JP2007202085A - Wideband antenna element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wideband element which improves communication sensitivity, further is small-sized and simplifies a structure, further, a wideband antenna using the element in an antenna to be integrated into an information terminal device such as a personal computer or a PDA. <P>SOLUTION: An elliptic portion (2a) facing a ground plate (4) is provided and a projecting portion (2b) for impedance correction is provided in an upper end portion of a narrow element body (1). Furthermore, the narrow element body (1) and the ground plate (4) are electrically connected by a short-circuiting part (3), an inner conductor (5a) of a coaxial cable (5) is connected to a feed point (P1) of the elliptic portion (2a), and an outer conductor (5b) of the coaxial cable (5) is connected to a ground point (P2) on the ground plate (4). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a broadband antenna element incorporated in an information terminal device such as a personal computer, a PDA (portable information device), a mobile phone, or a VICS. More specifically, the present invention relates to a small antenna element that is particularly excellent in communication sensitivity in a wide band.

In recent years, in a PDA or the like mounted on a wireless LAN or BLUETOOTH (short-range wireless data communication system), there is an increasing demand for downsizing as the frequency of antennas increases. In order to cope with this, in recent years, a monopole or dipole wideband (UWB) antenna element including a ground plate and an arc-shaped radiation electrode element body that is electrically disconnected has been proposed (for example, Patent Document 1). reference).

However, in these antenna elements, the ground plate and the radiating electrode element main body are not electrically connected, so when incorporated in an information terminal device such as a personal computer, the metal casing portion of the information terminal device The problem that the communication became unstable was affected. Furthermore, since this phenomenon varies depending on the information terminal device in which the antenna element is incorporated, in reality, adjustment is required for each device, and there is a problem in the workability of the incorporation.

On the other hand, a broadband antenna element in which the arc-shaped radiation electrode element is electrically connected to a ground plate is also known (see, for example, Patent Document 2).

However, this antenna element does not have sufficient broadband characteristics as can be seen from FIG. 4 of the same document 2, and furthermore, as shown in FIGS. 1 (a) to 1 (d), its configuration is complicated. Because of its three-dimensional structure, there is a problem that the installation location is restricted.

JP 2004-328703 A JP 2001-217636 A

Accordingly, an object of the present invention is to be incorporated in an information terminal device such as a personal computer or a PDA, and at that time, stable communication can be performed without being affected by the information terminal device, and a small-sized and simple structure wideband. An object of the present invention is to provide an antenna element and a broadband antenna employing the element.

In the planar antenna element in which one end portion of the narrow radiation electrode element body is electrically connected to the ground plate by a short-circuit portion, the inventors have made a wideband by adding a special shape change to the element body. An element and a broadband antenna employing the element have been realized.

That is, according to the present invention, the narrow radiation electrode element main body is provided on the end of the element main body excluding the arc-shaped portion or on the opposite side surface, provided on the side surface of the main body facing the ground plate. In addition, the shape is changed to a special shape that also has a protruding portion as an impedance correction means. In addition, the inner conductor of the feeding coaxial cable is connected to the arcuate portion at the shortest distance from the ground plate, and at the same time, the outer conductor of the cable is connected to the ground plate.

According to the present invention, a special shape change is added to the narrow-width radiation electrode element main body, thereby realizing the correspondence to a small and wide-band planar antenna element. When this is compared with the prior art, a particularly remarkable effect is achieved in that the bandwidth is greatly expanded. Furthermore, the width and height of the antenna element itself are comparable to the conventional one, and the configuration is simplified from the conventional one. As a result, the broadband antenna element of the present invention is extremely useful for incorporating information terminal equipment such as a personal computer.

Hereinafter, the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a plan view showing an example of a broadband antenna element according to the present invention.
FIG. 2 is a perspective view showing an example of an antenna employing the broadband antenna element of FIG.
FIG. 3 is a diagram (graph) showing frequency characteristics (VSWR characteristics) of the antenna of FIG.
FIG. 4 is a plan view showing another embodiment of the broadband antenna element according to the present invention.
FIG. 5 is a plan view showing still another aspect of the broadband antenna element according to the present invention.
FIG. 6 is a diagram showing frequency characteristics (VSWR characteristics) of an antenna that employs the wideband antenna element of FIG.

