JP5995059B2 - Antenna device - Google Patents

Description

  The present invention relates to a dual-band antenna device using a dielectric antenna.

  2. Description of the Related Art Conventionally, in a communication device, one of antenna elements mounted on a wireless circuit board is a surface mount antenna using a dielectric, so-called dielectric antenna. In this dielectric antenna, a radiation electrode for performing an antenna operation is provided on a dielectric substrate. Conventionally, an open antenna type such as a monopole antenna or an inverted F antenna using the dielectric antenna has been mainly used.

  Usually, in the case of an open type antenna such as a monopole type or an inverted F type, since the impedance of the open end is high, it is necessary to secure the distance between the mounted antenna element and the ground as long as possible. Therefore, in order to sufficiently secure the antenna performance, it is necessary to remove the ground around the mounted antenna element and separate the antenna element from the ground plane on the substrate on which the ground plane is formed. However, in fact, when a dielectric antenna is mounted on a substrate as an antenna element, the space that can be used as an antenna (antenna occupying area) is often limited in consideration of downsizing of the device, and the influence of the ground around the antenna element As a result, the antenna performance cannot be fully exhibited. Therefore, in order to reduce the influence of the ground as much as possible, the position where the antenna element is mounted is often mounted on the edge of the substrate or the like.

  For this reason, conventionally, for example, in Patent Document 1, a capacitive power supply type radiation electrode that performs an antenna operation is provided on a base body, and the base body is mounted in a non-ground region of the circuit board. An antenna structure has been proposed in which a grounding line for electrically connecting the radiation electrode is provided. The grounding line of this antenna structure has a shape having a folded portion. Patent Document 2 includes a surface-mount antenna in which a radiation electrode for performing antenna operation is formed on a base, a ground region in which a ground electrode is formed, and a non-ground region in which no ground electrode is formed. There is described an antenna structure having a substrate and one end side of the radiation electrode being a ground connection portion grounded to the ground electrode.

International Publication No. WO2006 / 120762 International Publication No. WO2008 / 035526

However, the following problems remain in the above-described conventional technology.
In the technique described in Patent Document 1, since the antenna performance largely depends on the folded portion of the grounding line, there is a problem that the antenna performance is deteriorated and unstable elements are increased depending on the state of the folded portion. That is, since it is necessary to secure the length of the folded portion and increase the antenna occupation area, sufficient antenna performance cannot be obtained when the antenna occupation area is limited.

In the technique described in Patent Document 2, since the antenna element itself has no feed point and the radiation electrode is directly connected to the ground, the antenna performance is in the state of the ground plane. There is an inconvenience that it is difficult to improve the antenna performance. In addition, in order to adjust the resonance frequency, a configuration in which it is connected to the ground via an inductor and a capacitor is described, but it becomes difficult to suppress the flow of high-frequency current spreading to the ground, which also increases the antenna occupation area. There is a need to. In addition, since the stray capacitance with the ground is suppressed, it depends on the radiation of the antenna element, is affected by the state around the antenna element, and it is difficult to improve the antenna performance.
Thus, conventionally, in order to improve the antenna performance, measures to increase the antenna occupation area including the antenna elements and peripheral elements are necessary, the degree of design freedom is small, and it is difficult to improve the antenna performance. there were.

  Furthermore, in recent years, it has been required to mount a dual-band antenna that operates independently at two different frequencies in a communication device, and this dual-band antenna is also required to have a small antenna occupation area. However, since the dual-band antenna requires an antenna element that operates independently at each frequency, the area occupied by the antenna tends to increase. Further, since the antenna performance depends on the distance between the antenna portion and the ground plane, a certain distance is required to obtain the antenna performance. For this reason, a dual-band antenna with a relatively large number of antenna elements requires a wider antenna occupation area than a single-band antenna. As described above, communication devices are becoming more and more compact, electronic components are mounted at higher density, and the area allocated to the antenna is limited. Therefore, further space saving of the antenna occupation area is required. ing.

