KR20110047483A - Internal antenna apparatus for low frequency band - Google Patents

Abstract

An internal antenna device for a low frequency band is disclosed that makes it easy to tune a resonant frequency using a capacitor, and realizes double resonance using a capacitor to widen the resonant frequency in a low frequency band. The proposed low frequency band built-in antenna device includes a polyhedron block on which a radiation pattern and a coupling pattern are formed; A circuit board including a first conductive pad connected to one side of the radiation pattern and a second conductive pad connected to the coupling pattern; And a capacitor formed between the first conductive pad and the ground region of the circuit board.

Description

Internal antenna apparatus for low frequency band

The present invention relates to a low frequency band built-in antenna device, and more particularly to a low frequency band built-in antenna device capable of tuning the resonance frequency and double resonance using a capacitor and an inductor.

With the spread of mobile terminals, it is possible to make and receive calls anytime and anywhere, which has revolutionized the real world. In addition, as more users always carry a mobile communication terminal, various functions are added to help real life. Among the various functions of the mobile communication terminal, the rapid progress is the part related to multimedia, and mobile communication terminals to which functions for generating and playing various multimedia files have been added are pouring out.

That is, the mobile communication terminal is no longer treated as a wireless telephone for voice call only, but as an integrated portable device in which communication means are combined with various user-friendly functions and entertainment functions. As users watch movies, listen to music, communicate with each other, and make voice calls with only one mobile communication terminal, the time for carrying and using the mobile communication terminal is gradually increasing. However, since multimedia files such as downloaded movies and music have to be updated by the user, addition of FM radio broadcast reception listening function is required in order to enjoy fresher contents without additional burden.

Therefore, among the recent mobile communication terminals emphasizing multimedia functions, an FM radio broadcast receiver is built in the mobile communication terminal focused on music-related functions so that the user can listen to the FM radio broadcast. To this end, a built-in antenna for the FM band is mounted on the mobile communication terminal.

The built-in antenna for the FM band is gradually miniaturized as the mobile communication terminal becomes smaller and slimmer. Then, the built-in antenna for the FM band is reduced in space for forming a radiation line for reception of frequency. Accordingly, a problem arises that the reception ratio of the internal antenna for a band is deteriorated due to the characteristics of the FM antenna whose gain increases as the radiation area (or radiation length) is wider.

However, in the case of an antenna that receives FM radio and has a high radio wave reception efficiency, it is not easy to integrate into a terminal because of the required antenna length. In the case of an antenna receiving FM, the radiation line of the antenna is long because the antenna has to resonate in a low frequency band of approximately 87.5 to 108 MHz, thereby increasing the size of the antenna. (The antenna's physical size increases as the frequency to be used is lower, that is, as the wavelength is longer.) To overcome this, antennas are often miniaturized using high-k dielectrics, but in this case, the low frequency band The problem arises in that the frequency bandwidth becomes narrower.

In order to solve the above problems, the built-in antenna for the FM band has formed an auxiliary radiation line on the circuit board. That is, the problem of narrowing the bandwidth by forming a meander-shaped auxiliary radiation line on the circuit board to increase the length (or area) of the radiation line. However, when the auxiliary radiation line is formed on the circuit board, there is a problem in that resonant frequency tuning of the built-in antenna for the FM band becomes inconvenient. That is, the built-in antenna for the FM band is soldered (Soldering) and connected to the auxiliary radiation line formed on the circuit board, there is a problem that frequency tuning using the etching of the auxiliary radiation line is difficult.

Due to the problems as described above, there is a need for a built-in antenna for the FM band to increase the bandwidth of the frequency, easy tuning of the resonant frequency.

The present invention has been proposed in view of the above-described conventional problems, and an object thereof is to provide a built-in antenna device for a low frequency band to facilitate tuning of a resonance frequency using a capacitor.

Another object of the present invention is to provide a built-in antenna device for a low frequency band to realize a double resonance using a capacitor to widen the resonance frequency in a low frequency band.

