KR100732113B1 - Ceramic Antenna - Google Patents

Abstract

The present invention relates to a small ceramic antenna, and more particularly, to a small ceramic antenna having a multi-band characteristic by the electromagnetic coupling coupling of the radiation patch and the feed strip line and the short strip line implemented on the surface of the ceramic dielectric.

Ceramic antenna according to the present invention is a single layer, a multi-stage dielectric with one end of the front surface removed; A radiation patch formed on the front surface of the dielectric; A feed strip line formed at the removed end of the dielectric and having one end connected to the radiation patch; A shorting stripline formed at a rear surface of the dielectric and having one end connected to a ground plane and electrically coupling with the feed strip line; And at least one meander stripline connected to the shorting stripline.

The present invention can improve the resonance characteristics while maintaining a small size by combining a radiation patch having a slit and a shorting strip line in which two different lengths of wires are connected by electromagnetic coupling. In addition, the present invention can control the resonance characteristics and the resonant frequency of the two bands by adjusting the length of a plurality of different lines connected to the shorted stripline, and the separation distance between the feed stripline and the shorting stripline.

Dual Band, Ceramic, Chip, Antenna

Description

Ceramic Antenna

1 is a configuration diagram in which a small ceramic antenna according to the present invention is mounted on a substrate;

2 is a perspective view of a small ceramic antenna according to an embodiment of the present invention;

3 is a view showing the front, side, back of the small ceramic antenna according to an embodiment of the present invention;

4 is a perspective view of a small ceramic antenna according to another embodiment of the present invention;

5 is a graph showing the return loss of the antenna having the structure of FIG.

6 is a graph showing return loss of a shorting stripline;

7 is a graph showing the return loss of the antenna having the structure of FIG.

FIG. 8 is a graph illustrating return loss characteristics according to a separation distance between a feed strip line and a short strip line in the antenna having the structure of FIG. 2; FIG.

9 shows a radiation pattern at 2.0 GHz of an antenna having the structure of FIG. 2; FIG. And

FIG. 10 is a diagram illustrating a radiation pattern at 5.25 GHz of the antenna having the structure of FIG. 2.

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

1,20,40: small ceramic antenna 21: radiation patch

22: feed stripline 23: slit

24: ceramic dielectric 25: short-circuit stripline

26: Meander stripline 27: Folded stripline

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic antenna, and more particularly, to a small ceramic antenna having a multi-band characteristic by electromagnetically coupling and coupling a radiation patch and a feed strip line and a shorting strip line implemented on a ceramic dielectric surface.

Current wireless mobile communication terminals have various functions in a small and limited structure. And as the design of the terminal is as important as the function, the antenna for the terminal is also changing from external to internal. At present, active researches are focused on chip-type ceramic antennas that can achieve miniaturization and multi-band as an internal antenna for terminals.

The chip-shaped ceramic antenna may reduce the size of the antenna by stacking a dielectric having a high dielectric constant in multiple layers and then printing a metal pattern on the surface of the dielectric. As the most basic form, there is a structure that is miniaturized by implementing a metal pattern having a plurality of helical forms in a multilayer dielectric (KR 2002-30514). However, in the conventional ceramic antenna, when the antenna size is reduced, the radiation resistance of the antenna is also reduced, thereby reducing resonance characteristics. This reduces the bandwidth of the antenna and lowers the efficiency.

In addition, the use of a multi-layered substrate or a plurality of helical complicated the manufacturing process, thereby increasing the manufacturing cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, the multi-band is simply implemented through the printing of a metal pattern on the surface of the single-layer dielectric, feed stripline connected to the radiation patch, stripline of a plurality of different lengths It is an object to provide a multi-band small ceramic antenna in which the connected short-circuit striplines are coupled by electromagnetic coupling to improve the resonant characteristics of the antenna.

Ceramic antenna according to the present invention is a single layer, a multi-stage dielectric with one end of the front surface removed; A radiation patch formed on the front surface of the dielectric; A feed strip line formed at the removed end of the dielectric and having one end connected to the radiation patch; A shorting stripline formed at a rear surface of the dielectric and having one end connected to a ground plane and electrically coupling with the feed strip line; And at least one meander stripline connected to the shorting stripline.
One or more slits are formed in the radiation patch. The ceramic antenna has a characteristic in which the resonant frequency is changed by the width and length of the slit, and also has a characteristic in which the resonant frequency is changed by the length of the meander stripline. The radiation patch and the short stripline form an electromagnetic coupling.
The ceramic antenna may further include one or more folded striplines connected to the shorting striplines. At this time, the ceramic antenna has a characteristic that the frequency of the high resonance band is changed by the length of the folded stripline. In addition, the ceramic antenna has a characteristic that the matching characteristic and the resonant frequency are changed by the separation distance between the shorting strip line and the feeding strip line. The radiation patch, the feed strip line, the short strip line, the meander strip line, and the folded strip line are formed by printing a metal pattern on the dielectric surface.