  Conventionally, when an antenna is miniaturized, the impedance of the antenna changes. Therefore, the impedance is usually adjusted by providing a passive element near the base of the antenna. However, in the case of a dual band antenna, the passive element for impedance adjustment is common to two frequencies, and it is difficult to individually adjust the impedance. In this case, since the impedance also changes depending on the surrounding environment of the antenna, there is an inconvenience that it is difficult to adjust when the impedance is individually shifted at two frequencies.

  For example, as shown in FIG. 17, a ground plane G and an antenna occupation area AOA in which the ground plane G is not formed are provided on the substrate body 2, and the antenna occupation area AOA is arranged in the vicinity of the ground plane G. A dual element in which a feeding point FP is provided on the base end side, and an element E102 extending toward one side of the substrate body 2 and a pair of elements E103 extending from the tip end of the element E102 to both sides are patterned with a metal foil. A band antenna will be described as an example. In this dual-band antenna, it is possible to radiate at two frequencies by adding a pair of elements E103, but there is a disadvantage that the area occupied by the antenna increases. Further, since the pair of elements E103 are connected to the passive element P0 for impedance adjustment through one element E102 and a ground connection part E101 that connects the element E102 and the ground plane G, individual impedances of each frequency are separated. Is difficult to adjust, and it is difficult to obtain an optimal antenna state.

  The present invention has been made in view of the above-described problems, and provides an antenna device that can save space by maximizing the use of an antenna occupation area in a dual-band antenna and can ensure sufficient antenna performance. For the purpose.

  The present invention employs the following configuration in order to solve the above problems. That is, an antenna device according to a 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. An antenna occupying region provided in contact with one side of the substrate body, an antenna element patterned with a metal foil in the antenna occupying region, and an antenna of a dielectric antenna connected to the antenna element and mounted on the substrate body The antenna element has a central pattern, a pair of lands, a pair of ground connection patterns, and a pair of loop patterns, and the central pattern is disposed in the vicinity of the ground plane. A feeding point is provided on the base end side and extends toward one side of the substrate body, and the antenna element includes a dielectric base and the dielectric base. A pair of both-end electrode portions formed at both ends of the substrate, and an intermediate electrode portion formed at an intermediate portion of the dielectric substrate and connected to a tip end portion of the central pattern. Each of which has a capacitive component, and the pair of land portions are arranged on both sides of the front end portion of the central pattern so that the pair of both end electrode portions are connected, and the pair of ground connection patterns are paired with the pair of the above-mentioned The land portion and the ground plane adjacent to the land portion are connected to each other through a first passive element to have an inductance component, and a pair of loop patterns are connected at the tips to the pair of ground connection patterns. And the other end is connected in the middle of the central pattern, and a second passive element is connected in the middle.

  In this antenna device, a pair of loop patterns are connected to the pair of ground connection patterns at the tip and the other end is connected in the middle of the center pattern, and the second passive element is connected in the middle. By individually setting the pair of second passive elements, the impedance can be individually adjusted for two high-frequency currents having different frequencies flowing through the pair of loop patterns. That is, in a pair of loop paths on both sides of the center pattern formed by a pair of loop patterns, a center pattern, an antenna element, and a pair of land portions, high-frequency current flows in a loop shape. Therefore, by individually setting the pair of first passive elements, the two frequencies can be individually adjusted, and by separately setting the second passive element connected to each loop pattern, It becomes possible to individually adjust the impedance with respect to the frequency.

Further, in this antenna device, the current distribution is concentrated in the antenna occupation area, and the flow of the high-frequency current to the ground plane can be suppressed. That is, it is possible to reduce the influence of peripheral components and the like during mounting.
That is, in this antenna device, a pair of parallel resonance obtained by a stray capacitance due to an inductance component by a pair of ground connection patterns and a gap between a land portion to which the electrode portions on both ends of the antenna element are connected and a ground plane, Resonance is caused by the loop shape from the antenna element to the antenna element through the inner edge of the loop pattern and the edge of the center pattern.
Accordingly, a pair of parallel resonances due to the resonance of the loop shape with a shortened opening surface by the antenna element and the passive element, and the stray capacitance between the land part to which the pair of both end electrode parts are connected and the loop pattern and the ground surface. Resonance suppresses the flow of high-frequency current spreading to the ground plane, and high antenna performance can be obtained by utilizing the limited antenna occupation area to the maximum.
Further, in the antenna element, the pair of both end electrode portions on both end sides operate as radiation electrodes, and there is no directionality and effective radiation power can be realized.

