WO2009078677A1

WO2009078677A1 - Intenna having multi-layered dielectric for decreasing human-effect

Info

Publication number: WO2009078677A1
Application number: PCT/KR2008/007505
Authority: WO
Inventors: Jin Woo Lee; Young Bok Lee
Original assignee: Ace Antenna Corp.
Priority date: 2007-12-18
Filing date: 2008-12-18
Publication date: 2009-06-25
Also published as: KR20090065619A; KR100956746B1

Abstract

Disclosed herein is an intenna having multi-layered dielectric capable of reducing the effect of the human body on mobile calls. The intenna having multi-layered dielectric includes a layered dielectric formed by disposing at least two dielectrics having different dielectric constants one on top of the other, and a multi-band radiation element formed in a symmetrical conductive pattern on a surface of the layered dielectric. Alternatively, the intenna having multi-layered dielectric includes a layered dielectric formed by disposing at least two dielectrics having different dielectric constants one on top of the other, and a radiation element formed in a conductive pattern on the surface of the layered dielectric.

Description

INTENNA HAVING MULTI-LAYERED DIELECTRIC FOR DECREASING HUMAN-EFFECT

Technical Field

[1] The present invention relates generally to a intenna having multi-layered dielectric, and more particularly, to a intenna having multi-layered dielectric for decreasing the effect of the human body on calls to and from a mobile terminal. A symmetrical multi- band radiation element is formed on the surface of a layered dielectric, which is created by disposing two low-dielectric constant dielectrics and a high-dielectric constant dielectric, having a dielectric constant similar to that of the human body, on top of each other. The symmetrical multi-band radiation element operates both in a complementary manner and in a broad band spectrum due to its symmetry.

[2] Furthermore, the present invention relates to a layered-dielectric antenna for reducing the effect of the human body on calls to and from a mobile terminal, in which a high- frequency radiation element in the multi-band radiation element operates in a relatively high frequency band, and a low-frequency radiation element operates in a relatively low frequency band, and which are respectively formed on the surfaces of the dielectrics of the layered dielectric having different dielectric constants. The layered- dielectric antenna operates in each band at the optimal efficiency and the size of the layered-dielectric antenna can be reduced. The high-dielectric constant dielectric has a dielectric constant similar to that of the human body, so that a change in dielectric constant caused by the effect of the human body is minimized, thereby improving the call quality of a mobile terminal. Background Art

[3] Mobile terminals are being made smaller and lighter, yet they must provide improved service functions. In order to meet these demands, circuits and parts embedded in mobile terminals have been reduced in size, including antennas, which are one of the principal parts of mobile terminals. Antennas using a ceramic dielectric are being developed in order to meet these demands.

[4] FIG. 1 is a front perspective view showing a prior art ceramic twin antenna 10 formed on a low-dielectric constant dielectric, and FIG. 2 is a rear perspective view of the ceramic twin antenna 10 shown in FIG. 1.

[5] As shown in FIGS. 1 and 2, a plurality of high-frequency radiation elements 13 and

14 operating in relatively high frequency bands, and a plurality of low-frequency radiation elements 15 and 16 operating in relatively low frequency bands are formed on the surface of a low-dielectric constant dielectric 11 in an integrated form, thus forming a symmetrical radiation element that can operate in multiple bands.

[6] The symmetrical radiation element formed on the surface of the low-dielectric constant dielectric 11 is configured such that first, second and third radiation elements 13-15 symmetrically extend toward both sides in parallel at predetermined intervals across a central connecting strip conductor 12 formed on the top surface of the low- dielectric constant dielectric 11.

[7] Predetermined portions of both ends of the third radiation element 15 are bent at an end adjacent to one side surface of the low-dielectric constant dielectric 11, and extend across one side surface of the low-dielectric constant dielectric, thus forming the fourth radiation element 16 having a symmetrical spiral structure.

[8] Predetermined portions of the fourth radiation element 16 extend toward the lower end of one side surface of the low-dielectric constant dielectric 11, thus forming fixed terminals 17.

