is rotated by 90 ° around the device axis Ax, the resonance structure 3 forms a cross shape as a whole when viewed from the Z-axis direction. .. 31m shown in FIG. 2 represents a portion from the center to one end of the upper element 31 (hereinafter, the upper first half-long portion), and 31n is a portion from the center to the other end of the upper element 31 (hereinafter, the upper second half). Semi-long part). Further, 32m represents a portion from the center to one end of the lower element 32 (hereinafter, the lower first half-long portion), and 32n is a portion from the center to the other end of the lower element 32 (hereinafter, the lower side). It represents the second half (long part).

The total length (hereinafter, element length) La of the upper element 31 is set to a value twice the length that resonates at the target frequency (hereinafter, resonance length). As a result, the length from the center of the upper element 31 to each end becomes the resonance length. That is, the lengths of the upper first half-length portion 31m and the upper second half-length portion 31n are set to the resonance length.

The resonance length is basically a length that electrically corresponds to 0.5λ. By electrically setting the length from the center to the end of the upper element 31 to a length corresponding to 0.5λ, resonance can be generated in the section from the center to the end (hereinafter, half section). can. However, depending on the separation distance α, resonance may occur in a half section even if it is 0.65λ, 0.75λ, or 0.76λ. Therefore, the resonance length is a length corresponding to any of 0.5λ to 0.76λ. The element length La is a parameter that should be finely adjusted in combination with the separation distance α so that resonance occurs every half section at the target frequency.

In this embodiment, it is assumed that the separation distance α is set to 0.6λ and the element length La is set to 1.2λ as an example. That is, the lengths of the upper first half-length portion 31m and the upper second half-length portion 31n are set to 0.6λ, respectively. Such a configuration corresponds to a configuration in which 0.6λ is adopted as the resonance length.

Since the lower element 32 is formed in the same shape as the upper element 31, the total length of the lower element 32 coincides with the total length of the upper element 31. That is, the length of the lower element 32 is set to twice the resonance length as in the upper element 31, and the length from the center of the lower element 32 to each end is set to the resonance length. Has been done. As a result, the lengths of the lower first half-long portion 32m and the lower second half-long portion 32n become resonance lengths. According to such a configuration, the lower element 32 also resonates at the target frequency every half section.

FIG. 3 is a diagram showing the result of simulating the operation of the upper element 31 when the radio wave is radiated from the first antenna 1, and FIG. 4 is a diagram showing the lower element when the radio wave is radiated from the first antenna 1. It is a figure which shows the result of simulating the operation of 32. Since the element length La is set to twice the resonance length and the center is arranged in a posture that passes through the device axis Ax and is orthogonal to the device axis Ax, the upper element 31 has the upper first half length. The portion 31m and the upper second semi-long portion 31n operate point-symmetrically via the device axis Ax. Specifically, when radio waves are radiated from the first antenna 1, resonance occurs in each of the upper first half-length portion 31m and the upper second half-long portion 31n as shown in FIG. That is, two resonances occur in the upper element 31 so that the point through which the device axis Ax passes is a node.

However, since the upper second half length portion 31n is located on the opposite side of the device axis Ax from the upper first half length portion 31m, the phase of the current exciting to the upper second half length portion 31n is the upper first half length. It is 180 ° out of phase with the current that excites the portion 31m. Therefore, the electric field radiated from the upper first half-long portion 31m and the electric field radiated from the upper second half-long portion 31n cancel each other out.

As a result, the electric field radiated from the upper element 31 can be effectively suppressed by transmitting the signal from the first antenna 1. The electric field radiated from the upper element 31 by transmitting a signal from the first antenna 1 corresponds to an electric field re-radiated by the upper element 31 in response to the electric field radiated from the first antenna 1. That is, the upper element 31 plays a role of weakening the strength of the electric field propagating from the first antenna 1.

As for the lower element 32, the total length is set to twice the resonance length, the center passes through the device axis Ax, and the lower element 32 is arranged in a posture orthogonal to the device axis Ax, so that the lower first half The long portion 32m operates point-symmetrically with the lower second semi-long portion 32n via the device axis Ax. Specifically, when radio waves are radiated from the first antenna 1, the phases of the lower first semi-long portion 32 m and the lower second semi-long portion 32 n are shifted by 180 °, respectively, as shown in FIG. Resonance occurs.

Therefore, the electric field radiated from the lower first half-long portion 32m and the electric field radiated from the lower second half-long portion 32n cancel each other out. As a result, the electric field radiated from the lower element 32 can be effectively suppressed by transmitting the signal from the first antenna 1. That is, the lower element 32 also plays a role of weakening the strength of the electric field propagating from the first antenna 1 by the same principle as the upper element 31.