The antenna device according to a second aspect of the present invention is the antenna device according to the first aspect, wherein a third passive element is connected in the middle of the central pattern and closer to a tip side than a connection portion with the pair of loop patterns. It is characterized by being.
That is, in this antenna device, the third passive element is connected in the middle of the center pattern and further to the tip side than the connection portion with the pair of loop patterns. In both cases, frequency adjustment and impedance adjustment can be performed.

An antenna device according to a third invention is the antenna device according to any one of the first and second inventions, wherein the antenna element is installed in the vicinity of one side of the substrate body, and the ground connection pattern is provided on one side of the substrate body. It is characterized by being formed in contact.
That is, in this antenna device, the antenna element is installed in the vicinity of one side of the board body, and the ground connection pattern is formed in contact with one side of the board body. Therefore, the antenna element and the ground connection pattern are arranged on the edge of the board. By doing so, the performance of the antenna element can be maximized and utilized. In particular, a pair of ground connection patterns, which are ground lines, are in contact with one side of the substrate body to be linear, thereby reducing the influence of the ground lines and unstable elements and realizing low loss.

The antenna device according to a fourth invention is the antenna device according to any one of the first to third inventions, wherein the antenna element is formed on at least one of the surface and the inside of the dielectric substrate and is spaced apart from each other and corresponding And a pair of both end conductor patterns connected to the intermediate electrode portion and an intermediate conductor pattern connected to the intermediate electrode portion.
That is, in this antenna device, the antenna element is formed on at least one of the surface and the inside of the dielectric substrate, and is separated from each other and connected to the corresponding both-end electrode portion and the intermediate electrode portion connected to the intermediate electrode portion. Since the conductor pattern is provided, a composite capacitance component can be formed between the two-end conductor pattern and the intermediate conductor pattern according to the shape and arrangement of the two-end conductor pattern and the intermediate conductor pattern.

An antenna device according to a fifth invention is the antenna device according to the fourth invention, wherein the antenna element is formed on at least one of a surface and an inside of the dielectric substrate, and between the both end conductor pattern and the intermediate conductor pattern. The present invention is characterized in that floating conductor patterns arranged apart from each other are provided.
That is, in this antenna device, the antenna element includes a floating conductor pattern formed on at least one of the surface and the inside of the dielectric substrate and disposed between the both-end conductor pattern and the intermediate conductor pattern so as to be separated from them. Therefore, a composite capacitive coupling or impedance component can be generated between the both-end conductor pattern and the intermediate conductor pattern by the floating conductor pattern. As a result, the frequency and impedance can be adjusted, and the size and gain can be reduced. In addition, by reducing the number of passive elements and selecting an optimum dielectric constant material, it is possible to reduce the cost by using an inexpensive material, reducing the number of layers in the multilayer structure, or the like.

The present invention has the following effects.
That is, according to the antenna device of the present invention, the pair of loop patterns has the tip connected to the pair of ground connection patterns and the other end connected in the middle of the center pattern, and the second passive elements are respectively connected in the middle. Since they are connected, the impedance can be individually adjusted for two high-frequency currents of different frequencies that flow through the pair of loop patterns by individually setting the pair of second passive elements.
In addition, according to the antenna device of the present invention, high-frequency current to the ground plane can be suppressed, and high antenna performance can be obtained even in a small antenna occupation region.
Therefore, the antenna device of the present invention can realize the maximum antenna performance even in a space-saving manner as a dual-band antenna, and can also obtain a high degree of installation freedom.