First, the basic concept of the present invention will be described with reference to FIGS. In these figures, a narrow radiation electrode element body (hereinafter abbreviated as “element body”) has an arc-shaped portion on the side of the body facing the ground plate, and the element body excluding the arc-shaped portion. A broadband antenna element is shown in which a protrusion as an impedance correction means is provided at the end or on the opposite side. Here, (1) is the element body, (2a) is an arcuate portion attached to the element body (1), and (2b) is a protrusion for impedance correction attached to the upper side surface of the element body (1). (3) is a short circuit, (4) is a ground plate, (P1) is a feeding point to which the inner conductor of the feeding coaxial cable is connected, and (P2) is an outer conductor of the feeding coaxial cable. Earth point to be played. In this case, the short circuit plate (3) electrically connects one end of the element body (1) and the ground plate (4).

FIG. 2 shows an antenna employing the above elements. In the figure, the symbols (1), (2a), (2b), (3), (4), (P1), and (P2) are the same as those in FIG. On the other hand, (5) is a coaxial cable for feeding, (5a) is an inner conductor of the feeding coaxial cable (5), and (5b) is an outer conductor of the feeding coaxial cable (5). In this case, the inner conductor (5a) and the outer conductor (5b) are connected to the feeding point (P1) and the earth point (P2), respectively.

FIG. 3 shows the antenna frequency characteristics (VSWR characteristics) that are the experimental results of the antenna shown in FIG. From FIG. 3, in the antenna using the wideband antenna element of the present invention, widening over a wide range of 3 GHz to 10 GHz is realized while maintaining the VSWR characteristics well.

What is characteristic in the embodiment described above is that one end of the element body (1) and the ground plate (4) are connected via the short-circuit portion (3) and then opposed to the ground plate (4). An arcuate portion (2a) is attached to the side surface of the element body (1), and a projection (2b) for impedance correction is attached to the opposite side surface (upper side surface as viewed in the figure) of the element body (1). It is to have done. By doing so, as shown in FIG. 3, it is possible to realize a wide band over a wide band (UWB band) of 3 GHz to 10 GHz.

This point will be described in more detail with reference to FIGS. 1 to 3 again.

First, when one end of the element body (1) and the ground plate (4) are connected via the short-circuit portion (3), when the antenna is incorporated into an information terminal device such as a personal computer. However, it is not affected by the metal casing of the information terminal device, and therefore communication is basically stabilized.

In this state, the high-frequency current from the feeding point (P1) provided in the arc-shaped portion (2a) of the element body (1) not only disperses from side to side but also flows along various paths of the element body (1). Along with this, a high frequency electromagnetic field including not only the fundamental wave but also a harmonic such as a double frequency is generated, and many resonance points are generated. Therefore, the position of the feeding point (P1) is also important. That is, by providing this feeding point (P1) at a location closest to the ground plate (4) in the arcuate part (2a), various paths with different element lengths are generated, and therefore as many as possible. The resonance point is obtained. About the dimension of the element main body (1) at this time, the length should just exist in the range of 20-40 mm and the width | variety 1-5 mm. In addition, the dimension of the arcuate part (2a) may be 0.5 to 1.5 times based on the length of the element body (1), but generally 0.8 to 1.2 times. If it is in the range.

At that time, the protrusion (2b), which is an impedance correction means arranged on the upper side surface of the element body (1), contributes to increase the reactance component and widen the bandwidth. The dimensions (vertical and horizontal) of the protrusion (2b) may be selected appropriately depending on the reactance component to be increased. In general, the length (20% to 50%) in the vertical direction is based on the length of the element body. %, In the range from 30% to 60% in the horizontal direction.

