KR100674667B1 - Dual band small chip antenna with stacked meander structure for wireless mobile terminal - Google Patents

Abstract

The present invention is to provide a small chip antenna that can improve the miniaturization characteristics of the radiating element by forming a resonant frequency of the dual band through one via hole formed on the meander-shaped radiation patch, the high frequency transmitted through the feed line A lower radiating element having a meander shape in which a resonance frequency is formed by a current supplied through a feed line to emit a signal; A lower end radiator having a double band formed between the lower radiating element to emit a frequency signal, the upper radiating element having a meander shape formed at a predetermined interval apart from an upper portion of the lower radiating element; And a via hole coupling a high frequency signal flowing through the lower radiating element to the upper radiating element to form a resonance frequency in the upper radiating element.

Mobile communication, terminal, meander line, chip, antenna

Description

Dual-band chip antenna with stacked meander structures for mobile communication applications             

Figure 1 is an illustrative view of the spin patch of the meander form applied to the present invention.

2A and 2B are characteristic diagrams of surface current peak values of magnetic field components in the Y-axis direction of a single basic meander antenna according to the present invention;

3 is a perspective view of a dual band small chip antenna of a stacked meander structure for a wireless mobile terminal according to an embodiment of the present invention.

4A is a detailed cross-sectional view of the lower radiating element in FIG. 3.

4B is a detailed cross-sectional view of the upper radiating element in FIG. 3.

5A and 5B are explanatory diagrams for the surface current distribution of meander antenna tangential components stacked at different design center frequencies.

6A and 6B are characteristic diagrams of a resonance frequency and an impedance bandwidth of a dual band small chip antenna according to a vertical via hole height design variable according to the present invention.

7 is a view showing the resonant frequency characteristics of the small chip antenna according to the present invention in the GPS band and K-PCS band.

8A and 8B are diagrams illustrating a radiation pattern of a small chip antenna according to the present invention measured by a near field pattern measuring device.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual band small chip antenna having a stacked meander structure for a wireless mobile terminal. In particular, a miniaturization characteristic of a radiating element is achieved by forming a resonant frequency of a dual band through one via hole formed on a meander shaped radiation patch. It relates to a small chip antenna that can improve the.

Recently, new information such as navigation system using the GPS (Global Position System) function, wireless Internet, and Bluetooth are emerging, and derivative information products that can generate new profits are emerging one after another. As a conventional personal mobile communication service is widely used, a lot of research and development has been concentrated on such a wireless communication system so that the wireless communication system can operate in conjunction with a cellular and personal communication service (PCS) mobile communication system. In fact, the recent trend of legislation of emergency rescue services in preparation for dangerous situations such as fire and distress, and the newly launched mobile terminal to operate GPS function and LBS (Location-Based Service) system in conjunction with personal mobile communication at home and abroad. GPS functions are mandatory in the country, and additional service functions such as transportation, security, and logistics are being actively developed to create new added value. As such, the development of information society demands miniaturization and multifunctionality to increase the mobility of personal terminal for mobile communication, and antenna for SOC (System on Chip) of passive / active parts that make up the entire RF-Front End. Miniaturization is required.

As described above, for miniaturization of the resonant antenna applied to the mobile terminal, a substrate having a high value of the non-genetic constant used in the past or a lumped element (such as a resistor, a capacitor, and an inductor) are externally used. Loading methods show a disadvantage of limiting the electrical characteristics of the antenna by significantly reducing the surface waves and the efficiency of the antenna. Therefore, in recent years, a method of structurally modifying a radiation patch or designing a three-dimensional radiation structure in order to increase the effective current length of a resonant antenna has attracted attention as a structure for miniaturizing the antenna. In particular, Planar Inverted F- Like the antenna structure, a miniaturized chip antenna structure has been introduced in various ways by combining a resonance structure which minimizes the reactance in the feeding direction and a simple deformation structure by slit laying. In addition, to secure the multi-band characteristics of the resonant antenna, the method of using higher order modes (TM ₁₀ , TM ₂₀ , ...) by changing the surface current distribution of the basic resonance mode, the main radiating patch Parasitic patches are laid in a planar and stacked manner to design different center frequencies in the parasitic patch by the coupling effect, and slits are provided to secure multiple resonance paths in the limited planar radiating element. The method was mainly used.

As such, the slit laying suitable for the radiating element increases the effective length of the surface current distributed on the patch, and effectively reduces the resonance frequency compared to the radiating patch of the same size. It can be a useful method for designing antennas that can be implemented and for designing antennas operating in multiple bands such as dual bands, or for extending impedance bandwidth by reducing the frequency ratio (FR) ratio of resonant frequencies in dual bands. have. In addition, a structure for miniaturization and securing multiband characteristics has been required due to the improvement of the narrowband impedance bandwidth characteristics of the microstrip patch antenna by lowering the Q-factor of the antenna, or the advantage of tolerance error in manufacturing.

