JP3570609B2 - antenna - Google Patents

Description

【００１７】
比較例の試料と比べ実施例の試料は放射電極２の温度変化及び、アンテナの共振周波数の変動率が小さい。また交流電源から電力を供給し続けても温度変化は著しく小さく、共振周波数の変化は実用上まったく問題のない程度であった。一方比較例の試料は温度上昇を続け数℃〜十数℃温度変化し、共振数周波数は大きく変化した。
【００１８】
（実施例２）
ジルコン酸カルシウムからなる誘電体材料の粉体を加圧成形し焼結した後、幅５ｍｍ高さ３ｍｍ長さ５ｍｍの直方体形状に切削加工した誘電体１の外表面にＡｇを主体としたペースト材料を用いて略３ターンの放射電極２を印刷し形成した。さらに前記放射電極に電圧を印加するための給電用端子４を誘電体の外表面にＡｇペーストを用いて印刷し形成し、その後、放射電極２、給電用端子４を８５０℃で焼き付けた。放射電極２、給電用端子４を形成した誘電体１を電極３を形成したテフロン基板にはんだ付けして２ＧＨｚ帯アンテナを得た。以下実施例１と同様なのでその説明を省く。
【００１９】
【表２】

【００２０】
本実施例も実施例１と同様に比較例の試料と比べ実施例の試料は導体線路２の温度変化及び、アンテナの共振周波数の変動率が小さく、駆動試験を続けても温度変化は著しく小さく、共振周波数の変化は実用上まったく問題のない程度であった。
【００２１】
【発明の効果】
以上の通り本発明によれば、アンテナの小型化に伴う導体線路の電力損失による発熱を抑えるとともに、波長変動の小さなアンテナを得ることが出来る。
【図面の簡単な説明】
【図１】本発明の一実施例に係るアンテナの斜視図である。
【図２】本発明の他の実施例に係るアンテナの斜視図である。
【図３】従来のヘリカルアンテナの斜視図である。
【符号の説明】
１ 絶縁体
２ 放射電極
３ 電極
４ 給電用端子[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an antenna, and particularly to a small antenna used for a microwave radio communication device such as a mobile phone and a wireless LAN (local area network).
[0002]
[Prior art]
In a microwave wireless communication device, a monopole antenna, a helical antenna in which a radiation electrode is spirally wound on a surface of a base made of a dielectric material, and the like are generally used as antennas. These antennas are described in, for example, pages 50 to 59 of the "Antenna Engineering Handbook" (published on October 30, 1980) edited by the Institute of Electronics, Information and Communication Engineers published by Ohmsha.
[0003]
FIG. 3 is a perspective view of a conventional helical antenna. In all the drawings, the same reference numerals are given to parts having the same function. This helical antenna has a structure in which a spiral conductive wire 2 is wound around an insulator 1 made of, for example, a dielectric material.
[0004]
Japanese Patent Application Laid-Open No. 9-51221 discloses that a dielectric layer in which a conductor line is formed on a surface by a thick film printing method or the like is laminated, and the conductor line is electrically connected through a through hole to form a circulating coil. A small laminated antenna in which the line 2 is formed is described.
[0005]
[Problems to be solved by the invention]
It is known that these antennas resonate where the line length of the radiation electrode is slightly longer than １ ／ wavelength. Also, the higher the relative permittivity of the dielectric 1, the shorter the wavelength of the current flowing through the radiation electrode and the shorter the line length of the radiation electrode, so that the antenna can be miniaturized. However, in view of electrical characteristics, the line width of the radiation electrode 2 is preferably formed to be 1/10 or less of 1/4 wavelength. As a result, the line width of the radiation electrode 2 becomes narrower as the antenna becomes smaller. For this reason, since the cross-sectional area of the radiation electrode 2 is reduced and the electric resistance is increased, there is a problem that the power loss at the radiation electrode 2 is increased.
[0006]
Further, the radiation electrode 2 and the insulator 1 thermally expand due to the heat generated by the power loss generated from the radiation electrode 2, and the line length of the radiation electrode changes. As a result, there is a problem that the wavelength of the antenna fluctuates during use of the microwave radio communication device.
[0007]
The present invention has been made in order to solve the above-described problems, and it is an object of the present invention to provide an antenna that suppresses heat generation due to power loss of a radiation electrode and has small wavelength fluctuation.
[0008]
[Means for Solving the Problems]
According to the present invention, on the outer surface of the insulator, one end has a radiation electrode having a free end, and the other end of the radiation electrode has an electrode having a width larger than the line width of the radiation electrode. An antenna in which a ratio (b / a) of a to a width b of the electrode is 1.5 to 20. With this configuration, heat generated by power loss of the radiation electrode is radiated by the electrode, temperature rise of the radiation electrode and the insulator is suppressed, and variation in antenna wavelength can be reduced. In the present invention, after the radiation electrode and the electrode are formed on different insulators, the radiation electrode and the electrode may be electrically connected by means such as soldering.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
An antenna according to the present invention will be described with reference to FIG. FIG. 1 is a perspective view of an antenna according to one embodiment of the present invention. This antenna has an electrode 3 having a width larger than the line width of the radiation electrode 2 so as to be electrically connected to a spiral radiation electrode 2 formed on the outer surface of the insulator 1.
[0010]
The insulator 1 is made of dielectric ceramics such as barium titanate, calcium titanate, calcium zirconate, lead titanate, lead zirconate titanate, and alumina, and low-loss glass epoxy and Teflon from the viewpoint of antenna characteristics. Is preferable, and in a frequency band up to 1 GHz, a soft magnetic material such as NiZn ferrite having a relative permeability of less than 10 may be used.
[0011]
The radiation electrodes 2 and the electrodes 3 are formed by appropriately selecting from methods such as printing, vapor deposition, and plating. Further, the radiation electrode 2 and the electrode 3 are preferably formed of a metal material having a small electric resistance, such as Au, Pt, Ag, Cu, or an alloy containing these as a main component.
[0012]
The radiation electrode 2 may be formed inside the dielectric 1 by a lamination technique used for a chip capacitor or the like, or a plurality of conductor lines formed inside the dielectric 1 may be formed on the outer surface of the dielectric 1. It may be formed so as to be electrically connected by at least one or more formed conductor lines.
[0013]
The width of the electrode 3 is formed to be larger than the width of the radiation electrode 2. If the ratio (b / a) of the maximum width b to the width a of the radiation electrode 2 (b / a) is less than 1.5, the power of the radiation electrode 2 is reduced. Heat generated due to the loss is not enough to be radiated by the electrode 3, and if it exceeds 20, it is not preferable because the insulator 1 becomes large.
[0014]
【Example】
(Example 1)
A powder of a dielectric material composed of calcium zirconate was subjected to pressure molding and sintering, followed by cutting to obtain a rectangular parallelepiped dielectric 1 having a width of 5 mm, a height of 3 mm and a length of 10 mm. By using a paste material mainly composed of Ag, the radiation electrode 2 and the electrode 3 of approximately three turns were printed and formed on the outer surface. Furthermore said feeding terminal 4 for mark pressurizing the voltage to the radiation electrode printed with an Ag paste on the outer surface of the dielectric is formed, then radiation electrode 2, electrode 3, the feeding terminal 4 at 850 ° C. This was baked to obtain a 2 GHz band antenna. The line width a of the radiation electrode 2 after baking was 0.5 mm and the thickness was 10 μm, the width b of the electrode 3 was 1 mm and the length was 5 mm, and the thickness was 10 μm. In another embodiment, the line width a of the radiation electrode 2 is fixed at 0.5 mm and the width b of the electrode 3 is 0.75 mm. As a comparative example, the width b of the electrode 3 is 0.25 mm and 0.5 mm. The manufactured antenna was manufactured in the same procedure.
[0015]
After the power supply terminal 4 of the antenna was soldered to the evaluation board and left at room temperature for 2 hours, the temperature t ₀ of the radiation electrode and the resonance frequency f _{0 of the} antenna were measured at room temperature with a radiation thermometer and a spectrum analyzer, respectively. It was measured. Further, an antenna drive test in which 1 W of power was continuously supplied from the AC power source to the radiation electrode 2 for one minute was performed, and the temperature t ₁ of the radiation electrode 2 and the resonance frequency f _{1 of the} antenna after the test were measured. Table 1 shows the results of evaluating changes in temperature and resonance frequency before and after the test.
[0016]
[Table 1]

