GB2436167A

GB2436167A - Liquid-coupled antenna built into a mobile communication device

Info

Publication number: GB2436167A
Application number: GB0625703A
Authority: GB
Inventors: Hyun Hak Kim; Jae Chan Lee; Jong Lae Kim
Original assignee: Samsung Electro Mechanics Co Ltd
Current assignee: Samsung Electro Mechanics Co Ltd
Priority date: 2006-03-16
Filing date: 2006-12-22
Publication date: 2007-09-19
Anticipated expiration: 2026-12-22
Also published as: DE102006060564A8; GB0625703D0; FI20065849A0; ITMO20060424A1; KR100703219B1; FI20065849L; GB2436167B; DE102006060564A1

Abstract

A liquid-coupled antenna, suitable for a mobile communication device, comprises a tubular structure 22 filled with a polar liquid 23. A radio frequency radiator 24 is also located within the tubular structure 22. A radio frequency cable 21 provides signal transmission means 21a connected to the radiator 24 and a grounding part 21c connected to the liquid 23. The signal transmission means 21a and grounding part 21c are separated by an insulating sheath 21b. The tubular structure 22 may be hermetically sealed and made from rigid or soft material and bent to fit around the periphery of a circuit board. Insulating material may be arranged to separate the radiator 24 from the polar liquid 23. A conventional monopole antenna may be connected to the other end of the radiator 24 and tubular structure 22 to that connected to the cable 21. The cable 21 may be connected in a detachable manner. The polar liquid 23 may be water or an electrolyte. The polar liquid 23 may also contain magnetic powder, ethylene glycol-based anti-freeze liquid and/or a corrosion inhibitor such as nitrite, triethanolamine or mixtures thereof. The liquid-coupled antenna is intended to provide high gain, broadband and/or improved low frequency performance for a compact antenna structure which may be readily used in mobile hand-held devices.

Description

LIQUID COUPLED BUILT-IN ANTENNA AND MOBILE CObtJNICATION

TERMINAL

CLAIM OF PRIORITY

[0001] This application claims the benefit of Korean Patent Application No. 2006-24467 filed on March 16, 2006 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

[0002] The present invention relates to a built-in antenna for a mobile communication terminal, and more particularly, to a liquid coupled built-in antenna which can be mounted with antenna characteristics minimally degraded, and a mobile cornrnunicatior-i terminal having the same.

Description of the Related Art

[0003] In general, a built-in antenna for a mobile communication terminal has a conductor patterned uniformly as a radiator on a dielectric or magnetic body.

[0004] Such an antenna has a unique resonant frequency determined by the conductor structure and a dielectric constant of the dielectric body. For example, with the conductor or dielectric material determined to specific properties, the ( resonant frequency cannot be adjusted until tne geometry of the conductor body is changed. However, since the resonant frequency tends to be adjusted in a wide band and/or to a low band, the conductor pattern, i.e., the radiator is elongated or complicated to ensure a proper electrical resonance length.

SUARY OF THE INVENTION

[0005] The present invention has been made to solve the foregoing problems of the prior art and it is therefore an aspect of the present invention is to provide a liquid coupled antenna which is configured to occupy a minimal mounting area in a mobile communication terminal and can enable an effective mounting according to the selection of mounting locations.

[0006] Another aspect according to the present invention is to provide a mobile communication terminal in which the liquid coupled antenna is mounted in an optimal position.

[0007] According to an aspect of the invention for realizing the object, there is provided a liquid coupled built-in antenna including a tubular structure having an inner space hermetically sealed and a polar liquid filled in the inner space; a radiator disposed in the inner space of the tubular structure; and an RF cable provided at one end of the tubular structure to be partially inserted into the inner space of the tubular structure, the RF cable including a feed line connected to the radiator, a ground formed to contact the polar liquid ( and a sheath for insulating the feed line from the ground.

[0008] The tubular structure is made of a rigid material, and has at least one bending. This ensures the tubular structure to be easily mounted along an edge of the printed circuit board in the mobile communication terminal.

[0009] Preferably, the tubular structure is made of a soft material. Here, the tubular structure may be changed in its shape according to a mounting position required for the mobile communication terminal to be easily mounted therein.

[0010] Preferably, the tubular structure comprises a cylinder that can be easily attached to or detached from the main body case of the terminal.

[0011] Preferably, the radiator is applied with an insulating material so as not to contact the polar liquid. Preferably, the radiator comprises a linear structure with a certain length such that the radiator can be mounted along the edge of the printed circuit board in the terminal.

