KR100708064B1 - Internal antenna of variable impedance - Google Patents

Abstract

There is provided an antenna whose impedance changes in response to a change in the ground plane due to a change in shape of the terminal. The antenna of the present invention includes a parasitic patch whose arrangement is changed according to the change of the terminal, and changes the coupling of the slit formed in the antenna radiator according to the change in the ground plane. In addition, the antenna of the present invention includes a variable slit in which the shape of the slit is changed according to the change of the terminal, thereby changing the coupling of the slit formed in the antenna radiator.

According to the present invention, the impedance of the radiating element changes in accordance with the change of the ground plane, so that the impedance of the entire antenna can be kept constant.

Parasitic Patch, Slit Patch, Slit, Ground Surface

Description

Internal impedance variable antenna {INTERNAL ANTENNA OF VARIABLE IMPEDANCE}

1 is a view showing a conventional built-in antenna.

Fig. 2 is a top view showing a state of the closed folder of the built-in antenna according to the first embodiment of the present invention.

3 is a cross-sectional view taken along line AA ′ of the antenna of FIG. 2;

Fig. 4 is a top view showing a state at the time of opening of a folder of the built-in antenna according to the first embodiment of the present invention.

5 is a cross-sectional view taken along line AA ′ of the antenna of FIG. 4;

Fig. 6 is a top view showing a state when the built-in antenna closes the folder according to the second embodiment of the present invention.

Fig. 7 is a top view showing a state when the built-in antenna of the built-in antenna according to the second embodiment of the present invention is opened.

8 shows a comparative example of the present invention;

9 is a graph showing the impedance characteristics during folder opening and closing according to a comparative example of the present invention.

10 is a graph showing the impedance characteristics during folder opening and closing according to the first embodiment of the present invention.

Fig. 11 is a graph showing the impedance characteristics during folder opening and closing according to the second embodiment of the present invention.

* Explanation of symbols for main parts of drawings *

10: radiator 12: substrate

14 slit 16: ground plane

18: Parasitic Patch 20: Slit Patch

The present invention relates to an internal antenna, and more particularly, to an internal antenna in which impedance characteristics do not change due to a change in shape of a terminal.

Recently, due to the rapid development of mobile communication, terminals are becoming smaller and lighter. In addition, much attention is paid to not only the function of the terminal but also to the design. Accordingly, not only a conventional bar type flip type terminal, but also a folding type terminal or terminal which can be folded in the entire terminal type A slide type terminal in which a part of the terminal moves up and down has been released, and recently, a swing type terminal in which a part of the terminal rotates has been released.

In addition, the antenna of the wireless communication terminal has evolved from an existing external antenna protruding to the outside of the terminal to an internal type mounted inside the terminal. As the built-in antenna, a PIFA, an inverted L-type antenna, a patch antenna, and a loop antenna are used.

This variety of handset design affects handset antenna performance.

Especially in the case of the built-in antenna, the bandwidth is narrow, and the influence of the terminal design is large. Referring to Figure 1 will be described the problem of the conventional built-in antenna.

The conventional built-in antenna includes a dielectric substrate 120 and a radiator 110 disposed on the substrate 120, the radiator 110 is connected to the feeding element of the RF circuit at the feed section 150, the current is input / Is output. Meanwhile, ground planes 140 and 160 are formed below the substrate 120. The ground plane 140 and the ground plane 160 are respectively formed in the lower half and the upper half of the clamshell terminal, and are connected by various connection means. The antenna of FIG. 1 is basically an inverted L type antenna. Slit 130 is formed in the radiator 110, and adjusts the length and width of the slit to adjust the bandwidth of the antenna.

In such a conventional antenna, opening and closing of a foldable terminal, vertical movement of a slide type terminal, or rotational movement of a swing type terminal affect the performance of the antenna. For example, in the case of a clamshell terminal, referring to FIG. 1, when the folder is closed, the upper half and the lower half of the terminal overlap, so that the ground planes 140 and 160 installed in each of them also overlap. However, when the folder is opened, the upper half and the lower half are arranged in a line without overlapping, whereby the ground plane 140 and the ground plane 160 form one large ground plane.

