Multi band built-in antenna

CROSS-REFERENCE TO RELATED APPLICATION

P-0001[0001] This application claims the benefit of Korean Application No. 2002-19824, filed on Apr. 11, 2002, in the Korean Industrial Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

P-0002[0002] 1. Filed of the Invention

P-0003[0003] The present invention relates to a multi band antenna built in a telecommunication terminal, and more particularly, to a planar inverted F antenna having a LC coupled feed line spaced-apart from a radiating patch by a predetermined distance to obtain multi frequency bands each having a wide frequency bandwidth.

P-0004[0004] 2. Description of the Related Art

P-0005[0005] Recently, a mobile communication terminal is required to be compact, light, and multi-functional according to a recent demand. Electrical circuits and components built in the mobile communication terminal become smaller and multi-functional in order to satisfy the above requirement. Also, this requirement is applied to an antenna, which one of major components of the mobile communication terminal.

P-0006[0006] A conventional antenna used in the mobile communication terminal is a helical antenna and a planar inverted F antenna. The helical antenna is mounted on a top side of the mobile communication terminal together with a mono pole antenna. The helical antenna and the mono pole antenna have a quarter wavelength (λ/4) and are disposed inside the mobile communication terminal to be extended to an outside of the mobile communication terminal together with the helical antenna.

P-0007[0007] Although the helical antenna has an advantage in obtaining a high gain in a frequency band, a characteristic of synthetic aperture radars (SAR), which is an industrial standard relating to an electromagnetic wave, becomes low due to a non-directional characteristic of the helical antenna. Moreover, because the helical antenna is built on an outside of the mobile communication terminal, the helical antenna is not suitable to a portable apparatus, and an outer appearance of the mobile communication terminal will not be neat. Furthermore, it is very difficult to design the mobile communication terminal to be compact since the monopole needs a space to be built inside the mobile communication terminal.

P-0008[0008] In an effort to overcome the above problems, the planar inverted F antenna has been proposed. FIG. 1 shows a structure of a conventional planar inverted F antenna (PIFA). The PIFA includes a radiating patch <b>2</b>, a shorting pin <b>4</b>, a coaxial line <b>5</b>, a ground plane (plate) <b>9</b>. The radiating patch <b>2</b> is electrically coupled to the coaxial line <b>5</b> and has an impedance match with the ground plane <b>9</b> by forming a short circuit. A length L of the radiating patch <b>2</b> and a height H of the PIFA are designed in accordance with a first width Wp of the shorting pin <b>4</b> and a second width of the radiating patch <b>2</b>.

P-0009[0009] The PIFA reduces the amount of harmful electromagnetic waves generated toward a user because the electromagnetic waves generated by current induced in the radiating patch <b>2</b> and directed toward the ground plane <b>9</b> are re-induced to the radiating patch <b>2</b>. Moreover, the SAR characteristic is improved by a directional increase of the radiation waves induced (directed) in a direction toward the radiating patch <b>2</b>. Furthermore, the radiating patch <b>2</b>, which is used as a rectangular micro strip antenna having a predetermined length, is reduced by half in size and has a low profile structure.

P-0010[0010] The PIFA is still improved to be multi functional and developed as a dual band antenna used in two different frequency bands. FIG. 2 shows a dual band PIFA antenna <b>10</b> using the same operational principle as the PIFA of FIG. 1. The dual band antenna <b>10</b> includes a radiating patch <b>12</b> a shorting pin <b>14</b> coupling the radiating patch <b>12</b> to a ground, a coupling feed pin <b>15</b> feeding current to the radiating patch <b>12</b>, a dielectric block <b>11</b> having a ground plane (plate). A slot S having a U shape is formed inside the radiating patch <b>12</b> to have the dual frequency bands and divides the radiating patch <b>12</b> into two radiating patch areas to induce (direct) the current fed through the coupling feed pin <b>15</b> along the slot S to have a resonance electric length corresponding to two different frequency bands. The dual band antenna <b>12</b> may be used in a dual frequency band, for example a GSM frequency band and a DCS frequency band.