delete

delete

The above objects and features will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those of ordinary skill in the art may easily implement the technical idea of the present invention. . In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a configuration diagram in which a small ceramic antenna according to the present invention is mounted on a substrate. The small ceramic antenna 1 is mounted on the dielectric 2 of the substrate. The ground plane 3 of length L _g and width W _g may be located at the rear of the substrate or at the front of the substrate. When the ground plane 3 is located in front of the substrate, the ground plane 3 is configured to be spaced apart from the 50 ohm feed line 4 by a predetermined distance, and is directly connected to the shorting point of the small ceramic antenna 1. When the ground plane 3 is located on the bottom surface of the substrate, the metal plane is inserted into the via hole of the substrate so that the ground plane 3 is connected to the shorting point of the small ceramic antenna 1.

2 is a perspective view of a small ceramic antenna 20 according to an embodiment of the present invention, Figure 2 (a) is a front portion of the small ceramic antenna 20, Figure 2 (b) of the small ceramic antenna 20 The rear part is shown, respectively. 3 shows a front view, a side view, and a rear view of the small ceramic antenna 20.

The small ceramic antenna 20 has a length L, a width W, a thickness T, and a single layer dielectric 24 having a dielectric constant e _r = 10.2. The ceramic dielectric material 24 has a multi-stage shape in which the dielectric material of length L, width w _c and thickness T t _c is partially removed. The front face of the ceramic dielectric material 24 is printed with a radiation patch 21 and a feed strip line 22, and on the opposite back face a short strip line 25, a meander strip line 26 and a folded strip line 27 Are printed respectively. In the figure, portions marked in dark are printed with conductive materials such as the radiation patch 21, the feed strip line 22, the short strip line 25, the meander strip line 26, and the folded strip line 27. Indicates that The portions shown in light represent the ceramic dielectric 24 surface.

The thickness T-tc of the ceramic dielectric material 24 may be designed in a multistage form or a planar form depending on the size and material of the dielectric and the resonant frequency.

Slits 23 having a length l _s and a width w _s are formed at positions apart from d ₁ from the lower end of the spinning patch 21 and positions apart from d ₂ therefrom. The resonance frequency of the radiation patch 21 can be moved to another frequency by changing the electrical resonance length by adjusting the length and width of the slit 23.

In addition, multiple frequency bands are formed by adjusting the position and number of slits 23 in accordance with the resonant frequency of the radiation patch.

The upper end of the feed strip line 22 is connected to the radiation patch 21, and the lower end is connected to the 50 ohm feed line 4 at the feed point 22a.

Short-circuit strip lines 25 are printed on the dielectric back surface opposite to the radiation patch 21 at points spaced apart from the side ends of the feed strip lines 22 by g. The lower end of the shorting stripline 25 is connected to the ground plane 3 at the shorting point 25a directly or through a via hole of the substrate and shorted. The upper end of the shorting stripline 25 is connected with a meander stripline 26 and a folded stripline 27. Meander stripline 26 has a length l _a and folded stripline 27 has a length l _b .

The short strip line 25 is electrically coupled and resonated with the feed strip line 22. Therefore, the antenna may be designed to have a single band or a multi band characteristic by adjusting the impedance matching characteristic and the resonant frequency according to the spaced distance between the short strip line 25 and the feed strip line 22.

The meander strip line 26 and folded strip line 27 may be formed in plural numbers according to the resonance frequency, and the position, shape, and direction may be modified.

The small ceramic antenna 20 having the above-described configuration includes a shorting strip line to which the radiation patch 21 fed through the feed strip line 22 and the meander strip line 26 and the folded strip line 27 are connected. 25 is physically separated via the ceramic dielectric 24. Therefore, the resonance of the feed strip line 22 and the short-circuit strip line 25 to which the radiation patch 21 is connected is coupled by electromagnetic coupling to improve the resonance characteristics of the small ceramic antenna 20. In addition, the small ceramic antenna 20 is formed by printing a metal pattern on the surface of a single dielectric 24, and is simple to manufacture, and may be simply mounted on a substrate in a SMD (Surface Mounted Device) type and supplied with power. In addition, the small ceramic antenna 20 may be designed to have a multi-band by changing the resonant frequency by adjusting the length of the meander line and the folded strip line having different lengths.

