JP3264166B2 - Planar antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar antenna used for portable communication equipment and the like.

[0002]

2. Description of the Related Art In recent years, with the spread of portable communication devices, there has been an increasing demand for miniaturization of antennas used for transmitting and receiving high-frequency signals between the communication devices. In such a communication device, if the antenna is installed outside the communication device itself, it is difficult to reduce the size of the communication device, and since an external force acts directly on the antenna, mechanical strength and durability are increased. May cause problems such as deterioration of characteristics and changes in characteristics. Furthermore, in the case of a configuration in which the antenna and the communication device main body are connected by a connector, transmission and reception of high-frequency signals are performed through the connector,
Problems such as insertion loss and change in resonance frequency due to the connector occur. Also, the use of the connector increases the number of parts, which is not preferable in terms of workability and cost. Therefore, a planar antenna for surface mounting that can be directly surface-mounted on a substrate without using a connector has been proposed.

FIG. 7 is a perspective view showing a planar antenna for surface mounting proposed in Japanese Patent Application Laid-Open No. 7-221537. In the planar antenna 70 shown in FIG.
The radiation conductor film 72 is formed on the entire surface of the substrate. Further, a ground conductor film 73 is formed on the back surface of the dielectric substrate 71 near one short side and substantially over half of the back surface. Further, a power supply electrode 74 is formed from the back surface of the dielectric substrate 71 near the other short side to the side surface of the dielectric substrate 71. Further, inside the dielectric substrate 71, a through hole 75 having a conductor on the inner wall is formed, and thereby the radiation conductor film 72 and the feeding electrode 74 are electrically connected.
The planar antenna 70 thus configured is surface-mounted on a circuit board incorporated in the communication device main body, and power is supplied from the communication device main body to the radiation conductor film 72 via the power supply electrode 74 and the through hole 75. The electromagnetic wave is radiated from the radiation conductor film 72 into the air.

[0004]

However, in the above-described planar antenna in which the radiating conductor film and the feeding electrode are connected by a through hole, power is supplied from the feeding electrode to the radiating conductor film through the through hole. For this reason, the connection between the feed electrode and the through-hole, the connection between the through-hole and the radiation conductor film, and the like have a large effect on frequency characteristics, impedance matching, and the like (hereinafter, referred to as antenna characteristics). It is difficult to design to improve the characteristics.
Also, the processing accuracy of the through-hole has a great influence on the antenna characteristics, and it is difficult to manufacture a planar antenna having good antenna characteristics. Further, since the input impedance of the planar antenna depends on the position of the through hole with respect to the radiating conductor film, it is also difficult to adjust the input impedance of the manufactured planar antenna.

[0005] In view of the above circumstances, an object of the present invention is to provide a planar antenna which can easily obtain good antenna characteristics and can easily adjust impedance.

[0006]

A planar antenna according to the present invention that achieves the above object is a surface-mounted planar antenna.
Te, (1) a dielectric substrate (2) that the radiating conductor film (3) formed on the dielectric surface of the substrate ground conductor film (4) formed on the rear surface of the dielectric substrate inside the dielectric substrate The excitation conductor film formed and exposed from the dielectric substrate so that the tip can be trimmed. (5) The excitation conductor film formed on the side surface of the dielectric substrate.
A power supply electrode connected to the rear end opposite to the front end portion. (6) a radiation conductor film formed on a side surface of the dielectric substrate different from the portion where the power supply electrode is formed; A short-circuit plate connected to both of the ground conductor films is provided.

[0007] Here, the planar antenna of the present invention is used.
The ground conductor film on the back surface of the dielectric substrate is
Part has a notched shape, and the notched
A conductor film is formed on the part, and the conductor film is
And the power supply electrode is connected to the excitation conductor film.
Is preferred.

[0008]

Embodiments of the present invention will be described below. FIG. 1 is a perspective view showing a planar antenna according to a first embodiment of the present invention, FIG. 2 is a view showing a radiation conductor film side of the planar antenna shown in FIG. 1, and FIG. 3 is a grounding of the planar antenna shown in FIG. It is a figure which shows the conductor film side.