P-0011[0011] However, recently, the frequency band is variable to a CDMA frequency band (about 824-894 MHz), a GPS frequency band (about 1570-1580 MHz), a PCS frequency band (about 1750-1870 MHz or 1850-1990 MHz), or a blue tooth frequency band (2400-2480 MHz). The PIFA antenna is required to have a multi frequency band rather than the dual frequency band because the above conventional slot of the dual band antenna is not suitable to the multi band antenna. If the dual band antenna is built in the mobile communication terminal, the profile becomes too low, and a frequency bandwidth becomes too narrow.

P-0012[0012] Since a height of the dual band antenna, which is a major factor in designing the PIFA, is limited due to a limited width of the mobile communication terminal for the portability and a neat appearance, the narrow frequency bandwidth is disadvantageous in the mobile communication terminal.

P-0013[0013] A distribution circuit, such as a chip type LC component, may be additionally attached to the dual band antenna in order to remove the above problem. Although the dual band antenna obtains a much wider frequency bandwidth by controlling the impedance matching using the distribution circuit, unexpected problems, such as an efficiency of the dual band antenna, occur because the dual band antenna is interfered with the distribution circuit, which is an outside circuit coupled to the dual band antenna.

P-0014[0014] Therefore, we contemplate a PIFA to have a low profile structure, to be able to be used in a variety of frequency bands, and to improve characteristics of the narrowed frequency bands.

SUMMARY OF THE INVENTION

P-0015[0015] In order to overcome these and other problems, it is an object according to the present invention to provide a planar inverted F antenna having a LC coupled feed line spaced-apart from a radiation patch having a conductive pattern to obtain multi frequency bands each having a much wider frequency band width.

P-0016[0016] Additional objects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice.

P-0017[0017] These and other objects may be achieved by providing a planar inverted F antenna (PIFA) having predetermined structure, function, and shape of a feed line according to embodiments of the present invention.

P-0018[0018] According to an aspect of the present invention, the PIFA includes a feed pin directing a current, a feed line having one end electrically coupled to one end of the feed pin and having a predetermined resonance length, a coupling pin coupled to the other end of the feed line, and a radiating patch formed on a plane spaced-apart from the feed line by a predetermined distance to induce (feed) the current directed (fed) through the other end of the coupling pin, and a slot having one end starting at a portion of an edge and the other end disposed in an inside portion of the radiating patch, and a shorting pin having one end coupled to the radiating patch and the other end coupled to a ground.

P-0019[0019] According to another aspect of the present invention, the PIFA may include a feed pin directing a current, a feed line having one end electrically coupled to one end of the feed pin and having a predetermined resonance length, a radiating patch being spaced-apart from the feed line and being supplied through the feed pin, a shorting member having one end coupled to the radiating patch and the other end formed with a coupling pad to be coupled to a ground plate of a housing of a telecommunication terminal and to the other end of the feed line.

P-0020[0020] The PIFA may include a feed pin supplying a current, a first feed line having one end electrically coupled to one end of the feed pin and having a first resonance length, a second feed line having one end coupled to one end of the feed pin to be parallel to the first feed line and having a second resonance length, a radiating patch having a slot starting at an edge of the radiating patch and extended to an inside portion of the radiating patch, the radiating patch divided by the slot into a first patch area supplied with the current through the other end of the feed pin and a second patch area supplied with the current through the other end of the second feed line, a coupling pad formed to couple the radiating patch to a ground of a housing of a telecommunication terminal, and a shorting member having one end coupled to the coupling pad coupled to the other end of the first feed line and the other end coupled to the other end of the first patch area.

