JP5527584B2 - Antenna device - Google Patents

Description

  The present invention relates to an antenna device having a pair of planar antenna elements.

  As an antenna device configured as described above, in Patent Document 1, a radiation plate (antenna element of the present invention) having the same size with a gap formed as a slot is arranged, and the gap is held. The one corresponding to a wide band is shown by forming a power feeding portion at an opposing position. In the antenna device of Patent Document 1, a plurality of shapes are shown as the radiation plate (antenna element of the present invention), but basically, the gap is smooth so that the radiation plates approach each other at the center. An arc shape is formed and the outer shape is rounded.

  As an antenna device configured as described above, Patent Document 2 discloses a first radiation plate (antenna element of the present invention) and a similar second radiation plate (antenna element of the present invention) having a different size. Are arranged with a gap in the same plane, and a power feeding part is formed at a position facing each other across the gap. In the antenna device disclosed in Patent Document 2, the use of radiation plates of different sizes increases the number of resonance points compared to those using radiation plates of the same shape, thereby realizing a wider band.

JP 2005-117363 A JP 2007-110893 A

  With the start of terrestrial digital broadcasting, an antenna device capable of receiving terrestrial digital broadcasting is required in all vehicles, and it is also considered that a vehicle is provided with an antenna device that can be used for a mobile phone. In vehicles, the necessity of inter-vehicle communication is increasing, and the present situation is that an antenna having uniform transmission / reception performance in the horizontal direction is desired.

  In addition, when feeding power to antenna elements of the same size, it is conceivable to perform balanced feeding using feeder wires. However, the antenna device provided in the vehicle is affected by noise generated from the electrical equipment of the vehicle. Cheap. For this reason, a coaxial cable that is not easily affected by noise is used. However, the coaxial cable is inevitably unbalanced and there is a demand for an antenna device that can handle unbalanced feeding.

  In order to realize unbalanced power feeding, it is effective to provide a balun transformer. However, in the case of providing a balun transformer, there is room for improvement in that the number of parts increases and the cost increases.

  In this regard, it is also conceivable to realize unbalanced feeding by using antenna elements of different sizes as in the antenna device described in Patent Document 2. However, when antenna elements having different sizes are used, the radiation characteristics in the horizontal direction tend to be unbalanced.

  An object of the present invention is to rationally configure an antenna device that has no bias in horizontal directivity and supports a wide band.

A feature of the present invention is that a pair of planar antenna elements are spaced apart with a gap portion on the same plane,
The gap portion is a parallel region having a constant interval from one end portion in the length direction of the gap portion, and an enlarged region in which the interval monotonously increases toward the other end portion in the length direction of the gap portion. Configured with
Among the pair of antenna elements, a feeding point is set at a position sandwiching the parallel region ,
Each of the pair of antenna elements has an opening crossing a line connecting the one end portion in the length direction of the gap portion and the farthest point that is the farthest position in the pair of antenna elements from the one end portion. The point is that the part is formed .

In the antenna device having this configuration, it has been experimentally confirmed that the VSWR value is reduced by setting the width in the parallel region of the gap part, and the band is enlarged by setting the enlarged region of the gap part large.
The aforementioned enlarged region has a shape similar to the double ridge portion in the double ridge horn antenna having a double ridge inside the horn. This antenna is a kind of waveguide, and the frequency characteristics of the waveguide itself are considered to be equal at frequencies exceeding the cut-off frequency. Therefore, it seems that the operation corresponding to the excitation of this waveguide is performed. It is. It has also been confirmed that unbalanced feeding can be realized by setting feeding points at positions sandwiching the parallel region. Note that “monotonically expanding” means that the gap portion at a position closer to the other end in the length direction than the reference position is wider than the gap portion at an arbitrary position in the length direction. Means that.
Thus, an antenna device corresponding to a wide band with no bias in the directivity in the horizontal direction was configured.

Further, according to this configuration, the antenna length based on a line connecting one end portion in the length direction of the gap portion and the farthest point can be changed. Therefore, it is possible to easily set the antenna length according to the frequency band intended to be used. Further, according to such setting of the antenna length, the size of the antenna element does not increase, and thus the antenna device can be realized in a compact manner.

In addition, a feature of the present invention is that a pair of planar antenna elements are spaced apart with a gap portion on the same plane,
The gap portion is a parallel region having a constant interval from one end portion in the length direction of the gap portion, and an enlarged region in which the interval monotonously increases toward the other end portion in the length direction of the gap portion. Configured with
Among the pair of antenna elements, a feeding point is set at a position sandwiching the parallel region,
Each of the pair of antenna elements is formed with an opening crossing a diagonal of the antenna element with respect to the one end in the length direction of the gap.

With such a configuration, similarly to the above-described configuration, it is possible to configure an antenna device corresponding to a wide band with no bias in directivity in the horizontal direction.