[9] A feed strip conductor 18 that is connected to and integrated with a predetermined portion of the first radiation element 12 is formed on the other side surface of the low- dielectric constant dielectric 11.

[10] Furthermore, a feed terminal 19 is formed at one end of the feed strip conductor 18 in an integrated form, and then feeds the first to fourth radiation elements 12-16 with electricity.

[11] As described above, since the first and second radiation elements 13-14 operating in high frequency bands are formed on the low-dielectric constant dielectric 11, radiation efficiency can be maximized by the minimization of radiation losses. However, a problem occurs in that the sizes of the third and fourth radiation elements 15-16 operating in low frequency bands increase.

[12] Furthermore, the dielectric constant of the ceramic twin antenna 10 embedded in the mobile terminal changes due to the effect of the human body during a call, so that the radiation characteristics of the ceramic twin antenna 10 changes due to the change in dielectric constant, with the result that the problems of call drop and reduction in data transmission/reception speed occur. Disclosure of Invention Technical Problem

[13] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a layered-dielectric antenna, in which a high-frequency radiation element of a symmetrical multi-band radiation element, operating in a relatively high frequency band, is formed on the surface of a low-dielectric constant dielectric of the layered dielectric, and a low-frequency radiation element, operating in a relatively low frequency band, is formed on the surface of a high-dielectric constant dielectric of the layered dielectric, so that the radiation efficiency of the antenna is improved, the size of the antenna is reduced, and a broad band at corresponding frequencies and a complementary characteristic can be achieved due to the symmetrical structure of the multi-band radiation element.

[14] Furthermore, another object of the present is to provide a layered-dielectric antenna, in which the high-dielectric constant dielectric has a dielectric constant in the range of 40-50, similar to that of the human body, so that a change in dielectric constant caused by the human body during a call is minimized, thereby improving the transmission/ reception performance of the mobile terminal. Technical Solution

[15] In order to accomplish the above objects, the present invention provides a intenna having multi-layered dielectric for decreasing human-effect on mobile calls, comprising a layered dielectric formed by disposing at least two dielectrics having different dielectric constants one on top of the other; and a multi-band radiation element formed in a symmetrical conductive pattern on the surface of the layered dielectric.

[16] Additionally, in order to accomplish the above objects, the present invention provides a intenna having multi-layered dielectric for decreasing human-effect on mobile calls, including a layered dielectric formed by disposing at least two dielectrics having different dielectric constants one on top of the other; and a radiation element formed in a conductive pattern on the surface of the layered dielectric.

Advantageous Effects

[17] As described above, according to the present invention, two low-dielectric constant dielectrics and a high-dielectric constant dielectric having a dielectric constant similar to that of the human body are combined into a layered dielectric. A high-frequency radiation element, configured to operate in a relatively high frequency band, is symmetrically formed on any one of the two low-dielectric constant dielectrics of the layered dielectric, so that the radiation efficiency of the antenna is improved by minimizing radiation losses, and a low-frequency radiation element, configured to operate in a relatively low frequency band, is symmetrically formed on the high- dielectric constant dielectric, so that the size of the antenna is reduced. A symmetrical multi-band radiation element in which the high-frequency radiation element and the low-frequency radiation element are integrated together provides complementary and broadband characteristics due to its symmetrical structure. The effect of the human body is minimized because the high-dielectric constant dielectric has a dielectric constant in the range of 40-50, similar to that of the human body, thereby improving the performance of the antenna. Brief Description of Drawings

[18] FIG. 1 is a front perspective view showing a prior art ceramic twin antenna;

[19] FIG. 2 is a rear perspective view of the ceramic twin antenna shown in FIG. 1;

[20] FIG. 3 is a front perspective view showing a layered-dielectric antenna capable of reducing the effect of the human body on mobile calls according to the present invention;

[21] FIG. 4 is a rear perspective view of the layered-dielectric twin antenna shown in FIG.