The present invention has been made to meet the above requirements, a small chip that can improve the miniaturization characteristics of the radiating element by forming a resonant frequency of the dual band through a via hole formed on the meander-shaped radiation patch The purpose is to provide an antenna.

The present invention provides a substrate structure that increases the aspect ratio of the radiation patch or reduces the impedance bandwidth and efficiency by forming a meander shaped modified radiation structure to maximize the surface current distribution in the radiation patch by multiple symmetrical slit laying. An object of the present invention is to provide a small chip antenna capable of improving the miniaturization characteristics of an antenna by lowering the resonance frequency of the antenna without increasing the relative dielectric constant value.

The present invention forms a dielectric having a lower radiating element and an upper radiating element through a low temperature co-firing ceramic (LTCC) technique, thereby improving the miniaturization characteristics required for an antenna for a mobile terminal and simultaneously It is an object to provide a small chip antenna that can operate.

According to the present invention, by combining two meander radiators with different effective current lengths through vertical via holes, multi-frequency frequency ratio (FR) control is provided by independent design variables, and antenna design center frequency change and performance. It is an object to provide a small chip antenna that can provide flexibility for improvement.

The present invention for achieving the above object, the feed line for feeding a radio frequency signal; A lower radiating element having a meander shape in which a resonant frequency is formed by a current supplied through the feed line to radiate a high frequency signal transmitted through the feed line; A lower radiator having a dual band formed between the lower radiating element and the radiating frequency signal, the upper radiating element having a meander shape formed at a predetermined interval apart from the upper portion of the lower radiating element; And a via hole formed at a predetermined height in a predetermined portion of the lower radiating element and the upper radiating element to couple a high frequency signal flowing through the lower radiating element to the upper radiating element to form a resonance frequency in the upper radiating element. Include.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

1 is an explanatory diagram illustrating a meander type radiation patch applied to the present invention, in which a vertical / horizontal portion of a single meander shaped radiation structure is interpreted as an equivalent cavity model and a radiation mechanism. The surface current distribution is shown for explanation.

In the antenna structure of the meander form according to the present invention, the radiation pattern and the antenna efficiency largely depend on the current flowing in the radiation element, and the current flow in the vertical / horizontal direction of the meander form presented in the joint model explains the entire radiation mechanism of the antenna. Provide qualitative information. In the single meander antenna structure, the surface current flow in the X-axis direction is formed in opposite directions in the meander radiation patch structure to form a field canceled with each other in the far field. The surface current components in the direction form the same direction and contribute mainly to the radiation.

2A and 2B show simulation results of surface current peak values of magnetic field components in the Y-axis direction of a single basic meander antenna applied to the present invention.

As shown in FIGS. 2A and 2B, it can be seen that the magnetic field components formed in the Y-axis direction based on the same phase form a stronger field than the horizontal portion in seven vertical portions of the meander antenna. In addition, the magnitude of the magnetic field component weakens as the Y-axis coordinate increases, and it can be seen that the magnetic field components face the same direction with respect to the reference phase. Thus, it can be seen that the flow of current in the Y-axis direction is a major component contributing to radiation in the meander structure of a given coordinate system.

The structure of the dual band small chip antenna of the present invention using a meander-type radiation patch having such characteristics is as shown in FIG. 3.

3 is a perspective view of a dual band small chip antenna of a stacked meander structure for a wireless mobile terminal according to an embodiment of the present invention.

Referring to FIG. 3, the dual band small chip antenna according to the present invention includes a feed line 310 for feeding a radio frequency (RF) signal and a high frequency signal transmitted through the feed line 310. A low resonant frequency of a dual band is formed between the lower radiating element 320 having a meander shape and the lower radiating element 320 having a resonant frequency formed by a current fed through the feed line 310 to radiate a frequency. Coupling a high frequency signal flowing through the upper radiating element 330 and the lower radiating element 320 to the upper radiating element 330 for forming a resonant frequency in the upper radiating element 330 The via hole 340 is provided.

The small chip antenna of the present invention is located in a portion removed on the upper side of the double-sided substrate, the dielectric plate 360 is formed on the lower portion of the substrate on which the feed line consisting of the microstrip line 310 is disposed, the dual band small chip antenna Electrical connection with the lower radiating element 320 is taken. That is, the feed line 310 is formed on the dielectric plate 360 to apply a high frequency signal to a portion of the double-sided substrate.

A ground plate 370 is formed at a portion of the lower portion of the substrate 350, and the ground plate 370 is formed at a position symmetrical with the feed line 310 and the dielectric plate 360. In contrast, the ground plate 370 is not formed below the upper radiating element 330 and the lower radiating element 320, which is to improve the impedance bandwidth, which is an electrical characteristic of the antenna.