P-0021[0021] The PIFA may be formed with an LC coupling unit capable of adjusting a capacitance of an antenna by an area of the feed line and a distance with the radiating patch and controlling an inductance of the antenna by using a length of the feed line when the feed line having a predetermined resonance length is disposed to be spaced-apart from the radiating patch. The PIFA allow the frequency band to be expanded. A multi band antenna can be easily designed with various structures of the feed lines.

P-0022[0022] The feed line is coupled to the feed pin at one end thereof. There exist two different types of the feed lines in accordance with a coupling structure of the other end of the feed lines.

P-0023[0023] A first type feed line has the other end coupled to the radiating patch to be supplied with the current and combined with the radiating patch to have an electrical resonance length. A second type feed line has one end and the other end coupled to a feed pin and the shorting pin (or the coupling pad disposed below the shorting pin) to form the electrical resonance length. The above first type feed line and the second type feed line may be combined to form a third type feed line.

P-0024[0024] The LC coupled feed line has a predetermined electrical resonance length and one of various types of conductive patterns each disposed on a plane spaced-apart by a distance from another plane on which another conductive pattern (e.g. radiating patch) is formed to obtain different resonance length(s). The feed line may have a simple loop shape, a meander shape, and a combination of the simple loop shape and the meander shape.

P-0025[0025] A portion of the feed line disposed on a first plane is extended to a second plane different from and spaced-apart from the first plane. When the antenna is formed with at least two dielectric layers, and when the feed line has a first portion having a first conductive pattern and a second portion having a second pattern, the first portion and the second portion of the feed line are formed on the same plane or respective different planes. This antenna has the different electrical resonance lengths as well as the low profile.

BRIEF DESCRIPTION OF THE DRAWINGS

P-0026[0026] These and other objects and advantages of the present invention will become apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which:

P-0027[0027]FIG. 1 is a perspective view showing a principle of a conventional planar inverted F antenna;

P-0028[0028]FIG. 2 is a perspective view of a conventional dual band PIFA;

P-0029[0029]FIGS. 3A and 3B are perspective views of a planar inverted F antenna (PIFA) and a coupling deed line according to an embodiment of the present invention;

P-0030[0030]FIGS. 4A, 4B, and <b>4</b>C are perspective views of the PIFA and a plan view of a coupling feed line according to another embodiment of the present invention;

P-0031[0031]FIG. 5 is a graph showing a voltage standing wave ratio (VSWR) of the PIFA of FIG. 3A;

P-0032[0032]FIGS. 6A and 6B are perspective views of the PIFA and the coupling feed line according to another embodiment of the present invention;

P-0033[0033]FIG. 7 is a graph showing the VSWR of the PIFA of FIG. 6A;

P-0034[0034]FIG. 8 is a perspective view of the PIFA according to another embodiment of the present invention; and

P-0035[0035]FIG. 9 is a perspective view of the PIFA according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

P-0036[0036] Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.

P-0037[0037]FIG. 3A shows a perspective view of a planar inverted F antenna (PIFA) <b>20</b> according to an embodiment of the present invention. The PIFA <b>20</b> includes a radiating patch <b>22</b> and a ground plane (plate) <b>29</b> formed on a top and a bottom of a dielectric block <b>21</b>, respectively, and having a rectangular shape, a shorting pin <b>24</b>, a feed pin <b>25</b>, a feed line <b>26</b>, and a coupling pin <b>23</b>. The radiating pin <b>22</b> is formed with a slot S to obtain an electrical resonance length of a quarter wavelength (λ/4) corresponding to at least two frequency bands. It is possible that the slot S is formed to have at least the resonance length. It is possible that the slot S starts at one edge of the radiating plane <b>22</b>, makes a bend, and extends close to the feed pin <b>25</b> to form a U shape disposed inside a patch area of the radiating patch <b>22</b> as shown in FIG. 2.