[0012] According to detailed embodiments of the invention, the RF cable is integrally fixed to the tubular structure.

Alternatively, the RFcable is detachablymountedin the tubular structure.

[0013] Also, the liquid coupled built-in antenna further includes a monopol antenna provided at the other end of the tubular structure to be connected to the radiator.

[0014] Preferably, the RE' cable is configured as a coaxial ( cable structure. That is, the RE' cable is provided at the one end of the tubular structure to be partially inserted into the inner space thereof, and includes the feed line connected to the radiator, the sheath made of an insulating material for surrounding the feed line, and the ground formed on the sheath to contact the polar liquid.

[0015] Preferably, the polar liquid comprises a mixed solution of a polar liquid and an ethylene glycol liquid so as not to be frozen due to an ambient temperature. Further, the po'ar liquid further comprises an anti-corrosion agent. The anti-corrosion agent comprises one selected from a group consisting of nitride, triethanolamine and mixtures thereof.

[0016] According to another aspect of the invention for realizing the object, there is provided a mobile communication terminal including a main body case having an inner space for accomilLodation; a printed circuit board provided in the inner space of the main body case and having at least one RE' circuit installed therein; and a liquid coupled built-in antenna disposed in the inner space of the main body case, wherein the antenna includes a tubular structure having an inner space enclosed and a polar liquid filled therein; a radiator provided in the inner space of the tubular structure; and an RE' cable having a first terminal disposed at one end of the tubular structure and a second terminal connected to the RE' circuit so as to be partially inserted into the inner space of the tubular

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structure, and including a feed line connected to the radiator, a ground formed to contact the polar liquid and a sheath for insulating the feed line and the ground.

[0017] Preferably, the liquid coupled antenna is disposed along an edge of the printed circuit board to reduce interference from the RF circuit. This reduces a mounting area of the liquid coupled antenna in the mobile communication terminal. Optionally, depending on the length thereof, the tubular structure mounted on the printed circuit board may be bent along the edge of the printed circuit board.

[0018] The mobile communication terminal further includes at least one fixed part such as a clip disposed on an inner surface of the main body case located at a side portion of the printed circuit board to fix the tubular structure.

BRIEF DESCRIPTION OF THE DRAWINGS

(0019] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: [0020] FIGs. la and lb are perspective views illustrating configuration of a conventional liquid coupled antenna; [0021] FIG. 2a is a perspective view illustrating a liquid coupled antenna according to an embodiment of the invention, and FIG. 2b is a cross-sectional view illustrating an RF cable

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employed in the liquid coupled antenna of FIG. 2a; [0022] FIG. 3 is a perspective view illustrating a liquid coupled antenna according to another embodiment of the invention; [0023] FIG. 4 is a perspective view for explaining a mobile communication terminal in an assembled position, where the liquid coupled antenna of FIGs. 2a is mounted; and [0024] FIG. 5 is a schematic view illustrating a mobile communication terminal where the liquid coupled antenna of FIG. 3 is mounted.

DETAILED DESCRIPTION OF THE PREFERRED EODIbNT

[0025) Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0026] Recently, to solve the problem, Korean Patent Application No. 2005-0070730 (published on August 2, 2005, entitled "Broad Band Antenna Using Liquid Medium," assigned to the applicant of this application) discloses a liquid coupled antenna in which a polar liquid as a new radiation medium is combined with the conventional conductor pattern, i.e., the radiator.

[0027] In the document, as shown in FIGs. la and lb, a radiator 13, which is a conductive pattern, is combined with a polar liquid 12 to adjust a resonant frequency without changing the ( length or geometry of the conductor pattern. This accordingly leads to design of a novel antenna which can easily achieve wide-band or low-band performance.

[0028) Such a liquid coupled antenna includes a sealed container 14 for housing the polar liquid 12, and a feed part 11 connected to the radiator 13 positioned inside the sealed container. Thus, the liquid coupled antenna having the polar liquid, i.e., liquidmedium and the sealed container for housing the polar liquid is relatively bigger than other components, accordingly limited in its mounting position. Moreover, a change in instruments and components of the terminal may alter characteristics and posltion of the antenna.

[0029] Notably, in the liquid coupled antenna mounted in the mobile communication terminal, a polar solvent having a relatively large volume is combined with a radiator to perform radiation. This as a result renders the liquid coupled antenna considerably susceptible to interference from adjacent RF components of the mobile communication terminal.

[0030] Meanwhile, the polar liquid such as water is easily affected by environments where the mobile communication terminal is used. Most of all, the polar liquid may be frozen at a low temperature, thereby failing to achieve desired radiation properties.

