KR100773480B1 - Internal antenna with switching device - Google Patents

Abstract

Disclosed is a built-in antenna in which resonance characteristics are not deteriorated by a shape change of a terminal. The built-in antenna of the present invention includes a switch for switching the connection between the ground terminal and the ground plane according to the shape change of the terminal. The built-in antenna of the present invention can maintain a good resonance characteristic in spite of the ground plane change caused by the shape change of the terminal by switching the antenna to operate as an inverted L-type antenna or an inverted-F antenna in response to the shape change of the terminal. have.

Reverse L type antenna, reverse F type antenna, clamshell terminal, switch

Description

Built-in antenna with switching element {INTERNAL ANTENNA WITH SWITCHING DEVICE}

1 shows a conventional built-in antenna;

Fig. 2 is a diagram showing a built-in antenna according to the first embodiment of the present invention.

3 is a view showing an operating state of the antenna of FIG. 2 when the folder is closed;

4 is a view showing an operating state of the antenna of FIG. 2 when a folder is opened;

Fig. 5 shows a built-in antenna according to the second embodiment of the present invention.

Figure 6 is a graph showing the standing wave ratio of the built-in antenna of the present invention.

Figure 7 is a graph showing the radiation characteristics when the closed folder of the built-in antenna of the present invention.

8 is a graph showing the radiation characteristics when the folder is opened in the built-in antenna of the present invention.

* Description of the symbols for the main parts of the drawings *

10: radiator 12: feed terminal

14 ground terminal 16 switch

18 sensor 20 matching circuit

22, 24: ground plane

The present invention relates to an internal antenna, and more particularly, to an internal antenna in which resonance characteristics are not deteriorated by a shape change 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 in the power supply unit 150, the current is inputted / 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 interconnected 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. In particular, the inverted L-type antenna as shown in FIG. 1 has a disadvantage in that gain and sensitivity are low when the size of the ground plane is small, resulting in inferior antenna characteristics when the folder is closed.

In contrast, an inverted F type antenna having better gain and sensitivity than an L type antenna can be used to improve antenna characteristics upon folder closure. However, the F-type antenna has a problem that the resonance characteristic change due to the opening and closing of the folder is larger due to narrow bandwidth.

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 a built-in antenna capable of maintaining good antenna characteristics despite a change in terminal shape.

In addition, an object of the present invention is to provide a built-in antenna that maintains a good resonance characteristics in the GSM850, GSM900, DCS1800 and USPCS band even in the form of a terminal.

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 having a different shape, the first use state and the second use state And a radiator having a ground plane having a different size and / or shape, a first terminal, and a second terminal connected to a power supply means, the radiator disposed in parallel with the ground plane, and the first terminal according to the use state of the terminal. There is provided a built-in antenna comprising switching means for switching the connection between the ground planes.

The size of the ground plane in the second use state is larger than in the first use state, and the switching means connects the first terminal and the ground plane in the first use state, and in the second use state. It is preferable to cut off the connection between the first terminal and the ground plane.

Preferably the built-in antenna further comprises an impedance matching circuit, wherein the first terminal and the ground plane are interleaved with the matching circuit when interconnected.

In addition, the built-in antenna further includes a sensing means for sensing the use state of the terminal and accordingly transmitting a status signal to the switching means, the switching means preferably performs switching in accordance with the status signal.

In order to achieve the above object, according to another embodiment of the present invention, in a built-in antenna of a clamshell terminal, having a first terminal and a second terminal connected with a power supply means, in parallel with the ground plane of the terminal; Disposed radiators; And switching means for switching a connection between the first terminal and the ground plane in accordance with opening and closing of the foldable terminal.

The switching means preferably connects the first terminal and the ground plane when the clamshell terminal is closed, and disconnects the connection between the first terminal and the ground plane when the clamshell terminal is opened.

