KR100735454B1 - Liquid coupled antenna - Google Patents

Abstract

A liquid coupled antenna is provided to improve a bandwidth for a polar liquid by connecting a ground unit to the polar liquid additionally. A liquid coupled antenna includes a sealed type vessel(21), a radiator(25), a feeding unit(23), and a ground unit. A polar liquid having conductivity and a dielectric constant is filled in an inner space of the sealed type vessel(21). The radiator(25) is arranged on the inner space of the sealed type vessel(21). An insulating material is spread on a surface of the radiator(25) not to contact with the polar liquid. The feeding unit(23) is formed to be extended to the inside of the sealed type vessel(21) to be connected from the outside of the sealed type vessel(21) to the radiator(25). The ground unit is formed to be extended from the outside of the sealed type vessel(21) to the inside of the sealed type vessel(21) to be contacted with the polar liquid.

Description

Liquid Coupled Antennas {LIQUID COUPLED ANTENNA}

1A and 1B are perspective views each showing a conventional liquid coupled antenna.

2 is a perspective view showing a liquid-coupled antenna according to an embodiment of the present invention.

3A and 3B are perspective views showing a liquid-coupled antenna according to a preferred embodiment of the present invention, each employing a different radiator structure.

4 is a graph showing the frequency characteristics of the liquid-coupled antenna according to an embodiment of the present invention.

<Code Description of Main Parts of Drawing>

21: sealed container 22: polar liquid

23: feeder 25: radiator

27: insulator 31,41: sealed container

32,42: polar liquid 33,43: RF cable

33a, 43a: Feeding line 33b, 43b: insulation coating

33c, 43c: Ground line 35: Helical radiator

45: chip antenna 45a: dielectric body

45b: radiation pattern 37,47: insulator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid-coupled antenna, and more particularly, to a liquid-coupled antenna in which resonance frequency is easily determined and the frequency bandwidth is more effectively improved.

Antennas, which are essentially used for wireless and broadcast communications in mobile communication terminals, are manufactured by selecting various structures or materials according to frequency bands and purpose of use. In general, antennas used in mobile communication terminals tend to be more miniaturized in accordance with the demand for miniaturization and weight reduction of terminals.

However, as the antenna becomes smaller, there is a problem that the characteristics of the antenna deteriorate. Typically, miniaturized antennas have narrowband characteristics, so for antennas for T-DMB (DAB), DVB-H, DVB-T, and DVB-UMTB used in the VHF / UHF band, transmission and reception due to narrowband characteristics There is a problem that the efficiency is reduced. In addition, when the antenna is downsized, the gain of the antenna is proportional to the volume, so that there is usually a problem that the radiation gain is lowered.

Therefore, studies have been actively conducted to realize wideband and improve gain even if the antenna is miniaturized. In the course of this research, the present inventors have determined that the narrow bandwidth and the radiation gain reduction problem due to the miniaturization of the antenna are limited to the conventional solid-state antenna, and as a new method, Korean Patent Application No. 2005-0070730 (Invention name: liquid medium) In the broadband antenna device, filed: 2005.08.02, an antenna structure (hereinafter referred to as a "liquid-coupled antenna") in which a polar solution, a new radiation medium having a very low conductivity and a constant dielectric constant, and a radiator, which is a conventional conductor, is combined. Suggested. This liquid-coupled antenna offers the advantage of designing a new antenna that can be easily realized in wideband and lowband. Liquid-coupled antennas 10 and 10 'according to the above patent documents are illustrated in Figs. 1A and 1B.

As shown in Fig. 1A, the liquid-coupled antenna 10 includes a wire 5 or a monopole structure radiator 5 connected to the feed section 3, and a sealed container 1 in which the polar liquid 2 is accommodated. The radiator 5 may be combined with the polar liquid 2 having a new radiation medium property to adjust the resonance frequency without extending the length or geometrical change of the conductor pattern.

The liquid-coupled antenna may be implemented in combination with various conventional antenna structures such as a chip antenna. For example, in the liquid-coupled antenna 10 'shown in FIG. 1B, the radiator 15 is a helical structure connected to the feed section 13. Similar to FIG. 1A, the radiator 15 is disposed inside the hermetic container 11 and is in contact with the polar solution 12.

The conventional liquid-coupled antenna shown in FIGS. 1A and 1B has a structure in which a conventional radiator applied as a radiator is placed inside a hermetically sealed container and directly contacted with a polar liquid. In this case, the existing radiator combines with the polar liquid and exhibits the characteristic of widening while adjusting the resonant frequency. The resonance frequency is determined, and there is a problem that low pass is not realized according to the structure of the radiator.

