JP6011328B2 - 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 end of the second radiation electrode are disclosed. An antenna device has been proposed that includes a switch interposed between the first radiation electrode and the second radiation electrode to electrically connect or disconnect 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, the antenna device according to the first invention includes an insulating substrate body, a ground plane patterned with metal foil on the substrate body, and a first element, a second element, and a third element, The first element is provided with a feeding point at a base end disposed on the ground surface side and extends in a direction away from the ground surface, and from the distal end of the first extension portion, the first element A second extension portion extending in a direction along the ground surface, and the second extension portion extends from the vicinity of the proximal end of the first element in a direction away from the first extension portion. And a fourth extending portion extending in a direction away from the ground surface along the first extending portion from the tip of the third extending portion, and the third element is a base of the first element. Extending from the end and the tip from the feed point It is connected to the ground plane at a gap, and the second extension part is connected to a narrow part narrower than the other part of the second extension part in the middle and to the tip of the narrow part. And a capacity loading pattern portion that is wider than the narrow portion and extends longer in the extending direction of the second extending portion.

In this antenna device, the second extending portion having the antenna element extends at a distance from the ground surface so that stray capacitance between the antenna element and the ground element can be generated, and the second element is connected to the first element. The stray capacitance between each element and the ground plane can be generated, and the first element and the ground plane are spaced apart from each other. Can be used to achieve multiple resonances.
In particular, the second extending portion is narrower than the other portion of the second extending portion, and the second extending portion is connected to the tip of the narrowed portion and wider than the narrowed portion. Since it has a capacitive loading pattern portion that extends long in the extending direction of the extending portion, it is possible to increase the impedance of the element by the narrow portion and obtain a large stray capacitance at the tip portion by the capacitive loading pattern portion. be able to. In addition, when the capacity | capacitance loading pattern part is wide and does not extend long in the extending direction of a 2nd extension part, the effect which expands a bandwidth cannot fully be acquired.

The antenna device according to a second invention is the antenna device according to the first invention, wherein an antenna element of a dielectric antenna in which a conductor pattern is formed as the narrow portion is connected in the middle of the second extending portion. Features.
That is, in this antenna device, since the antenna element of the dielectric antenna in which the conductor pattern is formed as the narrow part is connected in the middle of the second extending part, the loading element that does not self-resonate at a desired resonance frequency. With the antenna element, the element length can be shortened and the impedance can be increased, and the stray capacitance can be increased. Thus, the adjustment of the double resonance can be facilitated, and the size and the antenna characteristics can be improved.
Further, by selecting the antenna element and each passive element connected to the element, it is possible to flexibly adjust each resonance frequency and impedance, and to obtain an antenna device capable of dual resonance according to the application, equipment, and design conditions. it can.
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.

An antenna device according to a third invention is the antenna device according to the first or second invention, wherein the third extending portion is in a direction away from the ground surface from the vicinity of the base end of the first element. It is characterized by extending in an oblique direction with respect to the existing portion.
That is, in this antenna device, the third extending portion extends in a direction away from the ground surface from the vicinity of the base end of the first element and obliquely with respect to the first extending portion. The coupling between the two elements and the ground plane can be suppressed, and the high-frequency current flowing through the ground plane can be suppressed.

The present invention has the following effects.
That is, according to the antenna device of the present invention, the second extending portion extends at a distance from the ground plane so as to generate stray capacitance between the second element and the second element. Since the stray capacitance between the element and the ground plane can be generated, the first element and the ground plane are spaced apart from each other. Each resonance frequency can be adjusted flexibly, two resonances can be achieved according to design conditions, and miniaturization and high performance can be achieved.
In particular, the second extending portion is narrower than the other portion of the second extending portion, and the second extending portion is connected to the tip of the narrowed portion and wider than the narrowed portion. Since it has a capacitive loading pattern portion that extends long in the extending direction of the extending portion, it is possible to increase the impedance of the element by the narrow portion and obtain a large stray capacitance at the tip portion by the capacitive loading pattern portion. be able to.
Therefore, the antenna device of the present invention can easily achieve multiple resonances corresponding to various applications and devices, and can save space and improve the degree of freedom of wiring and installation.

It is a top view of the important section showing one embodiment of the antenna device concerning the present invention. In this embodiment, it is the whole top view which shows an antenna apparatus. 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), a bottom view (d), and a rear view (e) showing an antenna element. 5 is a graph showing VSWR characteristics at two resonances in Example 1 of the antenna device according to the present invention. It is a graph which compares and shows the bandwidth of a 2.4 GHz band and a 5.2 GHz band in the Example and comparative example of the antenna apparatus which concern on this invention. It is a top view of the principal part which shows the other example of this embodiment.