It is a top view which shows one Embodiment of the antenna device which concerns on this invention. In this embodiment, it is a bottom view which shows an antenna device. In this embodiment, it is a typical equivalent circuit diagram which shows an antenna device. In this embodiment, it is the perspective view which saw through the inside which shows an antenna element. In this embodiment, it is the perspective view (a) of the state cut | disconnected along the conductor pattern which shows an antenna element, and the perspective view (b) of the state cut | disconnected perpendicularly | vertically with respect to the mounting surface. In this embodiment, it is explanatory drawing which shows the composite capacitive coupling and inductance component inside an antenna element. In this embodiment, it is a typical equivalent circuit diagram for demonstrating the parallel resonance by a ground connection pattern. In this embodiment, it is explanatory drawing which shows simply the flow of the high frequency current of the simulation result which shows the current distribution in the surface of an antenna apparatus. In the Example of the antenna apparatus which concerns on this invention, it is a graph which shows a VSWR characteristic (voltage standing wave ratio). In a present Example, it is a graph which shows the 1.5 GHz band radiation pattern (a) and 2.4 GHz band radiation pattern (b) of an antenna apparatus. In a present Example, it is a graph which shows the simulation result of the frequency change at the time of changing each setting value of 1st passive element P1b (a), P1a (b), and 3rd passive element P3 (c). In a present Example, it is a graph which shows the simulation result of the frequency change at the time of changing each setting value of 2nd passive element P2b (a) and P2a (b). It is a top view which shows the comparative example 1 (a) and the comparative example 2 (b) which concern on the antenna apparatus of this invention. In the present Example, it is the graph which compared the antenna gain of the comparative example 1, the comparative example 2, and a present Example. In one Embodiment of the antenna device which concerns on this invention, it is a perspective view of the state cut | disconnected along the conductor pattern which shows the other example of an antenna element. FIG. 16 is an explanatory diagram showing complex capacitive coupling and inductance components inside the antenna element of FIG. 15. It is a top view which shows the prior art example of the antenna device based on this invention.

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

  As shown in FIG. 1, the antenna device 1 according to the present embodiment includes an insulating substrate body 2, a ground surface G formed by patterning a metal foil such as a copper foil on the substrate body 2, and the ground surface G An antenna occupation area AOA provided on the substrate body 2 in contact with the vicinity of one side of the substrate body 2 as an unformed area, and an antenna patterned with a metal foil such as a copper foil in the antenna occupation area AOA An element 3 and an antenna element AT of a dielectric antenna connected to the antenna element 3 and mounted on the substrate body 2 are provided.

The antenna element 3 has a center pattern E1, a pair of land portions E2, a pair of ground connection patterns E3, and a pair of loop patterns E4.
The central pattern E <b> 1 is provided with a feeding point FP on the base end side disposed in the vicinity of the ground plane G and extends toward the one side 2 a of the substrate body 2.

  As shown in FIGS. 4 and 5, the antenna element AT is an antenna element that does not self-resonate at a desired resonance frequency of antenna operation, and is a chip-shaped dielectric substrate 11 such as ceramics, and the dielectric A pair of both end electrode portions 12 formed at both ends of the base body 11 and an intermediate electrode portion 13 formed at an intermediate portion of the dielectric base body 11 and connected to the tip end portion of the central pattern E1 are provided. A capacitance component C is provided between each electrode portion 13 and the electrode portion 13.

  The antenna element AT includes a pair of both-end conductor patterns 14 formed in the dielectric substrate 11 and connected to the corresponding both-end electrode portions 12 and the intermediate conductor pattern 15 connected to the intermediate electrode portion 13. And a floating conductor pattern 16 formed inside the dielectric substrate 11 and disposed between the both end conductor pattern 14 and the intermediate conductor pattern 15 so as to be separated from them. That is, the both-end conductor pattern 14, the intermediate conductor pattern 15, and the floating conductor pattern 16 are formed in the same plane, and these conductor patterns have a single layer structure.

The pair of both-end conductor patterns 14 and the intermediate conductor pattern 15 each have a rectangular shape, and the floating conductor pattern 16 is formed in an H shape arranged between the both-end conductor patterns 14 and the intermediate conductor pattern 15.
The antenna element AT is installed in the vicinity of one side 2a of the board body 2, and a ground connection pattern E3 is formed in contact with the side 2a of the board body 2.
A pair of the intermediate electrode portions 13 are provided on the side surface of the dielectric substrate 11 so as to face each other. In addition, the intermediate conductor patterns 15 are provided in a pair so as to be opposed to each other with their ends connected to the pair of intermediate electrode portions 13. Therefore, this antenna element AT has a symmetrical structure, and has no polarity and no directionality on the front and back.