<Effect of embodiment>
FIG. 5 shows the result of simulating the electric field distribution when the target radio wave is radiated from the first antenna 1. As described above, by arranging the upper element 31 and the lower element 32 so that two resonances are generated at the point where the device axis Ax passes in each resonance element, an electric field (in other words, in other words) to the second antenna 2 is generated. Propagation of radio waves) can be suppressed. This is because the electric field is canceled by the current excited by the upper element 31 and the lower element 32.

FIG. 6 shows the passage characteristics when the separation distance α = 0.6λ and the element length La = 1.2λ are set. The passing characteristic here is a parameter representing the ratio of the magnitude of the received power of the second antenna 2 to the transmitted power (in other words, the degree of interference) when a radio wave of a predetermined power is radiated from the first antenna 1. Is. The smaller the passage characteristic, the lower the degree of interference, that is, the higher the isolation. As shown in FIG. 6, according to the configuration of the present embodiment, it is possible to achieve a passing characteristic of −80 to −90 dB in the vicinity of the target frequency of 760 MHz. In other words, it provides isolation close to 90 dB.

Further, as shown in FIGS. 7 and 8, while maintaining the omnidirectionality in the horizontal plane, the disturbance of the directivity in the vertical plane can be suppressed to the extent that it can be regarded as almost zero. The horizontal plane here is a plane orthogonal to the device axis Ax (in other words, an XY plane), and the vertical plane is a plane passing through the device axis Ax. In the present embodiment, by arranging the lower element 32 in a posture in which the upper element 31 is rotated by 90 °, the electric field from the first antenna 1 can be canceled in a well-balanced manner, and the isolation between the antennas can be enhanced.

In the above-described embodiment, the configuration in which the upper element 31 and the lower element 32 are arranged so that the angle formed by the upper element 31 and the lower element 32 is a right angle (including a substantially right angle) in the top view is disclosed. Not limited to this. The angle formed by the upper element 31 and the lower element 32 in the top view may be an angle other than 90 °, for example, 30 °, 60 °, 120 °, or the like.

However, as a result of various tests (in other words, as a result of trial and error), the inventors have set the angle formed by the upper element 31 and the lower element 32 at a right angle in the configuration of the above-described embodiment. It was found that the isolation at the target frequency is maximized. Therefore, in the configuration of the embodiment, it is preferable that the upper element 31 and the lower element 32 are arranged at right angles in the top view. The right angle here is not limited to a strict right angle (in other words, 90 ° / 270 °), and the range from 85 ° to 105 ° can be regarded as a right angle.

For reference, FIGS. 9 and 10 show the results of simulating the electric field distribution in the antenna device 10p not provided with the resonance structure 3 as the first comparative configuration, and the passing characteristics thereof. It is assumed that the positional relationship between the first antenna 1p and the second antenna 2p in the antenna device 10p is set in the same manner as in the antenna device 10 of the present embodiment.

As shown in FIG. 9, in the configuration in which the resonance structure 3 is not arranged between the antennas (that is, the first comparative configuration), the electric field radiated from the first antenna 1p reaches the second antenna 2p as it is. Therefore, the isolation in the first comparative configuration has a relatively low value. Specifically, as shown in FIG. 10, the isolation of the first comparative configuration in the vicinity of the target frequency of 760 MHz is about 43 dB.

On the other hand, according to the configuration of the present embodiment, isolation of nearly 90 dB can be secured as described above. That is, by introducing the resonance structure 3 including the upper element 31 and the lower element 32, the isolation can be improved by 40 dB or more as compared with the first comparative configuration.

By the way, as another comparison configuration (hereinafter, the second comparison configuration) assumed other than the first comparison configuration, as shown in FIG. 11, the length Lb from the center to the end is set to 0.6λ. It is also conceivable that the cross-shaped linear conductor member (hereinafter, cross-shaped parasitic element) 4 is arranged at the center point C of the device. However, as shown in FIG. 12, in the second comparative configuration, the isolation at the target frequency is 52 dB. Isolation is improved by about 9 dB as compared with the first comparative configuration, but it is not as good as this embodiment. According to the configuration of the present embodiment, the isolation can be increased by about 30 dB or more as compared with the second comparative configuration.

Further, as another comparative configuration (hereinafter referred to as the third comparative configuration), as shown in FIG. 13, six linear conductor elements having a predetermined length are connected so as to extend from the center of the regular hexagon to each vertex. It is also conceivable that the conductor member (hereinafter, hexagonal parasitic element) 5 is arranged at the center point C of the device. However, the isolation in the third comparative configuration is 67 dB as shown in FIG. 14, which is 10 dB or more lower than that of the present embodiment.