For example, in the liquid-coupled antenna shown in Fig. 1B, a helical structure radiator is manufactured by rotating a metal wire at a pitch angle and a distance according to a desired resonance frequency, and a polar liquid acts as a substantial conductor between pitch angles. The gap shows a phenomenon similar to that shorted. As a result, the actual resonant frequency is not determined by the length and structure of the radiator, but there is a problem in that the frequency is determined in the diagonal direction due to the shorted intervals. This similar problem can occur in combination with other chip types. That is, in the case of the chip antenna made of the conductor pattern implemented in the dielectric block, since the polar liquid is almost filled with the slot on the conductor pattern for lowering the resonance frequency, the above-described problem may be similarly caused. In addition, there has been a problem that the conventional liquid-coupled antenna cannot obtain sufficient radiation gain.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems of the prior art, and an object thereof is a liquid having a new structure that can properly expect a bandwidth improvement effect by a polar liquid while maintaining the radiator structure and length for determining a resonance frequency in antenna characteristics. It is to provide a combined antenna.

In order to solve the above technical problem, the present invention,

A sealed container filled with an inner space of a polarity liquid having conductivity and dielectric constant, a radiator disposed in an inner space of the sealed container, the surface of which is coated with an insulating material so as not to contact the polar liquid, A liquid-coupled type including a feed portion extending from the outside of the hermetic container to the radiator and a ground portion extending from the outside of the hermetic container to the polar liquid to contact the polar liquid; Provide an antenna.

Preferably, in order to simplify the connection structure, the ground portion and the feed portion may be provided in an RF cable structure including a feed line and a ground line separated by an insulator. In this case, the RF cable may be in the form of a coaxial cable structure. That is, the feeding line is connected to the radiator, the insulator is an insulating coating surrounding the feeding line, and the ground line may be formed on the insulating coating to be in contact with the polar liquid.

According to a specific embodiment, the RF cable may be integrally formed by being fixed to the sealed container, but the RF cable may be mounted to be detachable from the sealed container.

The polar liquid is not limited thereto, but may be at least one polar liquid selected from the group consisting of water, methanol, ethanol, butanol, acetonitrile, acetone, and a SAR solution.

In terms of improving the radiation gain, it is preferable to use a polar liquid having a low electrical conductivity of 10 S / m or less. More preferably, it has a low electrical conductance of 8 S / m or less. One example of such a polar liquid may be pure water.

Alternatively, if necessary, the polar liquid may be an electrolyte solution in which at least one electrolyte such as NaCl, K ₂ SO ₄ Al (OH) ₃ , or the like is dissolved in order to adjust electrical characteristics. The polar liquid may comprise a conductor powder subject to magnetic force, for further improvement of antenna properties.

In addition, the polar liquid employed in the present invention may further include an ethylene glycol-based liquid which is an antifreeze component. In this case, it is possible to reduce the change in the antenna characteristics due to the antenna use environment, especially the temperature conditions. This mixed form can be very advantageously employed when the polar liquid is water.

In combination with or separately, the polar liquid may further comprise a corrosion inhibitor to prevent unwanted corrosion of the ground or feed portion in direct contact with the polar liquid. Such corrosion inhibitors include, but are not limited to, materials selected from the group consisting of nitrites, triethanol amines and mixtures thereof.

The radiator structure employed in the present invention may have various forms. For example, the radiator may be a monopole, dipole or helical structure. Alternatively, the radiator may be part of a chip antenna. That is, the radiator may be a conductor pattern implemented in a dielectric body that is a solid. In this case, the entire chip antenna may be mounted in a hermetically sealed container, and the insulating material may be formed at least in a portion where a conductive pattern is formed.

Hereinafter, with reference to the accompanying drawings, the present invention will be described in more detail.

2 is a perspective view showing a liquid-coupled antenna according to an embodiment of the present invention.

Referring to Fig. 2, the liquid-coupled antenna 20 according to the present embodiment includes a hermetically sealed container 21 filled with a polar liquid 22, and a radiator 25 located inside the hermetically sealed container.

The radiator 25 employed in the present embodiment has a wire structure, and a desired resonance frequency band can be adjusted according to its length and structure. As such, the radiator 25 designed according to a specific resonance frequency band may be coated with the insulating material 27, thereby preventing direct contact with the polar liquid 22. Therefore, in the present invention, the resonance frequency band determined by the radiator 25 may not be greatly changed by the polar liquid 22. The radiator 25 located inside the hermetic container 21 is connected to a feeder 23 extending from the outside.

In this structure, the polar liquid 22 may participate in radiation through electromagnetic coupling with each other even though the polar liquid 22 is not directly in contact with the radiator 25 by an insulating material.

In particular, in the present invention, the ground portion 24 is further connected inside the hermetic container 21 to be in contact with the polar liquid 22. As such, by connecting the ground portion 24 to the polar liquid 22, the bandwidth of the antenna can be greatly improved. This will be described in more detail with reference to FIG. 4.