3;

[22] FIG. 5 is a detailed view showing the bottom surface of the layered-dielectric antenna shown in FIG. 3;

[23] FIG. 6 is a detailed view showing the radiation element of the layered-dielectric antenna shown in FIG. 3;

[24] FIG. 7 is a diagram showing the return loss characteristics of the layered-dielectric antenna of FIG. 3 in free space;

[25] FIG. 8 is a diagram showing the return loss characteristics of the layered-dielectric antenna of FIG. 3 while being carried;

[26] FIG. 9 is a diagram showing the return loss characteristics of the layered-dielectric antenna of FIG. 3 during a call; and

[27] FIG. 10 is a diagram comparing the return loss characteristics of the layered-dielectric antenna of FIG. 3 and the return loss characteristics of the prior art antenna. Mode for the Invention

[28] A preferred embodiment of the present invention will be described in detail below, with reference to the accompanying drawings.

[29] FIG. 3 is a front perspective view showing a layered-dielectric antenna 100 capable of reducing the effect of the human body on mobile calls according to the present invention.

[30] As shown in Fig. 3, a high-dielectric constant dielectric 112 and two low-dielectric constant dielectrics 111 and 113, disposed on either side of the high-dielectric constant dielectric 112 and having different dielectric constants ε_ri are combined into a single- layered dielectric 110. First, second and third radiation elements 122, 123 and 124 formed on the top surface of the layered dielectric 110, and a fourth radiation element 125 formed on one side surface of the layered dielectric 110, are integrated into a single symmetrical structure, thereby forming the layered-dielectric antenna 100 capable of reducing the effect of the human body on mobile calls in multiple bands.

[31] The layered dielectric 110 is formed by disposing at least two dielectrics having different dielectric constants one on top of the other. [32] Here, the layered dielectric is configured such that a high-dielectric constant dielectric is disposed below a low-dielectric constant dielectric in a vertical direction. In particular, it is preferred that the high-dielectric constant dielectric be the lowest layer of the layered dielectric.

[33] The low-dielectric constant dielectric may be made of any one of a ceramic and a general composite resin having a low dielectric constant.

[34] The high-dielectric constant dielectric may be made of a high-dielectric constant ceramic. In particular, the effect of the human body on call quality during a call can be reduced by using a ceramic having a dielectric constant in the range of 40-50.

[35] A ceramic or Liquid Crystal Polymer (LCP)-based dielectric having a low dielectric constant is further included below the high-dielectric constant dielectric in order to enable surface mounting on the main circuit board of a mobile terminal.

[36] For example, the layered dielectric 110 is formed by disposing the high-dielectric constant dielectric 112 between two low-dielectric constant dielectrics 111 and 113, having different dielectric constants.

[37] That is, the layered dielectric 110 is formed by disposing the first low-dielectric constant dielectric 111 in a first layer, the high-dielectric constant dielectric 112 in a second layer and the second low-dielectric constant dielectric 113 in a third layer in a vertical direction.

[38] It is preferred that the first low-dielectric constant dielectric 111 be made of a ceramic having a dielectric constant in the range of about 3.5-5. It is also preferred that the second low-dielectric constant dielectric 113 be formed of an LCP-based dielectric in order to enable surface mounting on a main circuit board within the mobile terminal.

[39] Furthermore, it is preferred that the high-dielectric constant dielectric 112 have a dielectric constant in the range of 40-50, similar to that of the human body.

[40] As shown in FIG. 3, a symmetrical multi-band radiation element 120 formed on the layered dielectric 110 includes, in an integrated form, the first and second radiation elements 122 and 123, which are high-frequency radiation elements, configured to operate in relatively high frequency bands, and the third and fourth radiation elements 124-125, which are low-frequency radiation elements, configured to operate in relatively low frequency bands.

[41] In greater detail, the first radiation element 122, the second radiation element 123 and the third radiation element 124 are spaced apart at predetermined intervals, and are formed in parallel on the top surface of the layered dielectric 110.