  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, a ground surface GND that is patterned with a metal foil on the substrate body 2, and first to fourth elements. Passive elements P1 to P4 are provided with a first element 3, a second element 4 and a third element 5 connected in the middle.
A mounting area for RF circuit components and the like is provided on the ground plane GND.

  The first element 3 includes a first extending portion E1 having a feeding point FP provided at a proximal end disposed on the ground surface GND side and extending in a direction away from the ground surface GND, and the first extending portion E1. And a second extending portion E2 extending in a direction along the ground surface GND (an end side of the opposing ground surface GND). Moreover, the 1st passive element P1 and the 2nd passive element P2 are connected in series in the middle of the 1st extension part E1.

  The second extending portion E2 is connected to the narrow portion E2a whose line width is narrower than the other portions of the second extending portion E2 in the middle, and to the tip of the narrow portion E2a, and more than the narrow portion E2a. And a capacity loading pattern portion E2b which is wide and extends long in the extending direction of the second extending portion E2. Here, the term “extending in the extending direction” means that the dimension in the extending direction is longer than the dimension in the direction orthogonal to the extending direction in the capacity loading pattern portion E2b. .

In this embodiment, the antenna element AT of the dielectric antenna in which the conductor pattern 102 is formed as the narrow portion E2a is connected in the middle of the second extending portion E2. As described above, the second extending portion E2 extends at a distance from the ground surface GND so that stray capacitance between the second extending portion E2 and the ground surface GND can be generated, and the antenna element of the dielectric antenna is provided in the intermediate portion. AT is provided.
The capacitive loading pattern portion E2b is wider than the conductor pattern 102 and the first extending portion E1 of the antenna element AT, is formed in a rectangular shape or a strip shape, and extends along the ground surface GND.

The second element 4 includes a third extension E3 extending from the vicinity of the proximal end of the first element 3 in a direction away from the first extension E1, and a first extension from the tip of the third extension E3. A fourth extending portion E4 extending in a direction away from the ground surface GND along the portion E1 is provided. A third passive element P3 is connected to the proximal end side of the fourth extending portion E4.
The third extending portion E3 extends from the vicinity of the base end of the first element 3 away from the ground surface GND and in an oblique direction with respect to the first extending portion E1. The third extending portion E3 preferably extends at an angle of 45 degrees with respect to the first extending portion E1 (or the end side of the opposing ground surface GND).

  The third element 5 extends from the base end of the first element 3 and is connected to the ground plane GND at a position where the tip is separated from the feeding point FP. That is, the third element 5 extends to the opposite side to the second element 4 with respect to the first extending portion E1, is bent in the middle, and is connected to the ground plane GND at a position separated from the first extending portion E1. . A fourth passive element P4 is connected in the middle of the third element.

The substrate body 2 is a general printed circuit board, and in this embodiment, a printed circuit board body made of a rectangular glass epoxy resin or the like is employed.
The feeding point FP is connected to a feeding point of a high-frequency circuit (not shown) through a feeding means such as a coaxial cable. This power supply means includes various connectors such as a coaxial cable, a connector such as a receptacle, a connection structure in which the contact has a leaf spring shape, a connection structure in which the contact has a pin probe shape or a pin shape, and a connection structure using a soldering land. The structure can be adopted.
For example, when a coaxial cable is employed as the power feeding means, the ground wire of the coaxial cable is connected to the base end side of the ground surface GND, and the core wire of the coaxial cable is connected to the feeding point FP.

  The antenna element AT is a loading element that does not self-resonate at a desired resonance frequency, and is a chip antenna in which a conductor pattern 102 such as Ag is formed on the surface of a dielectric 101 such as ceramic as shown in FIG. is there. That is, in this antenna element AT, the narrow conductive portion 102 having a narrow line width is formed as the narrow portion E2a so as to be spirally wound around the chip-like dielectric 101.

As the antenna element AT, elements having different lengths, widths, conductor patterns 102, and the like may be selected according to the setting of the resonance frequency and the like. Depending on the desired frequency, the dielectric 101 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.
As the first passive element P1 to the fourth passive element P4, for example, an inductor, a capacitor, or a resistor is employed.

The second element 4 extends at a distance from the first element 3 and the ground plane GND so as to be able to generate a stray capacitance between the first element 3 and a stray capacitance between the first element 3 and the ground plane GND. doing.
That is, as shown in FIG. 3, the stray capacitance Ca between the first element 3 (mainly the first extension E1) and the second element 4 (mainly the fourth extension E4), and the second extension Stray capacitance Cb between the existing portion E2 (mainly the antenna element AT) and the ground plane GND, stray capacitance Cc between the second element 4 (mainly the third extending portion E3) and the ground plane GND, A stray capacitance Cd between the capacitance loading pattern portion E2b and the ground plane GND can be generated.