The length Lc from the center of the six-star parasitic element 5 to each end may be appropriately designed with reference to 0.5λ so as to increase the isolation as a whole. The simulation result shown in FIG. 14 is a value when Lc = 0.7λ is set. As a result of various tests, the inventors found that in the configuration in which the six-star parasitic element 5 is arranged instead of the resonance structure 3, the isolation at the target frequency is maximum when Lc = 0.7λ is set. I got the knowledge that it will be. That is, it can be said that the simulation result shown in FIG. 14 shows the maximum value of isolation that can be realized in the configuration in which the six-star parasitic element 5 is arranged instead of the resonance structure 3.

Further, as another comparative configuration (hereinafter referred to as the fourth comparative configuration), as shown in FIG. 15, eight linear conductor elements having a predetermined length are connected so as to extend from the center of the regular octagon to each vertex. It is also conceivable that the conductor member (hereinafter, octagonal parasitic element) 6 is arranged at the center point C of the device. However, the isolation in the fourth comparative configuration is 49 dB as shown in FIG. 16, which is 30 dB or more lower than that of the present embodiment.

The length Ld from the center of the eight-star parasitic element 6 to each end may be appropriately designed with reference to 0.5λ so as to increase the isolation as a whole. The simulation result shown in FIG. 16 is a value when the length Ld of the linear conductor element 51 is set to 0.7λ. As a result of various tests, the inventors have found that in the fourth comparative configuration, the isolation at the target frequency is maximized when Ld = 0.7λ is set. Therefore, it can be said that the simulation result shown in FIG. 16 shows the maximum value of isolation that can be realized in the configuration in which the eight-star parasitic element 6 is arranged instead of the resonance structure 3.

By the way, as can be seen by comparing the third comparative configuration and the fourth comparative configuration, isolation can be achieved by simply increasing the number of linear elements extending from the center as the configuration of the conductor member arranged at the device center point C. It does not increase. This is because the interaction between linear elements also affects the isolation. In addition, although not shown, a configuration in which a disk-shaped conductor element having a radius of 0.5λ to 0.75λ (hereinafter, a disk-type parasitic element) is arranged at the device center point C has also been examined. It was not possible to achieve such isolation. That is, higher isolation can be realized in a configuration in which two linear conductor elements are arranged in a twisted posture as in the present embodiment, as in a configuration in which one conductor element is arranged.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications described below are also included in the technical scope of the present invention, and other than the following. Can be implemented with various changes within the range that does not deviate from the gist. In addition, embodiments and various modifications can be combined as appropriate.

The members having the same functions as the members described in the above-described embodiment are designated by the same reference numerals, and the description thereof will be omitted. Further, when only a part of the configuration is referred to, the configuration of the embodiment described above can be applied to the other parts.

[Modification 1]
In the above, the configuration in which the antenna device 10 includes only one resonance structure 3 has been disclosed, but the present invention is not limited to this. The antenna device 10 may include a plurality of resonance structures 3. In that case, the separation distance of each resonance structure 3 is set to a different value, and it is assumed that the relatively large resonance structure 3 is arranged so as to sandwich the relatively small resonance structure 3.

Here, an example of a configuration in which the antenna device 10 includes two resonance structures 3 will be described with reference to FIGS. 17, 18, and the like. FIG. 17 is a perspective view showing a schematic configuration of the antenna device 10 in the first modification. The antenna device 10 in the first modification has a second resonance structure including a first resonance structure 3A including a first upper element 31A and a first lower element 32A, and a second upper element 31B and a second lower element 32B. It has a body 3B. The first upper element 31A and the second upper element 31B are members corresponding to the upper element 31 in the above-described embodiment, and the first lower element 32A and the second lower element 32B are the lower side in the above-described embodiment. It is a member corresponding to the element 32.

As shown in FIG. 18, the first resonance structure 3A is a resonance structure 3 in which the separation distance is set to an arbitrary value α, and the second resonance structure 3B is a resonance structure 3 in which the separation distance is an arbitrary value. It is a resonance structure 3 set to β. However, β is larger than α. Note that FIG. 18A is a diagram showing a schematic configuration when the first resonance structure 3A is viewed from the X-axis direction, and FIG. 18B is a diagram showing the second resonance structure 3B when viewed from the X-axis direction. It is a figure which shows the schematic structure at the time.