  In addition, as shown in FIG. 3, the antenna element AT has a capacitance C between the conductor patterns. Further, as shown in FIG. 6, not only the composite capacitance C but also an inductance component L exists. The capacitance and impedance are determined by the shape and interval of each conductor pattern. The impedance of the antenna element AT is preferably set to a high impedance with respect to the operating frequency. In the antenna element AT, each conductor pattern is embedded inside, but a pattern may be formed on the front surface or the back surface. The antenna element size is selected from the frequency used, the dielectric material used, and the like.

The pair of land portions E2 are arranged on both sides of the tip portion of the central pattern E1, and the pair of both end electrode portions 12 are connected thereto.
The pair of ground connection patterns E3 connect the pair of land portions E2 and the ground plane G adjacent to the land portions E2 via the first passive elements P1a and P1b, respectively, and have inductance components.

The pair of loop patterns E4 has a tip connected to the pair of ground connection patterns E3 and the other end connected in the middle of the central pattern E1, and the second passive elements P2a and P2b are connected in the middle. .
Further, in the middle of the central pattern E1, the third passive element P3 is connected to the front end side of the connection portion with the pair of loop patterns E4.

The feeding point FP is connected to a feeding point of a high frequency circuit (not shown). A high frequency circuit is mounted on the ground plane G.
For example, an inductor, a capacitor, or a resistor is used for the first passive elements P1a and P1b, the second passive elements P2a and P2b, and the third passive element P3. These first to third passive elements adjust two different frequencies and impedances.
Note that the third passive element P3 may be omitted as long as desired antenna performance is obtained.

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. On the surface of the substrate body 2, the ground plane G is cut out in a substantially rectangular shape, and the antenna occupation area AOA is provided. Further, as shown in FIG. 2, a ground surface G is formed on the back surface of the substrate body 2 in the same manner as the front surface, and a portion of the ground surface G corresponding to the area directly below the antenna occupation area AOA is removed. .
In addition, as shown in FIG. 2, the surface side and the back surface side of the ground plane G are electrically connected through through holes (not shown).

  In the antenna device 1 of this embodiment, as shown in FIG. 7, the inductance component L1 due to one ground connection pattern E3, the stray capacitance C1 between one loop pattern E4 and the ground plane G, and the other ground An inductance component L2 due to the connection pattern E3 and a stray capacitance C2 between the other loop pattern E4 and the ground plane G are generated.

  That is, the parallel resonance (part R1 in the figure) obtained by the inductance component L1 and the stray capacitance C1, the parallel resonance (part R2 in the figure) obtained by the inductance component L2 and the stray capacitance C2, and the central pattern Resonance due to the loop shape formed by E1, the antenna element AT, the land portion E2, and the loop pattern E4 (the portion R3 in the figure) occurs.

  Therefore, the flow of high-frequency current spreading to the ground plane G is achieved by a pair of parallel resonances obtained on the left and right sides of the central pattern E1, the resonance by the loop shape, and the final impedance adjustment by the second passive elements P2a and P2b. It is possible to obtain a high antenna performance by using the limited antenna occupation area AOA to the maximum.

  Next, FIG. 8 shows a flow of a high-frequency current simply indicated by an arrow with respect to a result of analyzing a current distribution at an arbitrary phase on the surface of the antenna device 1 of the present embodiment by simulation. As can be seen from this figure, the current distribution is concentrated in the antenna occupation area AOA, the flow of the high-frequency current spreading to the ground plane G is suppressed, and two antenna elements AT, the land portion E2, and the loop pattern E4 are used. A high-frequency current flows in a loop shape in a loop shape in the direction of the arrow.

  As described above, in the antenna device 1 according to the present embodiment, the pair of loop patterns E4 are connected to the pair of ground connection patterns E3 at the ends and the other ends are connected to the middle of the center pattern E1, and each of the patterns E4 is arranged in the middle. Since the two passive elements P2a and P2b are connected, by setting the pair of second passive elements P2a and P2b individually, the impedance is individually set for two high-frequency currents having different frequencies flowing through the pair of loop patterns E4. Can be adjusted.