A change in ground plane results in a change in the impedance of the antenna, which in turn degrades the radiation characteristics of the antenna. The same is true for the slide type or swing type terminal.

Such an impedance change of the antenna leads to deterioration of the call quality when a call is attempted without a terminal operation such as opening a folder, for example, when using an earphone. In addition, in recent years, various functions other than a call are integrated into a terminal, and there are many cases in which transmission and reception in a closed state such as a broadcast reception and a GPS service are required. In this case, degradation of antenna performance due to opening and closing of a terminal is a significant problem in terminal performance. Can be generated.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an internal antenna in which the overall impedance does not change even when the shape of the terminal is changed.

In order to achieve the above object, according to an embodiment of the present invention, in the built-in antenna of the terminal having a first use state and a second use state, a dielectric, a radiator formed on the dielectric, the slit formed, At least one of a size and a shape different from each other in the first use state and the second use state, and disposed at a first position spaced apart from the radiator and opposite to the slit according to a use state of the terminal, An impedance varying built-in antenna is provided, including a patch electrically coupled with a slit forming portion thereof.

The size of the ground plane in the second use state is larger than in the first use state, and the patch is preferably disposed in the first position in the first use state.

Further, the patch is preferably disposed in a second position spaced apart from the radiator in the second use state and opposite the slit unformed portion of the radiator.

Meanwhile, preferably, the patch is connected to the ground plane.

In addition, in order to achieve the above object, according to another embodiment of the present invention, in the built-in antenna of the terminal having the first use state and the second use state, a dielectric, formed on the dielectric, the slit is formed A radiator, a ground plane having at least one of a size and a shape different in the first use state and the second use state, and a patch connected to the radiator and covering a portion of the slit according to the use state of the terminal; A variable impedance internal antenna is provided.

The size of the ground plane in the second use state is larger than in the first use state, and the patch preferably covers a portion of the slit in the second use state.

According to another embodiment of the present invention. A built-in antenna of a foldable terminal, comprising: a dielectric, a radiator formed on the dielectric and having a slit formed therein, and a patch disposed at a first position spaced apart from the radiator and opposite to the slit when the foldable terminal is closed; There is provided an impedance varying internal antenna.

Preferably, the patch is disposed at a second position spaced apart from the radiator and facing the slit unformed portion of the radiator when the foldable terminal is opened.

Further, according to another embodiment of the present invention, in a built-in antenna of a clamshell terminal, a dielectric, a radiator formed on the dielectric, the slits are formed, and covering a part of the slits when the clamshell terminal is opened; There is provided a variable impedance internal antenna including a patch.

EMBODIMENT OF THE INVENTION Hereinafter, specific embodiment of this invention is described with reference to attached drawing.

2 to 5 show a built-in antenna according to the first embodiment of the present invention. The built-in antenna of the present embodiment includes a dielectric substrate 12 and a radiator 10 formed on the substrate 12, the slit 14 is formed in the radiator 10, and a lower portion of the substrate 12 Ground plane 16 is provided. The shape and size of the ground plane 16 is different depending on the shape of the terminal, and in the case of a clamshell terminal, the size can be changed by opening and closing the folder.

The radiator 10 is formed of a conductor and has an electrical length for resonating at a predetermined frequency. The radiator 10 may be separately manufactured by press working or the like and bonded on the substrate, or may be directly formed on the substrate by plating, double injection, printing, or the like. The substrate 12 is formed of a dielectric so as to support the radiator 10, maintain the shape of the antenna, and reduce the effective frequency of electromagnetic waves so that the antenna can be miniaturized. It is preferable that the base material 12 is formed by injection molding. On the other hand, the radiator 10 has a power feeding portion connected to the power feeding element of the RF circuit, and is not directly connected to the ground plane 16. The antenna of this embodiment basically has a configuration of an inverted L-shaped antenna in which the slits 14 are formed. The slits 14 formed in the radiator generate electrical coupling in the radiator 10, which greatly affects the impedance of the antenna.

