JP6032001B2 - Antenna device - Google Patents

Description

  The present invention relates to an antenna device capable of making multiple resonances.

2. Description of the Related Art Conventionally, in communication equipment, an antenna device using a radiation electrode and a dielectric block, an antenna device using a switch, and a control voltage source has been proposed to make the resonance frequency of the antenna double resonant.
For example, as a conventional technique using a dielectric block, Patent Document 1 proposes a composite antenna that achieves high efficiency by forming a radiation electrode on a resin molded body and further integrating the dielectric block with an adhesive. .

  Further, as a conventional technique using a switch and a control voltage source, in Patent Document 2, a first radiation electrode, a second radiation electrode, a middle portion of the first radiation electrode, and a base of the second radiation electrode are disclosed. An antenna device has been proposed that includes a switch that is interposed between the end portion and electrically connects or disconnects the second radiation electrode with the first radiation electrode.

JP 2010-81000 A JP 2010-166287 A

However, the following problems remain in the above-described conventional technology.
That is, in the technique using the dielectric block as described in Patent Document 1, a dielectric block that excites the radiation electrode is used, and it is necessary to design the dielectric block, the radiation electrode pattern, etc. for each device. Depending on design conditions, antenna performance may be degraded, and unstable elements may increase. In addition, since the radiation electrode is formed on the surface of the resin molding, it is necessary to design the radiation electrode pattern on the resin molding. Depending on the communication equipment to be mounted and its application, the antenna design and mold design This is necessary and causes a significant increase in cost. Furthermore, since the dielectric block and the molded resin are integrated with an adhesive, the antenna performance may be degraded or unstable depending on the adhesive conditions (adhesive thickness, adhesive area, etc.) in addition to the adhesive Q value. There is a disadvantage that the number of elements increases.
In addition, in the case of an antenna device using a switch and a control voltage source as described in Patent Document 2, a configuration of a control voltage source, a reactance circuit, and the like are required to switch the resonance frequency with the switch. However, there is a problem in that each device is complicated, there is no degree of freedom in design, and easy antenna adjustment is difficult.

  The present invention has been made in view of the above-mentioned problems, and can flexibly adjust each resonance frequency that has been double-resonated. It is an object of the present invention to provide an antenna device that can be thinned.

  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, and a ground pattern, a first element, and a second element each formed by patterning a metal foil on the surface of the substrate body, The element is provided with a feeding point on a proximal end side close to the ground pattern and extends in a direction away from the ground pattern, and the element extends from the distal end of the first extension portion to the ground pattern. A second extension portion extending along the second extension portion, and the second element extends along the second extension portion with a proximal end connected to the middle of the first extension portion. A base part of the first extension part, and a fourth extension part extending from the tip of the third extension part toward the ground pattern and connected to the ground pattern. Is connected to the ground pattern And features.

In this antenna device, since the ground pattern, the first element, and the second element, each of which is patterned with a metal foil, are provided on the surface of the substrate body, each stray capacitance between each element and between the ground patterns and By effectively utilizing this, it is possible to make a double resonance.
In particular, the second element includes a third extending portion extending along the second extending portion with a base end connected in the middle of the first extending portion, and a ground pattern from the distal end of the third extending portion. Since the first extending portion extends toward the first end and is connected to the ground pattern, an opening pattern portion is formed by the second element, the ground pattern, and the first extending portion. A resonance frequency different from the resonance frequency mainly composed of elements can be obtained.
In addition, the stray capacitance generated in the formed opening pattern portion can reduce the influence of the human body and peripheral parts.

An antenna device according to a second invention is characterized in that, in the first invention, an antenna element of a dielectric antenna is connected in the middle of the second extending portion.
That is, in this antenna device, the element length of the loading element that does not self-resonate at a desired resonance frequency can be shortened, the impedance can be increased, and the stray capacitance can be increased. In addition, the size and the antenna characteristics can be improved.
In addition, the stray capacitance between the antenna element and the third extension portion does not cause the stray capacitance between the antenna element and the ground pattern directly, and the dependence due to the distance between the antenna element and the ground pattern. And the high-frequency current to the ground pattern can flow efficiently.

