JPH11127014A - Antenna system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna system which is small-sized and has a wide band by forming a radiation electrode film and plural parasitic electrode films which have a resonance frequency close to the resonance frequency of the radiation electrode film on the same plane and putting resonances together. SOLUTION: A dielectric as the material of a base body 1 is preferably stable in specific dielectric constant and low in loss in a frequency band for its use, and an Al2 O3 -based ceramic dielectric is employed. For a small-sized antenna in three-element structure having a radiation electrode film 12 and two parasitic electrode films 13 and 14 on the same plane, to put two peaks appearing on an intermediate-frequency and a high-frequency side closer and on over the other into one peak is the most suitable method for widening the band. Normally, the peak regarding the radiation electrode film 12 among three peaks has the largest radiation resistance and the band becomes wide. The radiation electrode film 12 is arranged at an end part to make it possible to use the peak with the widest band. Consequently, the wide-band, small-sized antenna system is actualized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an antenna device used for portable communication equipment and the like.

[0002]

2. Description of the Related Art In recent years, portable communication devices such as portable telephones have been required to be further reduced in size, higher in performance, and reduced in cost. There is a need for an antenna that is small, broadband, high-gain, low-cost, and easy to mount.

[0003] As one of small antennas that can be incorporated in portable communication equipment, there is a so-called planar antenna composed of a print and a patch, and a device for widening the band with this planar antenna has been proposed ( See JP-A-4-157905). FIG. 7 is a configuration diagram of the broadband planar antenna proposed in the above publication.

[0004] A planar antenna 30 shown in FIG.
A strip-shaped parasitic element 32, 33 having the same length of two elements is arranged in parallel with a strip-shaped radiating electrode 31 having a parasitic element 11, and a parasitic element 35 is disposed above the dielectric element 34 with a dielectric plate 34 interposed therebetween. I have. FIG. 8 shows the band characteristics of this antenna. The large circle in FIG. 8 is a Smith chart, and the inside of the small circle is VSWR <1.5.
(−14d or less). In this example, a bandwidth of 17% is shown for VSWR <1.5.

[0005]

The broadband planar antenna having the structure shown in FIG. 7 requires two dielectric plates to be assembled to assemble the antenna.
There is a disadvantage that the weight is increased. Further, in order to obtain the characteristics shown in FIG.
A dimension of mx 6 mmt or more is required, and it is too large to be mounted on a portable device terminal or the like these days. If it is made smaller as it is, for example, the peak in the return loss characteristic as shown in FIG. 2 becomes narrower, whereby a plurality of overlapping peaks are separated from each other, losing the feature of wide band. .

In view of the above problems, the present invention realizes an antenna device having a small size and a wide band performance required for a portable terminal or the like by a simple one-layer structure in which a parasitic element is arranged in the same plane as a radiation electrode. The purpose is to do.

[0007]

The antenna device of the present invention that achieves the above object has the following features: (1) a rectangular parallelepiped base; (2) a ground electrode film extending on the lower surface of the base; and (3) an upper surface of one end of the base. Radiation electrode film (4) Parasitic electrode film that extends over each of a plurality of portions of the upper surface from the one end to the other end, excluding the one end, and (5) extends vertically on the side surface of the base and emits light. A grounding conductive film that connects each of the electrode film and the parasitic electrode film to the ground electrode film. (6) An excitation conductive film having a portion extending vertically on the one end side surface of the base. .

According to the present invention, a broadband antenna device is realized by forming a radiation electrode film and a plurality of parasitic electrode films having a resonance frequency close to the radiation electrode film and combining a plurality of resonances. Since the present invention has a structure in which both the radiation electrode film and the parasitic electrode film are formed on the upper surface of the base, a simple and lightweight antenna device can be manufactured without impairing mass productivity. Further, by arranging the radiation electrode film at one end of the upper surface of the base, a small and wide antenna device can be realized.

The operation of the radiation electrode film formed on one end of the upper surface of the base will be described. Here, as an example, an antenna having a three-element structure (each of the radiation electrode film and the parasitic electrode film is referred to as an element) having a radiation electrode film and two parasitic electrode films on the upper surface of the base will be described. In this case, three peaks usually appear in the return loss characteristics. Among these three peaks, the peak most strongly associated with the central parasitic electrode film appears on the lowest frequency side among the three peaks, and the remaining two peaks appear on the middle and high frequency sides. As the outer dimensions of the antenna are reduced, the three peaks each have a narrower band. In short, three narrow band peaks appear separately. When aiming for a wider band, it is necessary to approach each peak, but it is difficult to approach the peaks at both ends within a certain interval. On the other hand, the peak appearing at the middle frequency position moves relatively easily by changing the parameter, but mainly moves to the high frequency side, and it is difficult to move to the low frequency side. From this, in the case of a small antenna having a three-element structure having a radiation electrode film and two parasitic electrode films on the same plane, two peaks appearing on the medium frequency and high frequency sides are brought closer to become one peak. Is considered to be the most suitable method for widening the bandwidth. Usually, of the three peaks, the peak relating to the radiation electrode film has the highest radiation resistance and has a broad band. Here, when the radiation electrode film is disposed at the center as in the flat antenna proposed in the above-mentioned publication (see FIG. 7), the lowest frequency peak most strongly related to the element is broadened. On the other hand, the present invention is characterized in that the broadest peak can be used by disposing the radiation electrode film at the end. As a result, a wider band and smaller antenna device can be realized.