According to this configuration, the antenna length based on the diagonal length of the antenna element can be changed. Therefore, it is possible to easily set the antenna length according to the frequency band intended to be used. Further, according to such setting of the antenna length, the size of the antenna element does not increase, and thus the antenna device can be realized in a compact manner.

In the present invention, the feeding point may be set at a position of 1/6 of a dimension in the length direction of the gap portion with respect to the one end portion.

As a form of connecting a coaxial cable to a pair of antenna elements, an experiment was conducted in which the core wire of the coaxial cable was opposed to one side of the antenna element across the parallel region, and the mesh line of the coaxial cable was connected to the other. According to this, the position of 1/6 of the dimension in the length direction of the gap portion on the inner side from one end portion (end portion on the anti-enlargement region side) of the parallel region with reference to one end portion. In the situation where the VSWR value is the lowest and unbalanced power feeding is performed, good power feeding is realized. As described above, it is possible to obtain a good VSWR value even when unbalanced power feeding is performed.

In the present invention, the dimension in the length direction of the parallel region may be set to 40% or more of the dimension in the length direction of the gap portion.

In the gap portion, a parallel region and an enlarged region are formed in a series. When setting the ratio of the dimension of the length of the parallel region to the dimension in the length direction of the gap portion, When the dimension is a value exceeding 40% of the dimension in the length direction of the gap portion, it is easy to balance the unbalanced power supply. As a result, a good balance performance was obtained by setting the ratio of the dimension of the parallel region to the dimension of the gap portion.

The present invention forms the gap portion by removing the conductor at the center of the long side of the conductor made of a rectangular metal foil having a ratio of the long side to the short side of 2: 1 on the substrate. You may form a pair of said antenna element in the position which pinches | interposes a gap part.

According to this configuration, the antenna element can be configured only by removing a part of the conductor from the substrate on which the conductor made of a metal foil such as a copper foil is formed to form a gap portion. Also, by setting the ratio of the length between the long side and the short side of the conductor formed on the substrate to 2: 1, the pair of antenna elements becomes substantially square, for example, the antenna element is set to be rectangular In comparison, the area of the antenna element can be increased and used effectively without causing an increase in the size of one side. Thus, the antenna device was configured using the substrate on which the conductor was formed.

In the present invention, the parallel region may be formed in a parallel posture with respect to the short side.

According to this structure, the conductor which comprises an antenna element is shape | molded by the symmetrical shape on both sides of a parallel area | region.

In the present invention, the parallel region may be formed so as to be inclined at a predetermined angle with respect to the short side.

According to this configuration, the conductor constituting the antenna element is formed into an asymmetric shape across the parallel region.

In the present invention, the lower limit wavelength to be used may be λ, and the diagonal length of the rectangular conductor may be set to λ / 4.

According to this configuration, by setting the diagonal length of the antenna element to ¼ of the wavelength λ to be used, a high-performance antenna device can be configured using the resonance of the antenna element.

  In the present invention, the opening may be extended from an edge that forms the enlarged region of the antenna element.

  According to this configuration, the antenna length is set along the end side where the opening is not formed, so that the antenna length can be set longer. Therefore, use in a lower frequency band is possible as compared with the case where the opening is not extended from the edge forming the enlarged region of the antenna element. Moreover, even when a compact antenna element is used, the antenna length can be set long, so that the antenna device can be realized in a compact manner.

  In the present invention, the opening portion extends from the edge forming the enlarged region to the center side of each antenna element, and the gap portion is more than a line virtually extending the first portion. And a second portion bent toward the one end in the length direction.

  According to this configuration, the length from the one end portion in the length direction of the gap portion to the point where the first portion and the second portion are connected to each other, and the second portion from the connecting point to the second portion, The antenna length can be set by the length from one end portion to the farthest point in the length direction of the gap portion. Therefore, the antenna length can be set long even when a compact antenna element is used.

  In the present invention, the opening is formed in an L shape having the first portion parallel to the upper side or the lower side of the pair of antenna elements and the second portion bent from the first portion. Also good.

  According to this configuration, it is possible to easily set the antenna length to be long.