[42] The first radiation element 122 is formed such that one end of a connection strip conductor 121, formed at the center of the top surface of the first low-dielectric constant dielectric 111, branches off to both sides and symmetrically extends along one end of the top surface of the first low-dielectric constant dielectric 111. [43] The second radiation element 123 is formed in such a way that the connection strip conductor 121 branches off to both sides at a location spaced from the end of the connection strip conductor 121 at which the first radiation element 122 branches off, extends symmetrically, and is formed in parallel with the first radiation element 122.

[44] Furthermore, the length of the second radiation element 123 is formed so as to be shorter than that of the first radiation element 122.

[45] The third radiation element 124 is formed in such a way that the other end of the connection strip conductor 121 branches off to both sides along the other end of the top surface of the first low-dielectric constant dielectric 111, extends symmetrically, and is formed in parallel with the second radiation element 123.

[46] As described above, the first to third radiation elements 122-124, which are spaced at predetermined intervals along the connection strip conductor 121, branch off from the connection strip conductor 121 and extend symmetrically, are parallel to each other, and are formed in an integrated form.

[47] Furthermore, the first and second radiation elements 122 and 123, operating in high frequency bands, are formed on the first low-dielectric constant dielectric 111, so that radiation efficiency is improved by minimizing the radiation losses of the layered-dielectric antenna 100 according to the present invention.

[48] The fourth radiation element 125 is formed on one side surface of the layered dielectric 110, and more specifically, on one side surface of the high-dielectric constant dielectric 112 of the layered dielectric 110.

[49] The fourth radiation element 125 is formed in such a way that predetermined portions of both ends of the third radiation element 124 are bent at one end adjacent to one side surface of the layered dielectric 110 and extend across one side surface of the first low-dielectric constant dielectric 111, thus forming a symmetrical spiral structure on one side surface of the high-dielectric constant dielectric 112.

[50] Furthermore, predetermined portions of the fourth radiation element 125 extend across one side surface of the second low-dielectric constant dielectric 113 and are bent at the lower end of the second low-dielectric constant dielectric 113, thus forming two fixed terminals 126 that are used to install the antenna in the mobile terminal.

[51] Since the fourth radiation element 125, configured to operate in a low frequency band, is formed on the high-dielectric constant dielectric 112 having a high-dielectric constant similar to that of the human body, the following additional effects can be achieved: The size of the layered-dielectric antenna 100 for reducing the effect of the human body according to the present invention can be reduced, the antenna 100 of the present invention embedded in the mobile terminal can reduce a change in dielectric constant caused by the effect of the human body, such as a hand and head, during a call, so that a rapid change in the radiation characteristics of the antenna 100 can be minimized, thereby providing reliable call quality to the mobile terminal.

[52] As described above, the first to fourth radiation elements 122-125 are configured in an integrated form and are each formed symmetrically, thus operating in corresponding broad frequency bands and complementing each other.

[53] Furthermore, the first to fourth radiation elements 122-125 are formed using any one of a Flexible Printed Wiring Board (FPWB) method, metal stamping and silver pasting.

[54] FIG. 4 is a rear perspective view of the layered-dielectric antenna 100 of the present invention shown in FIG. 3, FIG. 5 is a detailed view showing the bottom surface of the layered-dielectric antenna 100 shown in FIG. 3, and FIG. 6 is a detailed view showing the radiation element 120 of the layered-dielectric antenna 100 shown in FIG. 3.

[55] As shown in FIG. 4, a feed strip conductor 127 is formed across the center portion of the other side surface of the layered dielectric 110, and is connected to a predetermined portion of the first radiation element 122 formed on the top surface of the layered dielectric 110, thus constituting an integrated form.

[56] Furthermore, a feed terminal 128 is formed at one end of the feed strip conductor

127. The feed terminal 128 is bent at the lower end of the layered dielectric 110, particularly at the lower end of the second low-dielectric constant dielectric 113, and feeds the radiation element 120.

[57] FIG. 7 is a diagram showing the return loss characteristics of the layered-dielectric antenna of the present invention shown in FIG. 3 in free space (where the effect of a human body is absent). As shown in Fig. 7, the layered-dielectric antenna operates in the cellular band of 800-900 MHz, which is a relatively low frequency band, with the aid of the third and fourth radiation elements 124 and 125, and operates in a GPS frequency of 1.575 GHz, a DCS/PCS band of 1.7-2 GHz, an IMT 2000 band of 1.8-2.2 GHz and a Bluetooth band of 2.4-2.5 GHz, which are relatively high frequency bands, with the aid of the first and second radiation elements 122 and 123.

