JP6004173B2 - Antenna device - Google Patents

Description

  The present invention relates to an antenna device capable of flexibly adjusting directivity.

  In recent years, wireless communication devices have been used in various fields as well as mobile phones and notebook personal computers with built-in wireless communication functions, and there is a demand for thinning and miniaturization thereof. With such a demand, the formation area and arrangement of the mounted antenna device are limited, and it is often difficult to obtain directivity in a required direction.

  For this reason, a technique in which two antennas are provided on one substrate has been studied. For example, Patent Document 1 describes a diversity antenna device in which two chip antennas are arranged on a circuit board via a space. In this diversity antenna device, each chip antenna is a corner of the circuit board, and the length of the chip antenna with respect to the length (Ls) of the circuit board in the direction in which the first chip antenna and the second chip antenna face each other. The length (La) ratio (La / Ls) in the direction is set to 1/10 to 2/5, and the length h from the short side of the circuit board is set to be about 1/10 of Ls. I have to.

  Further, in Patent Document 2, when two antennas that make a pair are arranged on a substrate with a space therebetween, and an in-phase electric field is excited in each antenna, the center line in the longitudinal direction of the substrate is set as the in-phase-oriented substrate center line. A diversity antenna device is described in which when a reverse-phase electric field is excited, a center line in the short direction of the substrate is a substrate direction line in the opposite-phase directivity direction.

Japanese Patent No. 3997517 JP 2004-282136 A

However, the following problems remain in the above-described conventional technology.
That is, in Patent Document 1, it is necessary to control the resonance current to be excited in the circuit board by adjusting the length of the chip antenna and the length of the circuit board, and adjusting the antenna, the circuit board design, the board size, etc. There is no degree of freedom in each design, and it is difficult to flexibly adjust the desired directivity. In addition, since the longitudinal direction of each chip antenna is arranged perpendicular to the longitudinal direction of the module, the main directivity direction is limited to the direction (longitudinal direction of the substrate) in which the chip antenna is orthogonal, and the desired directivity. It is difficult to adjust the property flexibly.
Each chip antenna has a radiation electrode and a ground electrode that are excited at λ / 2 or λ / 4 with respect to the wavelength (λ) of the transmission / reception frequency, and the ground electrode is on one side in the longitudinal direction of the circuit board. Therefore, it is difficult to flow a resonance current for exciting the circuit board in a desired direction due to the influence of the antenna installation state, the circuit board, and the surrounding GND arrangement. It is difficult to flexibly adjust the desired directivity.
Furthermore, Patent Document 1 also describes an example in which two chip antennas installed near one side of the circuit board are installed in directions orthogonal to each other and parallel or orthogonal to the one side of the circuit board. However, since radiation from one chip antenna interferes with the other, the directivity is limited in the longitudinal direction of the circuit board in this case as well.
In Patent Document 2, the antenna performance, in particular, the directivity direction is affected by the board size and the board shape, so that the degree of freedom of design is limited and the antenna performance including the desired directivity is flexibly realized. It is difficult to do. Furthermore, a phase changer is required, and complicated, frequency adjustment, and impedance adjustment may be difficult due to the effect of the spacing between antennas and the area occupied by the antenna. It is difficult to realize a diversity effect flexibly.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an antenna device that can flexibly realize desired directivity and diversity effect.

  The present invention employs the following configuration in order to solve the above problems. That is, the antenna device according to the first aspect of the present invention includes an insulating substrate body, a ground surface patterned with a metal foil on the substrate body, and an area on which the ground surface is not formed on the substrate body. A pair of antenna occupying regions disposed on one end side of the substrate body across a part of the ground surface, and a pattern formed with metal foil in the pair of antenna occupying regions and disposed in the vicinity of the ground surface A pair of antenna elements each provided with a feeding point on the base end side, and the antenna element extends in a direction in which at least a part on the base end side is orthogonal to the edge of the ground plane near the feeding point. A passive element is connected in the middle of the base end side, and an antenna element of a dielectric antenna extending in a direction along the end of the ground plane is connected to the tip end side. An end of the ground plane arranged on the base end side of the antenna element extends in a different direction with respect to one and at least one is inclined with respect to the end of the substrate body. It is characterized by being.

  In this antenna device, the end of the ground plane arranged on the base end side of the pair of antenna elements extends in a direction different from the other, and at least one of the ends is on the end of the substrate body. Because it is inclined, the radiation of a pair of antenna elements does not interfere with each other, the radiation pattern between each antenna is inclined according to the angle of inclination, and the desired directivity can be obtained to achieve a flexible diversity effect It is.