1 is an overall view showing an antenna device according to a first embodiment. It is the II-II sectional view taken on the line of FIG. It is an enlarged view which shows the shape of the antenna element of 1st Embodiment. It is a graph which shows the VSWR value of the antenna device of 1st Embodiment. It is a general view which shows the antenna apparatus of 2nd Embodiment. It is an enlarged view which shows the shape of the antenna element of 2nd Embodiment. It is a graph which shows the VSWR value of the antenna device of 2nd Embodiment. It is a general view which shows the antenna apparatus of 3rd Embodiment. It is an enlarged view which shows the shape of the antenna element of 3rd Embodiment. It is a graph which shows the VSWR value of the antenna device of 3rd Embodiment. It is a figure which shows the directivity in the 800 MHz band in the antenna device of 2nd Embodiment. It is a figure which shows the directivity in the 1500 MHz band in the antenna device of 2nd Embodiment. It is a figure which specifies the directivity of an antenna device. It is a general view which shows the antenna apparatus of 4th Embodiment. It is an enlarged view which shows the shape of the antenna element of 4th Embodiment. It is a figure used for description of antenna length in the antenna element of 4th Embodiment. It is a graph which shows the VSWR value of the antenna device of 4th Embodiment. It is a figure which shows the directivity in the antenna apparatus of 4th Embodiment. It is a figure which specifies the directivity of the antenna device of 4th Embodiment. It is a figure which shows the antenna apparatus of other embodiment. It is a figure which shows the antenna apparatus of other embodiment. It is a figure which shows the antenna apparatus of other embodiment. It is a figure which shows the antenna apparatus of other embodiment. It is a figure which shows the antenna apparatus of other embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
As shown in FIGS. 1 to 3, a pair of antenna elements A made of a metallic conductor 2 such as a copper foil is sandwiched with a gap G between one surface of an insulating substrate 1 such as glass epoxy. The feeding point P is formed on the pair of antenna elements A. Thus, a dipole antenna device is configured in which antenna elements A that are planar and symmetrical are arranged on the same plane.

  This antenna device has a wide bandwidth, is not biased in directivity in the horizontal direction (close to omnidirectionality), and is configured to be capable of unbalanced feeding. This antenna device covers most of 470-710 MHz terrestrial digital television broadcasts as a target frequency band, and also covers communication of 800 MHz band mobile phones, and has specific dimensional relationships and ratios. Is described below. Although this antenna device can be used in any posture, each part will be described with the upper side shown in FIG.

  In this antenna device, the conductor 2 made of a metal foil such as copper foil or aluminum foil is formed on the entire surface, and the ratio of the dimension H of the horizontally long side to the dimension V of the vertically long side is 2: 1. A substrate 1 having a thickness of 1.6 mm is used. The lower side of the long sides is referred to as the lower side B, and the upper side is referred to as the upper side T.

  By removing the conductor 2 of the substrate 1 by a process such as etching, the gap portion G having a vertically long posture is formed, and a pair of the antenna elements A are formed at positions sandwiching the gap portion G. In particular, in this antenna device, a substrate 1 having a long side dimension H of 200 mm and a short side dimension V of 100 mm is used.

  In this antenna device, it is assumed that a pair of antenna elements A having the same size are arranged in a symmetrical positional relationship, but even a pair of antenna elements A having a slight difference in performance Is not a big influence. The ratio of the long side, the short side, and the dimension of the conductor 2 need not be exactly 2: 1, and may include a slight difference.

  In this antenna device, the size of the substrate 1 may be smaller than the conductor. In this case, the outer end of the conductor 2 is overhanging from the substrate 1. In the antenna device of the present invention, a circuit is made of metal foil on the surface (back surface side) opposite to the surface on which the antenna element A of the substrate 1 is formed. You may form the circuit which comprises a transmission circuit etc.

  The gap portion G is formed along a straight reference line S that bisects the long side of the substrate 1 and is orthogonal to the long side. That is, the gap portion G is a parallel region Gp having a constant interval along the reference line S from the lower side B (one end portion in the length direction of the gap portion G) upward in the length direction of the gap portion G. Then, the upper side T (the other end in the length direction of the gap part G) in the length direction of the gap part G at a position continuous with the parallel region Gp is linearly and monotonously expanded (as it approaches the upper side T). And an enlarged region Ge. The parallel region Gp formed in this way is in a parallel posture with respect to the short side of the substrate 1.

  In the present invention, monotonously expanding means that the length direction is larger than the reference position in comparison with the gap portion G interval (interval in the horizontal direction in FIGS. 1 and 2) at an arbitrary position in the length direction. This means that the gap G is wide at a position close to the other end (upper side in FIGS. 1 and 2). The shape of the edge (end) 2e corresponding to the enlarged region Ge includes not only a straight line but also a curve such as a quadratic curve, a bent straight line, and a combination of a straight line and a curve.

  That is, of the conductors 2 constituting the pair of antenna elements A, the edge (end) 2p corresponding to the parallel region Gp is formed in a posture parallel to the reference line S from the lower side B upward. Further, the edge 2e corresponding to the enlarged region Ge is formed in an inclined posture that is separated from the reference line S toward the upper side.

  The slit width N of the parallel region Gp of the gap portion G is set to 1 mm, and this parallel region Gp extends from the lower side B (one end portion in the length direction of the gap portion G) to the length direction of the gap portion G. Set to 40 percent or more of dimensions. Specifically, it is formed from the lower side B to a position of 50 percent (50 mm from the lower side B), and the enlarged region Ge is formed in the remaining region. In the enlarged region Ge of the gap portion G, the opening width W is set to 20 mm at the portion of the upper side T.