Here, in the antenna device of the present invention, the excitation conductor film may be connected to the radiation electrode film. It is preferable that the upper end of the portion extending to the ground electrode film is connected to a ground electrode film that connects the radiation electrode film to the ground electrode film, or the excitation conductor film is connected to the radiation electrode film. And
In a preferred embodiment, the excitation conductor film is connected to a ground conductor film that connects the radiation electrode film to the ground electrode film in a portion extending in the vertical direction on the side surface of the base. It is also a preferable embodiment that the excitation conductor film is separated from both the radiation electrode film and the grounding conductor film.

Further, it is a preferable embodiment that the above-mentioned base has a parasitic electrode film separated from the ground electrode film by lacking the corresponding grounding conductor film on the upper surface. In general, the return loss characteristic is mainly determined by the input resistance, and is most favorable when this is near 50Ω. The input resistance may vary depending on the size, the dielectric constant, and the like of the circuit board on which the antenna is mounted, in addition to the structure of the antenna.
Therefore, it is necessary to design such that the input impedance of the antenna can be controlled in consideration of those conditions. Also, if the input resistances of the two close peaks are significantly different, it is difficult to match both peaks simultaneously. Therefore, a design that can improve the resistance difference between the two peaks is also important.

In the present invention, when any of the above measures is taken, the input impedance and the resistance difference can be easily adjusted in the production.

[0013]

Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram of a first embodiment of the antenna device of the present invention. The antenna device 10 shown in FIG.
Is an antenna device having a resonance frequency of 1.9 GHz. It is desirable that the dielectric used as the material of the base 11 has a stable relative dielectric constant and a low loss in a frequency band to be used.
In the present embodiment, the Al ₂ O ₃ ceramic dielectric (1.
A relative dielectric constant at 9 GHz 8) is employed. This base 11
The conductor film formed on the surface of the substrate is desirably a good conductor such as silver or copper. In the present embodiment, a copper conductor paste is used, the conductor film is formed on the surface of the dielectric substrate 11 by a screen printing method, and a reducing atmosphere is used. Fired in.

The dimensions of the dielectric substrate 11 are 28 mm × 10 m
The radiation electrode film 12 having a width of 6 mm along the right edge of the dielectric substrate shown in FIG. 1 was placed on the upper surface of the dielectric substrate 11 at a distance of 9 mm from the radiation electrode film 12.
And a parasitic electrode film 14 having a width of 6 mm is formed along the left edge of the dielectric substrate. On the lower surface of the dielectric substrate 11, the ground electrode film 15 is formed on almost the entire surface except for a part of the region for preventing an excitation conductor film 19 to be described later from contacting the ground electrode film 15. Grounding conductor film 1 formed on the dielectric conductor side surface
6, 17, and 18 have a width of 1 mm, and these grounding conductors 16, 17, and 18 respectively connect the right end of the radiation electrode film 12 and the ground electrode film 15, and each of the parasitic electrode films 1
The left ends of the electrodes 3 and 14 are connected to the ground electrode film 15. An excitation conductor film 19 for supplying high-frequency power to the radiation electrode film 12 is provided on a side surface of the dielectric substrate with a grounding conductor film 16.
Are formed in parallel. The upper end of the excitation conductor film 19 is connected to the radiation electrode film 12. The conductor film 19 for excitation and the conductor films 16, 17, and 18 for grounding can also be used as mounting electrodes for mounting and fixing the antenna device 10 to a circuit board.

FIG. 2 is a diagram showing a return loss-frequency characteristic of the antenna device 10 shown in FIG. -10dB
Below, the fractional bandwidth is about 1.5%, which is sufficient performance as a PHS antenna. The antenna device 10 shown in FIG. 1 can also be used in terms of size.