[58] FIG. 8 is a diagram showing the return loss characteristics of the layered-dielectric antenna of the present invention shown in FIG. 3, and shows return losses when the antenna is held by hand.

[59] FIG. 9 is a diagram showing the return loss characteristics of the layered-dielectric antenna of FIG. 3 during a call, and shows return losses during a call with the antenna held by hand.

[60] FIG. 10 is a diagram comparing the return loss characteristics of the layered-dielectric antenna of FIG. 3 and the return loss characteristics of the prior art antenna in free space.

[61] The results of the comparison between the actual transmission/reception performance of a mobile terminal in which the layered-dielectric antenna 100 according to the present invention has been embedded with the actual transmission/reception performance of a mobile terminal in which the prior art antenna has been embedded, which are shown in FIGs. 7 to 10, are listed in the following Table 1.

[62] As listed in the following Table 1, measured data includes Received Signal Strength Indicators (RSSIs) and transmission/reception level data that was measured while the mobile terminal was being carried by a human and in free space within a far field non- reflective chamber.

[63] Table 1 [Table 1] [Table ]

[64] As listed in Table 1, in the cellular band, the difference between the transmission/ reception level measured while the mobile terminal is being carried (that is, in the state of the mobile terminal is held by hand) and the transmission/reception level measured in free space (that is, in the state of the mobile terminal is not held by hand) is about 17-18 dBm in the case of the prior art antenna, and is about 5-6 dBm in the case of the antenna of the present invention.

[65] As described above, the fact that the difference between the reception level measured while carrying a mobile terminal and the reception level measured in free space is low when the antenna according to the present invention is embedded in a mobile terminal means that the antenna according to the present invention is less influenced by the human body. This signifies that the radio performance of the mobile terminal in which the antenna of the present invention has been embedded is excellent.

[66] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

[1] An intenna having multi-layered dielectric for decreasing human-effect on calls to and from a mobile terminal, comprising: a layered dielectric formed by disposing at least two dielectrics having different dielectric constants one on top of the other; and a multi-band radiation element formed in a symmetrical conductive pattern on a surface of the layered dielectric.

[2] The intenna having multi-layered dielectric according to claim 1, wherein the layered dielectric is configured such that one of the at least two dielectrics has a high dielectric constant in the range of 40-50.

[3] The intenna having multi-layered dielectric according to claim 2, wherein the high-dielectric constant dielectric is disposed in the lowest layer of the layered dielectric.

[4] The intenna having multi-layered dielectric according to claims 2 or 3, further comprising a low-dielectric constant ceramic or an LCP-based dielectric disposed below the high-dielectric constant dielectric in order to enable surface mounting.

[5] The intenna having multi-layered dielectric according to any one of claims 1 to

3, wherein the multi-band radiation element is configured such that a high- frequency radiation element configured to operate in a relatively high frequency band and a low-frequency radiation element configured to operate in a relatively low frequency band are integrated into a symmetrical structure, the high- frequency radiation element is formed on a surface of the low-dielectric constant dielectric, and the low-frequency radiation element is formed on a surface of the high-dielectric constant dielectric.

[6] The intenna having multi-layered dielectric according to claim 5, wherein the multi-band radiation element is formed using any one of a metal stamping, a Flexible Printed Wiring Board (FPWB) method, pad printing and silver pasting.

[7] A layered-dielectric antenna for reducing the effect of the human body, comprising: a layered dielectric formed by disposing at least two dielectrics having different dielectric constants one on top of the other; and a radiation element formed in a conductive pattern on a surface of the layered dielectric.

[8] The layered-dielectric antenna according to claim 7, wherein the layered dielectric is configured such that one of the at least two dielectrics has a high dielectric constant in the range of 40-50.