  With such a configuration, the antenna element A is formed in a substantially square shape, and the diagonal length D is a value corresponding to λ / 4, where λ is the lower limit wavelength of the target band.

  Note that the slit width N of the parallel region Gp is not limited to 1 mm, and an ideal value is 2 mm or less, and it has been confirmed that a value exceeding 4 to 5 mm deteriorates the VSWR value. In addition, when the opening width W of the enlarged region Ge is less than 20 mm, it is confirmed that the band becomes too narrow, and that the band becomes wider when the opening width W exceeds 20 mm. That is, 20 mm is a lower limit value as the opening width W, and a value exceeding 20 mm is set according to the band.

  The feeding point P described above is set at a position separated by a distance C with reference to the lower side B (one end portion in the length direction of the gap portion G) in the parallel region Gp of the gap portion G. This distance C is about 1/6 of the dimension (full length) in the length direction of the gap portion G (specifically, a position 15 mm from the lower side B). As a result, the core wire 3A of the coaxial cable 3 is connected to one of the feeding points P, and the network line 3B of the coaxial cable 3 is connected to the other.

[VSWR characteristics]
FIG. 4 shows the VSWR characteristics of the antenna device shown in the first embodiment. In the graph of FIG. 4, the horizontal axis represents frequency and the vertical axis represents VSWR value. Further, the frequency and VSWR value at the measurement points M1 and M2 shown in FIG.

  From this figure, in the antenna device of the first embodiment, the frequency at the measurement point M1 is 532.38 MHz and the VSWR value is 1.98, the frequency at the measurement point M2 is 1846.77 MHz and the VSWR value is 1.97. It can be understood that the VSWR value in the frequency band from the measurement point M1 to the measurement point M2 is a good value less than 2.

[Second Embodiment]
In the second embodiment, the size, material, and structure of the substrate 1 are not fundamentally different from those of the first embodiment, and the shape of the gap portion G is different from that of the first embodiment. In the second embodiment, components having the same functions as those in the first embodiment are given the same numbers and symbols as those in the first embodiment.

  As shown in FIGS. 5 and 6, the gap portion G is formed along a linear reference line S that is inclined to the long side. The gap portion G has a parallel region Gp that is spaced upward along the reference line S from the lower side B (one end portion in the length direction of the gap portion G) upward in the length direction of the gap portion G, An enlarged region Ge that monotonously expands toward the upper side T (the other end portion in the length direction of the gap portion G) in the length direction of the gap portion G at a position continuous with the parallel region Gp is provided.

  The reference line S is set to a posture inclined by about 85 degrees with respect to the long side, and one of the edge 2e corresponding to the enlarged region Ge of the pair of antenna elements A is on the extension of the line of the parallel region Gp. To position. The opposing edge 2e is formed in an inclined posture that is bent linearly from the parallel region Gp and linearly separated from the reference line S, and separated from the reference line S toward the upper side T side. The parallel region Gp formed in this way is inclined with respect to the short side of the substrate 1. The angle at which the reference line S is inclined with respect to the long side is not limited to about 85 degrees, and an arbitrary angle can be set.

  The slit width N of the parallel region Gp of the gap portion G is set to 1 mm, and this parallel region Gp extends from the lower side B (one end portion in the length direction of the gap portion G) to the length direction of the gap portion G. Set to 40 percent or more of dimensions. Specifically, it is formed from the lower side B to the position of 50 percent in the direction along the reference line S (50 mm from the lower side B), and the enlarged region Ge is formed in the remaining region. In the enlarged region Ge of the gap portion G, the opening width W is set to 20 mm at the portion of the upper side T.

  In particular, the dimension Lt on the upper side T of the antenna element A is equal in the pair of antenna elements A, and the dimension Lb on the lower side B of the antenna element A is equal in the pair of antenna elements A. Also in this antenna element A, the diagonal length D is a value corresponding to λ / 4, where λ is the lower limit wavelength of the target band.

  Also in the second embodiment, the above-described feeding point P is along the reference line S with reference to the lower side B (one end in the length direction of the gap portion G) of the parallel region Gp of the gap portion G. It is set at a position separated by a distance C in the direction. This distance C is about 1/6 of the dimension (full length) in the length direction of the gap portion G (specifically, a position 15 mm from the lower side B). As a result, the core wire 3A of the coaxial cable 3 is connected to one of the feeding points P, and the network line 3B of the coaxial cable 3 is connected to the other.

[VSWR characteristics]
FIG. 7 shows the VSWR characteristics of the antenna device shown in the second embodiment. In the graph of FIG. 7, the horizontal axis represents frequency and the vertical axis represents VSWR value. Further, the frequency and VSWR value at the measurement points M1 and M2 shown in FIG.