The second upper element 31B constituting the second resonance structure 3B is arranged above the first upper element 31A constituting the first resonance structure 3A. Further, the second lower element 32B constituting the second resonance structure 3B is arranged below the first lower element 32A constituting the first resonance structure 3A. That is, the second upper element 31B and the second lower element 32B constituting the second resonance structure 3B sandwich the first upper element 31A and the first lower element 32A constituting the first resonance structure 3A from above and below. It is arranged like this. The value obtained by subtracting the separation distance α from the separation distance β corresponds to the separation between the second upper element 31B and the first upper element 31A and the separation between the first lower element 32A and the second lower element 32B.

Specific values of the separation distances α and β may be appropriately designed. Here, as an example, it is assumed that the separation distance α = 0.02λ and the separation distance β is set to a value obtained by multiplying α by 3 (that is, 0.06λ). According to such settings of α and β, the second upper element 31B, the first upper element 31A, the first lower element 32A, and the second lower element 32B are 2α (= 0.04λ) in the Z-axis direction. The configurations are arranged at equal intervals.

The angle formed by the first upper element 31A and the first lower element 32A constituting the first resonance structure 3A in top view may be appropriately adjusted. Here, as an example, it is assumed that the first lower element 32A is arranged in a posture perpendicular to the first upper element 31A in the top view. Specifically, it is assumed that the first upper element 31A is arranged in a posture parallel to the Y axis, and the first lower element 32A is arranged in a posture parallel to the X axis.

Further, the angle formed by the second upper element 31B and the second lower element 32B constituting the second resonance structure 3B in the top view may be appropriately adjusted. Here, as an example, it is assumed that the second lower element 32B is arranged in a posture perpendicular to the second upper element 31B in the top view. Specifically, it is assumed that the second upper element 31B is arranged in a posture parallel to the X axis, and the first lower element 32A is arranged in a posture parallel to the Y axis. Such a configuration corresponds to a configuration in which two resonance structures 3 having different separation distances are arranged by rotating them by 90 ° around the device axis Ax.

Specific values of the element length La1 of the resonance element included in the first resonance structure 3A and the element length La2 of the resonance element included in the second resonance structure 3B may be appropriately adjusted with reference to λ. For example, the element length La1 of the first resonance structure 3A is set to 1.4λ, and the element length La2 of the second resonance structure 3B is set to 1.5λ. Such a configuration corresponds to a configuration in which half the length of the resonance element of the first resonance structure is set to 0.7λ and half the length of the resonance element of the second resonance structure is set to 0.75λ. That is, it corresponds to the configuration in which 0.7λ and 0.75λ are adopted as the resonance lengths.

FIG. 19 is a diagram showing a result of simulating the passing characteristics in the above configuration. As shown in FIG. 19, according to the configuration of the present modification 1, it is possible to provide isolation of −84 dB or more at the target frequency. The broken line in FIG. 19 shows the passing characteristics of the embodiment. As can be seen by comparing the broken line and the solid line, according to the configuration of the present modification 1, the isolation in the target frequency band of 755 to 765 MHz can be improved as compared with the configuration of the embodiment.

Further, according to the configuration of the present modification 1, sufficient isolation can be realized even if the separation distances α and β are set to relatively small values. That is, even if the separation distance β of the second resonance structure 3B is set to about 1/10 of the separation distance in the embodiment (specifically, 0.06λ), isolation equal to or higher than that in the embodiment is realized. can.

Further, since the first resonance structure 3A is arranged inside the second resonance structure 3B, the size of the entire resonance structure formed by combining the resonance structures 3A and 3B (specifically, the length in the Z-axis direction). Is defined by the second resonant structure 3B. Therefore, according to the configuration of the present modification 1, the size of the entire resonance structure formed by combining the resonance structures 3A and 3B can also be set to about 1/10 of the separation distance as compared with the embodiment. That is, the size of the resonance structure as a whole can be reduced. In the above, the separation distance α is set to 0.02λ, but the present invention is not limited to this. The separation distance α may be set to a value other than 0.02λ, for example, 0.06λ, 0.04λ, 0.01λ, or the like.

[Modification 2]
A linear parasitic element 7 which is a linear conductor member having a predetermined length may be arranged on a plane located between the upper element 31 and the lower element 32, that is, a reference surface Pc. Hereinafter, such a configuration will be described as a modification 2 with reference to FIG. 20 and the like.

The antenna device 10 in the second modification includes a linear parasitic element 7 in addition to the first antenna 1, the second antenna 2, the upper element 31, and the lower element 32. The length (that is, element length) La of the upper element 31 and the lower element 32 in this modification 2 is set to, for example, 1.5λ. Such a configuration corresponds to a configuration in which half the length of the resonant element is set to 0.75λ. That is, it corresponds to a configuration in which 0.75λ is adopted as the resonance length. Of course, the specific length of the element length La may be adjusted with reference to 0.5λ.