An antenna device according to a third invention is the antenna device according to the first or second invention, wherein a first passive element is connected in the middle of the first extension portion, and the third extension portion and the fourth extension portion are connected. A second passive element is connected to at least one, and a base end of the first extending portion is connected to the ground pattern via a third passive element.
That is, in this antenna device, the second passive element and the third passive element connected to the formed opening pattern portion cause parallel resonance, so that high impedance can be achieved, and resonance that can be obtained mainly from the first element. It becomes possible to reduce the influence between the frequency and the ground pattern. It is desirable that the opening pattern portion to be formed has a large opening area.

Further, by selecting the antenna element and the passive element, it is possible to flexibly adjust each resonance frequency, and it is possible to obtain an antenna device capable of making multiple resonances according to design conditions. Thus, since each resonance frequency can be flexibly adjusted in terms of the antenna configuration, the resonance frequency can be switched, and the adjustment location by a passive element or the like can be changed according to the application or device.
In addition, it is possible to design in the plane of the substrate body, and it is possible to reduce the thickness compared to the case of using a conventional dielectric block or resin molded body, and by selecting an antenna element that is a dielectric antenna, Miniaturization and high performance are possible. Further, there is no need for costs due to molds, design changes, etc., and low costs can be realized.

The antenna device according to a fourth invention is the antenna device according to any one of the first to third inventions, wherein the first element is connected to the tip of the second extension portion via a fourth passive element, and It has the 5th extension part extended along with the 2nd extension part toward the base end side of the 2nd extension part, It is characterized by the above-mentioned.
That is, in this antenna device, the first element is connected to the distal end of the second extending portion via the fourth passive element, and the second extending portion toward the proximal end side of the second extending portion. Since it has the 5th extension part extended along, it chooses what becomes a high impedance to the 4th passive element, and it is between the 4th passive element from the base end of the 5th extension part. It is possible to obtain another resonance frequency.

The present invention has the following effects.
According to the antenna device of the present invention, since the ground pattern, the first element, and the second element, each of which is patterned with a metal foil on the surface of the substrate body, are provided, between each element and between the ground patterns, etc. As a result, stray capacitance is generated, and multiple resonances can be achieved with at least two resonance frequencies.
In particular, an opening pattern portion is formed by the second element and the ground pattern, and a resonance frequency different from the resonance frequency mainly composed of the first element can be obtained.
In addition, each resonance frequency can be flexibly adjusted by selecting antenna elements and passive elements to be connected to each element, making it possible to achieve multiple resonances according to design conditions, and to reduce size and increase performance. become.
Therefore, the antenna device of the present invention can easily achieve multiple resonances corresponding to various applications and devices, and can save space.

In one Embodiment of the antenna device which concerns on this invention, it is a top view which shows the positional relationship of each element. In this embodiment, it is a wiring diagram which shows the main area | regions which contribute to each resonance frequency. In this embodiment, it is a wiring diagram which shows the stray capacitance produced with an antenna apparatus. In this embodiment, they are a perspective view (a), a plan view (b), a front view (c), and a bottom view (d) showing an antenna element. In this embodiment, it is a graph which shows the VSWR characteristic (voltage standing wave ratio) at the time of making it 3 resonance. In this embodiment, it is a graph which shows the radiation pattern of an antenna device.

  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 an insulating substrate body 2 and a ground pattern GND formed by patterning a metal foil such as a copper foil on the surface of the substrate body 2. A first element 3 and a second element 4 are provided.
The first element 3 includes a first extending portion E1 provided with a feeding point FP on the proximal end side close to the ground pattern GND and extending in a direction away from the ground pattern GND, and the first extending portion E1. And a second extending portion E2 extending along the ground pattern GND from the front end.
In addition, an antenna element AT of a dielectric antenna is connected in the middle of the second extending portion E2.
The direction along the ground pattern GND is a direction along the end side of the opposing ground pattern GND.

  The second element 4 includes a third extending portion E3 having a proximal end connected in the middle of the first extending portion E1 and extending along the second extending portion E2, and a distal end of the third extending portion E3. And a fourth extending portion E4 extending from the ground pattern GND toward the ground pattern GND and having a tip connected to the ground pattern GND. That is, an opening surrounded by the second element 4, the ground pattern GND, and the first extending portion E1 is formed, and the opening pattern portion is formed by the second element 4, the ground pattern GND, and the first extending portion E1. Is configured.