  From this figure, in the antenna device of the second embodiment, the frequency at the measurement point M1 is 530.90 MHz and the VSWR value is 1.96, the frequency at the measurement point M2 is 1778.04 MHz and the VSWR value is 1.98. It can be understood that the VSWR value in the frequency band from the measurement point M1 to the measurement point M2 is a good value less than 2.

[Third Embodiment]
In the third embodiment, the size, material, and structure of the substrate 1 are not fundamentally different from those of the first embodiment, and the shape of the gap portion G is different from that of the first embodiment. In the third embodiment, those having the same functions as those in the first embodiment are given the same numbers and symbols as those in the first embodiment.

  As shown in FIGS. 8 and 9, the gap portion G is formed along a straight reference line S that bisects the long side of the substrate 1 and is orthogonal to the long side. That is, the gap portion G is a parallel region Gp having a constant interval along the reference line S from the lower side B (one end portion in the length direction of the gap portion G) upward in the length direction of the gap portion G. And an enlarged region Ge that monotonously expands in an arc shape toward the upper side T (the other end in the length direction of the gap portion G) in the length direction of the gap portion G at a position continuous with the parallel region Gp. Yes.

  Of the conductors 2 constituting the pair of antenna elements A, the edge 2p corresponding to the parallel region Gp is formed in a posture parallel to the reference line S from the lower side B upward. Further, the edge 2e corresponding to the enlarged region Ge is formed in an inclined posture that becomes an arc shape from the reference line S toward the upper side.

  The slit width N of the parallel region Gp of the gap portion G is set to 1 mm, and this parallel region Gp extends from the lower side B (one end portion in the length direction of the gap portion G) to the length direction of the gap portion G. Set to 40 percent or more of dimensions. Specifically, it is formed from the lower side B to a position of 50 percent (50 mm from the lower side B), and the enlarged region Ge is formed in the remaining region. In the enlarged region Ge of the gap part G, the opening width W is set to 60 mm at the site of the upper side T.

  With such a configuration, the antenna element A is formed in a substantially square shape, and the diagonal length D is a value corresponding to λ / 4, where λ is the lower limit wavelength of the target band.

  The feeding point P described above is set at a position separated by a distance C with reference to the lower side B (one end portion in the length direction of the gap portion G) in the parallel region Gp of the gap portion G. This distance C is about 1/6 of the dimension (full length) in the length direction of the gap portion G (specifically, a position 15 mm from the lower side B). As a result, the core wire 3A of the coaxial cable 3 is connected to one of the feeding points P, and the network line 3B of the coaxial cable 3 is connected to the other.

[VSWR characteristics]
FIG. 10 shows the VSWR characteristics of the antenna apparatus shown in the third embodiment. In the graph of FIG. 10, the horizontal axis represents frequency and the vertical axis represents VSWR value. Further, the frequency and VSWR value at the measurement points M1 and M2 shown in FIG.

  From this figure, in the antenna device of the third embodiment, the frequency at the measurement point M1 is 530.90 MHz and the VSWR value is 1.94, the frequency at the measurement point M2 is 1778.04 MHz and the VSWR value is 1.60. It can be understood that the VSWR value in the frequency band from the measurement point M1 to the measurement point M2 is a good value less than 2.

[Directivity]
In the antenna device of the present invention, the structure of the antenna element A is slightly different as shown in the first to third embodiments, but the basic configuration is common and the VSWR characteristics described above are also used. It can be understood that they are similar. 11 and 12 show the directivities of the 800 MHz band and the 1500 MHz band in the antenna apparatus of the second embodiment as a representative of the antenna apparatus of the present invention. The direction of directivity can be specified from the direction shown in FIG.

  As is apparent from the charts of FIGS. 11 and 12, in the case where the YZ plane is made to correspond to the horizontal plane, the shape of the pattern indicating the directivity of the antenna is slightly distorted, but the amount of distortion is the pattern. It can be understood that the overall shape is relatively small, and there is almost no deviation in directivity in the horizontal direction, and it corresponds to a wide band.

  As described above, the antenna device of the present invention has a pair of antennas with the gap portion G sandwiched between the substrates having conductors such as copper foil by a relatively simple structure in which some conductors are removed by a technique such as etching. Element A is created. In the antenna device of the present invention, by setting the positional relationship between the gap portion G and the feeding point P, unbalanced feeding using the coaxial cable 3 is realized without using a balun transformer, and the shape of the gap portion G With this setting, there is no bias in the directivity in the horizontal direction, and a wide bandwidth and a good VSWR value are realized.

  In particular, the antenna device of the present invention has little influence on the VSWR value even in an environment where conductors are close to each other, and can function well even when attached to the end of a bumper lean hose at the front end or rear end of an automobile. It has been confirmed experimentally.