In order to achieve the above object, a low-frequency band internal antenna device according to the present invention includes a polyhedron block having a radiation pattern and a coupling pattern; A circuit board including a first conductive pad connected to one side of the radiation pattern and a second conductive pad connected to the coupling pattern; And a capacitor formed between the first conductive pad and the ground region of the circuit board.

It further includes an inductor formed between the first conductive pad and the ground region of the circuit board.

The capacitor and inductor are connected in series.

The capacitor and inductor are connected in parallel.

The circuit board further includes an auxiliary radiation pattern connected to the first conductive pad.

The auxiliary radiation pattern is formed in a meander shape.

The radiation pattern is formed in the form of a winding along the outer circumferential surface of the polyhedron block.

The capacitor is composed of a variable capacitor.

The circuit board is a printed circuit board of a portable terminal in which a polyhedral block is mounted.

The circuit board is a flexible circuit board on which a polyhedral block is mounted and connected to a printed circuit board of a portable terminal.

The built-in antenna device for a low frequency band according to the present invention can easily tune the resonance frequency by adjusting the capacitor's capacitance by connecting a capacitor to a feed stage.

In addition, the built-in antenna device for a low frequency band according to the present invention can implement a double resonance in a low frequency band by connecting a capacitor and an inductor in series or parallel to the feed stage.

Incidentally, the built-in antenna device for a low frequency band according to the present invention can implement a double resonance in the low frequency band, thereby widening the resonance frequency in the low frequency band.

Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. . First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape and size of elements in the drawings may be exaggerated for clarity.

Hereinafter, a low frequency band built-in antenna device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 are diagrams for explaining a chip antenna applied to an embodiment of the present invention.

The chip antenna 100 includes a polyhedron block 100 formed of a magnetic material, a radiation pattern 120 formed on an outer circumferential surface of the polyhedron block 100, and a coupling pattern 130 formed to be spaced apart from the radiation pattern 120 by a predetermined distance. It includes.

The polyhedron block 100 is composed of a polyhedron magnetic material. Magnetic material (Magneto-dielectric) refers to a material that can be magnetic, and there are iron oxide, chromium oxide, cobalt, ferrite and the like. In general, ferrite is used as a magnetic material constituting the polyhedral block 100. Of course, since the polyhedral block 100 has different permeability and permittivity, it can be selected according to the resonance frequency to be implemented. In addition, the size and shape of the polyhedral block 100 may vary depending on the frequency band to be implemented.

Radiation pattern 120 is formed along the outer circumferential surface of the polyhedral block 100 in the form of a winding (that is, helical). That is, as shown in Figure 2, the radiation pattern 120 is I _1, the radiation line of I ₁ ~ I _k formed in the first side surface (110a) of the polyhedral block 100 is formed on the second side (110b) ~ Each connected to the radiation line of I _{k +1} . In FIG. 2, the radiation lines I ₁ to I _k formed on the first side surface 110a and the radiation lines I ₁ to I _{k + 1} formed on the second side surface 110b are illustrated as separate, but FIG. When implemented in a state, the radiation pattern 120 is wound along the outer circumferential surface of the polyhedral block 100 starting from one side of the second side surface 110b of the polyhedral block 100 to form a single radiation line (ie, a helical shape). Spin line). Here, the length and line width of the radiator pattern and the spacing between the radiator patterns may vary depending on the resonance frequency to be implemented.

The coupling pattern 130 is formed on the lower surface of the polyhedral block 100 (that is, the second side surface 110b of the polyhedral block 100) independently of the radiation pattern 120 by a predetermined distance. That is, the coupling pattern couples the flow of current flowing into the radiator pattern to widen the bandwidth of the antenna. In the embodiment of the present invention, the first coupling pattern 130a and the second coupling pattern 130b are formed on the bottom surface of the polyhedral block 100 to resonate in the FM radio frequency band (87.5 to 108MHz). Here, the number of coupling patterns causing coupling may vary depending on the frequency band and bandwidth to be implemented, and the resonance frequency and bandwidth to be implemented may be adjusted by increasing or decreasing the number of coupling patterns.

3 to 7 are views for explaining a circuit board applied to the embodiment of the present invention.