An antenna device according to a second invention is the antenna device according to the first invention, wherein an end side of the ground plane arranged on a base end side of the pair of antenna elements is perpendicular to the end side of the substrate body. It is characterized by extending at 45 ° and −45 °.
That is, in this antenna device, the end sides of the ground plane arranged on the base end sides of the pair of antenna elements are inclined at 45 ° and −45 ° with respect to the direction orthogonal to the end sides of the substrate body. Since it extends, it is possible to complement the direction of weak sensitivity and polarization between the pair of antennas, and to obtain characteristics close to isotropic.

An antenna device according to a third aspect is characterized in that, in the first or second aspect, the antenna elements of the pair of antenna elements extend with their tips directed opposite to each other.
That is, in this antenna device, the antenna elements of the pair of antenna elements extend opposite to each other, i.e., outward with respect to each other. It is difficult to obtain good antenna characteristics.

According to a fourth aspect of the present invention, there is provided the antenna device according to the third aspect, wherein the antenna element is connected to the ground plane at one end connected in the middle of the base end and the other end separated from the feeding point. It has a connection extension part, a passive element for impedance adjustment is connected to the ground connection extension part, and the ground connection extension parts of the pair of antenna elements are arranged inward of each other. Features.
That is, in this antenna device, the passive element for impedance adjustment is connected to the ground connection extending portion, and the ground connection extending portions of the pair of antenna elements are arranged inward from each other. As a result, the impedance can be adjusted flexibly, and the ground connection extension portion does not interfere between the antenna element facing outward and the ground plane, and good antenna characteristics can be obtained. Further, a high-frequency current can be effectively passed from the antenna element to the ground plane disposed between the antennas.

An antenna device according to a fifth invention is the antenna device according to any one of the first to fourth inventions, wherein a distance between the antenna element and the ground plane is λ / 16 ( 1/16 wavelength) or less.
That is, in this antenna device, the distance between the antenna element and the ground plane is set to λ / 16 or less when the wavelength corresponding to the resonance frequency is λ, so that the antenna occupation area can be reduced in size and the antenna characteristics. It is possible to achieve both high performance and high performance.

The antenna device according to a sixth aspect of the present invention is the antenna device according to any one of the first to fifth aspects, wherein the distance between the pair of feeding points is λ / 4 (4 when the wavelength corresponding to the resonance frequency is λ. It is characterized in that it is set to be equal to or less than one wavelength.
That is, in this antenna device, since the distance between the pair of feeding points is set to λ / 4 or less when the wavelength corresponding to the resonance frequency is λ, the overall size of the substrate body and the antenna characteristics are reduced. It is possible to achieve both high performance and high performance.

The present invention has the following effects.
According to the antenna device of the present invention, the end of the ground plane arranged on the base end side of the pair of antenna elements extends in a different direction with respect to one and at least one of the ends of the substrate body Because it is tilted with respect to the edges, the radiation of a pair of antenna elements does not interfere with each other, and the radiation pattern between each antenna is tilted according to the tilted angle, resulting in the desired directivity and flexible diversity effect Is feasible.

It is a top view which shows one Embodiment of the antenna device which concerns on this invention. In this embodiment, it is the wiring diagram to which the principal part which shows an antenna device was expanded. In this embodiment, it is the perspective view (a) which shows an antenna element, a top view (b), a front view (c), and a bottom view (d). In this embodiment, it is explanatory drawing which shows the transition image of a radiation pattern. In this embodiment, it is the wiring diagram (a) which shows one antenna element, and the wiring diagram (b) which shows the antenna of the conventional reverse F type | mold pattern. In this embodiment, it is a graph which shows the relationship between the distance of an antenna element and a ground surface, and antenna gain. In the Example of the antenna apparatus which concerns on this invention, it is a graph which shows the VSWR characteristic of a pair of antenna element. In the Example of this invention, it is a graph which shows the radiation pattern of a pair of antenna element. It is a wiring diagram which shows one antenna element which shows other embodiment of the antenna device concerning this invention.

  Hereinafter, an embodiment of an antenna device according to the present invention will be described with reference to FIGS.

  As shown in FIGS. 1 and 2, the antenna device 1 according to the present embodiment includes a rectangular insulating substrate body 2, and a ground plane patterned on the substrate body 2 with a metal foil such as a copper foil. A pair of antenna occupying regions OP1 and OP2 disposed on one end 2a side of the substrate body 2 with a part of the ground surface GND sandwiched between the GND and the substrate body 2 as a region where the ground surface GND is not formed. And a pair of antenna elements 3A and 3B each provided with a feeding point FP on the base end side, which is patterned in the pair of antenna occupying regions OP1 and OP2 with a metal foil such as a copper foil and arranged near the ground plane GND. I have.