[003].] As described above, the liquid coupled antenna carries out wide-band and low-band performance superbly. Nonetheless, the liquid coupled antenna has been beset by problems associated with the mounting area, mounting position and liquid characteristics when applied to the mobile communication terminal, thus demonstrating a limited commercial viability.

[0032] FIG. 2a is a perspective view illustrating a liquid coupled antenna according to an embodiment of the invention and FIG. 2b is a cross-sectona1 view illustrating an RF cable employed in the liquid coupled antenna of FIG. 2b.

[0033] Referring to FIG. 2a, the liquid coupled antenna of the invention includes a tubular structure 22 filled with a polar liquid 23, a radiator 24 disposed in the tubular structure 22, and an RF cable 21 having a feed line and a ground formed therein.

[0034) The radiator 24 disposed in the tubular structure 22 is connected to the feed line 21a of the RF cable 21 and may be applied with an insulating material 24a. The radiator 24, if applied with the insulating material 24a, does not contact the polar liquid 23 directly but can be electromagnetically coupled with the polar liquid 23 to perform radiation.

Alternatively, the polar liquid 23 may be in direct contact with the ground 21c of the RF cable 21 to atLain desired antenna characteristics. This structure allows the liquid coupled antenna 20 to adjust its own resonant frequency in a wide band and/or to a low band.

[0035] The tubular structure 22 employed in this embodiment has an inner space filled with the polar liquid 23. Such a

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tubular structure 22 can be adequately disposed in a small mounting area of a mobile communication terminal. Also, the tubular structure is adjustable in its length to be mounted in arequiredposition. Thetubularstructure22smadeofargjd material having no elastic or restoring force, or a soft material. The tubular structure 22 made of the rigid material me.y have at least one bending to suit configuration of the mounting area. Ontheotherhand, the tubular structure 22 made of the soft material is modifiable depending on configuration of its mounting area, thus more easily mounted compared with the rigid material tubular structure.

(003] The poLar liquid 23 of this embodiment adopts water with considerably low conductivity. Optionally, the polar liquid 23 may contain electrolytic or magnetic powder. The polar liquid 23 of the invention is disclosed in Korean Patent Application No. 2005-0070730, entire contents of which are incorporated herein by reference. Preferably, the polar liquid 23 may further contain an ethylene glycol liquid. The ethylene glycol liquid is anti-freezing and thus is not cooled down at a low temperature of less than 00 when mixed with water.

This assures stable antenna properties in a low temperature environment. Additionally, the polar liquid 23 may preferably contain an anti-corrosion agent to inhibit corrosion in the feed line 21a and the ground 21c in contact therewith. The anti-corrosion agent is selected from a group consisting of nitride, triethanolamine and mixtures thereof.

[0037] The radiator 24 of this embodiment may have various configurations such as a bar, helical shape and plate. However, preferably, the radiator 24 is linearly structured since it is mounted inside the terminal in combination with the tubular structure. Also, to ensure superior antenna characteristics, preferably, the radiator 24 has a surface applied with an insulating material. As described above, the radiator 24 and the polar liquid are electromagnetically coupled to perform radiation as desired.

[0038] Moreover, the RF cable 21 of this embodiment, as shown in FIG. 2b, is preferably structured as a coaxial cable. The RF cable 21 includes the feeding line 21a, a sheath 21b for surrounding the feed line 21a, and the ground 21c formed on the insulating sheath 21b. Here, the insulating sheath 21b electrically insulates the feed line 21a from the ground 21c.

As in this embodiment, the ground 21c may be configured as a sheath and an additional insulating sheath (not illustrated) may be disposed around the ground 21c. The RF cable 21 is partially inserted into one end of the tubular structure 22 so that the feed line 21a exposed at one end of the RF cable 21 is connected to one end of the radiator 24 and the ground line 21b, exposed at the one end of the RF cable 21, contacts the polar liquid 23. This structure allows the polar liquid 23 and the radiator 24 to function as an antenna.

(0039] The liquid coupled antenna according to the invention may be variously configured. Optionally, the liquid coupled antenna can be combined with a monopol antenna employed in the typical mobile cozmmunication terminal. Such a configuration is depicted in FIG. 3.

(0040] FIG. 3 is a schematic perspective view illustrating an embodiment in which a radiator 34 of the antenna 20 is connected with a monopol antenna 39. The liquid coupled antenna of the invention can be combi ned with the conventional mnonopol antenna, thereby boosting antenna characteristics. Also, the antenna can he mounted in the mobile communication terminal in various configurations.