[Fourth Embodiment]
The fourth embodiment is different from the first to third embodiments described above in that an opening SL is provided in each of the pair of antenna elements A. Further, the size, material, and structure of the substrate 1 may be configured in the same manner as in the first to third embodiments, but in this embodiment, as described below, the first embodiment to the third embodiment. A description will be given as an example of different cases. In addition, in this 4th Embodiment, the number and code | symbol which is common in 1st Embodiment is attached | subjected to what has the same function as 1st Embodiment.

  FIG. 14 shows an overall view of the antenna device according to the fourth embodiment. As in the first embodiment, this antenna device gaps a pair of antenna elements A made of a metal conductor 2 such as a copper foil with respect to one surface of an insulating substrate 1 such as a glass epoxy resin. Arranged across the part G. The pair of antenna elements A is provided with a feeding point P (see FIG. 15).

  As the substrate 1 according to the fourth embodiment, a substrate on which a conductor 2 made of a rectangular metal foil having a ratio of a long side to a short side of approximately 2: 1 can be used. Each antenna element A shown in FIG. 14 is formed by cutting a pair of end portions far from the gap portion G obliquely at a predetermined angle with respect to the upper side T among the end portions in contact with the upper side T. . In the following description, it is assumed that the long side dimension H is 32 mm and the short side dimension V is 15 mm. The substrate 1 has a long side dimension H1 of 33 mm and a short side dimension V1 of 20 mm so that at least such a conductor 2 can be provided on the substrate 1. In FIG. 14, four corners (four corners of the rectangle) of the substrate 1 are shown as being cut obliquely at a predetermined angle, but the present invention is not limited to this. Of course, it is also possible to use the substrate 1 formed in other shapes.

  FIG. 15 is a partially enlarged view of the antenna element A. As shown in FIG. 15, the gap part G is configured to have a parallel region Gp and an enlarged region Ge. The edge 2p of the antenna element A corresponding to the parallel region Gp is formed in parallel along the reference line S perpendicular to the lower side B. One end of the edge 2e of the antenna element A corresponding to the enlarged region Ge is connected to the edge 2p, and the distance between the pair of edges 2e increases as the other end approaches the upper side T in the length direction of the gap portion G. Formed. The slit width N of the parallel region Gp is set to 0.4 mm. The parallel region Gp is formed up to a position of 6 mm from the lower side B, and the enlarged region Ge is formed in the remaining region. In the enlarged region Ge of the gap portion G, the opening width W is set to 16 mm at the portion of the upper side T.

  The feeding point P is provided in the parallel region Gp of the gap part G in each antenna element A, and the dimension C with respect to the lower side B is set to 2.5 mm. As shown in FIG. 14, the core 3 </ b> A of the coaxial cable 3 is connected to one of the feeding points P, and the net 3 </ b> B of the coaxial cable 3 is connected to the other.

  An opening SL is formed in each of the pair of antenna elements A. The opening SL is formed so as to cross the diagonal line Q of the antenna element A with one end in the length direction of the gap G as a reference. The length direction of the gap part G is a direction parallel to the reference line S. Further, the one end portion in the length direction of the gap portion G is an end portion on the lower side B side of the gap portion G. That is, in the antenna element A, it is an end portion on the side close to the feeding point P. The diagonal line Q of the antenna element A connects the end on the antenna element A side near the feeding point P and the position farthest from the end near the feeding point P (farthest point). The line corresponds. Accordingly, the opening SL is formed so as to cross a line connecting one end portion in the length direction of the gap portion G and the farthest point that is the farthest position in the pair of antenna elements A from the one end portion. Will be. In FIG. 14, the diagonal line Q corresponds to a line indicated by a one-dot chain line. Here, the opening SL is formed in an open state by cutting the conductor 2 constituting the antenna element A with a predetermined width. Therefore, “crossing the diagonal line Q” means that the diagonal line Q and the opening SL formed by cutting the conductor 2 in an open state are at least crossed.

  Such an opening SL is formed to extend from the edge 2e that forms the enlarged region Ge of the antenna element A. In the example shown in FIG. 14, an example in which the opening SL extends from the enlarged region Ge is shown. In the example shown in FIG. 14, the position extending from the enlarged region Ge is a position having a height R1 from the lower side B, and is set to 10 mm. Further, the width SLW of the opening SL is formed with a constant width. FIG. 14 shows an example in which the width SLW of the opening SL is 0.4 mm. Therefore, the height R1 is defined by the height from the lower side B to the center of the width SLW of the opening SL.

  Further, the opening portion SL has a first portion SL1 extending from the edge 2e forming the enlarged region Ge to the center side of each antenna element A, and a gap portion G than a line virtually extending the first portion SL1. And a second portion SL2 bent toward one end in the length direction. The opening SL according to the present embodiment has an L shape having a first portion SL1 parallel to the upper side T or the lower side B of the pair of antenna elements A and a second portion SL2 bent from the first portion SL1. It is formed.