EMBODIMENT OF THE INVENTION Hereinafter, specific embodiment of this invention is described with reference to attached drawing. 2 shows a built-in antenna according to the first embodiment of the present invention. In the built-in antenna of the present embodiment, the radiator 10, the power supply terminal 12 for connecting the radiator 10 and the power feeding element, one end is connected to the radiator 10, and the other end is connected to the ground plane through the switch 16. Ground terminal 14 and a switch 16 which connects the ground terminal 14 and the ground plane and is switched in accordance with the signal of the sensor 18.

The radiator 10 is formed of a conductor and has an electrical length for resonating at a predetermined frequency. The radiator 10 may be formed in various shapes such as a rectangle, a meander shape, a circle, and the like, which may be selectively applied by the frequency of use of the antenna, the antenna mounting space, and the like. In addition, a slit is formed in the radiator 10 to increase the bandwidth of the antenna. The resonant frequency of the antenna is determined differently according to the shape and size of the radiator 10, and by having a plurality of resonant frequencies, a multi-band antenna operating in a plurality of frequency bands may be implemented. The antenna of this embodiment reduces the occupied space and simultaneously uses the GSM850 frequency band of 824 to 894 MHz, the GSM900 frequency band of 880 to 960 MHz, the DCS1800 frequency band of 1710 to 1880 MHz, and the USPCS of 1850 to 1990 MHz. It has a shape bent to resonate in the frequency band used.

On the other hand, the radiator 10 may be coupled to a substrate (not shown) that supports the radiator 10 and facilitates the connection with the RF circuit. In this case, the radiator 10 may be formed by press working or the like and then bonded to the substrate, or may be directly formed on the substrate by double injection, plating, printing, or the like.

The power supply terminal 12 is formed in the radiator 10, is connected with the power supply element of an RF circuit, and inputs and outputs the electric current as an electrical signal. In addition, the radiator 10 is connected to the switch 16 via the ground terminal 14. The radiator 10 is formed in parallel with the ground plane so that the antenna operates as an inverted L-type or inverted-F antenna in accordance with the opening and closing of the switch 16.

The switch 16 switches the connection between the ground terminal 14 and the ground plane according to the signal of the sensor 18. The sensor 18 detects the shape change of the terminal, for example, opening and closing of the foldable terminal, and transmits a status signal to the switch 16. Accordingly, the switch 16 connects the ground terminal 14 with the ground plane to ground the radiator 10, or blocks the connection between the ground terminal 14 and the ground plane so that the radiator is not connected to the ground plane. .

As the switch 16, any well-known switch, such as a diode and a transistor, can be used. As the sensor 18, any means for generating a status signal in accordance with the shape change of the terminal can be used, and a known sensor such as an optical sensor or a piezoelectric sensor can be used. In addition, the present embodiment may be implemented without using a separate element by using a mechanism change detection sensor which is already included in the terminal as the sensor 18 and detects the opening and closing of the terminal and generates a signal. On the other hand, it is also possible to implement the sensor 18 and the switch 16 as one element using a photodiode or the like, which is also within the scope of the present invention.

When the radiator 10 is connected to the ground plane by the switch 16, the radiator is connected to both the power feeding element and the ground plane, and the antenna of this embodiment operates as an inverted F-type antenna. On the other hand, when the connection between the radiator 10 and the ground plane is cut off, the radiator is connected only to the power feeding element so that the antenna of this embodiment operates as an inverted L-type antenna. Inverted F type antennas have good gain and sensitivity but have a narrow bandwidth, whereas inverted L type antennas have a wide bandwidth but have a relatively low gain and sensitivity when the ground plane is narrow. Therefore, by detecting a change in the state of the terminal causing a change in the ground plane area and appropriately switching the connection between the radiator 10 and the ground plane, the inverted L-type antenna and the inverted-F antenna are operated complementarily. Can be.