  In addition, first passive elements P1a and P1b are connected in the middle of the first extending portion E1. Furthermore, the second passive elements P2a and P2b are connected to the third extending part E3 and the fourth extending part E4, and the base end of the first extending part E1 is connected to the ground pattern via the third passive element P3. Connected to GND. That is, the second passive element P2a is connected between the base end of the third extension portion E3 and the first extension portion E1, and the base end of the fourth extension portion E4 and the third extension portion E3. The second passive element P2b is connected to the tip of the first passive element. Thus, the two second passive elements P2a and P2b and the third passive element P3 constitute a π-type resonator.

  The first element 3 has a proximal end connected to the distal end of the second extending portion E2 via a fourth passive element P4 and is connected to the second extending portion E2 toward the proximal end side of the second extending portion E2. It has the 5th extension part E5 extended along. The fifth extending portion E5 extends from the fourth passive element P4 once in the direction away from the ground pattern GND and then bends and extends in the direction along the second extending portion E2. ing. In other words, the fifth extending part E5 extends from the second extending part E2 with the fourth passive element P4 as a starting point.

  The first extending portion E1 has a wide portion E1a that is wider at the base end portion than the distal end side, and the third extending portion E3 has the second passive element P2a at the distal end portion of the wide portion E1a. Connected through. In addition, the connection point between the feeding point FP and the third passive element P3 at the base end of the wide part E1 is arranged away from each other.

The board body 2 is a general printed board, and in the present embodiment, a printed board made of glass epoxy resin or the like is employed.
The feed point FP is connected to a feed point of a high frequency circuit (not shown). A high frequency circuit is mounted in the area of the ground pattern GND.
For example, an inductor, a capacitor, a resistor, or a jumper line is used as each passive element.

The antenna element AT is a loading element that does not self-resonate at a desired resonance frequency. For example, as shown in FIG. 4, the antenna element AT is a chip antenna in which a conductor pattern 22 such as Ag is formed on the surface of a dielectric 21 such as ceramics. is there.
As the antenna element AT, elements having different lengths, widths, conductor patterns, and the like may be selected according to the setting of the resonance frequency and the like. Depending on the desired frequency, the dielectric 21 used for the antenna element AT may be a magnetic material or a composite material in which a dielectric and a magnetic material are mixed.

The first element 3 and the second element 4 extend at a distance from each other so as to generate a stray capacitance between them and a stray capacitance between the ground pattern GND.
That is, as shown in FIG. 3, the stray capacitance Ca between the fifth extending portion E5 and the antenna element AT, the stray capacitance Cb between the fifth extending portion E5 and the second extending portion E2, The stray capacitance Cc between the second extension portion E2 and the ground pattern GND, the stray capacitance Cd between the antenna element AT and the third extension portion E3, the second extension portion E2, and the third extension portion The stray capacitance Ce between E3 and the stray capacitance Cf between the third extending portion E3 and the ground pattern GND can be generated.

  Next, each resonance frequency in the antenna device of the present embodiment will be described with reference to the drawings.

In the antenna device 1 according to the present embodiment, as shown in FIG. 5, the first resonance frequency f1, the second resonance frequency f2, and the third resonance frequency f3 are combined in three frequency bands in order from the lowest frequency. Resonated.
The first resonance frequency f1 is determined by the first element 3, the antenna element AT, the first passive elements P1a and P1b, the second passive elements P2a and P2b, and the stray capacitance. The second resonance frequency f2 is determined by the antenna element AT, the first passive elements P1a and P1b, the first extending part E1, the second extending part E2, and the stray capacitance. Further, the third resonance frequency f3 is determined by the second element 4 and the ground pattern GND, the second passive elements P2a and P2b, and the stray capacitance that form the opening pattern portion.

Hereinafter, these resonance frequencies will be described in more detail.
“About the first resonance frequency f1”
The frequency of the first resonance frequency f1 is set and adjusted by the first element 3, the antenna element AT, the first passive elements P1a and P1b, the fourth passive element P4, and the stray capacitances Ca, Cb, Cc, Cd, and Ce. be able to.
Further, the impedance adjustment of the first resonance frequency f1 can be performed by setting each of the stray capacitances Ca, Cb, Cc, Cd, and Ce.
Furthermore, the final frequency adjustment can be flexibly performed by selecting the first passive elements P1a and P1b and the fourth passive element P4.
Thus, the first resonance frequency f1 is adjusted mainly at the portion indicated by the broken line A1 in FIG.