FIG. 3 is a configuration diagram of a second embodiment of the antenna device of the present invention. The differences from the first embodiment shown in FIG. 1 will be described. In the second embodiment shown in FIG.
The difference from the first embodiment shown in FIG.
9 is directly connected to the grounding conductive film 16. By employing this configuration, the input impedance can be reduced as compared with the first embodiment shown in FIG.
It becomes possible to cope with a change in the size of the circuit board and the like. The excitation conductor film 19 and the ground conductor film 16 also serve as mounting electrodes, as in the embodiment shown in FIG.

FIG. 4 is a configuration diagram of a third embodiment of the antenna device of the present invention. In the third embodiment shown in FIG. 4, the excitation conductor film 19 is connected to the grounding conductor film 16 on the way. This allows further control of the input impedance, as in the embodiment shown in FIG. Exciting conductor film 19 and grounding conductor film 16 also serve as mounting electrodes, as in the first and second embodiments.

FIG. 5 is a configuration diagram of a fourth embodiment of the antenna device of the present invention. In the fourth embodiment shown in FIG. 5, the excitation conductor film 19 is separated from both the radiation electrode film 12 and the ground conductor film 16 and is formed with a gap between them. Thereby, the imaginary part of the impedance can be controlled relatively easily, and matching can be easily performed. Exciting conductor film 19 and grounding conductor film 16 also serve as mounting electrodes, as in the above-described embodiments.

FIG. 6 is a configuration diagram of a fifth embodiment of the antenna device of the present invention. In the antenna device shown in FIG. 6, a parasitic electrode film 20 which is not short-circuited to the ground electrode film 15 is arranged on the upper surface of the dielectric substrate 11 as compared with the antenna device shown in FIG. As a result, it is possible to improve the difference in resistance between two peaks that contribute to broadening the input impedance. The fact that the excitation conductor film 19 and the ground conductor film 16 also serve as mounting electrodes is the same as in the antenna device shown in FIG.

[0020]

According to the present invention, a broadband antenna device is realized by forming a radiation electrode film and a plurality of parasitic electrode films having a resonance frequency close to the radiation electrode film on the same plane and combining a plurality of resonances. . Since the present invention has a structure in which the radiation electrode film and the parasitic electrode film are all formed in the same plane, a lightweight antenna device can be easily manufactured without impairing mass productivity. Further, in the present invention, since the radiation electrode film is disposed at one end of the upper surface of the base, a small and wide band antenna can be realized. In addition, it is easy to change the power supply structure or add a parasitic electrode film that is not connected to the ground, and by adopting such a configuration,
The input impedance can be controlled.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment of an antenna according to the present invention.

FIG. 2 is a diagram showing a return loss-frequency characteristic of the antenna device shown in FIG.

FIG. 3 is a schematic diagram of a second embodiment of the antenna device of the present invention.

FIG. 4 is a schematic diagram of a third embodiment of the antenna device of the present invention.

FIG. 5 is a configuration diagram of a fourth embodiment of the antenna device of the present invention.

FIG. 6 is a configuration diagram of a fifth embodiment of the antenna device of the present invention.

FIG. 7 is a configuration diagram of a conventional broadband planar antenna.

FIG. 8 is a diagram showing band characteristics of the antenna shown in FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Antenna device 11 Base | substrate 12 Radiation electrode film 13,14 Parasitic electrode film 15 Ground electrode film 16,17,18 Grounding conductor film 19 Excitation conductor film 20 Parasitic electrode film

Claims (6)

[Claims] 1. A rectangular parallelepiped base, a ground electrode film extending on a lower surface of the base, a radiation electrode film spreading on an upper surface of one end of the base, and one end to the other end of the base excluding the one end A parasitic electrode film extending over each of a plurality of portions of the upper surface facing the portion; a grounding conductive film extending vertically on the side surface of the base and connecting each of the radiation electrode film and the parasitic electrode film to the ground electrode film; An antenna device, comprising: an excitation conductor film having a portion extending vertically in the side surface of the one end of the base. 2. The antenna device according to claim 1, wherein said excitation conductor film is connected to said radiation electrode film. 3. An upper end of a portion of said excitation conductor film extending in a vertical direction on a side surface of said base is connected to a ground conductor film connecting said radiation electrode film to said ground electrode film. The antenna device according to claim 1. 4. The excitation conductor film is connected to the radiation electrode film, and the excitation conductor film is
2. The antenna device according to claim 1, wherein the radiation electrode film is connected to a ground conductor film that connects the radiation electrode film to the ground electrode film at a part of the base extending in the vertical direction. 5. The antenna device according to claim 1, wherein the excitation conductor film is separated from both the radiation electrode film and the grounding conductor film. 6. The antenna device according to claim 1, further comprising a parasitic electrode film on the upper surface of the base, the corresponding grounding conductor film being missing and being separated from the ground electrode film.