As shown in FIG. 3, the circuit board is a printed circuit board 200 of a portable terminal in which the chip antenna 100 is mounted, and is divided into a ground area 220 and a NO-GND area 210. Here, the chip antenna 100 is mounted in the NO-GND region 210 of the printed circuit board 200. In general, the NO-GND region 210 is formed at one side of the printed circuit board 200 and refers to a space for keeping a distance from other chips mounted in the ground region 220 of the printed circuit board 200. The first conductive pad 230, the second conductive pad 240, the third conductive pad 250, the fourth conductive pad 260, and the fifth conductive pad 270 are formed on the NO-GND region 210. have. As shown in FIG. 3A, the first conductive pad 230 is formed on the upper surface of the printed circuit board 200 and used as a feed end, and is disposed on the second side 110b of the polyhedral block 100. Soldering is connected to the feeder of the formed radiation pattern 120 is connected. The second conductive pad 240 is formed on the upper surface of the printed circuit board 200 and used as a ground end, and is soldered with the ground portion of the radiation pattern 120 formed on the second side surface 110b of the polyhedral block 100. Connected. The third conductive pad 250 and the fourth conductive pad 260 are formed on the upper surface of the printed circuit board 200 and the first couple of the radiation pattern 120 formed on the second side surface 110b of the polyhedral block 100. The ring pattern 130a and the second coupling pattern 130b are respectively soldered and connected to each other. As shown in (b) of FIG. 3, the fifth conductive pad 270 is formed on the bottom surface of the printed circuit board 200 in a meander line shape and used as an auxiliary radiation pattern. The second conductive pads 240 formed on the upper surface of the via holes 280 are connected to each other.

As shown in FIG. 4, a sixth conductive pad 290 may be further formed on the NO-GND region 210 of the printed circuit board 200. That is, the sixth conductive pad 290 is formed on the upper surface of the NO-GND region 210 of the printed circuit board 200 in a meander line shape and used as an auxiliary radiation pattern, and is disposed on the upper surface of the printed circuit board 200. It is connected to the formed second conductive pads 240 and 320. Here, the sixth conductive pad 290 may be formed in various shapes and connected to the second conductive pads 240 and 320 as shown in FIG. 5. Of course, the shape of the sixth conductive pad 290 is not limited to the shape shown in FIG. 5.

The circuit board may be formed of a flexible circuit board 300 on which the chip antenna 100 is mounted and connected to the printed circuit board 200 of the portable terminal. 6, the flexible printed circuit board 300 includes a first conductive pad 310, a second conductive pad 320, a first conductive pad 310, a second conductive pad 320, and a first conductive pad 310. The five conductive pads 350 are formed. The first conductive pad 310 is used as a feed end, is soldered and connected to the feed part of the radiation pattern 120 formed on the second side 110b of the polyhedral block 100, one side of the printed circuit board of the portable terminal The feed end formed in the 200 is soldered and connected. The second conductive pad 320 is used as a ground terminal, and is soldered and connected to the ground portion of the radiation pattern 120 formed on the second side 110b of the polyhedral block 100, and one side of the printed circuit board of the portable terminal. It is connected to the ground terminal formed in the soldering (200). In this case, the second conductive pad 320 is connected to the fifth conductive pad 350 used as the auxiliary radiation pattern. Here, the fifth conductive pad 350 is formed in various shapes, as shown in FIG. The third conductive pad 330 and the fourth conductive pad 340 may include the first coupling pattern 130a and the second coupling of the radiation pattern 120 formed on the second side surface 110b of the polyhedral block 100. Each of the patterns 130b is soldered and connected to each other.

FIG. 8 is a view for explaining a low frequency band embedded antenna device according to a first embodiment of the present invention, and FIG. 9 is a view for explaining an equivalent circuit of the antenna device of FIG. 8.