  That is, in the pair of loop paths on both sides of the center pattern E1 formed by the pair of loop patterns E4, the center pattern E1, the antenna element AT, and the pair of land portions E2, high-frequency current flows in a loop shape. To do. Accordingly, by individually setting the pair of first passive elements P1a and P1b, the two frequencies can be adjusted individually, and the second passive elements P2a and P2b connected to the loop pattern E4 can be individually set. By setting, it becomes possible to individually adjust the impedance with respect to the two frequencies.

Further, the current distribution is concentrated in the antenna occupation area AOA, and the flow of the high-frequency current to the ground plane G can be suppressed. That is, it is possible to reduce the influence of peripheral components and the like during mounting.
That is, in this antenna device 1, a pair of stray capacitances obtained by the gap between the inductance component of the pair of ground connection patterns E3 and the land portion E2 to which both end electrode portions 12 of the antenna element AT are connected and the ground plane G are obtained. Parallel resonance and resonance due to the loop shape from the antenna element AT to the antenna element AT through the inner edge of the loop pattern E4 and the edge of the center pattern E1 occur.

  Therefore, the resonance of the loop shape with the shortened opening surface due to the antenna element AT and the passive element, and the stray capacitance between the land portion E2 and the loop pattern E4 to which the pair of both end electrode portions 12 are connected and the ground surface G are connected. Due to the pair of parallel resonances, the flow of the high-frequency current spreading to the ground plane G can be suppressed, and the high antenna performance can be obtained by making maximum use of the limited antenna occupation area AOA.

Further, in the antenna element AT, the pair of both end electrode portions 12 on both end sides operate as radiation electrodes, and there is no directionality and effective radiation power can be realized.
In addition, since the third passive element P3 is connected in the middle of the center pattern E1 and further to the front end side than the connection portion with the pair of loop patterns E4, the frequency is set to two frequencies by setting the third passive element P3. Both frequency adjustment and impedance adjustment can be performed.

In addition, since the antenna element AT includes a pair of both end conductor patterns 14 connected to the both end electrode portions 12 and the intermediate conductor pattern 15 connected to the intermediate electrode portion 13, both end conductor patterns 14 and the intermediate conductor pattern 15 are provided. Depending on the shape and arrangement, a composite capacitive component can be formed between them.
Furthermore, since the antenna element AT includes the floating conductor pattern 16 that is formed inside the dielectric substrate 11 and is disposed between the both-end conductor pattern 14 and the intermediate conductor pattern 15 so as to be separated from these, the floating conductor pattern 16 makes it possible to generate a composite capacitive coupling and impedance component between the both-end conductor pattern 14 and the intermediate conductor pattern 15. As a result, the frequency and impedance can be adjusted, and the size and gain can be reduced. In addition, by reducing the number of passive elements and selecting an optimum dielectric constant material, it is possible to reduce the cost by using an inexpensive material, reducing the number of layers in the multilayer structure, or the like.

  Further, since the antenna element AT is installed in the vicinity of the one side 2a of the substrate body 2, and the ground connection pattern E3 is formed in contact with the one side 2a of the substrate body 2, the antenna element AT and the ground connection pattern E3 are formed on the substrate. By being arranged at the end, the performance of the antenna element AT can be maximized and used. In particular, the pair of ground connection patterns E3 which are ground lines are in contact with the side 2a of the substrate body 2 to be linear, thereby reducing the influence of the ground lines and unstable elements, and realizing low loss.

The antenna element AT is preferably installed as close as possible to the end of the substrate body 2, that is, the side 2a, in order to ensure a wide radiation space from the antenna element AT.
The ground connection pattern E3 need not be the shortest, but is preferably connected to the adjacent ground plane G with a straight line.
Furthermore, it is desirable that the antenna occupation area AOA is as large as possible. Further, it is desirable that the opening area by the loop shape using the loop pattern E4 is wide.

  Next, the results of evaluation in an example in which the antenna device of the present embodiment was actually manufactured will be described with reference to FIGS.