“About the second resonance frequency f2”
The frequency of the second resonance frequency f2 is set by the antenna element AT, the first extending part E1, the second extending part E2, the first passive elements P1a and P1b, and the stray capacitances Ca, Cb, Cc, Cd, and Ce. And can be adjusted.
Moreover, the impedance adjustment of the second resonance frequency f2 can be performed by setting each of the stray capacitances Ca, Cb, Cc, Cd, and Ce.
Further, the final frequency adjustment can be flexibly performed by selecting the first passive elements P1a and P1b.
In this way, the second resonance frequency f2 is adjusted mainly at the portion of the alternate long and short dash line A2 in FIG.

“About the third resonance frequency f3”
The frequency of the third resonance frequency f3 can be set and adjusted by the first extending portion E1, the second element 4, the ground pattern GND, the second passive elements P2a and P2b, and the stray capacitances Cd and Cf.
Further, the impedance adjustment of the third resonance frequency f3 can be performed by setting each of the stray capacitances Cd and Cf.
Further, the final frequency adjustment can be flexibly performed by selecting the second passive elements P2a and P2b.
In this way, the third resonance frequency f3 is adjusted mainly at the portion of the two-dot chain line A3 in FIG.

  The final impedance adjustment at each of the resonance frequencies f1, f2, and f3 can be flexibly performed by controlling the flow of the high-frequency current flowing to the ground pattern GND side by selecting the third passive element P3. .

  As described above, the antenna device 1 according to the present embodiment includes the ground pattern GND, the first element 3 and the second element 4 each formed by patterning a metal foil on the surface of the substrate body 2. By effectively utilizing each stray capacitance such as between the ground pattern GND and the ground pattern GND, a double resonance can be achieved.

In particular, the second element 4 includes a third extending portion E3 having a proximal end connected in the middle of the first extending portion E1 and extending along the second extending portion E2, and the third extending portion E3. Since it has the 4th extension part E4 extended toward the ground pattern GND from the front-end | tip and connected to this ground pattern GND, the 2nd element 4, the ground pattern GND, and the 1st extension part E1 Thus, an opening pattern portion is formed, and a resonance frequency different from the resonance frequency mainly composed of the first element 3 can be obtained.
In addition, the stray capacitance generated in the formed opening pattern portion can reduce the influence of the human body and peripheral parts.

In addition, the antenna element AT, which is a loading element that does not self-resonate at a desired resonance frequency, can shorten the element length, increase the impedance, and increase the stray capacitance. It is possible to improve the antenna characteristics.
Further, the stray capacitance Cd between the antenna element AT and the third extending portion E3 does not cause the stray capacitance between the antenna element AT and the ground pattern GND directly, and the antenna element AT and the ground pattern GND. , And the high-frequency current to the ground pattern GND can be efficiently passed.

In addition, since the second passive elements P2a and P2b and the third passive element P3 connected to the formed opening pattern portion generate parallel resonance, the resonance can be obtained with high impedance and mainly the first element 3. It becomes possible to reduce the influence between the frequency and the ground pattern GND.
Further, by selecting the antenna element and each passive element, it is possible to flexibly adjust each resonance frequency, and it is possible to obtain an antenna device capable of making multiple resonances according to design conditions. Thus, since each resonance frequency can be flexibly adjusted in terms of the antenna configuration, the resonance frequency can be switched, and the adjustment location by a passive element or the like can be changed according to the application or device.

  In addition, the design can be performed within the plane of the substrate body 2, and the thickness can be reduced as compared with the case where a conventional dielectric block or resin molding is used, and each antenna element that is a dielectric antenna can be selected. Thus, miniaturization and high performance can be achieved. Further, there is no need for costs due to molds, design changes, etc., and low costs can be realized.

  In addition, the first element 3 is connected to the distal end of the second extending portion E2 via the fourth passive element P4, and is connected to the second extending portion E2 toward the proximal end side of the second extending portion E2. Since it has the 5th extension part E5 extended along, selecting what becomes a high impedance as the 4th passive element P4 makes it 4th passive element P4 from the base end of the 5th extension part E5. It is possible to obtain another resonance frequency between

  Next, with respect to an example in which the antenna device of this embodiment was actually manufactured, the results of measuring the VSWR characteristics (voltage standing wave ratio) and the results of measuring the radiation pattern at each resonance frequency are shown in FIG. This will be described with reference to FIG.