P-0038[0038] The feed line <b>26</b> includes a predetermined length to form a loop structure disposed between the radiating patch <b>22</b> and the ground plane <b>29</b>. FIG. 3B is a perspective view of the feed line <b>26</b> of the PIFA <b>20</b> of FIG. 3A. The feed line having a loop type structure includes a first end coupled to the feed pin <b>25</b>, a second end being opposite to the first end to be coupled to the radiating patch <b>22</b> through the coupling pin <b>23</b>, and a loop shaped line formed between the first and second ends to be spaced-apart from the radiating patch <b>22</b>.

P-0039[0039] The feed line <b>26</b> has an inductance value L determined by a length of the feed line <b>26</b> and a capacitance value determined by an area and a distance from the radiating patch <b>22</b>. These values of the feed line are dependent from a material forming the dielectric block disposed between the radiating patch <b>22</b> and the ground plane <b>29</b>. Accordingly, when the feed line <b>26</b> is implemented in the PIFA <b>20</b>, the feed line <b>26</b> functions as an LC coupling circuit for impedance matching without any additional external matching circuit and obtains much wider frequency bands without sacrificing a decrease of an efficiency of the PIFA <b>20</b>.

P-0040[0040] The feed line <b>26</b> has an electrical resonance length thereof since a current is supplied to the second end of the loop type feed line <b>26</b> through the radiating patch <b>22</b> and forms additional electrical resonance lengths due to a combination of the feed line <b>22</b> and the slot S of the radiating patch <b>22</b>. As a result, the PIFA <b>20</b> having the feed line <b>26</b> has a triple antenna structure being resonated in various different frequency bands. Respective frequency bands are explained in reference with shape of the slot S of the radiating patch <b>22</b> and the feed line <b>26</b>.

P-0041[0041] The loop type feed line <b>26</b> is capable of adjusting the impedance matching and the frequency tuning in accordance with the electrical resonance lengths and the shape of the feed line. In order to enable the loop type feed line <b>26</b> to easily adjust the impedance matching and the frequency tuning, another additional component may be added to the PIFA <b>20</b> of FIG. 3A as shown in FIGS. 4A, 4B, and <b>4</b>C.

P-0042[0042]FIGS. 4A, 4B, and <b>4</b>C show another improved PIFA <b>40</b> having the same impedance matching and the frequency tuning as well as the same structure as the PIFA <b>20</b> as shown in FIG. 3A. FIGS. 4A through 4C show a perspective view, a partial perspective view, and a plan view of the PIFA <b>40</b>, respectively.

P-0043[0043] The PIFA <b>40</b> shown in FIG. 4A does not include a dielectric block of FIGS. 2 and 3A and is mounted on and coupled to a ground plate (not shown) provided in a housing of a communication terminal not having the ground plane <b>29</b> of the PIFA <b>20</b> of FIG. 3A. Although a case <b>41</b> of the PIFA <b>40</b> is made of an insulation material, the case <b>41</b>, however, is not limited to the insulation material. The case of the PIFA <b>40</b> is made of a plastic material according to this embodiment of the present invention.

P-0044[0044] The PIFA <b>40</b> of FIG. 4A includes a radiating patch <b>42</b> at a top surface thereof. the radiating patch <b>42</b> is formed with the slot S to form the electrical resonance length of a quarter wavelength (λ/4) corresponding to desired frequency bands as shown in the PIFA <b>20</b> of FIG. 3A. A position P<b>1</b> marked on the radiating patch <b>42</b> as a dot indicates a point electrically coupled to a third end of a feed line <b>46</b> as shown in FIGS. 4B and 4C. This coupling between the feed line <b>46</b> and the radiating patch <b>42</b> is provided by perforating the case <b>41</b> made of the insulation material. A shorting pin <b>44</b> extended from and coupled to the radiating patch <b>42</b> is formed along a side wall of the case <b>41</b>.