As shown in FIG. 21, the upper element 31 is arranged in a posture parallel to the X axis. The lower element 32 is arranged in a posture in which the upper element 31 is rotated by 120 ° around the device axis Ax. The separation distance α between each of the upper element 31 and the lower element 32 and the reference surface Pc is set to 0.04λ.

The length Le of the linear parasitic element 7 (hereinafter referred to as the parasitic element length) Le is set to twice the resonance length. Here, as an example, it is assumed that the parasitic element length Le is set to the same length as the upper element 31 and the lower element 32, that is, 1.5λ. As another configuration, the parasitic element length Le may be set to a value different from that of the upper element 31.

As a result of various tests, the inventors have found that the isolation is particularly enhanced when the parasitic element length Le is set to the same length as the upper element 31. Further, if the parasitic element length Le is set to the same length as the upper element 31, linear conductor members having the same dimensions can be used as the upper element 31, the lower element 32, and the linear parasitic element 7, resulting in a manufacturing cost. It can be suppressed. Therefore, it is preferable to set the parasitic element length Le to the same length as the upper element 31.

In the linear parasitic element 7, the center of the linear parasitic element 7 is located at the device center point C, is orthogonal to the device axis Ax, and the upper element 31 is rotated by 60 ° around the device axis in top view. Arranged in a posture. In such a configuration, the angle formed by the upper element 31 and the linear parasitic element 7 in the top view is equal to the angle formed by the lower element 32 and the linear parasitic element 7 in the top view. It corresponds to the configuration in which the element 7 is arranged.

FIG. 22 is a diagram showing a result of simulating the passing characteristics when the element length La and the parasitic element length Le are set to 1.5λ in the configuration of the modified example 2. As shown in FIG. 22, according to the configuration of the present modification 2, it is possible to provide isolation of 76 dB or more at the target frequency. The broken line in FIG. 22 shows the passing characteristics of the embodiment. As can be seen by comparing the broken line and the solid line, in the configuration of the embodiment, in the target frequency band of 755 to 765 MHz, the passing characteristics change sharply according to the frequency. The above isolation may not be obtained. Therefore, in actual manufacturing, high accuracy is required as the accuracy of the length and arrangement of each member.

On the other hand, in the configuration of the present modification 2, in the target frequency band of 755 to 765 MHz, the amount of change of the passing characteristic according to the frequency is gradual. Therefore, there is a relatively small risk that design isolation cannot be obtained due to misalignment of the members or the like. That is, according to the configuration in which the element length La and the parasitic element length Le are set to 1.5λ in the present modification 2, the difficulty of position accuracy and the like in the manufacturing process can be alleviated.

Further, according to the configuration of the present modification 2, by arranging the linear parasitic element 7, sufficient isolation can be realized even if the separation distance α is set to a relatively small value. Specifically, even if the separation distance α is set to about 1/30 of the separation distance in the embodiment, isolation of 76 dB or more can be realized. In other words, the height of the resonance structure 3 can be suppressed by arranging the linear parasitic element 7 between the upper element 31 and the lower element 32 forming the resonance structure 3.

Further, FIG. 23 shows the result of simulating the passing characteristics when the element length La is set to 1.4λ and the parasitic element length Le is set to 1.5λ in the configuration of the second modification. As shown in FIG. 23, according to the above settings, isolation of 85 dB or more can be secured in the target frequency band of 755 to 765 MHz. In addition, 100 dB of isolation can be realized at the target frequency. The broken line in FIG. 23 shows the passing characteristics of the embodiment.

As shown in FIG. 24, a part of the mounting jig 7a for fixing the antenna device 10 to the predetermined structure 8 may be used as the linear parasitic element 7. According to such a configuration, the number of parts can be reduced. The broken line in the figure represents an example of the schematic shape of the radome 9 of the antenna device 10.

[Modification 3]
In the second modification, as described with reference to FIG. 21, the configuration in which the upper element 31, the linear parasitic element 7, and the lower element 32 are arranged so as to be offset by 60 ° is disclosed. Not exclusively. As shown in FIG. 25, the upper element 31, the linear parasitic element 7, and the lower element 32 may be arranged so as to be offset by 45 °. In such a configuration, the upper element 31 and the lower element 32 are arranged at right angles in the upper view, and the angle between the linear parasitic element 7 and the upper element 31 and the lower element 32 is set between them. Corresponds to the configuration arranged so as to be equal.