  First, an example in which the size of the substrate body 2 was set such that the one side 2a was 130 mm and the side perpendicular to the one side 2a was 70 mm, and the size of the antenna occupation area AOA was 10 mm × 10 mm. In this case, the first passive elements P1a and P1b employ a 30 pF capacitor and a 1.3 pF capacitor, respectively. The second passive elements P2a and P2b employ a 5.0 nH inductor and a 1.0 nH inductor, respectively. Furthermore, a 3.0 pF capacitor was used for the third passive element P3.

The VSWR characteristics in this example are shown in FIG. Moreover, the radiation pattern in a present Example is shown in FIG. At this time, the ZX plane when the extending direction of one side 2a of the substrate body 2 is the Y direction, the extending direction of the central pattern E1 is the X direction, and the direction orthogonal to the surface of the substrate body 2 is the Z direction. The vertical polarization with respect to was measured at 1.5 GHz band and 2.4 GHz band.
From these results, in the VSWR characteristics of this example, VSWR _min. 1.61 and a radiation efficiency of −0.71 dBi are obtained, and VSWR _min. It can be seen that 1.56 and a radiation efficiency of −0.83 dBi are obtained, and a high antenna gain is realized. Moreover, the omnidirectional radiation pattern is obtained in both the 1.5 GHz band and the 2.4 GHz band.

  Next, simulation results of two resonance frequencies when the set value of the passive element is changed are shown in FIGS. 11A, 11B, and 11C show simulation results when the set values of the first passive element P1a, the first passive element P1b, and the third passive element P3 are changed, respectively. 12A and 12B show simulation results when the set values of the second passive element P2a and the second passive element P2b are changed, respectively. From these simulation results, it can be seen that the frequency and impedance can be adjusted by changing the set values of the passive elements.

  Next, the same substrate body is provided for the embodiment of the present invention and the comparative example 1 and the comparative example 2 which are the reverse F type dual band antennas as shown in FIGS. 13 (a) and 13 (b). The antenna gain was compared by size.

  In the comparative example 1, as shown in FIG. 13A, the size of the antenna occupation area AOA is set to 10 mm × 10 mm similarly to the present embodiment, and as an antenna element in the antenna occupation area AOA, A first element E11 having a base end portion which is disposed in the vicinity of the ground plane G and serves as a feeding point, and a first element E11 which is connected to the distal end of the first element E11 and extends to the right and left perpendicular to the first element E11. Two elements E12, a pair of third elements E13 extending along the extending direction of the first element E11 from both ends of the second element E12 via the passive elements P12, and the passive element P11 in the middle of the first element E11. A ground connection portion E10 connected at one end to the ground plane G at a position where the other end is separated from the base end portion of the first element E11. It is.

  In the comparative example 2, as shown in FIG. 13B, the size of the antenna occupation area AOA is set to 20 mm × 10 mm, which is larger than the embodiment of the present invention. The difference is that it has a pair of fourth elements E14 extending in directions away from the tips of the pair of third elements E13.

  A graph comparing the antenna gains of the present example and Comparative Examples 1 and 2 is shown in FIG. As can be seen from this result, in Comparative Example 1 (“inverted F10 × 10 mm” in FIG. 14), the omnidirectional antenna gain is as low as −8.49 dBi in the 1.5 GHz band and −1.59 dBi in the 2.4 GHz band. In Comparative Example 2 (“inverted F type 20 × 10 mm” in FIG. 14) in which the antenna occupation area AOA was expanded to improve this, the omnidirectional antenna gain was improved to −0.38 dBi in the 2.4 GHz band. However, only -2.25 dBi is improved in the 1.5 GHz band.

  On the other hand, in the example of the present invention (“present invention 10 × 10 mm” in FIG. 14), the antenna occupation area AOA is the same as in Comparative Example 1, but the omnidirectional antenna gain is −1.5 GHz band − An antenna gain as high as -0.83 dBi is obtained in the 0.71 dBi and 2.4 GHz bands. Thus, in this embodiment, high antenna performance can be realized even when the antenna occupation area AOA is small.