The present embodiment employs the variable parasitic patch 18 to reduce the shape change of the terminal, that is, the impedance change of the antenna due to the change of the terminal ground plane. The conductive parasitic patch 18 is disposed below the substrate 12 at a predetermined distance from the radiator 10 and electrically coupled with the radiator 10 to change the impedance of the radiating element. The parasitic patch 18 may be installed at a predetermined position of the terminal so that its arrangement is changed according to opening and closing of the folder.

FIG.2 and FIG.3 is a figure which shows the state at the time of the folder closing of the built-in antenna of this embodiment. In closing the parasitic patch 18, the parasitic patch 18 is disposed to partially overlap the radiator 10 directly under the slit 14. As shown in FIG. 3, the parasitic patch 18 is disposed below the substrate 12 spaced a predetermined distance d from the radiator. The parasitic patch 18 is electrically coupled with the radiator 10 to change the coupling in the slit 14. The coupling degree of the parasitic patch 18 and the radiator 10 is adjusted by adjusting the length L ₁ , the width W ₁ , and the distance d from the radiator 10 of the parasitic patch. The impedance can be adjusted.

4 and 5 are diagrams showing a state when the folder of the built-in antenna of the present embodiment is opened. As shown in Figs. 4 and 5, the size of the ground plane 16 changes when the folder is opened, with the parasitic patch 18 not directly under the slit 14, but directly below the radiator 10 under the antenna. Is placed. Therefore, the coupling change in the slit 14 by the parasitic patch 18 disappears. Since the parasitic patch 18 is coupled with the radiator 10, the impedance of the antenna appears different from the impedance in the absence of the parasitic patch 18. In this case, however, the coupling degree is not large and the difference is minute.

In this way, the arrangement of the parasitic patches 18 is changed in accordance with the opening and closing of the folder, so that the impedance of the overall antenna can not be changed. That is, the impedance of the radiating element changes in accordance with the change of the ground plane according to the opening and closing of the folder. As a result, the impedance of the antenna by both the ground plane and the radiating element does not change despite the opening and closing of the folder. Therefore, performance degradation of the antenna due to opening and closing of the folder can be prevented.

In particular, by placing the patch 18 below the slit 14 to change the coupling in the slit 14 which has the greatest impact on the antenna bandwidth, it is possible to maximize the radiated element impedance change corresponding to the ground plane change. Can be.

It is also possible to cause the patch 18 to move out of the antenna formation range so that there is no change in impedance by the patch 18 upon opening the folder. However, the impedance when the parasitic patch 18 moves below the radiator 10 in which the slit 14 is not formed is almost similar to that without the patch 18, and according to the present embodiment, It can minimize the travel distance and facilitate the implementation of the antenna.

In addition, the parasitic patch 18 of this embodiment can also be used in connection with a ground plane. In this case, the parasitic patch 18 is not a parasitic element causing coupling with the radiator 10, but functions as a virtual ground element. By the patch 18 functioning as the ground plane, the change of the ground plane due to the opening and closing of the folder can be canceled and the impedance change of the antenna seen in the RF circuit can be minimized.

6 and 7 show a built-in antenna according to the second embodiment of the present invention, in which the same components as in the previous embodiment are denoted by the same reference numerals and will not be described in detail. The built-in antenna of the present embodiment includes a dielectric substrate 12 and a radiator 10 formed on the substrate 12, the slit 14 is formed in the radiator 10, and a ground is formed below the substrate 12. Face 16 is installed. The antenna of this embodiment basically has a configuration of an inverted L-shaped antenna in which the slits 14 are formed. The slits 14 formed in the radiator generate electrical coupling in the radiator 10, which greatly affects the impedance of the antenna.