  The pair of antenna elements 3A and 3B has at least part of the base end side extending in a direction orthogonal to the end sides G1 and G2 of the ground plane GND near the feeding point FP, and 2 in the middle of the base end side. The first passive elements P1a and P1b are connected, and the antenna elements AT1 and AT2 of the dielectric antenna extending in the direction along the edges G1 and G2 of the ground surface GND are connected to the tip side. That is, the antenna elements AT1 and AT2 are arranged in parallel to the end sides G1 and G2 of the ground plane GND that face each other.

Further, the antenna elements AT1 and AT2 of the pair of antenna elements 3A and 3B extend with their tips directed to opposite sides.
Further, the end sides G1 and G2 of the ground plane GND arranged on the base end sides of the pair of antenna elements 3A and 3B extend in different directions with respect to one, and at least one of the substrate main body 2 It inclines with respect to the edge 2a. That is, at least one of the end sides G1 and G2 of the ground surface GND extends with respect to the end side 2a of the substrate body 2 at an angle of more than 0 ° and less than 90 ° in absolute value.

  In the present embodiment, the end sides G1 and G2 of the ground plane GND arranged on the base end side of the pair of antenna elements 3A and 3B are in a direction orthogonal to the end side 2a of the substrate body 2 as shown in FIG. In contrast, it extends at an angle of 45 ° and −45 °. That is, the end sides G1 and G2 of each ground plane GND extend obliquely with respect to the longitudinal direction of the substrate body 2, and the end sides G1 of the ground plane GND arranged on the base end side of the antenna element 3A and the substrate body. 2 is set to 45 °, and the angle θ between the end side G2 of the ground plane GND arranged on the base end side of the antenna element 3B and the longitudinal direction of the substrate body 2 is −45 °. Is set to The angles of the edges G1 and G2 of the ground plane GND are set to have the same absolute value as described above so as to complement each other in directions and polarizations with low sensitivity, but the desired diversity effect is obtained. Depending on the above conditions, the angles of the end sides G1, G2 of the ground plane GND may not be the same.

The antenna elements 3A and 3B have a ground connection extending portion 3a having one end connected in the middle of the base end side and the other end connected to the ground plane GND at a position separated from the feeding point FP. A second passive element P2 for adjusting impedance is connected to 3a.
Further, the ground connection extending portions 3a of the pair of antenna elements 3A and 3B are arranged inward from each other.

The substrate body 2 is a general printed circuit board, and in this embodiment, a printed circuit board body made of a rectangular glass epoxy resin or the like is employed.
The pair of antenna occupying regions OP1 and OP2 are provided in a pair of corners at both ends of the same edge 2a of the substrate body 2 in a shape in which the ground plane GND is cut out in a triangular shape. Further, the end sides G1 and G2 of the ground plane GND in contact with the antenna occupation regions OP1 and OP2 extend in directions orthogonal to each other.
Note that an RF circuit component mounting area can be provided on the ground plane GND, and a plurality of components can be mounted.

The antenna elements 3A and 3B extend from the feed point FP to one end of the antenna elements AT1 and AT2 in a direction perpendicular to the edges G1 and G2 of the ground plane GND. The antenna elements 3A and 3B have land portions 3b for mounting the other ends of the antenna elements AT1 and AT2.
For example, a core wire of a coaxial cable (not shown) connected to a high-frequency circuit is connected to the feed point FP, and the ground wire of the coaxial cable is connected to a nearby ground plane GND.

As the first passive elements P1a and P1b and the second passive element P2, for example, inductors, capacitors or resistors are employed. In the present embodiment, two first passive elements P1a and P1b are connected in series.
The antenna elements AT1 and AT2 are loading elements that do not self-resonate at a desired resonance frequency. For example, as shown in FIG. 3, a chip in which a conductor pattern 22 such as Ag is formed on the surface of a dielectric 21 such as ceramics. It is an antenna.

The distance a between the antenna elements AT1, AT2 and the ground plane GND is set to λ / 16 (1/16 wavelength) or less, where λ is a wavelength corresponding to the resonance frequency.
For example, as shown in FIG. 5 (b), when an inverted F-type antenna formed with a normal pattern antenna 13 is considered, it varies depending on the substrate size and surrounding design conditions, but as shown in FIG. The distance a between the pattern antenna 13 and the ground plane GND increases as the distance increases, and tends to be saturated at about λ / 4. In addition, since the length of the pattern antenna 13 at that time is as long as about λ / 4, it is difficult to easily achieve both miniaturization and high performance.