  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, as shown in FIGS. 15 and 16, the antenna element may be provided with a more complicated conductor pattern. That is, this antenna element has a portion in which a pair of both end conductor patterns 24 protrudes in the opposing direction, a pair of intermediate conductor patterns 25 are formed in a cross shape, and a floating conductor pattern 26 is formed from each H-shaped tip. Furthermore, it has four L-shaped parts bent in the direction orthogonal to each other after extending to both ends. In this antenna element, as shown in FIG. 16, complex capacitive coupling can be further increased by complex conductor patterns, and many inductance components can be obtained.

  In the above embodiment, the conductor pattern has a single-layer structure, and capacitive coupling is configured by the distance between the electrodes on the same surface, whereas capacitive coupling is configured between the upper and lower electrodes using a multilayer structure. It doesn't matter. That is, a capacitance may be generated in the conductor pattern between the layers by the both-end conductor pattern, the intermediate conductor pattern, and the floating conductor pattern formed above and below the dielectric layer.

  DESCRIPTION OF SYMBOLS 1 ... Antenna apparatus, 2 ... Board | substrate main body, 2a ... One side of board | substrate main body, 3 ... Antenna element, 11 ... Dielectric base | substrate, 12 ... Both-end electrode part, 13 ... Intermediate electrode part, 14, 24 ... Both-ends conductor pattern, 15, 25 ... Intermediate conductor pattern, 16, 26 ... Floating conductor pattern, AOA ... Antenna occupied area, AT ... Antenna element, E1 ... Center pattern, E2 ... Land part, E3 ... Ground connection pattern, E4 ... Pattern for loop, FP ... Power supply Point, G: Ground plane, P1a, P1b: First passive element, P2a, P2b: Second passive element, P3: Third passive element

Claims (5)

Insulating board body, ground plane patterned with metal foil on the board body, and antenna occupation provided on one side of the board body as a region where the ground plane is not formed A region, an antenna element patterned with a metal foil in the antenna occupation region, and an antenna element of a dielectric antenna connected to the antenna element and mounted on the substrate body,
The antenna element has a center pattern, a pair of land portions, a pair of ground connection patterns, and a pair of loop patterns.
The central pattern is provided with a feeding point on the base end side arranged in the vicinity of the ground surface and extends toward one side of the substrate body,
The antenna element includes a dielectric substrate, a pair of both-end electrode portions formed at both ends of the dielectric substrate, and an intermediate electrode portion formed at an intermediate portion of the dielectric substrate and connected to a tip portion of the central pattern. Each having a capacitance component between the both end electrode portion and the intermediate electrode portion,
The pair of land portions are arranged on both sides of the front end portion of the central pattern, and the pair of both end electrode portions are connected,
A pair of the ground connection patterns have an inductance component by connecting the pair of land portions and the ground plane adjacent to the land portions through first passive elements, respectively.
A pair of loop patterns has a tip connected to a position away from the ground plane of the pair of ground connection patterns, and the other end is connected in the middle of the central pattern, and a second passive element is connected in the middle. Has been
An antenna device , wherein a pair of parallel resonances occur between an inductance component of the pair of ground connection patterns and a stray capacitance between the pair of land portions, the pair of loop patterns, and the ground plane . The antenna device according to claim 1,
An antenna device, wherein a third passive element is connected in the middle of the central pattern and closer to the tip side than a connection portion between the pair of loop patterns. In the antenna device according to any one of claims 1 and 2,
The antenna element is installed on one side of the substrate body,
The antenna device, wherein the ground connection pattern is formed in contact with one side of the substrate body. In the antenna device according to any one of claims 1 to 3,
The antenna element is formed on at least one of the surface and the inside of the dielectric substrate, and a pair of both end conductor patterns connected to the corresponding both end electrode parts spaced apart from each other and an intermediate conductor pattern connected to the intermediate electrode part An antenna device comprising: The antenna device according to claim 4, wherein
The antenna element includes a floating conductor pattern formed on at least one of the surface and the inside of the dielectric substrate, and disposed between the both-end conductor pattern and the intermediate conductor pattern so as to be separated from them. An antenna device.