P-0045[0045] In FIG. 4B, the case <b>41</b> of the PIFA <b>40</b> has a structure having a box shape, an inside surrounded by the side wall, and an outside corresponding to the inside. The shorting pin <b>44</b> formed along the side wall of the case <b>41</b> forms a short circuit between the radiating patch <b>42</b> and the ground plate of a housing of a communication terminal. An additional ground coupling pad having a predetermined area may be provided between the shorting pin <b>44</b> and the ground plate of the housing of the communication terminal to form the short circuit.

P-0046[0046] The feed line <b>46</b> is formed and disposed in an inside of the case <b>41</b> and has a third end coupled to a feed pin <b>45</b> and a fourth end coupled to the radiating patch <b>46</b> through the coupling pin <b>43</b>. Although the feed line <b>46</b> has a predetermined length surrounding the inside of the case <b>41</b>, the length and shape of the feed line <b>46</b> vary in response to a desired LC coupling structure, such as a meander shape and a three dimensional shape having a first portion formed on a first plane and a second portion coupled to the first portion and formed on a second plane different from the first plane. According to the embodiment of the present invention, the PIFA <b>40</b> may include a matching pad <b>47</b> and an open stub <b>48</b> to easily adjust the impedance matching and the frequency tuning. The feed pin <b>45</b> is formed along the side wall of the case <b>41</b> through a perforation formed on the side wall of the case <b>41</b>. The feed pin <b>45</b> and the shorting pin <b>44</b> have a longer height than that of the side wall of the case <b>41</b> to be bent along the side wall of the case <b>41</b> and to be coupled to an external feed circuit and the ground plate of the telecommunication terminal, respectively.

P-0047[0047]FIG. 4C shows the matching pad <b>47</b> and the open stub <b>48</b> in detail. The matching pad <b>47</b> is formed on the feed line <b>46</b> disposed adjacent to the feed pin <b>45</b>, and the open stub <b>48</b> is disposed to be parallel to the feed line <b>46</b> and has one end coupled to the feed line <b>46</b>.

P-0048[0048] The PIFA <b>40</b> may have various shapes and types of the feed line <b>46</b> reducing entire profile of the PIFA <b>40</b> and perform the impedance matching and the frequency tuning in wide frequency bands. Any type of the matching pad <b>47</b> and the open stub <b>48</b> may be selectively combined with any type of a PIFA according to the embodiment of the present invention.

P-0049[0049] As described above, the PIFA <b>40</b> becomes smaller than a conventional PIFA in size and obtains the wider frequency bandwidth than the conventional PIFA. FIG. 5 is a voltage standing wave ratio (VSWR) graph showing a triple band antenna used in the GSM frequency band (890-960 MHz), the DSC frequency band (1.71-1.88 GHz), the blue tooth frequency band (2.4-2.45 GHz).

P-0050[0050] As shown in FIG. 5, VSWR values in three frequency bands are lower than 2.5. This means that the PIFA <b>40</b> is more efficient than a conventional PIFA. If the PIFA <b>40</b> is implemented in the triple band antenna, sufficiently broad frequency bandwidths are obtained corresponding to respective desired frequency band. Although the VSWR value of the PIFA <b>20</b> of FIG. 3A is higher in the GSM frequency band (about 890 MHz) than the VSWR value of the PIFA <b>40</b> of FIG. 4A, the VSWR value of the PIFA <b>20</b> can be improved and lowered by adding the matching pad <b>47</b> and the open stub <b>48</b> to the PIFA <b>20</b> of FIG. 3A.

P-0051[0051] A second type of the PIFA is provided according to another embodiment of the present invention and is different from the loop type feed line of FIG. 4A. The feed line may have one end coupled to a shorting pin or a ground coupling pad directing the current to a radiating patch and may have a predetermined length and another end disposed to be spaced-apart from the radiating patch to form a LC coupling with the radiating patch.