As a result of simulating by changing the value of the separation distance α in the above setting, by setting α = 0.6, isolation of 72 to 80 dB can be realized in the target frequency band as shown in FIG. 26. As a result of simulating by changing the separation distance α to various values, it was found that the separation distance α needs to be set to about 0.6λ in order to realize isolation of 70 dB or more in the configuration of the modified example 3. Got Therefore, from the viewpoint of suppressing the height of the resonance structure 3 itself, it is preferable to arrange the upper element 31, the linear parasitic element 7, and the lower element 32 by shifting them by 60 °, as in the second modification.

[Modification example 4]
In the second modification, the configuration in which the linear parasitic element 7 is arranged at the center point C of the device is disclosed, but the present invention is not limited to this. As shown in FIG. 27, in a configuration in which the upper element 31 and the lower element 32 are arranged in a cross shape in a top view, the cross-shaped parasitic element 4 is arranged at the device center point C instead of the linear parasitic element 7. You may.

The cross-shaped parasitic element 4 is arranged in a posture facing each of the upper element 31 and the lower element 32 (in other words, a posture in which they overlap in a top view). The length Lb from the center to the end of the cross-shaped parasitic element 4 (hereinafter, the parasitic half length) Lb may be appropriately set according to the half length of the element length La, and here, as an example, Lb = La / 2 It is assumed that it is set to. The parasitic half-length Lb is a parameter that should be fine-tuned appropriately with reference to half of the element length La.

Even with such a configuration, relatively high isolation can be realized as shown in FIG. 28. That is, isolation of 83 dB or more can be realized in the target frequency band. Note that FIG. 28 is a diagram showing the results of simulating the passing characteristics when the separation distance α = 0.1λ and the element length La = 1.5λ are set.

By the way, as a result of various tests, the inventors have stated that when the parasitic half-length Lb is set to be slightly longer than half of the element length La (for example, about 0.02λ), the isolation can be further enhanced. I got the knowledge. Therefore, in the configuration of the modified example 4, it is preferable to set the parasitic half-length Lb to be slightly longer than half of the element length La.

[Modification 5]
In the above-described embodiment, the configuration in which the upper element 31 and the lower element 32 are formed in a straight line is disclosed, but the present invention is not limited to this. As shown in FIG. 29, the upper element 31 and the lower element 32 may be formed in a cross shape. Here, an embodiment of the antenna device 10 including the upper element 31 and the lower element 32 formed in a cross shape will be described as a modification 5.

In each of the upper element 31 and the lower element 32 of the modified example 5, the length from the center to each end is set to the resonance length. The length from one end to the opposite end corresponds to the above-mentioned element length La. The specific value of the element length La may be adjusted so that a desired isolation can be obtained with reference to 1λ, and here, it is set to 1.5λ as an example. Such a setting corresponds to a configuration in which the length from the center to the end (that is, La / 2) is set to 0.75λ. That is, it corresponds to a configuration in which 0.75λ is adopted as the resonance length.

The upper element 31 and the lower element 32 are arranged so as to face each other. The separation distance α may be adjusted as appropriate, and here, it is assumed that it is set to 0.04λ as an example. As a result, the separation between the upper element 31 and the lower element 32 becomes 0.08λ.

FIG. 30 is a diagram showing the result of simulating the passing characteristics of the present modification 5. As shown in FIG. 30, according to the configuration of the present modification 5, it is possible to provide isolation of 76 to 78 dB or more in the target frequency body. Further, according to the configuration of the present modification 5, sufficient isolation can be realized even if the separation distance α is set to a relatively small value (for example, a value of 0.1λ or less).

Here, as an example, a configuration in which the upper element 31 and the lower element 32 are arranged so as to face each other (in other words, to overlap each other in the top view) is disclosed, but the present invention is not limited to this. The lower element 32 may be arranged in a posture in which the upper element 31 is rotated by a predetermined angle (for example, 45 °) around the device axis Ax. Further, a plurality of resonance structures 3 in which the resonance elements are formed in a cross shape may be arranged as described in the first modification.

[Modification 6]
As shown in FIG. 31, the linear resonance element may be provided with a reactance element 39 (in other words, loaded) that provides a predetermined reactance at symmetrical positions with respect to the center. As the reactance element 39, a coil, a capacitor, a gap structure, a wiring pattern formed in a meander shape, or the like can be adopted. The distance from the center to the reactance element 39 and the reactance provided by the reactance element 39 may be appropriately designed. By loading the reactance element 39 at symmetrical positions with respect to the center in this way, the target wavelength can be electrically shortened, and each member can be further miniaturized.