(0041] In the embodiment 30, the radiator 34 of the antenna has one end connected to a feed line 31a and the other end connected to the mnonopol antenna 39. Here, a feed terminal C should extend through one end of a tubular structure 32 to electrically connect the radiator 34 disposed inside the tubular structure 32 with the monopol antenna 39 located outside the tubular structure 32. Accordingly, the tubular structure 32 needs to be adequately sealed to prevent the polar liquid therein from leaking.

0042] In the embodiments of FIGs. 2 and 3, the cable 31 is integrally or detachably formed with the tubular structure 32.

[0043J In a case where the cable 31 and the tubular structure 32 are detachably formed, the polar liquid 33 should be r guaranteed not to leak from the tubular structure 32 when the cable 31 is detached from the tubular structure 32. The cable 31 and the tubular structure 32, when detachably configured, can be applied to terminals of various dimensions. Also, the tubular structure alone may be replaced and repaired.

(0044] FIG. 4 is a schematic perspective view illustrating a mobile communication terminal where a liquid coupled antenna is mounted according to the embodiment of FIG. 2a.

[0045] Here, the liquid coupled antenna 20 occupies a smaller mounting area in the mobile communication terminal.

Preferably, the liquid coupled antenna 20 is disposed along an edge of a printed circuit board 45 to reduce interference from the RE' circuit 46. The tubular structure 22 of the antenna is bent along a bending of the printed circuit board 45 in a different way depending on the material type of the tubular structure 22, i.e., a rigid material or a soft material.

[0046] A main body case of the terminal of this embodiment is merely illustrative of a folder type terminal, and the antenna is applicable to various configurations of terminals such as a flip type and a slide type.

[0047) Furthermore, preferably, to assure the antenna 20 to be mounted easily and stably, a groove 42 is formed in the main body case 41a of the terminal to accommodate the antenna.

[0048] Preferably, the groove 42 has a configuration in accordance with that of the tubular structure 22 of the antenna r 20. That is, as in this embodiment, in a case where the tubular structure 22 is cylindrical, the groove has a semi-spherical cross-section.

[0049) As described above, the tubular structure of the antenna 20 is preferably mounted along the edge of the printed circuit board 45 to reduce interference from the RF component 46.

Accordingly, the groove 42 is positioned suitably according to size and configuration of the printed circuit board 45.

[0050] The groove 42 has at least one fixed part 43 therein for fixing the antenna 20. This prevents the antenna mounted from being disengaged from the groove 42. The fixed part 43, as in the embodiment, may be integrally formed with the main body of the terminal 41a. Alternatively, the fixed part 22 may be of various configurations such as a clip to fix the tubular structure 22. Alternatively, another groove (not illustrated) may be formed in a cover 41b of the main body case 41b of the terminal to be symmetrical about the groove 42. Thus when the antenna is mounted, the printed circuit board 45 is centered in a side portion of the antenna 20.

[0051] FIG. 5 is a perspective view illustrating a mobile communication terminal where an antenna 30 of the embodiment of FIG. 3 is mounted.

[0052] li-i this embodiment, the antenna 30 of the embodiment of FIG. 3 has a cable 31 connected to a feed part 57 and a tubular structure 32 mounted therein along an edge of a printed circuit board 55. Here, a monopol antenna 39 connected to a radiator 34 inside the tubular structure 32 is protruded from a terminal case.

[0053] The monopol antenna 39 may be a typical antenna for use in a communication mobile terminal. Therefore, the rnonopol antenna can be protruded out of the terminal or mounted therejnsjde.

[0054] IL\s set forth above, according to preferred embodiments of the invention, a liquid antenna is configured as a tubular structure and mounted along an edge of a printed circuit board, thereby occupying a minimum mounting area and minimizing interference from an RF circuit on the printed circuit board.

Thus, this liquid coupled antenna can be easily applicable to a more compact mobile communication terminal.

[0055] In addition, an anti-freezing liquid and anti-corrosion agent can be added to a polar liquid of the liquid coupled antenna to be minimally affected by an atmosphere where the mobile communication terminal is used, thereby maximizing characteristics of the liquid coupled antenna.

[0056] While the present invention has been shown and described in connection with the preferred embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims. r

Claims

What Is Claimed Is: 1. A liquid coupled built-in antenna comprising: a

tubular structure having an inner space hermetically sealed and a polar liquid filled in the inner space; a radiator disposed in the inner space of the tubular structure; and an RE' cable provided at one end of the tubular structure to be partially inserted into the inner space of the tubular structure, the RF cable including a feed line connected to the radiator, a ground formed to contact the polar liquid and a sheath for insulating the feed line from the ground.