Table 1 is an example of each parameter of the small ceramic antenna 20 according to the preferred embodiment of the present invention.

Parameter (mm) Parameter (mm) L 8.7 W 6.2 h 6.2 T 1.7 w _s 0.2 w _c 1.0 t _c 0.5 d ₁ 3.5 d ₂ 3.5 L _t 1.0 L _sp 0.5 l _a 21 w _a 0.5 w _b 0.2 l _s 4.5 l _b 4.6 g 1.2 e _r 10.2

The parameter values shown in Table 1 are one embodiment of the invention. Those skilled in the art will appreciate that the dimensions, materials, and resonant frequencies of the antennas may vary sufficiently.

Meanwhile, as shown in FIG. 4, the folded stripline 27 having a length l _b may be removed from the small ceramic antenna 20 having the structure of FIG. 2 to configure the antenna. Figure 4 is a perspective view of a small ceramic antenna 40 according to another embodiment of the present invention, Figure 4 (a) is a front portion of the small ceramic antenna 40, Figure 4 (b) is a small ceramic antenna 40 Each of the rear parts of the is shown.

In the small ceramic antenna 40 according to another embodiment of the present invention, the radiation patch 41, the feed strip line 42, the slit 43, the ceramic dielectric 44, the short strip line 45, the meander strip Line 46 corresponds to radiation patch 21, feed stripline 22, slit 23, ceramic dielectric 24, shorting stripline 25, and meander stripline 26 of FIG. 2. The folded stripline 27 of FIG. 2 is removed and only the meander stripline 46 is connected to one end of the shorting stripline 45. The resonance frequency of the small ceramic antenna 40 may be adjusted by the length of the meander stripline 46. In the small ceramic antenna 40, the slit-shaped radiation patch 41 operates like a monopole, and the shorting stripline 45 also operates as a monopole. Therefore, the small ceramic antenna 40 has excellent resonance characteristics by combining the resonance of these two structures.

FIG. 5 is a graph showing the return loss of the radiation patch 41 and the shorting stripline 45 with respect to the antenna having the structure of FIG. 4. Material and dimensions of the small ceramic antenna 40 are as shown in Table 1.

In the small ceramic antenna 40 of FIG. 4, when the short strip line 45 and the meander strip line 46 are removed, the reflection loss of the radiation patch 41 to which the feed strip line 42 is connected (indicated by a long dotted line) ), The first resonance of the radiation patch 41 occurs in the 2 GHz band but is not matched. Next, when the feed strip line 42 and the radiation patch 41 of the small ceramic antenna 40 are removed, the reflection loss of the short strip line 45 to which the meander strip line 46 is connected (indicated by a short dotted line) ), The first resonance of the shorting stripline 45 also occurs in the about 2 GHz band but is not matched.

However, these two structures, that is, the feeding stripline 42 to which the radiation patch 21 is connected, and the shorting stripline 45 to which the meander stripline 46 is connected, are connected to each other. Looking at the characteristics, the resonance of each structure is combined to improve the matching characteristics in the 2 GHz band to satisfy the standing voltage ratio (VSWR) <2. However, in the 5 GHz band, the two structures are electromagnetically coupled to generate an input impedance mismatch, resulting in an increase in resonance frequency and poor matching.

The resonance characteristic of 5 GHz can be improved by further connecting the folded stripline 47 to the shorting stripline 45 to which the meander stripline 46 is connected, such as the small ceramic antenna 20 shown in FIG. 2. have.

FIG. 6 is a graph showing the return loss of the shorting stripline 25 depending on whether the folded stripline is connected. For comparison of the return loss characteristics, the folded patchline 27 is connected to the shorting stripline 25 to which the meander stripline 26 is connected while the radiation patch 21 and the feed stripline 22 are removed. The change in return loss is shown when connected (indicated by dashed lines) and when folded stripline 27 is not connected (indicated by solid lines).

As shown, the resonance in the 2 GHz band is not affected by the connection of the folded stripline 27. However, if there is no folded stripline 27, the shorting stripline 25 has a center frequency of about 4.95 GHz (based on the reflection loss of -10 dB), while the folded stripline 27 is a shorting strip. When connected to line 25 the shorting stripline 25 has a center frequency of about 4.75 GHz. Thus, the folded stripline 27 is connected to the shorting stripline 25 so that the high resonant frequency is lowered. From this, it can be seen that the resonant frequency of the 5 GHz band can be adjusted by changing the length of the folded stripline 27.