Similarly, the reactance element 39 may be arranged (in other words, loaded) at a symmetrical position with respect to the cross-shaped resonance element. Similarly, the reactance elements 39 may be arranged (in other words, loaded) at symmetrical positions with respect to the center of the linear parasitic element 7, the cross-shaped parasitic element 4, and the like.

[Modification 7]
In the above, the configuration in which the first antenna 1 and the second antenna 2 are dipole antennas has been disclosed, but the present invention is not limited to this. For example, it may be a patch antenna or an inverted F type antenna. It is preferable that each antenna is arranged so as to have directivity in a direction orthogonal to the device axis Ax.

[Modification 8]
In the above, the mode in which the first antenna is used as the transmitting antenna and the second antenna is used as the receiving antenna has been disclosed, but the present invention is not limited to this. The first antenna may be a receiving antenna and the second antenna may be a transmitting antenna. Further, both the first antenna and the second antenna may be used as a transmitting antenna or a receiving antenna. The roles of the first antenna and the second antenna (transmission / reception) may be appropriately designed. Further, the role of transmission / reception may be dynamically changed by using a switch or the like.

10 Antenna device, 1 1st antenna, 2nd antenna, 3 Resonant structure, 3A 1st resonance structure, 3B 2nd resonance structure, 4 Cross-shaped parasitic element, 5 Six-star parasitic element, 6 Eight-star Parasitic element, 7 Linear parasitic element, 9 Redome, 31 Upper element (1st resonant element), 31A 1st upper element, 31B 2nd upper element, 32 Lower element (2nd resonant element), 32A 1st lower side Element, 32B second lower element, Ax device axis, C device center point, Pc reference plane, α / β separation distance

Claims (12)