As shown in FIG. 8, the low frequency band internal antenna device is mounted in the NO-GND region 210 of the printed circuit board 200. In this case, the capacitor 400 is mounted on the second conductive pads 240 and 320 used as the ground of the printed circuit board 200 to tune the resonance frequency. 8, the radiation pattern 120 formed on the chip antenna 100 operates as an inductor 500 (that is, L in FIG. 9), and the printed circuit board 200. The auxiliary radiation patterns (ie, the fifth conductive pads 270 and 350 and the fifth conductive pads 270 and 350) formed in the N-th insulator are operated as a capacitor 400 (that is, C ₁ and C ₂ of FIG. 9), The fourth conductive pad 260 of the printed circuit board 200 operates as a capacitor 400 (that is, C ₃ of FIG. 9). At this time, the capacitor 400 C ₁ , C ₂ , C ₃ has a fixed capacitance value. Accordingly, the resonance frequency of the built-in antenna device for the low frequency band can be tuned by adjusting the capacitance of the capacitor 400 (that is, C ₄ of FIG. 9) mounted on the second conductive pad 240. To this end, it is preferable that the capacitor 400 (C ₄ of FIG. 9) uses a variable capacitor 400. Of course, in order to lower the production cost, a capacitor 400 having a capacity for forming a desired resonance frequency through repeated experiments may be used.

10 to 19 are diagrams for describing a resonant frequency of a built-in antenna device for a low frequency band according to a first embodiment of the present invention.

As shown in FIG. 10, a chip antenna 100 is mounted on a printed circuit board 200 on which an auxiliary radiation pattern and a plurality of conductive pads are formed. At this time, the capacitor 400 is removed. When the frequency of the received signal received from the radiation pattern 120 and the auxiliary radiation pattern is measured, as shown in FIG. 11, a resonance frequency of about 148 MHz is formed. At this time, as shown in FIG. 12, when the capacitor 400 having a capacitance value of about 0.75 kHz is mounted in the low-band internal antenna device according to the first embodiment of the present invention, a resonance frequency of about 98 MHz is obtained. To form (see FIG. 13). Here, when the capacitor 400 having a capacitance value of 0.5 Hz to 2.4 Hz is sequentially mounted and the resonance frequency is measured, the resonance frequency decreases as the capacitance value increases (see FIG. 14). By calculating the variation of the resonance frequency band according to the variation of the capacitance value using the table shown in FIG. 14, it can be seen that the resonance frequency of about 1 MHz decreases by approximately 0.1 Hz.

15 illustrates a chip antenna 100 having a standard different from that of the chip antenna 100 of FIG. 10 on a printed circuit board 200 on which an auxiliary radiation pattern and a plurality of conductive pads are formed. In this case, in the state in which the capacitor 400 is removed from the embedded antenna device for a low frequency band according to the first embodiment of the present invention, the frequency of the received signal received in the radiation pattern 120 and the auxiliary radiation pattern is measured in FIG. 16. As shown, it forms a resonant frequency of approximately 114.5 MHz. In this case, as shown in FIG. 17, when the capacitor 400 having a capacitance value of about 2.2 GHz is mounted in the built-in antenna device for a low frequency band according to the first embodiment of the present invention, a resonance frequency of about 98 MHz is obtained. Form (see FIG. 18). Here, when the capacitor 400 having a capacitance value of 1.5 kHz to 4.7 kHz is sequentially mounted and the resonance frequency is measured, the resonance frequency decreases as the capacitance value increases (see FIG. 19). By calculating the variation of the resonance frequency band according to the variation of the capacitance value using the table shown in FIG. 19, it can be seen that the resonance frequency of about 1 MHz decreases by approximately 0.1 Hz.

FIG. 20 is a diagram for explaining a low frequency band embedded antenna device according to a second embodiment of the present invention.

As shown in FIG. 20, in the low-frequency band built-in antenna device according to the second embodiment, the chip antenna 100 is mounted on the flexible circuit board 300 on which the auxiliary radiation pattern and the plurality of conductive pads are formed. The substrate 300 is mounted on the printed circuit board 200, which is different from the first embodiment. Other technical configuration and coupling structure is the same as the first embodiment described above, so a detailed description thereof will be omitted.

21 to 25 are diagrams for describing a resonant frequency of a built-in antenna device for a low frequency band according to a second embodiment of the present invention.