In this planar antenna 10, as shown in FIG. 1, the first dielectric substrate 11 has the same width as the first dielectric substrate 11, and the first dielectric substrate 1 has the same width.
Second dielectric substrates 13 having a length dimension longer than one length dimension (the left-right direction in FIGS. 2 and 3) are overlapped and integrated. On the surface of the first dielectric substrate 11, a radiation conductor film 12 for radiating electromagnetic waves is formed. On the surface of the second dielectric substrate 13 on the side in contact with the first dielectric substrate 11, the second dielectric substrate 1
An excitation conductor film 14 is formed as a strip line extending beyond the first dielectric substrate 11 in three longitudinal directions.
On the back surface of the second dielectric substrate 13, a ground conductor film 15 is formed. As shown in FIG. 3, the ground conductor film 15 has a shape in which one short side is partially cut out, and a conductor film 16 is formed in the cut out portion. A power supply electrode 17 is formed on a side surface of the second dielectric substrate 13. The power supply electrode 17 is connected to the excitation conductor film 14 and the conductor film 16. Further, short-circuit plates 18 and 19 are formed on both side portions of the side surfaces of the first and second dielectric substrates 11 and 13 with the feed electrode 17 interposed therebetween, and the short-circuit plates 18 and 19 connect the radiation conductor film 12 and the ground. Conductive film 15
Is short-circuited.

[0010] The planar antenna 10 thus configured
Is mounted on, for example, a circuit board of a portable communication device, and power is supplied from the portable communication device to the power supply electrode 17 of the planar antenna 10. Then, electromagnetic waves are radiated from the radiation conductor film 12 into the air by electromagnetic coupling between the excitation conductor film 14 and the radiation conductor film 12. Thus, in the planar antenna 10 of the present embodiment, the radiation conductor film 12 formed on the surface of the first dielectric substrate 11 and the excitation conductor film 14 formed on the surface of the second dielectric substrate 13 Since the connection is made by electromagnetic coupling, a through-hole unlike a conventional planar antenna is unnecessary, so that the antenna characteristics are not adversely affected, and the design and manufacture of the planar antenna 10 having good antenna characteristics are facilitated. .

Further, by forming the short-circuiting plates 17 and 18 on the side surfaces of the first and second dielectric substrates 11 and 13, the short-circuiting plate 1 is formed.
7, 18 can also serve as a ground electrode, which is effective in surface mounting and can reduce the number of components. Generally, like the planar antenna 10 of the present embodiment,
In a patch antenna mounted on a circuit board, the length of a radiating element (radiating conductor film) is set to a half wavelength with respect to a used wavelength to make a resonance state. Works as Here, as shown in FIG. 4A, the voltage / current distribution on the element is such that the voltage is maximum and the current is 0 at both ends of the element, and the voltage is 0 and the current is maximum at the center of the element. The patch antenna shown in FIG. 4B is cut at the center of the element to form a patch antenna shown in FIG. 4C. The relationship between current and voltage on the indicated element can be maintained and the element operates as an antenna. Further, when a part of the side surface of the element is short-circuited by a short-circuit plate (shaded portion) as shown in FIG.
(B), since the element is changed from the longitudinal direction of the element shown in FIG. 4 (c) to a diagonal direction or the like toward the short-circuit plate, the element size can be reduced.

In the planar antenna 10 of the present embodiment, the feed electrode 1 on the side surface of the first and second dielectric substrates 11 and 13 is provided.
Short-circuit plates 18 and 19 are formed at both ends with the radiation conductor film 12 and the ground conductor film 15 being short-circuited by these short-circuit plates 18 and 19. It flows toward the short-circuit plates 18 and 19. Therefore, the length of the radiation conductor 12 in the longitudinal direction may be short, and the size of the planar antenna 10 is reduced.

In the planar antenna 10 according to the present embodiment,
Since the length of the excitation conductor film 14 formed on the surface of the second dielectric 13 is longer than the length of the first dielectric substrate 11, the tip of the excitation conductor film 14 is exposed. ing. Here, the impedance of the planar antenna 10 can be easily adjusted by trimming the exposed end portion of the excitation conductor film 14 and changing the length of the excitation conductor film 14.

FIG. 5 is a perspective view showing a planar antenna according to a second embodiment of the present invention. Planar antenna 50 shown in FIG.
In the figure, a radiation conductor film 52 is formed on almost one half of the front surface of the dielectric substrate 51 near one short side, and a ground conductor film 53 is formed on the back surface. An excitation conductor film 54 is formed inside the dielectric substrate 51. Further, the power supply electrode 5 is provided on the side surface of the dielectric substrate 51.
The power supply electrode 55 and the excitation conductor film 5 are formed.
4 are connected. Further, on the side surface of the dielectric substrate 51,
Short-circuit plates 56 and 57 are formed at both ends of the power supply electrode 55, and the short-circuit plates 56 and 57 short-circuit the radiation conductor film 52 and the ground conductor film 53. Further, a circular window is provided in a portion of the dielectric substrate 51 different from the portion where the radiation conductor film 52 is formed, and a tip portion of the excitation conductor film 54 is exposed from the window.