P-0052[0052]FIGS. 6A and 6B are perspective views of a PIFA <b>60</b> and a loop type feed line <b>66</b>, respectively. In FIG. 6A, the PIFA <b>60</b> includes a ceramic body <b>61</b> of a hexahedron but excludes the ground plate to be coupled to a ground of a printed circuit board of the communication terminal in which the PIFA <b>60</b> is mounted. The PIFA includes a radiating patch <b>62</b>, a shorting pin <b>64</b>, and the ceramic body <b>61</b> formed with a loop type feed line <b>66</b> on each surface thereof.

P-0053[0053] A feed pin <b>65</b> may be spaced-apart from the radiating patch <b>62</b> to be electrically coupled to the radiating patch <b>62</b> or may be directly coupled to the radiating patch <b>62</b>. The shorting pin <b>64</b> includes one end coupled to the radiating patch <b>62</b> to form the short circuit, and the loop type feed line <b>66</b> includes one end coupled to the feed pin <b>65</b> and another end coupled to the shorting pin <b>64</b>. As shown in FIG. 6B, if a coupling pad <b>64</b>′ is provided to be disposed adjacent to another end of the shorting pin <b>64</b> tobe coupled to the ground of the housing of the communication terminal, it is possible that the loop type feed line <b>66</b> is coupled to the coupling pad <b>64</b>.

P-0054[0054] The loop type feed line <b>66</b> according to this embodiment of the present invention is illustrated in FIG. 6B. The loop type feed line <b>66</b> is coupled to the grounded shorting pin <b>64</b> or the coupling pad <b>64</b>′ and to the feed pin <b>65</b> to have the electrical resonance length corresponding to the desired frequency bands. Also, the feed line <b>66</b> can be used in different frequency bands by directing the current to the radiating patch <b>62</b> through the feed pin <b>65</b>. The PIFA <b>60</b> having the feed line <b>66</b> as shown in FIGS. 6A and 6B can be implemented in the dual band antenna. If the radiating patch <b>62</b> of the PIFA <b>60</b> is formed with the slot S, the PIFA <b>60</b> can be used as the triple frequency band antenna.

P-0055[0055]FIG. 7 shows the VSWR value of the PIFA <b>60</b> of FIGS. 6A and 6B. The VSWR value is indicated in the GPS frequency band (1.57-1.58 GHz) and the PCS frequency band (1.75-1.87 GHz). Where the VSWR value of the PIFA is below 2.5, a frequency bandwidth is in the range of about 600 MHz. The GPS frequency band and the PCS frequency band are included in the frequency bandwidth of about 600 MHz. If the PIFA is minimized in size, the PIFA <b>60</b> may be designed to be used in WCDMA (IMT-2000) frequency band. Various types of multi band antennas can be designed by using the loop type feed line constructed according to embodiments of the present invention, and the wider frequency band can be obtained.

P-0056[0056] A third type of a feed line of the PIFA may be made by any combination of the PIFA <b>20</b> of FIG. 3A, the PIFA <b>40</b> of FIG. 4A, and the PIFA of FIG. 6A. FIG. 8 shows the third type of the PIFA having two types of the feed lines.

P-0057[0057] In FIG. 8, the PIFA <b>70</b> includes a shorting pin <b>74</b> and a feed pin <b>75</b> both formed on a ceramic body <b>71</b>, a radiating patch <b>72</b>, <b>82</b>, a first loop type feed line <b>76</b>, and a second loop type feed line <b>86</b>. The first feed line <b>76</b> has a first length corresponding to that of the loop type feed line <b>66</b> of FIG. 6A, and the second feed line <b>86</b> has a second length other than the first length. The second feed line <b>86</b> is coupled to one end of the feed pin <b>75</b> and formed to be parallel to the first feed line <b>76</b>.