In these measurements, the following passive elements were used.
First passive element P1a: L = 2.7 nH inductor First passive element P1b: L = 3.3 nH inductor Second passive element P2a: C = 0.4 pF capacitor Second passive element P2b: C = 0.5 pF Capacitor third passive element P3: inductor with L = 2.7 nH fourth passive element P4: inductor with L = 22 nH

As can be seen from the measurement results, the first to third resonance frequencies f1 to f3 are obtained with a good bandwidth as shown in Table 1 below.
The frequency band of the first resonance frequency f1 is 1575 MHz, the frequency band of the second resonance frequency f2 is 2442 MHz, and the frequency band of the third resonance frequency f3 is 5470 MHz.

Next, FIG. 6 shows the measurement results of the radiation patterns at the first resonance frequency f1, the second resonance frequency f2, and the third resonance frequency f3 for the antenna device of the above example.
The extending direction from the proximal end of the second extending portion E2 to the distal end (the extending direction of the antenna element AT) is defined as the -Y direction, and the extending direction from the proximal end of the first extending portion E1 to the distal end is defined as the -Y direction. The −X direction was used, and the direction perpendicular to the surface of the substrate body 2 was the Z direction. At this time, vertical polarization, horizontal polarization, and power gain with respect to the ZX plane were measured.

  As a result, the average power gain of the first resonance frequency f1 in the ZX plane is -5.6 dBi, the average power gain of the second resonance frequency f2 is -5.7 dBi, and the average of the third resonance frequency f3 The power gain was -2.9 dBi.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, in the above embodiment, the antenna element is provided in the second extending portion. However, the antenna element may be provided in the fifth extending portion to shorten the element, thereby reducing the size of the entire apparatus. .

In addition, as described above, it is preferable to connect the antenna element to be a part of the element, but the second extending portion that is extended only by a metal foil such as a copper foil may be used without connecting the antenna element. . At this time, in order to increase the impedance, at least a part of the second extension part is formed into a narrow pattern narrower than the other parts, or a meander pattern extending in a certain direction as a whole while being folded back zigzag. It is preferable.
Furthermore, when there is a margin in the substrate size, a part of the element may be replaced with a pattern in which a linear or plate-like metal is folded. Moreover, you may make it the pattern swirled in shapes, such as a spiral shape, using a through hole with respect to the front and back of the same board | substrate body.

  DESCRIPTION OF SYMBOLS 1 ... Antenna apparatus, 2 ... Board | substrate main body, 3 ... 1st element, 4 ... 2nd element, AT ... Antenna element, E1 ... 1st extension part, E2 ... 2nd extension part, E3 ... 3rd extension part , E4 ... fourth extension, E5 ... fifth extension, GND ... ground pattern, P1a, P1b ... first passive element, P2a. P2b ... second passive element, P3 ... third passive element, P4 ... fourth passive element, FP ... feed point

Claims (3)

An insulating substrate body;
A ground pattern patterned with a metal foil on the surface of the substrate body, a first element and a second element,
The first element is provided with a feeding point on a proximal end side close to the ground pattern and extends in a direction away from the ground pattern, and from the tip of the first extension portion, the first element A second extending portion extending along the ground pattern,
The second element includes a third extending portion extending along the second extending portion with a base end connected in the middle of the first extending portion, and the ground from the distal end of the third extending portion. A fourth extension part extending toward the pattern and having a tip connected to the ground pattern;
A base end of the first extending portion is connected to the ground pattern ;
The first element has a proximal end connected to the distal end of the second extending portion via a fourth passive element and extends in a direction away from the ground pattern, and then the proximal end of the second extending portion. A fifth extending portion extending along the second extending portion toward the side;
The first extending portion has a wide portion that is wider at the base end portion than the distal end side,
The antenna device according to claim 1, wherein the wide portion is connected to the ground pattern on the fourth extending portion side with respect to the feeding point . The antenna device according to claim 1,
An antenna device, wherein an antenna element of a dielectric antenna is connected in the middle of the second extending portion. In the antenna device according to claim 1 or 2,
A first passive element is connected in the middle of the first extension part,
A second passive element is connected to at least one of the third extension part and the fourth extension part, and a base end of the first extension part is connected to the ground pattern via a third passive element. An antenna device characterized by being made.