JP3245299B2 - 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 the shape of a planar antenna built in a housing of a radio.

[0002]

2. Description of the Related Art As a planar antenna built in a housing of a wireless device such as a portable telephone, an inverted F antenna which is a one-side short-circuit type planar antenna is used.
A shaped antenna is used. FIGS. 4A and 4B are schematic views of an inverted F-shaped antenna provided with a folded portion for downsizing of the antenna. (A) is a side view of an inverted F-shaped antenna,
(B) is a top view of the inverted-F antenna. A resonance conductor plate 2 whose perimeter is about の of the wavelength of the operating frequency is disposed above the ground conductor plate 1. In some cases, a dielectric layer is provided between the ground conductor plate 1 and the resonance conductor plate 2 in order to reduce the perimeter. The conductor plate 2 for resonance and the conductor plate 1 for ground are connected by the conductor 4, and the conductor 4 is located at the edge of the conductor plate 2 for resonance. As shown in FIG. 4, an inverted F-shaped structure is formed by the conductor plate 2 for resonance, the conductor plate 1 for ground, the conductor 4, and the power supply unit 3, and the structure is separated from the conductor 4 to reduce the size of the conductor plate 2 for resonance. By providing the bent portion 5 at the position where the electric field of the resonance conductor plate 2 is maximized, the capacitance is increased by approaching the ground conductor plate 1, so that the resonance frequency of the antenna can be lowered and the area of the resonance conductor plate 2 can be reduced. The size can be reduced. Further, by providing a dielectric layer between the resonance conductor plate 2 and the ground conductor plate 1, the capacitance between the resonance conductor plate 2 and the ground conductor plate 1 is increased, and the resonance conductor plate is similarly formed. 2 can be reduced in area.

[0003]

With the recent miniaturization of mobile phones and the like and the increase in the frequency to which radio frequencies are allocated, it is necessary to provide a bent portion 5 as shown in FIG. In order to set the resonance frequency, highly accurate sheet metal processing and mounting of the resonance conductor plate 2 and the bent portion 5 are required. Further, in order to provide a dielectric layer between the conductor plate 2 for resonance and the conductor plate 1 for ground for downsizing of the antenna, a dielectric layer is provided between the conductor plate 2 for resonance and the conductor plate 1 for ground. Although it can be easily realized by using the laminated substrate having the above, the provision of the bent portion 5 on the laminated substrate has a problem that a conductor plate is further required between the dielectric layers, and the price becomes extremely high. .

[0004] It is an object of the present invention to provide a planar antenna which can be easily formed of a laminated substrate and has a reduced area of a conductor plate for resonance.

[0005]

In order to solve the above-mentioned problems, a resonance conductor plate having a circumference of about 1/2 of the wavelength of a working frequency and a grounding conductor plate arranged in parallel with the resonance conductor plate are provided. A conductor plate, an edge portion of the resonance conductor plate and a ground conductor plate are connected by a conductor, and a length of one side of the resonance conductor plate connected by the conductor is L, and the resonance is parallel to the side. When the maximum width of the conductor plate is W, L is about 1 of W
A planar antenna characterized in that the area of the conductor plate for resonance is reduced by setting it to / 3 or less.

[0006]

In the planar antenna according to the present invention, since the resonance conductor plate 2 has no bent portion, the resonance conductor plate 2 and the ground conductor plate 1 parallel to the resonance conductor plate 2 can be accurately formed by a laminated substrate, and the two conductor plates can be formed. The conductor 4 for connection can also be easily formed by a through hole in the laminated substrate. When the length of one side of the resonance conductor plate 2 connected by the conductor 4 is L and the maximum width of the resonance conductor plate 2 parallel to the side is W, L is about 約 or less of W By doing so, the area of the resonance conductor plate 2 can be reduced, so that the substrate area of the laminated substrate is reduced, the cost of the substrate is reduced, and the dielectric layer can be easily provided. The area of the plate can be reduced, and the area occupied by an antenna of a mobile phone or the like can be reduced.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIGS. 1A and 1B are views showing an embodiment of a planar antenna according to the present invention. In the drawings, the same parts are denoted by the same reference numerals. (A) is a side view of a plain antenna, and (b) is a top view of a planar antenna. Next, the operation in such a configuration will be described.

A resonance conductor plate 2 whose peripheral length is about half the wavelength of the operating frequency is disposed above the ground conductor plate 1. In some cases, a dielectric layer is provided in a space between the conductor plate for ground 1 and the conductor plate for resonance 2 in order to reduce the perimeter. The conductor 4 connects the two conductor plates, and is located at the edge of the resonance conductor plate 2. When the length of one side of the resonance conductor plate 2 connected by the conductor 4 is L and the maximum width of the resonance conductor plate 2 parallel to the side is W, L is set to about 1/3 or less of W. .