P-0058[0058] The radiating patch <b>72</b>, <b>82</b> is divided by the slot S starting at a portion of one edge and extended to another portion of the one edge of the radiating patch into a first patch area <b>72</b> coupled to another end of the feed pin <b>75</b> and a second patch area <b>82</b> coupled to another end of the second feed line <b>86</b>. The PIFA <b>70</b> may have a combination of the feed line <b>20</b> or <b>40</b> of FIGS. 3A and 4A and the feed line <b>60</b> of FIG. 6A. The PIFA <b>70</b> has first electrical resonance lengths corresponding to two loop type feed lines <b>76</b>, <b>86</b> and second electrical resonance lengths corresponding to the first and second radiating patch areas and being different from the first electrical resonance lengths to perform in four frequency bands.

P-0059[0059] Although the loop type feed line is used in the PIFA, various types of the feed lines may be implemented in a PIFA <b>90</b> as shown in FIG. 9. The PIFA <b>90</b> includes third, fourth, and fifth feed lines <b>96</b><i>a, </i><b>96</b><i>b, </i><b>96</b><i>c </i>disposed in respective different planes. Two dielectric layers <b>91</b><i>a, </i><b>91</b><i>b </i>are disposed between the third and fifth feed lines <b>96</b><i>a, </i><b>96</b><i>c, </i>and between the fifth and fourth feed lines <b>96</b><i>c, </i><b>96</b><i>b </i>in order to easily mount the feed lines in the PIFA <b>90</b>.

P-0060[0060] The PIFA <b>90</b> of FIG. 9 includes a radiating patch <b>92</b>, a feed pin <b>95</b>, the third, fourth, and fifth feed lines <b>96</b><i>a, </i><b>96</b><i>b, </i><b>96</b><i>c </i>extended from the feed pin <b>95</b>, and a shorting pin <b>95</b> grounding the radiating patch <b>92</b>. Since one of the third, fourth, and fifth feed line <b>96</b><i>a, </i><b>96</b><i>b, </i><b>96</b><i>c </i>may have the same structure as the PIFA <b>20</b> of FIG. 3A, and since two of the third, fourth, and fifth feed lines <b>96</b><i>a, </i><b>96</b><i>b, </i><b>96</b><i>c </i>are disposed on respective different planes, the PIFA <b>90</b> forms a three dimensional structure using two dielectric layers <b>91</b><i>a, </i><b>91</b><i>b. </i>

P-0061[0061] The third feed line <b>96</b><i>a </i>is disposed below the first dielectric layer <b>91</b><i>a </i>to be coupled to the feed pin <b>95</b>, the fourth feed line <b>96</b><i>c </i>is disposed between the first dielectric layer <b>91</b><i>a </i>and the second dielectric layer <b>91</b><i>b </i>(below the second dielectric layer <b>91</b><i>b </i>or on the first dielectric layer <b>91</b><i>a</i>) to be coupled to the third feed line <b>96</b><i>a, </i>and the fifth feed line <b>96</b><i>c </i>is disposed below the first dielectric layer <b>91</b><i>a </i>to be coupled to the radiating patch <b>92</b> through the coupling pin <b>93</b>.

P-0062[0062] Since at least two or three feed lines are disposed on respective different planes, various types of the three dimensional feed line structures can be implemented in the PIFA. The electrical resonance length, a distance between the different feed lines, and a pattern of each feed line may vary and increase a design flexibility of the PIFA. In addition to the three dimensional structure having feed lines disposed on respective different layers, a meander line structure may be partially or entirely used or combined with the above three dimensional structure of the PIFA.

P-0063[0063] Although two dielectric layers are used in the PIFA in the embodiment of the present invention, the number of the dielectric layers may vary, and a dielectric case having two layer structure may be used. The feed lines may be connected to each other through a conductive pin or a conductive through hole.

P-0064[0064] As described above, the PIFA according to the present invention enables an antenna structure to become smaller by using an electrical resonance length of a feed line, a shape of the feed line, and the open stub and the matching pad, to improve the flexibility of the antenna design, and to obtain a wider frequency band.

P-0065[0065] Although a few preferred embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in third embodiment without departing from the principles and sprit of the invention, the scope of which is defined in the claims and their equivalents.