About short circuit part (3), the length should just exist in the range of 1 mm-10 mm, and the width of 0.5 mm-10 mm. As long as this short circuit part (3) exhibits the function which connects an element main body (1) and a ground board (4), the shape is arbitrary. Further, for the ground plate (4), in order to obtain stable antenna operation, the necessary minimum area (mm2) is required to be λ / 4 * λ / 4 (λ is a wavelength) or more. Therefore, when more stable antenna operation is desired, it is preferable to increase the area as long as space permits.

As the material of the antenna element described above, a conductive metal such as white (white copper), copper, iron, or brass is preferably employed. In producing the antenna element, the single metal plate may be punched out by electric discharge machining to form an integrally punched body of all elements extending from the element body (1) to the ground plate (4). Alternatively, it is also useful to obtain a desired antenna element shape by etching the metal film in a state where a metal thin film such as a copper foil is attached to the flat insulating substrate.

When feeding power to such an antenna element, the inner conductor (5a) of the feeding coaxial cable (5) is connected to the feeding point (P1), while the outer conductor (5b) of the cable is connected to the ground point (P2). do it. In order to connect the power supply coaxial cable (5) to the power supply point (P1) and the ground point (P2), soldering or ultrasonic connection or the like may be used. As the feeding coaxial cable (5), a well-known high-frequency coaxial cable such as a fluororesin coating is preferably employed.

The embodiment described in FIGS. 1 to 3 is an example in which all elements extending from the element body (1) to the ground plate (4) are arranged on the same plane. However, it goes without saying that the planar element is provided with various modifications corresponding to the shape corresponding to the installation space.

Furthermore, there are various modes for the protrusion that is one element of the broadband element according to the present invention. Examples of these are shown in FIGS.

In the embodiment of FIG. 4, an L-shaped sub-element (6) is attached to the element body (1) so as to be folded back from the other end to the center of the body. Thereby, the specific band in the UWB of the element of FIG. 1 is further widened. For example, by providing a resonance point in the vicinity of 2.45 GHz via the L-shaped sub-element (6), the frequency characteristic (VSWR) of 2.4 GHz to 2.50 GHz outside the UWB band is improved. . As a result, in addition to the UWB band (3 GHz to 10 GHz), the frequency characteristic (VSWR) of 2.4 GHz to 2.50 GHz is also improved, resulting in a wider band.

In order to resonate at a frequency in the vicinity of 2.45 GHz, the length and width of the sub-element (6) may be appropriately adjusted so as to resonate in the vicinity of 2.45 GHz. That is, the length of the sub-element (6) may be set so as to be approximately a quarter wavelength as in the case of a normal monopole antenna. More specifically, in the case of 2.45 GHz, it may be about 10 mm. The width may be selected in the range of 0.5 mm to 3 mm in consideration of the induced electric field strength and dimensions.

In the aspect of FIG. 5, correspondence in a wider band of 2.4 GHz to 10.6 GHz is realized. In this case, an L-shaped sub-element (6a) extending from one end of the element main body (1) beyond the central portion of the main body is attached, whereby the element main body (1) is connected to the element main body (1). The slit (7) having an open end formed at the end functions as a slit antenna element.

In order to resonate the slit (7) that is open at one end in the wider range of frequencies in the embodiment of FIG. 5, the length and width of the sub-element (6a) and further the length of the slit (7) What is necessary is just to adjust a width | variety suitably according to the target frequency range. Specifically, the length of the sub-element (6a) may be a length (about 20 mm) that improves the frequency characteristics in the vicinity of the low band 2.4 GHz. In addition, in order to improve the frequency characteristics of a high region of 10 GHz or more, the slit (7) with one end opened is slit-resonated. In this sense, the sub-element (6) in FIG. 4 and the sub-element (6a) in FIG. 5 can be said to be impedance correction means that also serves as a sub-resonance function. The width of the one-end open slit (7) is preferably 0.1 mm to 4 mm, particularly preferably 0.5 mm to 1 mm, in order to function stably as a slit antenna element.

A specific example of an information terminal device built-in antenna that realizes a wide band of 3 GHz to 10 GHz, as shown in FIG. 2, connected to the wide-area antenna element of FIG. 1 as shown in FIG.