As shown in FIG. 21, the chip antenna 100 is mounted on the flexible circuit board 300 on which the auxiliary radiation pattern and the plurality of conductive pads are formed, and the flexible circuit board 300 is on the printed circuit board 200. It is mounted. At this time, the capacitor 400 is removed. Measuring the frequency of the received signal received in the radiation pattern 120 and the auxiliary radiation pattern, as shown in Figure 22, to form a resonance frequency of approximately 107MHz. In this case, as shown in FIG. 23, when a capacitor 400 having a capacitance value of about 0.5 Hz is mounted, a resonance frequency of about 98.25 MHz is formed (see FIG. 24). Here, when the capacitor 400 having a capacitance value of 0.5 Hz to 2.7 Hz is sequentially mounted and the resonance frequency is measured, the resonance frequency decreases as the capacitance value increases (see FIG. 25). By calculating the variation of the resonance frequency band according to the variation of the capacitance value using the table shown in FIG. 25, it can be seen that the resonance frequency of approximately 1 MHz decreases by approximately 0.1 Hz.

FIG. 26 is a diagram illustrating a resonant frequency variable range of a built-in antenna device for a low frequency band according to an embodiment of the present invention.

As shown in FIG. 26, in the conventional low frequency band built-in antenna device, when the meander line conductive pad is formed on the printed circuit board 200, each meander line is etched at about 0.5 MHz. The resonance frequency decreases, and the variable range of the resonance frequency is limited to about 10 MHz.

In addition, in the conventional low frequency band built-in antenna device, when the meander line conductive pad is formed on the flexible circuit board 300, the resonance frequency of about 2.5 MHz is decreased every time one meander line is etched. The variable range of frequency is limited to about 20 MHz.

Here, in the conventional low frequency band built-in antenna device, since the number of lines that can be formed as meander lines is limited by the circuit board (for example, the printed circuit board 200 and the flexible circuit board 300), the variable range of the resonance frequency Is limited. Of course, the variable range of the resonance frequency may vary depending on the number of meander lines formed on the circuit board.

On the other hand, in the low frequency band built-in antenna device according to an embodiment of the present invention, the variable range of the resonance frequency is limited according to the capacity of the capacitor 400, not the etching of the meander line. Therefore, the use of the same size circuit board has a wider resonant frequency variable range than the conventional low frequency band built-in antenna device. According to FIG. 26, in the low frequency band built-in antenna device according to the exemplary embodiment of the present invention, the resonance frequency of approximately 1.0 MHz decreases whenever the capacitance of the capacitor 400 increases approximately 0.1 Hz, and the variable range of the resonance frequency is It is about 40 MHz or more.

Therefore, in the low frequency band built-in antenna device according to the present invention, by connecting the capacitor 400 to the feed terminal, it is possible to easily tune the resonant frequency through the capacitance adjustment of the capacitor 400.

27 to 32 are views for explaining a low frequency band embedded antenna device according to a third embodiment of the present invention, Figure 33 is a resonance frequency of the low frequency band built-in antenna device according to a third embodiment of the present invention It is a figure for demonstrating.

In the third embodiment of the present invention, the LC resonance is formed through the mounting of the inductor 500 and the capacitor 400 to double resonate the embedded antenna device for the low frequency band. Through this, it is possible to implement the widening of the built-in antenna device for low frequency band.

As shown in FIG. 27, the built-in antenna device for a low frequency band forms a ground part formed on a circuit board as two branched lines. The capacitor 400 and the inductor 500 are mounted on the branched ground. Here, the capacitor 400 and the inductor 500 may be stacked on the ground formed in one line. In this case, the stacked capacitor 400 and the inductor 500 are mounted on the printed circuit board 200 through soldering. That is, in the low frequency band built-in antenna device, the capacitor 400 and the inductor 500 are connected in parallel to the ground. Accordingly, the equivalent circuit of the built-in antenna device for low frequency band shown in FIG. 27 is formed as shown in FIG.

As shown in FIG. 29, the low frequency band internal antenna device continuously mounts the capacitor 400 and the inductor 500 to a ground portion formed on a circuit board. In this case, the stacked capacitor 400 and the inductor 500 are mounted on the ground portion through soldering. That is, the low frequency band built-in antenna device is to connect the capacitor 400 and the inductor 800 in series with the ground. Accordingly, the equivalent circuit of the built-in antenna device for low frequency band shown in FIG. 29 is formed as shown in FIG.