A first antenna (1), which is a linear conductor arranged along a predetermined straight line device axis (Ax) for transmitting or receiving radio waves of a predetermined frequency, and
A second antenna (2), which is a linear conductor arranged along the device axis at a predetermined distance from the first antenna for transmitting or receiving the radio wave,
It comprises at least one resonant structure (3, 3A, 3B) disposed between the first antenna and the second antenna.
The resonance structure is
A first resonance element (31) and a second resonance element (32), which are linearly formed conductor members, are provided.
The first resonance element includes a point located in the middle from one end to the other end as the center of the first resonance element.
The second resonance element includes a point located in the middle from one end to the other end as the center of the second resonance element.
Said first resonance element, on the device axis, the first antenna and a predetermined distance than the distance a point is equal device center point from each of said second antenna, the position at which the first antenna side , The center of the first resonant element is located, and the first resonant element is arranged in a posture orthogonal to the device axis.
In the second resonance element, the center of the second resonance element is located at a position closer to the second antenna at a distance from the center point of the device, and the first resonance element is placed around the device axis. It is arranged in a posture rotated by a predetermined angle larger than 0 °.
The antenna device is characterized in that both the first resonance element and the second resonance element are set so that the length from the center to each end is set to the resonance length which is the length of resonance at the frequency. A first antenna (1), which is a dipole antenna arranged along a device axis (Ax) which is a predetermined straight line for transmitting or receiving radio waves of a predetermined frequency, and
A second antenna (2), which is a dipole antenna different from the first antenna for transmitting or receiving the radio wave and is arranged along the device axis,
It comprises at least one resonant structure (3, 3A, 3B) disposed between the first antenna and the second antenna.
The first antenna and the second antenna are arranged so that the feeding points have a predetermined interval (Lx) on the device axis.
The resonance structure is
A first resonance element (31) and a second resonance element (32), which are linearly formed conductor members, are provided.
The first resonance element includes a point located in the middle from one end to the other end as the center of the first resonance element.
The second resonance element includes a point located in the middle from one end to the other end as the center of the second resonance element.
It said first resonance element, on the device axis, the first antenna and the second in that the distance is equal from each of the feeding points is device center point of the antenna (C) a predetermined distance than the first the first antenna side and a position, and the center position of the first resonance element, and are disposed in a posture perpendicular to the device axis,
In the second resonance element, the center of the second resonance element is located at a position closer to the second antenna at a distance from the center point of the device, and the first resonance element is placed around the device axis. It is arranged in a posture rotated by a predetermined angle larger than 0 °.
The antenna device is characterized in that both the first resonance element and the second resonance element are set so that the length from the center to each end is set to the resonance length which is the length of resonance at the frequency. The antenna device according to claim 1 or 2.
Comprising a parasitic element is a conductor member of a linear or cross-shaped (4, 7),
The length from the center to each end of the parasitic element is formed as the resonance length.
The parasitic element is an antenna device in which the center of the parasitic element is located at the center point of the device and is arranged in a posture orthogonal to the device axis. The antenna device according to claim 3.
Wherein the first resonant element, said second resonance element, and both the parasitic element is a conductive member of straight linear, the overall length is set to 2 times the resonant length,
The parasitic element is arranged in a posture in which the first resonance element is rotated by 60 ° around the device axis.
The second resonance element is an antenna device characterized in that the first resonance element is arranged in a posture of being rotated by 120 ° around the device axis. The antenna device according to claim 3.
The first resonance element and the second resonance element are linear conductor members whose total length is set to twice the resonance length.
The parasitic element is a conductive member in the shape of a cross, and is formed in the resonant length Any length from each end from the center,
The second resonance element is arranged in a posture in which the first resonance element is rotated by 90 ° around the device axis.
The antenna device is characterized in that the parasitic element is arranged in a posture facing each of the first resonance element and the second resonance element. The antenna device according to any one of claims 3 to 5.
An antenna device characterized in that the parasitic element is loaded with a reactance element that provides a predetermined reactance at a position symmetrical with respect to the center. The antenna device according to claim 1 or 2.
As the resonance structure, a first resonance structure and a second resonance structure are provided.
The first resonance element and the second resonance element included in the second resonance structure are arranged so as to sandwich the first resonance structure.
The first resonance element included in the first resonance structure is arranged in a posture in which the first resonance element included in the second resonance structure is rotated by 90 ° around the device axis.
The second resonance element included in the first resonance structure is arranged in a posture in which the first resonance element included in the first resonance structure is rotated by 90 ° around the device axis.
The second resonance element included in the second resonance structure is characterized in that the first resonance element included in the second resonance structure is arranged in a posture of being rotated by 90 ° around the device axis. Antenna device. A first antenna (1), which is a linear conductor arranged along a device axis (Ax) which is a predetermined straight line for transmitting or receiving radio waves of a predetermined frequency, and
A second antenna (2), which is a linear conductor arranged along the device axis at a predetermined distance from the first antenna for transmitting or receiving the radio wave, and a second antenna (2).
A resonance structure (3) arranged between the first antenna and the second antenna is provided.
The resonance structure is
A first resonance element (31) and a second resonance element (32), which are conductor members formed in a cross shape, are provided.
The first resonance element is located on the device axis at a predetermined distance from the center point of the device, which is a point where the distances from the first antenna and the second antenna are equal to each other, on the side of the first antenna. The center of the first resonant element is located and is arranged in a posture orthogonal to the device axis.
The second resonance element is arranged so that the center of the second resonance element is located at a distance closer to the second antenna than the center point of the device and is orthogonal to the device axis. Orthogonal
Both the first resonance element and the second resonance element are antenna devices in which the length from the center to each end thereof is set to a resonance length which is a length that resonates at the frequency. .. A first antenna (1), which is a dipole antenna arranged along a device axis (Ax) which is a predetermined straight line for transmitting or receiving radio waves of a predetermined frequency, and
A second antenna (2), which is a dipole antenna different from the first antenna for transmitting or receiving the radio wave and is arranged along the device axis,
It comprises at least one resonant structure (3, 3A, 3B) disposed between the first antenna and the second antenna.
The first antenna and the second antenna are arranged so that the feeding points have a predetermined interval (Lx) on the device axis.
The resonance structure is
A first resonance element (31) and a second resonance element (32), which are conductor members formed in a cross shape, are provided.
The first resonance element is located on the device axis at a predetermined distance from the center point of the device, which is a point where the distances from the first antenna and the second antenna are equal to each other, on the side of the first antenna. The center of the first resonant element is located and is arranged in a posture orthogonal to the device axis.
The second resonance element is arranged so that the center of the second resonance element is located at a distance closer to the second antenna than the center point of the device and is orthogonal to the device axis. Orthogonal
Both the first resonance element and the second resonance element are antenna devices in which the length from the center to each end thereof is set to a resonance length which is a length that resonates at the frequency. .. The antenna device according to claim 8 or 9.
An antenna device characterized in that the first resonance element and the second resonance element are arranged in a posture facing each other. The antenna device according to any one of claims 1 to 10.
As the resonance length, the length from the center to each end of each of the first resonance element and the second resonance element is electrically any of 0.5 times to 0.76 times the wavelength of the radio wave. An antenna device characterized in that it is set to a length corresponding to the resonance. The antenna device according to any one of claims 1 to 11.
An antenna device characterized in that each of the first resonance element and the second resonance element is loaded with a reactance element (39) that provides a predetermined reactance at a position symmetrical with respect to the center.

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