With the planar antenna 50 thus configured, electromagnetic coupling may be performed between the excitation conductor film 54 and the radiation conductor film 52. Further, the impedance can be easily adjusted by trimming the exposed end portion of the excitation conductor film 54.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the planar antenna 10 shown in FIG. 1 will be described below. First, the first and second dielectric substrates 1
As 1 and 13, two glass epoxy substrates having a relative dielectric constant of 4.5 and a thickness of 1.6 mm were prepared. On the surface of the first dielectric substrate 11, which is the first glass epoxy substrate of these two glass epoxy substrates, the length of one side is approximately one quarter wavelength of the resonance frequency in the dielectric. A copper radiation conductor film 12 having a rectangular shape was formed by etching. Further, the radiation conductor film 1 of the first dielectric substrate 11
The portion other than the portion where 2 was formed was cut and removed. Further, the excitation conductor film 14 and the ground conductor film 15 are formed on the front and back surfaces of the second dielectric substrate 13 which is the second glass epoxy substrate by etching, respectively.
The conductor film 16 was formed on a portion of the back surface of the dielectric substrate 13 different from the portion where the ground conductor film 15 was formed. Further, the conductor film 16 and the excitation conductor film 14 are connected by soldering using a copper foil having a thickness of 50 μm.
The power supply electrode 17 was formed on the side surface of the.

Next, the back surface of the first dielectric substrate 11 and the second
The first and second dielectric substrates 11 and 13 were integrated with each other using an epoxy-based adhesive. Next, the integrated first and second dielectric substrates 11,
50 μm on both sides of the side surface of the power supply electrode 13 with the power supply electrode 17 interposed therebetween.
The short-circuit plates 18 and 19 were formed by soldering the radiation conductor film 12 and the ground conductor film 15 using a thick copper foil.

FIG. 6 shows the results of impedance adjustment by trimming of the five planar antennas 10 thus manufactured. Circles and arcs shown in FIG. 6 indicate a resistance component and a reactance component, respectively, of the impedance of the antenna, and an impedance value is determined by an intersection of the circle and the arc. In the portion indicated by the arrow P, the impedance values (circles and arcs are not shown) of the five planar antennas 10 by trimming are shown. Thus, the impedance of the planar antenna 10 could be easily adjusted.

[0019]

As described above, in the planar antenna of the present invention, good electromagnetic characteristics can be easily obtained because electromagnetic coupling is performed between the excitation conductor film and the radiation conductor film. Further, since the tip portion of the excitation conductor film is exposed, the impedance can be easily adjusted.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a planar antenna according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a radiation conductor film side of the planar antenna shown in FIG. 1;

FIG. 3 is a diagram showing a ground conductor film side of the planar antenna shown in FIG. 1;

FIG. 4 is a diagram showing voltage and current distributions on elements of a patch antenna, and element sizes of each patch antenna.

FIG. 5 is a perspective view showing a planar antenna according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a result of impedance adjustment by trimming of a manufactured planar antenna.

FIG. 7 is a perspective view showing a planar antenna for surface mounting proposed in Japanese Patent Application Laid-Open No. 7-221537.

[Explanation of symbols]

 10, 50 Planar antenna 11 First dielectric substrate 12, 52 Radiating conductor film 13 Second dielectric substrate 14, 54 Excitation conductor film 15, 53 Ground conductor film 16 Conductor film 17, 55 Feed electrode 18, 19, 56 , 57 Shorting plate 51 Dielectric substrate

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-196924 (JP, A) JP-A-7-162226 (JP, A) JP-A-2-308604 (JP, A) JP-A-4- 172001 (JP, A) JP-A-7-249932 (JP, A) JP-A-4-330806 (JP, A) JP-A-6-15328 (JP, U) JP-A 7-1619 (JP, U) (58) Field surveyed (Int.Cl. ⁷ , DB name) H01Q 13/08 H01Q 1/27 H01Q 1/48

Claims (2)

(57) [Claims] 1. A surface mounted planar antenna, comprising: a dielectric substrate; a radiation conductor film formed on a surface of the dielectric substrate; a ground conductor film formed on a back surface of the dielectric substrate; The tip portion is formed inside the dielectric substrate.
An excitation conductor film exposed from the dielectric substrate so as to be capable of being trimmed , and the tip of the excitation conductor film formed on a side surface of the dielectric substrate.
A feed electrode connected to the rear end opposite to the end portion; and the radiating conductor film and the grounding conductor film formed on a side surface of the dielectric substrate different from the portion where the feed electrode is formed. And a short-circuit plate connected to both of them. 2. The ground conductor film on the back surface of the dielectric substrate has one side.
Part of the short side of the
A conductor film is formed on the chipped part, and the conductor film is
The power supply electrode is connected to the excitation conductor film.
Planar antenna according to claim 1, characterized in that it is.