[0017]
Compared with the sample of the comparative example, the sample of the embodiment has a smaller temperature change of the radiation electrode 2 and a smaller variation rate of the resonance frequency of the antenna. Further, even when the power was continuously supplied from the AC power supply, the temperature change was extremely small, and the change in the resonance frequency was practically no problem. On the other hand, the sample of the comparative example continued to rise in temperature and changed in temperature by several degrees to several tens degrees Celsius, and the resonance frequency changed greatly.
[0018]
(Example 2)
A paste material mainly composed of Ag is formed on the outer surface of a dielectric material 1 obtained by pressing and sintering a dielectric material powder made of calcium zirconate into a rectangular parallelepiped shape having a width of 5 mm, a height of 3 mm and a length of 5 mm. The radiating electrode 2 of approximately three turns was printed and formed by using. Furthermore said feeding terminal 4 for mark pressurizing the voltage to the radiation electrode printed with an Ag paste on the outer surface of the dielectric is formed, then baked radiation electrode 2, the feeding terminal 4 at 850 ° C.. The dielectric 1 on which the radiation electrode 2 and the power supply terminal 4 were formed was soldered to the Teflon substrate on which the electrode 3 was formed to obtain a 2 GHz band antenna. Hereinafter, since it is the same as the first embodiment, the description thereof is omitted.
[0019]
[Table 2]

[0020]
In the present embodiment, as in the case of the first embodiment, the temperature of the conductor line 2 and the variation rate of the resonance frequency of the antenna are small, and the temperature change is extremely small even when the driving test is continued. The change of the resonance frequency was practically no problem.
[0021]
【The invention's effect】
As described above, according to the present invention, it is possible to suppress the heat generation due to the power loss of the conductor line due to the miniaturization of the antenna and to obtain an antenna with small wavelength fluctuation.
[Brief description of the drawings]
FIG. 1 is a perspective view of an antenna according to an embodiment of the present invention.
FIG. 2 is a perspective view of an antenna according to another embodiment of the present invention.
FIG. 3 is a perspective view of a conventional helical antenna.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Insulator 2 Radiation electrode 3 Electrode 4 Power supply terminal

Claims (3)

An antenna having a radiation electrode having a free end on one end on an outer surface of an insulator, the other end of the radiation electrode being provided with an electrode having a width larger than the line width of the radiation electrode, and having a line width a of the radiation electrode. An antenna having a ratio (b / a) of 1.5 to 20 to a width b of the electrode . The antenna according to claim 1 , wherein the radiation electrode is formed on an outer surface of a rectangular parallelepiped made of ceramics . The antenna according to claim 1, wherein the radiation electrode and the electrode are formed on different insulators.

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