FIG. 7 is a graph showing the return loss of the small ceramic antenna 20 of FIG. 2 depending on whether the folded strip line 27 is connected. The dotted line represents the return loss (indicated by the dashed line) of the small ceramic antenna 20 without the folded stripline 27. This is equivalent to the return loss indicated by the solid line in FIG. The solid line represents the return loss (indicated by the solid line) of the small ceramic antenna 20 to which the folded stripline 27 is connected. By connecting the folded stripline 27, the resonance characteristic of the 5 GHz band is improved, so that the antenna satisfies VSWR <2 in two bands of 2 GHz and 5.25 GHz. Accordingly, the small ceramic antenna 20 according to the present invention operates as a dual band antenna usable in both the HSDPA (TD-SCDMA) band and the 802.21a WLAN band.

FIG. 8 is a graph illustrating return loss characteristics of the antenna 20 of FIG. 2 according to a change in the separation distance g between the feed strip line 22 side end of the radiation patch 21 and the short strip line 25. When the separation distance g is 0.7 mm, the antenna has resonance in the 2 GHz and 5.45 GHz bands, and the matching characteristics are also excellent in both bands. However, when the spacing increases to 1.2 mm, the matching characteristic in the 2 GHz band slightly decreases the return loss peak from -19 dB to -14 dB, but the resonance in the 5 GHz band is lowered by about 200 MHz, resulting in the 5.25 GHz band. do. As the separation distance increases further to 1.7 mm, the matching characteristic of the 2 GHz band becomes worse. The separation distance g affects the electromagnetic coupling occurring between the feeding stripline 22 and the shorting stripline 25 of the radiation patch 21. Therefore, as the separation distance changes, the matching characteristic and the resonance frequency of the antenna change.

FIG. 9 shows antenna radiation patterns at a 2.0 GHz resonance frequency of the small ceramic antenna 20 having the structure of FIG. 2. The gain of the antenna in the maximum radiation direction is 3.1 dBi. FIG. 10 illustrates antenna radiation patterns of a small ceramic antenna 20 having the structure of FIG. 2 at a 5.25 GHz resonance frequency. The resonance generated at 5.25 GHz of the small ceramic antenna 20 is caused by harmonics of 2 GHz, which is the first resonance mode, and the current flowing in the antenna changes. Therefore, nulls are generated in the radiation pattern due to the change of the current distribution. At this time, the gain of the antenna in the maximum radiation direction represents a value of 4.2 dBi.

As described above, although the present invention has been described by way of limited embodiments and drawings, the present invention is not limited thereto and is intended by those skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of equivalents of the claims to be described.

The present invention can improve resonance characteristics while maintaining a small size by feeding and feeding a feed strip line to which a radiation patch is connected, and a shorting strip line to be coupled and resonated by an electromagnetic coupling.

In addition, the present invention enables wideband and multiband implementation by adjusting the resonant frequency by a plurality of different line lengths connected to the shorted stripline.

In addition, by adjusting the separation distance between the feed strip line and the short strip line by adjusting the resonance characteristics and the resonance frequency, it is possible to implement a wideband and multi-band.

In addition, by manufacturing a single layer by printing a conductor pattern on the surface of the ceramic dielectric, the manufacturing process can be simplified and miniaturized.

Claims (9)

A multi-layer dielectric having a single layer, with one end of the front surface removed; A radiation patch formed on the front surface of the dielectric; A feed strip line formed at the removed end of the dielectric and having one end connected to the radiation patch; A shorting stripline formed at a rear surface of the dielectric and having one end connected to a ground plane and electrically coupling with the feed strip line; And At least one meander stripline connected to the shorting stripline Ceramic antenna comprising a. delete The method of claim 1, The radiation patch Containing one or more slits Ceramic antenna. The method of claim 3, The resonance frequency is changed by the width and length of the slit Ceramic antenna. The method of claim 1, The resonance frequency is changed by the length of the meander stripline Ceramic antenna. The method of claim 1, One or more folded striplines formed on the back side of the dielectric and connected to the shorting striplines Ceramic antenna further comprising a. The method of claim 6, The frequency of the high resonance band is changed by the length of the folded stripline. Ceramic antenna. The method of claim 6, The matching characteristic and the resonant frequency change by the separation distance between the short-circuit stripline and the feed stripline. Ceramic antenna. The method of claim 6, The radiation patch, feed strip line, short strip line, meander strip line, folded strip line Formed by printing a metal pattern on the dielectric surface Ceramic antenna.

Images