In this embodiment, in order to reduce the impedance change of the antenna according to the terminal ground plane change, the slit patch 20 is adopted while the slit 14 of the form different from the conventional antenna is formed in the radiator 10. The slit patch 20 is arranged to cover a portion of the slit 14 to change the substantial size of the slit 14 and to change the impedance of the radiating element. The patch 20 may be installed at a predetermined position of the terminal so that its arrangement may be changed according to opening and closing of the folder.

Fig. 6 is a diagram showing a state when the built-in antenna of the present embodiment is closed in the folder. When the folder is closed, the antenna is not electrically connected or coupled with the patch. The slit 14 is formed in a size and shape so that the impedance of the antenna at the closing of the folder becomes a predetermined desired impedance. In this embodiment, the slit 14 has a form in which the rectangular slit shown by the dotted line of FIG. 6 is added to the slit of the conventional antenna. The shape and size of the slit 14 can be changed according to the desired impedance for the specific terminal.

Fig. 7 is a diagram showing a state when the folder of the built-in antenna of the present embodiment is opened. As shown in FIG. 7, the size of the ground plane 16 is increased upon opening of the folder, with a portion of the slit being removed by the conductive patch 20. The patch 20 is connected with the radiator 10 to substantially increase the size of the radiator 10 and reduce the size of the slit 14. In this case, the shape and size of the slit 14 changed by the patch 20 can be determined so that the impedance of the antenna at the time of folder opening becomes a predetermined desired impedance. That is, the patch 20 has a shape and size corresponding to the difference between the slit 14 of FIG. 6 so that the antenna has a predetermined impedance when the folder is closed and the slit 14 of FIG. 7 so that the antenna has a predetermined impedance when the folder is opened. It can have Alternatively, the patch 20 can be stably connected to the radiator 10 by having a shape and size slightly larger than the difference between the slits 14 in the two cases. In this embodiment, the difference in the form of the slit 14 in both cases can be set to a rectangle of length L ₂ and width W ₂ , whereby the patch 20 can also be formed in a rectangle.

In this way, as the connection between the patch 20 and the radiator 10 changes as the folder is opened and closed, the shape of the slit 14 changes and the impedance of the radiating element changes. Since the impedance of the radiating element changes in accordance with the change of the ground plane, the impedance of the antenna by both the ground plane and the antenna does not change despite the opening and closing of the folder. Therefore, performance degradation of the antenna due to opening and closing of the folder can be prevented.

In particular, by changing the shape and size of the slit 14 by the patch 20 to change the coupling in the slit 14 which has the greatest influence on the antenna bandwidth, the antenna impedance change corresponding to the ground plane change can be obtained. It can be maximized. In addition, when the folder is opened and closed, the shape and size of the slit 14 are determined to have a desired impedance for each, and the shape and size of the patch 20 are determined to correspond to the difference in the shape and size of the slit 14 in both cases. Despite the opening and closing, the impedance of the antenna can be maintained accurately.

Embodiments of the present invention were implemented and the simulation results of impedance using CST MicroWave Studio 5.1 from CST were compared with conventional antennas. 8 is a diagram showing a conventional antenna used as a comparative example. Each dimension of a comparative example is as follows.

Wg 41 Wr 28 Ws 2 Hg 72 Hr 14 Ls 18.5

(Unit: mm)

On the other hand, a dielectric having a dielectric constant of 3.5 and a thickness of 1.5 mm was used as the substrate, and the thickness of the radiator was 0.15 mm and the thickness of the ground plane was 1.5 mm.

In the same antenna as that of the comparative example, the parasitic patch 18 having a length L ₁ of 10 mm and a width W ₁ of 5 mm is arranged at a spaced distance d of 1.5 mm. An antenna was implemented (first embodiment).

As a second embodiment, the slit patch 20 has a length L ₂ of 5.3 mm and a width W ₂ of 4.3 mm, with the patch covering a part of the slit at the time of closing the folder, the second embodiment. The built-in antenna is implemented.