The polar liquid 22 employed in this embodiment is considerably low, but a polar solution having a constant conductivity and dielectric constant is used. The polar liquid 22 may be, but is not limited to, at least one polar liquid selected from the group consisting of water, methanol, ethanol, butanol, acetonitrile, acetone, and a SAR solution. However, in terms of improving radiation gain, a liquid having low electrical conductivity is advantageous. Preferably, a polar liquid having a low electrical conductivity of 10 S / m or less, more preferably 8 S / m or less is used. Such polar liquid may typically be pure water.

Alternatively, if necessary, the polar liquid 22 may be an electrolyte solution in which at least one electrolyte such as NaCl, K ₂ SO ₄ Al (OH) ₃ , or the like is dissolved in order to adjust electrical characteristics. The polar liquid 22 may include conductor powders that are affected by magnetic force for further improvement of antenna characteristics.

In addition, unlike the solid conductor, the polar liquid 22 is easily affected by the antenna use environment such as temperature. In order to alleviate this problem, the polar liquid 22 may further include an ethylene glycol-based liquid as an antifreeze component. This mixed form can be very advantageously employed when the polar liquid 22 is water. In combination with or separately, the polar liquid may further comprise a corrosion inhibitor to prevent unwanted corrosion of the ground or feed portion in direct contact with the polar liquid. Such corrosion inhibitors include, but are not limited to, materials selected from the group consisting of nitrites, triethanol amines and mixtures thereof.

In this embodiment, although illustrated and illustrated as a wire-shaped radiator 25, it can be used in the form of the conventional radiator, that is, monopole type, helical type, chip antenna radiator as needed. 3A and 3B illustrate a liquid coupled antenna according to a preferred embodiment of the present invention, each employing a different radiator structure.

Referring to FIG. 3A, the liquid-coupled antenna 30 according to the present embodiment includes a cylindrical container 31 filled with a polar liquid 32, and a radiator 35 positioned inside the container and coated with an insulator 37. ) And an RF cable 33 providing a power supply line 33a and a ground portion 33c.

The radiator 35 located inside the container 31 has a helical structure. The helical radiator 35 is designed to have a desired resonant frequency band with a pitch angle and a spacing, and as described above, since the helical radiator 35 is coated with the insulator 37, the helical radiator 35 does not directly contact the polar liquid 32. 32) and electromagnetic coupling is possible.

In the present embodiment, the power feeding portion and the grounding portion are provided in a single cable structure to exemplify the simplified structure. As shown in the drawing, the RF cable 33 employed in the present embodiment includes a feed line 33a directly connected to the radiator 35, an insulation coating 33b surrounding the feed line 33a, and the insulation. And a ground portion 33c formed on the covering body 33b. Here, the insulating coating 33b serves to electrically separate the feed line 33a and the ground portion 33c. As in the present embodiment, the grounding portion 33c may also have a structure surrounding the insulating coating 33b to have a coaxial cable structure, and may include an additional insulating coating (not shown) around the grounding portion 33c. Can be.

The feed line 33a exposed at one end of the RF cable 33 is connected to one end of the radiator 35, and the ground line 33c exposed at one end of the RF cable 33 is in contact with the polar liquid 32. At least a portion of the RF cable 33 is inserted through one end surface of the container 31 as much as possible. Through this connection structure, the polar liquid 32 and the radiator 35 can act as an antenna. In this embodiment, the RF cable 33 is illustrated as a coaxial cable structure, but may be provided in various known forms in which the ground line and the feed line are separated by an insulator.

In this way, the polar liquid 32 may be in direct contact with the ground portion 33c of the RF cable 33 to implement desired antenna characteristics. Through this structure, the liquid coupling antenna 30 can greatly improve the band characteristic of the natural resonance frequency of the radiator 35 itself.

Referring to FIG. 3B, there is shown a liquid coupled antenna 40 coupled with a chip antenna 45. The liquid coupled antenna 40, together with the chip antenna 45, provides a cylindrical container 41 filled with a polar liquid 42, a feed line 43a and a ground portion 43c, similar to FIG. 3A. RF cable 43 is included. The chip antenna 45 employed in this embodiment includes a dielectric block 45a and a conductor pattern 45b formed to have a specific resonance frequency band on its surface.

The conductive pattern 45b formed on the dielectric block 45a and acting as a radiator is applied to the insulator 47. In this embodiment, the insulator 47 is exemplified as being formed only on one surface of the dielectric block 45a so that only the conductor pattern 45b is insulated. However, the insulator 47 may be formed on the entire surface of the chip antenna 45 according to process convenience. It may be.