First, a rectangular flat plate of 44 mm in length, 30 mm in width, and 0.1 mm in thickness was processed with an electric discharge machine to obtain an antenna element having the shape shown in FIG. At this time, the length of the element body (1) is 25.5 mm, the width is 2 mm, a circular arc portion (2a) having a radius of 9.2 mm and a radial arc height of 8 mm on the lower side of the main body, and In the vicinity of the center of the upper side surface, a protrusion (2b) having a width of 10 mm and a height of 5.5 mm was provided.

Moreover, the right end part of the element main body (1) and the upper right end of the ground plate (4) were electrically connected by the short circuit part (3). At this time, the short-circuit portion (3) was 8.5 mm in height and 2 mm in width, and the ground plate (4) was 30 mm in both length and width.

Furthermore, the feeding point (P1) was set at a position 1 mm inside from the central end surface of the lowermost side of the arcuate part (2a). The ground point (P2) was set on the ground plate (4) at a position 1 mm inside from the upper end of the ground plate (4) facing the feeding point (P1). In this way, a small broadband antenna element having a height of 44 mm and a width of 30 mm was completed.

Next, the broadband antenna element described above was built in an information terminal device. In this case, in order to function as an antenna, a fluororesin (PFA) -coated high-frequency coaxial cable having an outer diameter of 0.93 mm and a conductor diameter of 0.24 mm is used as the feeding coaxial cable (5), and the inner conductor (5a) and the outer The conductor (5b) was connected to the feeding point (P1) and the ground point (P2) by soldering, respectively. Thus, an information terminal device built-in antenna was obtained.

Finally, when the frequency characteristic (VSWR) of this antenna was tested, the frequency characteristic shown in FIG. 3 was obtained. As is apparent from this figure, the antenna shown in this example resonates over a wide band of 3 GHz to 10 GHz, and it can be seen that a sufficient bandwidth is secured.

The above examples are merely examples of the present invention, and it goes without saying that various modifications and applications are possible within the scope of the idea of the present invention.

The wide-band antenna element of the present invention and the wide-band antenna including the element can be incorporated into information home appliances or automobile-related devices in addition to personal computers and various information terminal devices such as PDAs.

It is a top view showing one mode of a broadband element concerning the present invention. It is a perspective view which shows the example of a broadband antenna containing the broadband element of FIG. It is a figure which shows the frequency characteristic (VSWR characteristic) of the wideband antenna of FIG. It is a top view which shows the other aspect of the broadband element which concerns on this invention. It is a top view which shows the further another aspect of the broadband element which concerns on this invention. It is a figure which shows the frequency characteristic (VSWR characteristic) of the wideband antenna of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Narrow-shaped radiation | emission electrode element main body 2a Arc-shaped part 2b Protrusion part 3 Short-circuit part 4 Ground plate 5 Coaxial cable 5a for electric power feeding Internal conductor 5b of a high frequency coaxial cable External conductor 6 of a high frequency coaxial cable L-shaped subelement 6a L-shape Subelement 7 One end open slit P1 Feed point P2
Earth point

Claims (6)

A wide-band antenna element, wherein one end of the narrow radiation electrode element body is provided in an electrically connected state with a ground plate by a short-circuit portion, and satisfies the following requirements a to c.
a. The element body has an arcuate portion facing the ground plate;
b. A protrusion for impedance correction is provided on the end or opposite side of the element body excluding the arcuate portion; and c. A feeding point is provided in the arcuate portion at the shortest distance from the ground plate. The broadband antenna element according to claim 1, wherein the protrusion has a rectangular shape. The broadband antenna element according to claim 1, wherein the protrusion has an L shape. The broadband antenna element according to claim 3, wherein a slit having one open end is formed between the L-shaped protrusion and the element body. The broadband antenna element according to any one of claims 1 to 4, wherein all elements extending from the element body to the ground plate are arranged on the same plane. The internal conductor of the high-frequency coaxial cable is connected to the feeding point of the broadband antenna element according to any one of claims 1 to 5, and the external conductor of the high-frequency coaxial cable is connected to the end of the ground plate facing the feeding point. Wideband antenna characterized by being made.

Images