3 and 4, the operation of the antenna of this embodiment will be described. In this embodiment, the sensor 18 can detect the opening and closing of the foldable terminal, for example, and allow the switch 16 to connect the ground terminal 14 to the ground plane when the folder is closed. As shown in FIG. 3, when the folder is closed, the ground plane of the upper part of the terminal overlaps with the ground plane 22 of the lower part of the terminal so that substantially only the ground plane 22 of the lower part of the terminal functions as the ground plane. However, in this case, since the radiator 10 parallel to the ground plane is connected to the ground plane 22 and the antenna operates in an inverted F type, high gain and sensitivity can be obtained in spite of the small ground plane.

On the other hand, the sensor 18 can cause the switch 16 to cut off the connection between the ground terminal 14 and the ground plane when the folder is opened. As shown in FIG. 4, when the folder is opened, the ground plane 24 of the upper part of the terminal is arranged in line with the ground plane 22 of the lower part of the terminal, thereby increasing the size of the ground plane as a whole. In this case, since the radiator 10 is not connected to the ground planes 22 and 24 and the antenna operates in an inverted L shape, it is possible to obtain broadband characteristics while achieving good gain and sensitivity. In particular, since the inverted F-type antenna does not satisfy the wideband and multi-band characteristics when the folder is opened, good performance can be obtained in applications requiring multi-band characteristics by switching the operating state to the inverted L-type antenna.

According to this embodiment, since the operation state of the antenna changes in response to the change in the terminal form, good communication performance can be obtained despite the change in the terminal form.

With reference to FIG. 5, 2nd Embodiment of this invention is described. The same components as in the first embodiment are denoted by the same reference numerals and will not be described in detail. In the built-in antenna of the present embodiment, the radiator 10, the power supply terminal 12 for connecting the radiator 10 and the power feeding element, one end is connected to the radiator 10, and the other end is connected to the ground plane through the switch 16. Ground terminal 14 and a switch 16 which connects the ground terminal 14 and the ground plane and is switched in accordance with the signal of the sensor 18. In particular, the ground terminal 14 of the present embodiment is connected to the ground plane through the matching circuit 20 when the switch 16 is closed.

The matching circuit 20 of this embodiment is connected with the ground plane, and when the radiator 10 is connected to the ground terminal 14 by the switch 16, the impedance of the antenna is matched and the performance of the antenna is improved. As the matching circuit 20, any known element or a combination thereof can be used.

According to this embodiment, since the operation state of the antenna changes in response to the change in the terminal form, good communication performance can be obtained despite the change in the terminal form. In addition, according to the present embodiment, by further including a matching circuit 20 between the switch 16 and the ground plane, it is possible to minimize the antenna impedance change due to switching and improve the characteristics of the antenna.

By implementing the antenna of the present invention was measured the characteristics of the antenna. The implemented antenna has a radiator having a size of 35 mm in width and 11 mm in length, and a substrate of 43 mm in width and 70 mm in length is used. The antenna is implemented as a quad band antenna to operate in four bands: GSM850, GSM900, DCS1800, and USPCS. For the implemented antenna, the switch was opened and closed in each of the folder opening and closing states, and the characteristics of both the L type operating state and the F type operating state were measured in each state.

6 (a) and 6 (b) are graphs of standing wave ratios of the antennas when the folder is closed and the folder is opened, respectively. As shown in the figure, the F-type antenna has a lower standing wave ratio and better resonance characteristics than the L-type antenna in all antenna bands when the folder is closed. However, when the folder is opened, the resonance frequency of the F-type antenna moves to the low frequency region and the high frequency region, respectively, and the standing wave ratio increases, thereby degrading the performance of the antenna. On the other hand, the L-type antenna increases the size of the ground plane by opening the folder and reduces the standing wave ratio as a whole, thereby improving resonance characteristics. Therefore, it was confirmed that good antenna performance could be maintained at all times by using the L type antenna when opening the folder and the F type when closing the folder. In particular, the F-type operation does not satisfy the quad-band characteristics when the folder is opened, while the L-type operation has quad-band characteristics. Therefore, quadruple characteristics can be obtained by switching the antenna to L-type operation when the folder is opened, which is very useful in applications requiring multiple bands.