In this embodiment, similarly to FIG. 3A, the feeder and the ground part are provided in a single cable structure, and the RF coaxial cable has a simplified structure. That is, the RF cable 43 is formed on a feed line 43a directly connected to the radiator 45, an insulation coating 43b surrounding the feed line 43a, and the insulation coating 43b. And a ground portion 43c. The feed line 43a exposed at one end of the RF cable 43 is connected to the conductor pattern 45b. The RF cable 43 is fixed to the hermetically sealed container 41 and the conductive pattern 45b which is a radiator, and thus may be manufactured in an integrated structure. It may be mounted to enable.

In addition, the ground line 43c may insert at least a portion of the RF cable 43 through one end surface of the container 41 to directly contact the polar liquid 42. Through this connection structure, the liquid coupling antenna 40 can greatly improve the band characteristics of the natural resonance frequency of the radiator 45 itself.

As described above, the liquid-coupled antenna according to the present invention designs a desired resonance frequency by using a radiator composed of an existing conductor, and combines the radiator with liquid in a state where the radiator is coated with an insulator to maintain a desired resonance frequency range. Can be mad.

In addition, in the present invention, as described above, by directly contacting the ground portion with the polar liquid, the widened resonance frequency bandwidth characteristic can be further improved, and the radiation gain characteristic can be greatly improved. 4 is a graph showing the frequency characteristics of the liquid-coupled antenna for explaining the effect of the contact between the ground portion and the polar liquid.

For this experiment, a helical radiator having a band of about 1.5 to 1.7 kHz was designed, and a liquid-bonded antenna was manufactured by arranging a container containing pure water after applying the helical radiator with an insulator similarly to FIG. 3A.

First, the antenna characteristics were measured by connecting only a feeder to the radiator while the grounding part was not connected to the polar liquid. As a result, as indicated by A, the originally designed resonant frequency band was maintained due to the insulator while exhibiting a constant bandwidth improvement characteristic, but overall did not show excellent antenna characteristics in the form of low insertion loss.

On the contrary, as proposed in the present invention, the liquid-coupled antenna measured with the ground part additionally connected to the polar liquid, while still including the resonant frequency band designed in the helical radiator as indicated by B, improves the bandwidth. Was found to be significantly improved. In addition, it was confirmed that significantly improved, unlike A that the ground portion is not added in terms of insertion loss. This bandwidth improvement is expected to significantly improve the transmission and reception efficiency unlike the narrow band.

It is intended that the invention not be limited by the foregoing embodiments and the accompanying drawings, but rather by the claims appended hereto. Accordingly, various forms of substitution, modification, and alteration may be made by those skilled in the art without departing from the technical spirit of the present invention described in the claims, which are also within the scope of the present invention. something to do.

As described above, according to the liquid-coupled antenna of the present invention, by applying an insulating material to the existing radiator to prevent direct contact with the polar liquid, while maintaining a desired resonance frequency designed according to the length and structure of the radiator, the ground By additionally connecting the part with the polar liquid, the bandwidth improvement effect by the polar liquid can be greatly improved.

Claims (15)

An airtight container filled with an inner space of a polar liquid having conductivity and dielectric constant; A radiator disposed in an inner space of the sealed container, the radiator having a surface coated with an insulating material so as not to contact the polar liquid; A feeding part extending from the outside of the hermetic container and extending into the hermetic container so as to be connected to the radiator; And And a ground portion extending from the outside of the sealed container to the inside of the sealed container so as to contact the polar liquid. The method of claim 1, And the ground part and the feed part are provided in an RF cable structure including a feed line and a ground line separated by an insulator. The method of claim 2, And the feeding line is connected to the radiator, the insulator is an insulating coating surrounding the feeding line, and the ground line is formed on the insulating coating to be in contact with the polar liquid. The method of claim 2, The RF cable is a liquid-coupled antenna, characterized in that formed integrally fixed to the hermetic container. The method of claim 2, And the RF cable is detachably mounted to the hermetic container. The method of claim 1, And wherein the polar liquid is at least one polar liquid selected from the group consisting of water, methanol, ethanol, butanol, acetonitrile, acetone and SAR solution. The method of claim 1, And the polar liquid has an electrical conductivity of 10 S / m or less. The method of claim 1, The polar liquid is a liquid bonded antenna, characterized in that the electrolyte solution in which at least one electrolyte is dissolved. The method of claim 1, And wherein the polar liquid comprises a conductor powder subject to magnetic force. The method of claim 1, The polar liquid is a built-in liquid coupling antenna, characterized in that it further comprises an ethylene glycol-based liquid. The method of claim 10, And wherein the polar liquid is water. The method according to claim 1 or 10, And the polar liquid further comprises a corrosion inhibitor. The method of claim 12, And the corrosion inhibitor is selected from the group consisting of nitrite, triethanol amine and mixtures thereof. The method of claim 1, And the radiator is a monopole, dipole or helical structure. The method of claim 1, And the radiator is a conductor pattern implemented in a solid dielectric body, and the insulating material is formed in at least a portion where the conductor pattern is formed.

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