  On the other hand, in the case of the embodiment of the present invention, as shown in FIG. 5A, the ground plane GND does not overlap between the feeding point FP and the antenna elements AT1 and AT2, and the antenna element is not in between. 3A and 3B are provided and at least a part is arranged perpendicular to the edges G1 and G2 obtained by cutting the ground plane GND. Therefore, at least a portion not affected by the ground plane GND is present in the antenna elements 3A and 3B. By providing the first passive elements P1a and P1b at one location, the electrical length can be controlled and the resonance frequency can be adjusted flexibly.

Further, the antenna elements AT1 and AT2 are loading elements that do not self-resonate with respect to a desired resonance frequency, and the combination thereof can reduce the influence of the distance between the antenna elements AT1 and AT2 and the ground plane GND. It becomes possible.
Therefore, naturally, it is desirable that the distance a between the antenna elements AT1 and AT2 and the ground plane GND be separated, but as shown in FIG. 6, in the embodiment of the present invention, even if the distance a is λ / 16 or less, The reduction in antenna gain is small, and high performance can be realized. As a result, the antenna occupation areas OP1 and OP2 can be miniaturized, and at the same time, high performance can be realized.

  The distance between the pair of feed points FP is preferably set to λ / 4 (quarter wavelength) or less. That is, since the ground plane GND is interposed between the antenna occupation regions OP1 and OP2, there is little interference between the antennas, and high performance can be realized even if the distance between the feeding points is less than a quarter wavelength. Become.

  As described above, in the antenna device 1 according to the present embodiment, the end sides G1 and G2 of the ground plane GND arranged on the base end side of the pair of antenna elements 3A and 3B extend in a different direction with respect to one. Since at least one of the antenna elements 3A and 3B is inclined with respect to the edge 2a of the substrate body 2, the radiation of the pair of antenna elements 3A and 3B does not interfere with each other, and the radiation pattern between the antennas depends on the angle of inclination. Inclination and desired directivity can be obtained, and a flexible diversity effect can be realized.

Further, the end sides G1 and G2 of the ground plane GND arranged on the base end side of the pair of antenna elements 3A and 3B are 45 ° and −45 ° with respect to the direction orthogonal to the end side 2a of the substrate body 2. Since it is inclined and extended, it is possible to complement the direction of low sensitivity and polarization between the pair of antennas, and to obtain characteristics close to isotropic.
Further, since the antenna elements AT1 and AT2 of the pair of antenna elements 3A and 3B extend opposite to each other, that is, toward each other, with their tips directed toward the outside, compared to the case where the tips are arranged with the tips facing toward each other, It is difficult to interfere and good antenna characteristics can be obtained.

  Further, the second passive element P2 for impedance adjustment is connected to the ground connection extending portion 3a, and the ground connection extending portions 3a of the pair of antenna elements 3A and 3B are arranged inwardly, so that the first 2 The impedance can be adjusted flexibly by setting the passive element P2, and the ground connection extending portion 3a does not interfere between the antenna elements AT1 and AT2 facing outward and the ground plane GND, and is a good antenna. Characteristics are obtained. Further, a high-frequency current can be effectively passed from the antenna elements AT1 and AT2 to the ground plane GND disposed between the antennas.

In addition, since the distance a between the antenna elements AT1 and AT2 and the ground plane GND is set to 1/16 or less of the wavelength, both the miniaturization of the antenna occupying regions OP1 and OP2 and the high performance of the antenna characteristics are achieved. Is possible.
Furthermore, since the distance between the pair of feed points FP is set to be equal to or less than one-fourth of the wavelength, it is possible to achieve both reduction in the size of the entire substrate body 2 and improvement in antenna characteristics.

  Next, in the example produced based on the antenna device of the above embodiment, the results of measuring the VSWR characteristics and the radiation pattern will be described with reference to FIGS.

The antenna device of this embodiment has a substrate body size of 80 × 70 mm.
As each passive element, the first passive element P1a is an 8.7 nH inductor, and the first passive element P1b is a 35.0 nH inductor. The second passive element P2 is a 4.0 nH inductor.
The direction toward the antenna occupying region side in the longitudinal direction of the substrate body 2 is defined as the X direction, and the direction from the antenna occupying region OP1 toward the antenna occupying region OP2 along the edge 2a on the antenna occupying region side of the substrate body is defined as the X direction. The direction perpendicular to the surface of the substrate body 2 was taken as the Z direction. The power gain with respect to the XY plane at this time was measured.