2. The liquid coupled built-in antenna according to claim 1, wherein the tubular structure is made of a rigid material.

3. The liquid coupled built-in antenna according to claim 2, wherein the tubular structure comprises at least one bending.

4. The liquid coupled built-in antenna according to claim 1, wherein the tubular structure is made of a soft material.

5. The liquid coupled built-in antenna according to claim 1, wherein the tubular structure comprises a cylinder.

6. The liquid coupled built-in antenna according to claim 1, wherein the radiator is applied with an insulating material so as not to contact the polar liquid.

7. The liquid coupled built-in antenna according to claim 1, wherein the radiator comprises a linear structure.

8. The liquid coupled built-in antenna according to claim 1, wherein the RE' cable is integrally fixed to the tubular structure.

9. The liquid coupled built-in antenna according to claim 1. wherein the RE' cable is detachably mounted in the tubular structure.

10. The liquid coupled built-in antenna according to claim 1, further comprising: a monopol antenna provided at the other end of the tubular structure to be connected to the radiator.

11. The liquid coupled built-in antenna according to claim 1, wherein the RE' cable is provided at the one end of the tubular structure to be partially inserted into the inner space thereof, and includes the feed line connected to the radiator, the sheath made of an insulating material for surrounding the feed line, and the ground formed on the sheath to contact the polar liquid.

12. The liquid coupled built-in antenna according to claim 1, wherein the polar liquid comprises a mixed solution of a polar liquid and an ethylene glycol liquid.

13. The liquid coupled built-in antenna according to claim 12, wherein the polar liquid further comprises an anti-corrosion agent.

14. The liquid coupled built-in antenna according to claim 13, wherein the anti-corrosion agent comprises one selected from a group consisting of nitride, triethanolamine and mixtures thereof.

15. A mobile communication terminal comprising: a main body case having an inner space for accommodation; a printed circuit board provided in the inner space of the main body case and having at least one RF circuit installed therein; and a liquid coupled built-in antenna disposed in the inner space of the main body case, wherein the antenna comprises: a tubular structure having an inner space enclosed and a polar liquid filled therein; a radiator provided in the inner space of the tubular structure; and r an RE' cable having a first terminal disposed at one end of the tubular structure and a second terminal connected to the RE' circuit so as to be partially inserted into the inner space of the tubular structure, and including a feed line connected to the radiator, a ground formed to contact the polar liquid and a sheath for insulating the feed line from the ground.

16. The mobile communication terminal according to claim 15, wherein the radiator has a surface applied with an insulating material so as not to contact the polar liquid.

17. The mobile communication terminal according to claim 15, wherein the liquid coupled antenna is disposed along an edge of the printed circuit board to reduce interference from the RE' circuit.

18. The mobile communication terminal according to claim 15, wherein the tubular structure is bent along an edge of the printed circuit board.

19. The mobile communication terminal according to claim 15, further comprising at least one fixed part formed on an inner surface of the main body case located at a side portion of the printed circuit board to fix the tubular structure.

20. The mobile communication terminal according to one of claims 15, wherein the tubular structure is made of a rigid material.

21. The mobile communication terminal according to one of claims 15, wherein the tubular structure is made of a soft material.

22. The mobile communication terminal according to one of claims 15, wherein the tubular structure comprises a cylinder.

23. The mobile communication terminal according to one of claims 15, wherein the RF cable is integrally fixed to the tubular structure.

24. The mobile communication terminal according to one of claims 15, wherein the RE' cable is detachably mounted in the tubular structure.

25. The mobile communication terminal according to one of claims 15, wherein the RE' cable is provided at the one end of the tubular structure to be partially inserted into the inner space thereof, and includes the feed line connected to the radiator, the sheath made of an insulating material for surrounding the feed line, and the ground formed on the sheath to contact the polar liquid.

26. The mobile communication terminal according to one of claims 15, further comprising a rnonopol antenna mounted on the main body case and provided at the other end of the tubular structure to be connected to the radiator.

27. The mobile communication terminal according to one of claims 15, wherein the polar liquid comprises a mixed solution of water and an ethylene glycol liquid.

28. The mobile communication terminal according to claim 27, wherein the polar liquid further comprises an anti-corrosion agent.

29. The mobile communication terminal according to claim 28, wherein the anti-corrosion agent comprises one selected from a group consisting of nitride, triethanolamine and mixtures thereof.