On the substrate 350 where the dielectric plate 360 is not formed, a radiating body 380 having a rectangular parallelepiped shape formed of a dielectric material is formed, which is formed through a low temperature co-firing ceramic (LTCC) technique. However, the present invention is not limited thereto.

A lower radiating element 320 having a meander shape is formed below the radiating body 380, and an upper radiating element 330 having a meander shape is formed thereon. One via hole 340 is formed at a specific position of the lower radiating element 320 and the upper radiating element 330 thus formed.

The feed line 310 made of a microstrip line is formed to have a resistance value of 50Ω, which is to match the input impedance of the antenna to 50Ω.

The lower radiating element 320 and the upper radiating element 330 are made of a conductive material and include an LTCC series dielectric having different effective current lengths. The dielectric is a dielectric having a dielectric constant of 7.8 and a thickness of 1.2 mm. .

The via hole 340 couples the radio frequency signal applied through the feed line 310 to the upper radiating element 330 to form a resonance frequency in the upper radiating element 330. Accordingly, the electrical path difference between the lower radiating element 320 and the upper radiating element 330 formed on different layers can control the resonance characteristics of the radiating patch as independent design variables, thereby providing flexibility in improving antenna performance. do.

The meander-shaped radiating elements 320 and 330 having different lengths have a dielectric ceramic sheet having a specific dielectric constant of 7.8 having a predetermined size, for example, 9151.2 mm to improve antenna low-profile and miniaturization characteristics. Dielectric), which is made of a radial structure coated with silver (Ag), a conductive material, through a screen pattern printing operation.

A resonance frequency is formed in the lower radiating element 320 by a current supplied through the feed line 310, and in this state, a high frequency signal flowing through the lower radiating element 320 is transmitted by the via hole 340 by the upper radiating element 330. When coupled to the resonance frequency is formed in the upper radiating element 330. As such, when a resonant frequency of a dual band is formed between the lower radiating element 320 and the upper radiating element 330, the high frequency signal is radiated.

Detailed cross-sections of such radiating elements are as shown in FIGS. 4A and 4B, and the functions of the lower radiating element 320 and the upper radiating element 330 will be described in detail with reference to the following.

4A is a detailed cross-sectional view of the lower radiating element of FIG. 3.

4B is a detailed cross-sectional view of the upper radiating element of FIG. 3.

Referring to the drawings, the radiation patch in the present invention formed a meander-shaped radiation structure by laying multiple slits in order to elastically and effectively reduce the antenna volume, in the different direction of the X-axis direction in such a meander-shaped structure Since the current distribution of, forms a field canceled in the far field, the current distribution forming the radiation pattern is due to the current distribution in the Y-axis direction. In addition, the radiation patch by the multi-slit laying increases the effective length of the surface current to reduce the resonant frequency, increases the impedance bandwidth by reducing the Q-factor of the antenna and there is an advantage that the influence on the manufacturing error is insensitive.

5A and 5B show the surface current (H-field) distribution of meander antenna tangential components stacked at different design center frequencies.

As shown in Figs. 5A and 5B, the surface current distribution at the design center frequency (1.575 GHz) of the GPS system is confirmed to have a stronger surface current distribution than the upper meander line at the bottom of the stacked meander antenna, In the PCS design center frequency (1.8GHz) band, the surface current distribution can confirm the strong current distribution at the same time with the stacked upper meander antenna and the lower one. Therefore, the broadband characteristics in the PCS center frequency band can be confirmed by the parasitic effect of the stacked meander pattern, and the resonance characteristics of the GPS band can be confirmed that the coupling effect of the stacked meander pattern is not large. .

6A and 6B illustrate the characteristics of the resonance frequency and the impedance bandwidth of the dual band small chip antenna according to the vertical via hole height design variable according to the present invention.

As shown in the figure, the design variable h of the height constituting the via-hole in the stacked antenna structure serves as an important design variable that determines the ratio of the design center frequency to the dual band due to the mutual coupling effect of the radiation structure. do.

6A and 6B illustrate a change in resonance frequency when the height of the via hole 340 changes from 0.11 mm to 0.91 mm, and the low frequency band (GPS) of the dual band according to the change in the height of the via hole 340 is shown. Resonant frequency variation of -band is relatively small, but in the high frequency (K-PCS) band, the resonant frequency increases as the height of the via hole 340 increases. 340) increased from 1.2 to 1.48 as the height increased from 0.11mm to 0.91mm.

6B illustrates a change in the resonance frequency ratio according to the change in height of the via hole 340. When using the LTCC stacking process technology to secure the multi-band characteristics, it can be seen that the design parameters of the stacked height along with the effective resonance length of the individual radiating elements are important design parameters that determine the center frequency.