As can be seen from the VSWR characteristic of one antenna element 3A shown in FIG. 7 (a) and the VSWR characteristic of the other antenna element 3B shown in FIG. 7 (b), both antennas achieve good antenna characteristics. doing.
The antenna element 3A had a center frequency of 914 MHz, a center frequency of VSWE of 1.04, and a bandwidth of VSWR = 3 or less: 41.5 MHz. The antenna element 3B had a center frequency of 914 MHz, a center frequency of VSWE of 1.05, and a bandwidth of VSWR = 3 or less: 41.2 MHz.
Further, as can be seen from the radiation characteristic of one antenna element 3A shown in FIG. 8A and the radiation characteristic of the other antenna element 3B shown in FIG. -It is possible to obtain a sensitivity that is close to isotropic by complementing the polarization, and it is possible to realize an effective characteristic for the diversity method.

  In addition, this invention is not limited to the said embodiment and said Example, A various change can be added in the range which does not deviate from the meaning of this invention.

For example, in the above-described embodiment, the antenna element extends from the feeding point in a direction perpendicular to the edge of the ground plane, but at least part of the antenna element may be arranged vertically. For example, as another example of the embodiment, as illustrated in FIG. 9, the antenna element 33 extends obliquely from the feeding point FP in a direction at an angle of 45 ° with respect to the edges G1 and G2 of the ground plane GND. A portion 33a and a vertically extending portion 33b extending in a direction perpendicular to the ends G1 and G2 of the ground surface GND may be used. As described above, at least a part of the antenna element 33 (vertical extending portion 33b) extends in the vertical direction from the end sides G1 and G2 of the ground plane GND, so that the ends G1 and G2 of the ground plane GND and the antenna are provided. A portion orthogonal to the element AT is generated, and it becomes possible to reduce the interference and increase the bandwidth and performance.
Moreover, in the said embodiment, although the same antenna element and the passive element of the same constant are employ | adopted in a pair of antenna element, you may employ | adopt mutually different antenna elements and passive elements depending on conditions.

  DESCRIPTION OF SYMBOLS 1 ... Antenna apparatus, 2 ... Board | substrate body, 2a ... Edge of board body, 3A, 3B, 33 ... Antenna element, 3a ... Ground connection extension part, AT1, AT2 ... Antenna element, FP ... Feeding point, GND ... Ground Plane, G1, G2... Edge of ground plane, P1a, P1b... First passive element, P2.

Claims (5)

An insulating substrate body;
A ground surface patterned with a metal foil on the substrate body;
A pair of antenna occupying regions disposed on one end side of the substrate body across a portion of the ground surface on the substrate body as an area where the ground surface is not formed;
A pair of antenna elements each provided with a feeding point on the base end side that is patterned with a metal foil in the pair of antenna occupying regions and is arranged in the vicinity of the ground plane;
In the antenna element, at least a part on the base end side extends in a direction orthogonal to the edge of the ground plane near the feeding point, and a passive element is connected to a portion extending in the orthogonal direction. And the antenna element of the dielectric antenna extending in the direction along the edge of the ground surface is connected to the tip side,
An end of the ground plane disposed on the base end side of the pair of antenna elements extends in a direction different from the other with respect to one, and at least one is inclined with respect to the end of the substrate body And
A pair of antenna occupying regions are provided at a pair of corners at both ends of the edge of the substrate body,
The antenna elements of the pair of antenna elements have tips directed toward opposite sides and extended toward the tip opposite to the end side of the substrate body, and the corners of the substrate body from the ground plane. Near
The antenna device, wherein the antenna element extends to the vicinity of the edge of the substrate body . The antenna device according to claim 1,
An end of the ground plane disposed on the base end side of the pair of antenna elements extends at an angle of 45 ° and −45 ° with respect to a direction orthogonal to the end of the substrate body. An antenna device comprising: In the antenna device according to claim 1 or 2,
The antenna element has a ground connection extending portion that is connected to the ground surface at one end connected in the middle of the base end side and the other end separated from the feeding point. Passive elements for impedance adjustment are connected,
The antenna device, wherein the ground connection extending portions of the pair of antenna elements are arranged inward of each other. In the antenna device according to any one of claims 1 to 3,
The antenna device, wherein a distance between the antenna element and the ground plane is set to λ / 16 (1/16 wavelength) or less, where λ is a wavelength corresponding to a resonance frequency. In the antenna device according to any one of claims 1 to 4,
The distance between a pair of said feed points is set to (lambda) / 4 (1/4 wavelength) or less, when the wavelength according to a resonant frequency is set to (lambda).