  The first portion SL1 is formed to extend from the edge 2e corresponding to the enlarged region Ge to the center side of the antenna element A. The first portion SL1 is formed over a predetermined length U in parallel along the lower side B. The length U is set to 22 mm with reference to the center in the width SLW of the opening SL. Since the first portion SL1 of the opening SL shown in FIG. 14 is formed in parallel to the lower side B, a line virtually extending the first portion SL1 is also a line parallel to the lower side B.

  The second portion SL2 is formed by being bent toward one end in the length direction of the gap G with respect to a line obtained by virtually extending the first portion SL1. In the example shown in FIG. 14, the second portion SL2 is formed by being bent from the first portion SL1 to the lower side B side. The second portion SL2 is set with a dimension R of 6.5 mm from the bent position. The opening SL is formed in an L shape including the first portion SL1 and the second portion SL2.

  An antenna device configured in such a shape is compatible with transmission and reception in two frequency bands. This will be described below. FIG. 16 shows one of the antenna elements A, and the substrate 1 and the coaxial cable 3 are omitted. As described above, the L-shaped opening SL is formed in the antenna element A according to the fourth embodiment. The antenna length is determined by the opening SL.

  When the antenna element A is formed as described above, the length x1 between the point 31 and the point 32 in FIG. 16 is 14.4 mm. Further, the length x2 between the point 32 and the point 33 is 6.3 mm, and the length x3 between the point 33 and the point 34 is 0.4 mm. Furthermore, the length x4 between the point 34 and the point 35 is 11.9 mm. Therefore, 33.0 mm, which is the sum of x1, x2, x3, and x4, is the antenna length when the opening SL is interposed. The frequency at which the antenna length is 1 / 4λ is about 2270 MHz.

  Further, the length y1 between the points 31 and 36 is 15.8 mm. The length y2 between the points 36 and 37 is 15 mm, and the length y3 between the points 37 and 38 is 8 mm. Furthermore, the length y4 between the point 38 and the point 39 is 11.9 mm, and the length y5 between the point 39 and the point 31 is 6 mm. Therefore, 56.7 mm, which is the sum of y1, y2, y3, y4, and y5, is the antenna length when not passing through the opening SL. Note that an opening SL is formed between the point 38 and the point 39, but in the case of high frequency, if the width SLW of the opening SL is about 0.4 mm, the opening SL is passed through the width SLW. Ignored because it is propagated.

  The frequency at which the antenna length is λ is about 5290 MHz. In calculating y2 and y3, the point 37 is set as a right-angled vertex for easy understanding. This is such that it can be ignored in calculating the antenna length. In this way, the two frequencies that can be handled, calculated from the antenna length according to the fourth embodiment, are about 2270 MHz and about 5290 MHz.

[VSWR characteristics]
FIG. 17 shows the VSWR characteristics of the antenna apparatus shown in the fourth embodiment. In the graph of FIG. 17, the horizontal axis represents frequency and the vertical axis represents VSWR value. From FIG. 16, it can be understood that the antenna device of the third embodiment has good values at 2400 MHz and 4500 MHz or higher. At 2400 MHz, the VSWR value is slightly higher than 2, but it is a level that does not cause a problem in practice (VSWR value is 3 or less). From this result, it is apparent that the antenna element A according to the fourth embodiment can cope with two frequency bands as described above.

[Directivity]
FIG. 18 shows the directivity at 2450 MHz and the directivity at 5200 MHz in the antenna device of the fourth embodiment. The direction of directivity is as shown in FIG.

  As is apparent from these charts with FIG. 18, in the case where the YZ plane is made to correspond to the horizontal plane, the shape of the pattern indicating the directivity of the antenna is slightly distorted, but the amount of distortion is determined from the overall pattern shape. Then, it can be understood that it is relatively small, and there is almost no deviation in directivity in the horizontal direction, and it corresponds to a wide band. For this reason, the antenna device shown in the fourth embodiment can be appropriately used in two frequency bands.

[Other Embodiments]
In the said embodiment, as FIG. 14 showed, it demonstrated that a pair of antenna element A was spaced apart by the same shape. However, the scope of application of the present invention is not limited to this. As shown in FIG. 20, each of the pair of antenna elements A can be formed in different shapes. That is, it is naturally possible to form the gap region G by offsetting the position of the parallel region Gp from the center toward one of the antenna elements A. In such a case, it is preferable to form the coaxial cable 3 along the large antenna element A side.

  In the embodiment described above, the opening SL is described as being formed in an L shape having the first portion SL1 and the second portion SL2. However, the scope of application of the present invention is not limited to this. For example, as shown in FIG. 21, it is naturally possible to form the gap portion G with an angle with respect to the length direction and to form only the linear shape from the enlarged region Ge. Further, as shown in FIG. 22, it is naturally possible to form the gap portion G only in a straight line shape along the length direction.