The following table shows the results of measuring the gain of the implemented antenna in the radio dark room.

Use service Frequency (MHz) Peak gain (dBi) Folder closed Open folder L type operation F type action L type operation F type action GSM 850 824 -3.65 -1.42 0.35 0.98 894 -3.11 -2.46 -2.03 -1.75 GMS900 880 -3.61 -2.09 -1.32 -1.09 960 -1.37 -1.71 -1.16 -2.91 DCS1800 1710 -2.83 -2.2 1.49 0.68 1880 -1.93 -0.8 2.23 2.1 USPCS 1850 -1.98 -0.77 1.54 One 1990 -4.21 -3.33 1.26 2.89

As described above, when the folder is closed, the gain is high in the F-type operating state for all frequencies. In addition, when the folder is opened, the gain of the L-type antenna has a higher value in the GSM900 and DCS1800 bands which are used more and more in the world. Therefore, it was confirmed that excellent communication performance can be obtained by operating the antennas in the L-type and the F-type when opening and closing the folders, respectively.

(A) and (b) of FIG. 7 respectively show the radiation characteristics in the F type operating state and the L type operating state when the folder is closed, and FIGS. 8A and 8B respectively illustrate the F characteristics when the folder is opened. The radiation characteristics in the type operating state and the L type operating state are shown. As shown, the radiation characteristics of the F type operating state and the L type operating state are almost the same for both the folder opening and closing. Therefore, it was confirmed that the same radiation characteristic can be obtained even by switching the two operating states by the switch 14.

While the present invention has been described above in connection with specific embodiments, this is only an example and the present invention is not limited thereto. For example, although the present invention has been described with reference to a folding type terminal, the principles of the present invention can be applied to various types of terminals, such as swing type and slide type, which are within the scope of the present invention. In addition, the present invention is not limited to the quad band antenna, but may be applied to a single band antenna, a dual band antenna and other multi band antennas, which will be easily recognized by those skilled in the art.

According to the present invention, by switching the connection between the radiator and the ground plane in accordance with the change in the shape of the terminal to operate in a different operating state, it is possible to obtain an antenna having good characteristics despite the change in the shape of the terminal.

In addition, an F-type antenna having excellent resonance characteristics and an L-type antenna having a wide bandwidth can be complementarily used to obtain an antenna having good gain, sensitivity, and bandwidth despite a change in the terminal shape.

In addition, according to the present invention, by switching the operating state of the antenna according to the change of the terminal type, the resonance characteristics in the GSM850, GSM900, DCS1800, and USPCS bands are maintained satisfactorily, and an internal antenna having a quad band characteristic can be obtained.

Claims (6)

In the built-in antenna of the terminal having any of the first use state and the second use state different in the size or shape of the ground plane, A radiator having a first terminal and a second terminal connected to the power supply means, the radiator disposed in parallel with the ground plane; And And switching means for switching a connection between the first terminal and the ground plane in accordance with a usage state of the terminal. 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 switching means connects the first terminal and the ground plane in the first use state, and cuts off the connection of the first terminal and the ground plane in the second use state. The method according to claim 1 or 2, Further comprising an impedance matching circuit, And the first terminal and the ground plane are interleaved with the matching circuit when interconnected. The method according to claim 1 or 2, Sensing means for sensing a use state of the terminal and accordingly transmitting a status signal to the switching means, And said switching means performs switching in accordance with said status signal. In the built-in antenna of the clamshell terminal having a ground plane different in size or shape depending on the use state, A radiator having a first terminal and a second terminal connected to a feeding means, the radiator disposed in parallel with the ground plane of the terminal; And And switching means for switching a connection between the first terminal and the ground plane in accordance with opening and closing of the folding terminal. The method of claim 5, And the switching means connects the first terminal and the ground plane when the clamshell terminal is closed and blocks the connection of the first terminal and the ground plane when the clamshell terminal is opened.

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