9A and 9B are graphs showing impedance characteristics when the folder is closed and the folder is open in the comparative example, respectively. As shown, the S-parameter of the antenna has a peak value at 1.798 GHz when the folder is open, while it has a peak value at 2.14 GHz when the folder is closed, and shows a great difference in bandwidth.

10A and 10B are graphs showing impedance characteristics at the time of folder closing and folder opening, respectively, of the first embodiment. As shown, there is little difference in the S parameter value at the time of opening and closing of the folder, and shows almost the same characteristics as the case of opening the folder of the comparative example. Therefore, it was confirmed that the parasitic patch may be disposed under the slit when the folder is closed to adjust the coupling of the slit to prevent the impedance change due to the opening and closing of the folder. Moreover, the impedance characteristic at the time of folder opening was almost similar to b of FIG. 9, and it confirmed that there was no deterioration of the antenna characteristic by the parasitic patch 18. FIG.

11A and 11B are graphs showing impedance characteristics at the time of folder closing and folder opening, respectively, of the second embodiment. As shown, the S parameter at the time of closing the folder had a peak value at 1.82 GHz, and the value at 1.798 GHz at the time of opening the folder, thereby improving the difference by 10 times or more as compared with the comparative example. In addition, when the patch 20 is coupled to the slit when the folder is opened, the shape of the slit is the same as that of the comparative example, and thus exhibits the same characteristics as in FIG. You can check the sound.

As mentioned above, although this invention was demonstrated with reference to specific embodiment, this is only an illustration and the scope of the present invention is not limited to this. For example, while the above embodiments have been described with respect to a folding type terminal, the principles of the present invention can be applied to any terminal whose shape of the ground plane changes according to a slide type, swing type, or other use state. In addition, the present invention has been described in relation to an inverted L-type antenna, but the present invention can be applied to any type of antenna such as a Planar Inverted F Antenna (PIFA) and a patch antenna if the antenna is formed with a slit, which is also the scope of the present invention. Belongs to.

According to the present invention, by adjusting the coupling of the slit according to the opening and closing of the folder, it is possible to obtain an antenna that does not change the overall impedance even when opening and closing the folder.

In addition, according to the present invention, by adjusting the shape and size of the slit according to the opening and closing of the folder, it is possible to obtain an antenna that does not change the overall impedance even when opening and closing the folder.

Claims (9)

In the built-in antenna of the terminal having a first use state and a second use state, dielectric; A radiator formed on the dielectric and having slits formed thereon; A ground plane differing in at least one of a size and a shape in the first use state and the second use state; And And a patch disposed at a first position spaced apart from the radiator according to the use state of the terminal and facing the slit, and electrically coupled to the slit forming portion of the radiator. The method of claim 1, The size of the ground plane in the second use state is larger than in the first use state, And the patch is disposed at the first position in the first use state. The method of claim 2, And the patch is disposed at a second position spaced apart from the radiator in the second use state and opposite the slit unformed portion of the radiator. The method according to any one of claims 1 to 4, And said patch is connected to said ground plane. In the built-in antenna of the terminal having a first use state and a second use state, dielectric; A radiator formed on the dielectric and having slits formed thereon; A ground plane differing in at least one of a size and a shape in the first use state and the second use state; And And a patch connected to the radiator and covering a portion of the slit according to the use state of the terminal. The method of claim 5, The size of the ground plane in the second use state is larger than in the first use state, And the patch covers a portion of the slit in the second use state. In the built-in antenna of the clamshell terminal, dielectric; A radiator formed on the dielectric and having slits formed thereon; And And a patch disposed at a first position spaced apart from the radiator and facing the slit when the folding terminal is closed. The method of claim 7, wherein And the patch is disposed at a second position spaced apart from the radiator and facing the slit unformed portion of the radiator when the foldable terminal is opened. In the built-in antenna of the clamshell terminal, dielectric; A radiator formed on the dielectric and having slits formed thereon; And And a patch covering a part of the slit when the clamshell terminal is opened.

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