  Next, the resonance frequency in the antenna device 1 of the present embodiment will be described with reference to FIG.

In the antenna device 1 of the present embodiment, as shown in FIG. 5, two resonances are made, that is, a first resonance frequency f1 and a second resonance frequency f2.
The first resonance frequency f1 is in a lower frequency band (for example, 2.4 GHz band) of the two resonance frequencies, and the antenna element AT, the first passive element P1 and the second passive element P2, and the floating It is determined by the capacitance Ca, the stray capacitance Cb, and the stray capacitance Cd.
The second resonance frequency f2 is in a high frequency band (for example, 5.2 GHz band) of the two resonance frequencies, and the second element 4, the third passive element P3, the stray capacitance Ca, and the stray capacitance. And Cc.

The impedance at the first resonance frequency f1 is determined by the fourth passive element P4, the stray capacitance Ca, the stray capacitance Cb, and the stray capacitance Cd. Furthermore, the impedance at the second resonance frequency f2 is determined by the fourth passive element P4, the stray capacitance Ca, and the stray capacitance Cc.
That is, the final impedance adjustment is performed for each resonance frequency by controlling the flow of the high-frequency current flowing on the ground plane GND side using the fourth passive element P4.

Therefore, the first resonance frequency f1 is adjusted mainly at the portion surrounded by the broken line A1 in FIG.
Further, the second resonance frequency f2 is adjusted mainly at a portion surrounded by a broken line A2 in FIG.
As described above, in the antenna operation, not only each passive element but also the stray capacitance Ca between the elements and the stray capacitances Cb, Cc, and Cd between the elements and the ground plane GND are used. Miniaturization can be realized.

  In this antenna device 1, as shown in FIG. 1, the directions of the high-frequency currents flowing through the first element 3 and the second element 4 are orthogonal to each other (see the arrow in the figure), so that the interference between the two elements Is reduced. Further, since the third extending portion E3 extends obliquely with respect to the end side of the ground surface GND, the coupling between the third extending portion E3 and the ground surface GND is suppressed, and the ground surface GND. The high frequency current flowing through the Therefore, it is possible to reduce the influence between the elements and between the ground plane and the elements, thereby realizing downsizing.

The fourth extending portion E4 of the second element 4 for the second resonance frequency f2 (5.2 GHz) is preferably longer. Furthermore, it is desirable that the width of the second element 4 is wider.
The stray capacitance Ca between the elements is preferably tightly coupled.
In addition, it is desirable that the distance between the ground plane GND and the second element 4 (third extending portion E3) is longer.
Furthermore, it is desirable that the distance between the ground plane GND and the antenna element AT is longer.
Further, it is desirable that the capacity loading pattern portion E2b is wide and long in order to obtain a wide bandwidth.

  As described above, in the antenna device 1 of the present embodiment, the second extending portion E2 having the antenna element AT extends at a distance from the ground plane GND so as to generate the stray capacitance Cb between the antenna element AT and the ground plane GND. The second element 4 is spaced from the first element 3 and the ground plane GND so that the floating capacitance Ca between the first element 3 and the floating capacitance Cc between the first plane 3 and the ground plane GND can be generated. Therefore, multiple resonance can be achieved by effectively using the stray capacitance between the elements.

  Further, the second extending portion E2 is connected to the narrow portion E2a whose line width is narrower than other portions of the second extending portion E2 in the middle, and the tip of the narrow portion E2a. Also has a capacitive loading pattern portion E2b which is wide and extends long in the extending direction of the second extending portion E2, so that the impedance of the element is increased by the narrow portion E2a and the capacitive loading pattern portion E2b A large stray capacitance can be obtained at the tip.

  Furthermore, since the antenna element AT of the dielectric antenna having the conductor pattern 102 formed as the narrow part E2a is connected in the middle of the second extending part E2, the antenna of the loading element that does not self-resonate at a desired resonance frequency. The element AT can shorten the element length, increase the impedance, and increase the stray capacitance, thereby facilitating the adjustment of the double resonance and reducing the size and improving the antenna characteristics.

Also, by selecting the antenna element AT and each passive element connected to the element, each resonance frequency and impedance can be flexibly adjusted, and an antenna device capable of two resonances according to the application, equipment, and design conditions is obtained. be able to.
In addition, the design can be made in 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 the antenna element AT which is a dielectric antenna is 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.

Further, since the third extending portion E3 extends from the vicinity of the base end of the first element 3 in a direction away from the ground surface GND and obliquely with respect to the first extending portion E1, the second extending portion E3 Coupling between the element 4 and the ground plane GND can be suppressed, and a high-frequency current flowing through the ground plane GND can be suppressed.