Hereinafter, the impedance characteristics and the radiation pattern through the return loss characteristics of the dual band small chip antenna having the meander-shaped radiating element according to the present invention will be described in detail with reference to FIGS. 7 and 8A and 8B.

7 shows the resonance frequency characteristics of the small chip antenna according to the present invention in the GPS band and the K-PCS band.

In FIG. 7, in the GPS band and the K-PCS band, the resonant frequency characteristics according to the present invention correspond to the center frequency, and the return loss characteristics are represented by -29 dB and -20 dB, and the impedance bandwidth is based on "VSWR≤2", respectively. It shows good characteristics at about 80 MHz and 120 MHz.

8A and 8B illustrate the radiation pattern measured by the small chip antenna according to the present invention through a measurement apparatus of a near field pattern.

As shown in the figure, ripple occurs in a part of the XZ plane pattern in the radiation pattern measured at the resonant frequency of the dual band, but shows an omni-directional pattern in all directions, and the pattern on the XY plane is Y It can be seen that it is formed similarly to the dipole pattern lying in the -axial direction. It can be seen that the X-Z plane and X-Y plane radiation patterns measured at 1.86 GHz, the PCS design center frequency, are also formed similarly to the isotropic pattern and the dipole radiation pattern.

Here, the maximum gain in the main beam direction is lower than the simulated gains of 0.4 dBi and 0.8 dBi at -3.2 dBi and -2.8 dBi.

As described above, the formation of a dipole pattern on the XY plane can be regarded as the formation of the radiation field by the vertical current distribution in the Y-axis direction, and the current distribution in the X-axis direction indicates the radiation fields canceled with each other in the far-field. It can be seen that forming. In addition, it can be confirmed that a null point is formed relatively large in the ground part in the radiation pattern of the X-Y plane due to the ground effect of the stacked meender.

Although the technical spirit of the present invention has been described in detail according to the above preferred embodiment, it should be noted that the above embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

As described above, the present invention, by installing multiple slits in the radiation patch to ensure different effective current length through the vertical via hole, to have the dual band characteristics of the small chip antenna, thereby increasing the aspect ratio of the radiation patch Miniaturization and slimming of the antenna can be achieved without deteriorating the electrical characteristics of the other antenna.

In addition, the present invention can provide flexibility in the design that can control the frequency ratio of the multi-band by electrically coupling the two radiating elements through the vertical via hole having different effective current length.

Claims (9)

A feed line for feeding a radio frequency signal; A lower radiating element having a meander shape in which a resonant frequency is formed by a current supplied through the feed line to radiate a high frequency signal transmitted through the feed line; A lower radiator having a dual band formed between the lower radiating element and the radiating frequency signal, the upper radiating element having a meander shape formed at a predetermined interval apart from the upper portion of the lower radiating element; And Via holes formed at a predetermined height in predetermined portions of the lower radiating element and the upper radiating element to couple a high frequency signal flowing through the lower radiating element to the upper radiating element to form a resonance frequency in the upper radiating element. Small chip antenna comprising a. The method of claim 1, The small chip antenna is formed on a substrate, a dielectric plate is formed below the substrate on which the feed line formed of microstrip lines is disposed, and a dielectric plate is not formed on the substrate on which the lower radiating element is formed. Miniature chip antenna. The method of claim 2, The feed line is a small chip antenna, characterized in that formed on top of the dielectric plate formed on a portion of the substrate. The method of claim 3, wherein A small chip, wherein a ground plate is formed at a portion of the lower part of the substrate, wherein the ground plate is formed at a position symmetrical with the feed line and the dielectric plate, and a dielectric plate is not formed under the substrate where the lower radiating element is formed. antenna. The method according to any one of claims 1 to 4, The lower radiating element and the upper radiating element is a miniature chip antenna, characterized in that formed in the meander shape and having a different effective current length. The method of claim 5, The small chip antenna, characterized in that the meander shape pattern for physically increasing the effective current length of the lower radiating element and the upper radiating element is coated with a conductive material through a screen printing technique. The method of claim 2, A rectangular parallelepiped radiating body made of a dielectric is formed on the substrate where the dielectric plate is not formed. A lower radiating element of the meander shape is formed below the radiating body, and an upper radiating of the meander shape is formed thereon. Small chip antenna, characterized in that the element is formed. The method of claim 7, wherein The radiating body is a small chip antenna, characterized in that formed through a low temperature co-firing technique. The method of claim 1, The lower radiating element and the upper radiating element are made of a conductive material, and include an LTCC series dielectric having different effective current lengths, and the dielectric is a dielectric having a dielectric constant of 7.8 and a thickness of 1.2 mm. Chip antenna made with.

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