FIG. 2 shows that in FIG. 1, W = 25.7 mm, V
= 28.8 mm, the conductor 4 is a conductor having a diameter of 0.8 mm, and L is changed when the laminated substrate has a dielectric layer having a dielectric constant of 4 between the resonance conductor plate 2 and the ground conductor plate 1. The characteristic of the resonance frequency of the antenna when K is 5 mm, 10 mm, and 15 mm (measured value) is shown.

In FIG. 2, the maximum width W of the resonance conductor plate 2 parallel to one side of the resonance conductor plate 2 connected by the conductor 4 is shown.
When = 25.7 mm, it can be seen that the resonance frequency of the antenna is slightly higher when one side L of the resonance conductor plate 2 connected by the conductor 4 is between 25.7 mm and 9 mm. This is because the capacity between the conductor plate 2 for resonance and the conductor plate 1 for ground became smaller because the area of the conductor plate 2 for resonance was reduced. Also, as L becomes smaller than 9 mm, it can be seen that the resonance frequency of the antenna rapidly decreases this time. This is because the capacitance between the resonance conductor plate 2 and the ground conductor plate 1 is reduced because the area of the resonance conductor plate 2 is reduced.
It is considered that because L of a portion of the resonance conductor plate 2 connected to the conductor 4 has decreased, the inductance of the resonance conductor plate 2 has increased and the resonance frequency of the antenna has decreased. From FIG. 2, the resonance frequency of the antenna decreases sharply because the capacitance decreases and the resonance frequency of the antenna increases, and the inductance also increases when L is about 1/3 or less of W. You can see that there is. Also, by increasing K, the inductance is increased and the resonance frequency of the antenna is further reduced sharply.
Also at this time, L is about 1/3 or less of W.

FIGS. 3 (a) and 3 (b) show an embodiment in which the embodiment of FIG. 1 is mounted on the back of a radio unit housing. (A)
2 is a side view of the wireless device, and FIG. 2B is a rear view of the wireless device. In FIG. 3, by making L less than about 1/3 of W,
Since the inductance of the portion where L of the resonance conductor plate 2 to which the conductor 4 is connected is less than or equal to 1/3 of W becomes large, as shown in FIG. When attached to body 6, gain is improved in vertical polarization. For example, in FIG. 2, when L = 6 mm, the gain of the antenna is improved by about 0.5 dB as compared with when L = W. It is considered that the inductance contributes to the improvement of the gain of the vertical polarization because the mobile communication such as a mobile phone transmits with the vertical polarization.

Since the electrical length is affected by the structure and material of the housing and the power supply unit, the conductive parts, and the like, the length of the periphery of the resonance conductor plate is determined by fine adjustment.

[0013]

As described above, according to the structure of the present invention, since the resonance conductor plate 2 has no bent portion, the resonance conductor plate 2 and the ground conductor plate 1 parallel to the resonance conductor plate 2 are accurately formed by a laminated substrate. The conductor 4 for connecting the two conductor plates can be easily formed by the through hole of the laminated substrate. Further, since the area of the resonance conductor plate 2 can be reduced, the substrate area of the laminated substrate is reduced, and the price of the substrate is reduced. Further, since the dielectric layer can be easily provided, the area of the resonance conductor plate can be further reduced by the dielectric layer, and the area occupied by the antenna of the mobile phone or the like can be reduced.

The resonance conductor plate 2 to which the conductor 4 is connected
Since the inductance of the portion of the radio device 6 is large, the
, The gain in vertical polarization can be improved.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a planar antenna according to the present invention, wherein (a)
2B is a side view of the planar antenna, and FIG. 2B is a top view of the planar antenna.

FIG. 2 is a characteristic diagram of the planar antenna of the present invention.

3A and 3B show an embodiment in which the planar antenna of the present invention is attached to the back of a wireless device housing, and FIG. 3A is a side view of the wireless device;
(B) is a rear view of the wireless device.

4A and 4B show a conventional inverted-F antenna having a bent portion, wherein FIG. 4A is a side view of the inverted-F antenna, and FIG. 4B is a top view of the inverted-F antenna.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Grounding conductor plate 2 Resonance conductor plate 3 Feeding part 4 Conductor 5 Bending part 6 Radio equipment housing

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01Q 13/08 H01Q 1/24

Claims (2)

(57) [Claims] 1. The length of the circumference is about 1/2 of the wavelength of the operating frequency.
A resonance conductor plate is, and the ground conductor plate this and arranged in parallel are provided, in the planar antenna comprising a single edge portion and the ground conductors plate of the resonance conductor plate and the conductor connected The resonance conductor plate has a width in a predetermined direction.
It comprises two different plane parts, and one plane part is
An edge portion, wherein the one flat portion is the
It has one side of the length L in the same direction as the predetermined direction,
When the maximum width of the other flat portion in the predetermined direction is W,
2. The planar antenna according to claim 1, wherein said L is a plane conductor plate made to be about 1/3 or less of said W. 2. The planar antenna according to claim 1, further comprising a dielectric layer between the resonance conductor plate and the ground conductor plate.