  In the said embodiment, it illustrated in figure so that one opening part SL might be formed in each of a pair of antenna element A. However, the scope of application of the present invention is not limited to this. For example, as shown in FIG. 23, it is naturally possible to form a plurality of openings SL in each of the pair of antenna elements A.

  In the embodiment described above, the opening SL is described as being formed in an L shape having the first portion SL1 and the second portion SL2. However, the scope of application of the present invention is not limited to this. Of course, it is also possible to form the opening SL in a curved shape.

  In the embodiment described above, the pair of antenna elements A are described as being spaced apart with the same shape. However, the scope of application of the present invention is not limited to this. As shown in FIG. 24, it is naturally possible to apply the antenna element A according to the present invention to a monopole antenna. That is, it is naturally possible to provide the ground plane 4 using one of the pair of antenna elements A as a radiating element.

  In the above-described embodiment, the opening SL has been described as extending from the edge 2e that forms the enlarged region Ge. However, the scope of application of the present invention is not limited to this. The opening SL may be formed by extending from the edge 2p that forms the parallel region Gp, or a position where the edge 2e that forms the enlarged region Ge and the edge 2p that forms the parallel region Gp intersect each other. (In other words, it may be formed extending from both the edge 2e forming the enlarged region Ge and the edge 2p forming the parallel region Gp).

  In the above embodiment, in the example in which the antenna element A is formed in a polygonal shape, the opening SL is described as being formed so as to cross the diagonal line Q of the antenna element A. However, the scope of application of the present invention is not limited to this. As described above, the opening SL crosses a line connecting one end in the length direction of the gap G and the farthest point that is the farthest position in the pair of antenna elements A from the one end. It is formed. Therefore, when part or all of the antenna element A is formed in a shape that does not have a corner (for example, an arc shape), the one end in the length direction of the gap G and the one It is possible to form the opening portion SL so as to cross a line connecting the farthest point from the end portion.

  INDUSTRIAL APPLICABILITY The present invention can be used for receiving terrestrial digital broadcasting and inter-vehicle communication in a vehicle such as an automobile. It can also be used in communication equipment used in a vehicle.

1: Substrate 2: Conductor A: Antenna element D: Diagonal length G: Gap part Gp: Parallel region Ge: Enlarged region P: Feeding point

Claims (11)

A pair of planar antenna elements are spaced apart across the gap on the same plane,
The gap portion is a parallel region having a constant interval from one end portion in the length direction of the gap portion, and an enlarged region in which the interval monotonously increases toward the other end portion in the length direction of the gap portion. Configured with
Among the pair of antenna elements, a feeding point is set at a position sandwiching the parallel region ,
Each of the pair of antenna elements has an opening crossing a line connecting the one end portion in the length direction of the gap portion and the farthest point that is the farthest position in the pair of antenna elements from the one end portion. Antenna device in which the part is formed . A pair of planar antenna elements are spaced apart across the gap on the same plane,
The gap portion is a parallel region having a constant interval from one end portion in the length direction of the gap portion, and an enlarged region in which the interval monotonously increases toward the other end portion in the length direction of the gap portion. Configured with
Among the pair of antenna elements, a feeding point is set at a position sandwiching the parallel region,
The pair of the respective antenna elements, the antenna device in which the opening is formed across the diagonal of the antenna element relative to the said one end portion in the longitudinal direction of the gap portion. 3. The antenna device according to claim 1, wherein the feeding point is set at a position of 1/6 of a dimension in the length direction of the gap portion with respect to the one end portion. 4. The antenna device according to claim 1, wherein a dimension in a length direction of the parallel region is set to 40% or more of a dimension in a length direction of the gap portion. 5. The gap portion is formed by removing the conductor at the center of the long side of the conductor made of a rectangular metal foil having a ratio of the long side to the short side of 2: 1 on the substrate, and sandwiching the gap portion. The antenna device according to any one of claims 1 to 4 , wherein the antenna device has a structure in which a pair of antenna elements is formed at a position. The antenna device according to claim 5 , wherein the parallel region is formed in a parallel posture with respect to the short side. The antenna device according to claim 5 , wherein the parallel region is formed so as to be inclined at a predetermined angle with respect to the short side. The antenna device according to any one of claims 5 to 7 , wherein a diagonal length of the rectangular conductor is set to λ / 4, where λ is a lower limit wavelength to be used. The antenna device according to any one of claims 1 to 8, wherein the opening is extended from an edge that forms the enlarged region of the antenna element. The opening portion extends from the edge forming the enlarged region to the center side of each antenna element, and the length direction of the gap portion from a line virtually extending the first portion The antenna device according to claim 9 , further comprising: a second portion bent toward the one end portion side. The opening, and a first portion parallel to the upper side or lower side of the pair of antenna elements, to claim 10 which is formed in L-shape and a second portion bent from said first portion The antenna device described.

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