Here, as shown in FIG. 31, the internal antenna device for the low frequency band may be interchanged with the positions of the capacitor 400 and the inductor 500, and an equivalent circuit is formed as shown in FIG. 28.

When only the capacitor 400 is mounted on the low frequency band embedded antenna device according to the third embodiment of the present invention, the frequency of the received signal received in the radiation pattern 120 and the auxiliary radiation pattern is measured in FIG. As shown in Fig. 1, one resonant frequency is formed. At this time, when the inductor 500 is mounted in series or in parallel with the capacitor 400, as shown in FIG. 33B, two resonance frequencies are formed. Here, FIG. 33 (b) shows a somewhat wider spacing between the two resonant frequencies in order to explain that double resonance can be formed by mounting the inductor 500 and the capacitor 400 in parallel / serial, In application, the capacitance of the capacitor 400 and the inductor 500 may be adjusted to form a close resonance frequency.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but many variations and modifications may be made without departing from the scope of the present invention. It will be understood that the invention may be practiced.

1 and 2 are diagrams for explaining a chip antenna applied to an embodiment of the present invention.

3 to 7 are views for explaining a circuit board applied to the embodiment of the present invention.

8 is a view for explaining a low-frequency band built-in antenna device according to a first embodiment of the present invention.

9 is a view for explaining an equivalent circuit of the antenna device of FIG.

10 to 19 are diagrams for explaining the resonance frequency of the built-in antenna device for a low frequency band according to the first embodiment of the present invention.

20 is a diagram for explaining a low-frequency band internal antenna device according to a second embodiment of the present invention.

21 to 25 are diagrams for explaining the resonant frequency of the built-in antenna device for a low frequency band according to a second embodiment of the present invention.

FIG. 26 is a view illustrating a resonant frequency variable range of a built-in antenna device for a low frequency band according to an embodiment of the present invention. FIG.

<Description of the symbols for the main parts of the drawings>

100: chip antenna 110: polyhedral block

120: radiation pattern 130: coupling pattern

130a: first coupling pattern 130b: second coupling pattern

110a: first side 110b: second side

200: printed circuit board 210: NO-GND area

220: ground region 230: first conductive pad

240: second conductive pad 250: third conductive pad

260: fourth conductive pad 270: fifth conductive pad

280: via hole 290: sixth conductive pad

300: flexible circuit board 310: first conductive pad

320: second conductive pad 330: third conductive pad

340: fourth conductive pad 350: fifth conductive pad

400: capacitor 500: inductor

Claims (10)

A chip antenna including a polyhedron block on which a radiation pattern and a coupling pattern are formed; A circuit board including a first conductive pad connected to one side of the radiation pattern and a second conductive pad connected to the coupling pattern; And And a capacitor formed between the first conductive pad and the ground region of the circuit board. The method according to claim 1, And an inductor formed between the first conductive pad and the ground region of the circuit board. The method according to claim 2, The capacitor and the inductor is an internal antenna device for a low frequency band, characterized in that connected in series. The method according to claim 2, The capacitor and the inductor is an internal antenna device for a low frequency band, characterized in that connected in parallel. The method according to claim 1, The circuit board further includes an auxiliary radiation pattern connected to the first conductive pad, low frequency band built-in antenna device. The method according to claim 5, The auxiliary radiation pattern is a low frequency band built-in antenna device, characterized in that formed in the meander shape. The method according to claim 1, The radiation pattern is a low frequency band built-in antenna device, characterized in that formed in the form of a winding along the outer peripheral surface of the polyhedral block. The method according to claim 1, The capacitor is a built-in antenna device for a low frequency band, characterized in that consisting of a variable capacitor. The method according to any one of claims 1 to 8, The circuit board is a low-frequency band internal antenna device, characterized in that the printed circuit board of the portable terminal in which the chip antenna is mounted. The method according to any one of claims 1 to 8, The circuit board is a low-frequency band built-in antenna device, characterized in that the chip antenna is mounted is a flexible circuit board connected to the printed circuit board of the portable terminal.

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