  Next, in Example 1 in which the antenna device of the present embodiment was actually manufactured, the results of measuring the VSWR characteristics (voltage standing wave ratio) in the two-resonance at each resonance frequency will be described with reference to FIG. To do.

Each passive element is an inductor of any of the first passive element P1: 2.9 nH, the second passive element P2: 6.2 nH, the third passive element P3: 2.2 nH, and the fourth passive element P4: 2.5 nH. It was used. The size of the capacity loading pattern portion E2b was 2.5 × 3.0 mm.
As shown in FIG. 5, in the embodiment of the present invention, the bandwidth (VSWR ≦ 2.0) of the first resonance frequency f1 (2.4 GHz band) is 180.9 MHz, 2 resonance frequency f2: (5.2 GHz band) bandwidth (VSWR ≦ 2.0): 851.2 MHz.

Next, for comparison, the antenna element AT and the capacity loading pattern portion E2b are not provided, and the portion to which the antenna element AT is connected is a metal foil and the short second extending portion E2 extending with the same width as the base end. Comparative Example 2 in which the antenna element AT is mounted but the tip end of the second extending portion E2 is only the land portion for mounting the antenna element AT, although there is no capacity loading pattern portion E2b. Similarly, the first resonance frequency of the first embodiment of the present invention and the second embodiment in which the capacity loading pattern portion E2b of the first embodiment is longer and the size is 5.0 × 3.0 mm. The bandwidth between f1 (2.4 GHz band) and the second resonance frequency f2: (5.2 GHz band) was measured. The result is shown in FIG.
Table 1 shows the inductance values set for the respective passive elements of the comparative examples and the examples in the measurement.

As can be seen from the above results, compared to Comparative Example 1 in which the antenna element AT and the capacity loading pattern portion E2b are not provided, Comparative Example 2 in which the antenna element AT is connected, and Example 1 in which a capacity loading pattern portion E2b is further added, The bandwidth becomes wider in the order of the second embodiment in which the capacity loading pattern portion E2b is longer than the first embodiment.
In addition, by making it the comparative example 2 which connected the antenna element AT with respect to the comparative example 1 without the antenna element AT, not only the bandwidth of the 2.4 GHz band but also the 5.2 GHz band due to the effect of the stray capacitance Ca. Good results are also obtained for the bandwidth. Similarly, the same effect is obtained by mounting the antenna element AT under the conditions of the first and second embodiments.

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

For example, in the above embodiment, the antenna element is provided in the second extending portion, but the antenna element may be provided in the fourth extending portion. In this case, the length of the second element can be shortened by the antenna element of the fourth extending portion, which is suitable when the antenna occupation area is small.
In addition, the stray capacitance Ca can be increased by employing an antenna element in the fourth extending portion.

In addition, as described above, it is preferable to connect the antenna element AT and provide the conductor pattern 102 as the narrow portion E2a in the second extending portion E2, but as shown in FIG. Alternatively, a linear narrow portion E2a having a line width narrower than other portions of the second extending portion E2 and patterned with a metal foil may be used. The line width and length of the narrow portion E2a are set so as to obtain a desired impedance.
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, 5 ... 3rd element, AT ... Antenna element, E1 ... 1st extension part, E2 ... 2nd extension part, E2a ... capacity loading pattern part, E3 ... third extension part, E4 ... fourth extension part, GND ... ground plane, P1 ... first passive element, P2 ... second passive element, P3 ... third passive element, P4 ... Fourth passive element, FP ... feed point, S1 ... narrow part

Claims (3)

An insulating substrate body;
A ground plane patterned with a metal foil on the substrate body; a first element, a second element, and a third element;
The first element is provided with a feeding point at a base end disposed on the ground surface side and extends in a direction away from the ground surface, and from the distal end of the first extension portion, the first element A second extending portion extending in a direction along the ground surface,
The second element extends from the vicinity of the proximal end of the first element in a direction away from the first extension, and from the tip of the third extension to the first extension. And a fourth extension extending in a direction away from the ground surface along
The third element is connected to the ground plane at a position extending from a base end of the first element and having a tip separated from a feeding point;
The second extending portion includes a narrow portion narrower than the other portion of the second extending portion in the middle of the second extending portion, and is connected to the tip of the narrow portion and wider than the narrow portion. 2. An antenna device comprising: a capacity loading pattern portion extending long in the extending direction of the extending portion. The antenna device according to claim 1,
An antenna device, wherein an antenna element of a dielectric antenna in which a conductor pattern is formed as the narrow portion is connected in the middle of the second extending portion. In the antenna device according to claim 1 or 2,
The antenna is characterized in that the third extending portion extends in a direction away from the ground surface from the vicinity of the base end of the first element and in an oblique direction with respect to the first extending portion. apparatus.