Antenna device and communication device comprising same

Abstract

An antenna device according to one embodiment of the present invention comprises: a substrate; a ground surface disposed on the substrate; a radiator disposed on the substrate; a short pin disposed on the substrate and connected to the radiator between the ground surface and the radiator; and a feed line disposed on the substrate and drawn out from the radiator, wherein the short pin and the ground surface are connected by a plurality of passive elements.

Description

Antenna device and communication device including the same

[0001] The present invention relates to an antenna device and a communication device including the same.

[0002] Communication devices that include wireless communication functions such as WiFi and Bluetooth include built-in antennas for miniaturization and high performance. Generally, built-in antennas are mounted on a printed circuit board (PCB). An Inverted-F antenna (IFA) is an example of an antenna device embedded in a communication device. Communication devices incorporating an IFA can be applied to smartphones, tablets, wearable devices, etc.

[0003] The IFA includes a ground plane, a radiator, a short pin, and a feed line arranged in a planar structure on a substrate. The radiator can be designed to be λ / 4, and the short pin serves to adjust the electrical characteristics of the IFA to match the feed impedance to a desired level and to form a current path between the radiator and the ground plane to precisely adjust the resonant frequency.

[0004] In a typical IFA structure, the loop structure between the feed line and the short pin is fixed, and consequently, the current path remains constant. When the loop structure is fixed, optimal operating characteristics are provided at a given single resonant frequency, but it may be difficult to secure the wide bandwidth required in multi-band or broadband environments.

[0005] The technical problem that the present invention aims to solve is to provide an Inverted-F antenna device having a wide bandwidth and a communication device including the same.

[0006] An antenna device according to one embodiment of the present invention comprises a substrate, a ground plane disposed on the substrate, a radiator disposed on the substrate, a short pin disposed on the substrate and connected to the radiator between the ground plane and the radiator, and a feed line disposed on the substrate and drawn from the radiator, wherein the short pin and the ground plane are connected by a plurality of passive elements.

[0007] The plurality of passive elements are arranged to be spaced apart from each other between the short pin and the ground plane, one end of each passive element is connected to the ground plane, and the other end of each passive element can be connected to the short pin.

[0008] The above plurality of passive elements may include a plurality of inductors.

[0009] The inductances of the above plurality of inductors may differ from each other.

[0010] The inductance of the plurality of inductors can sequentially increase in the direction from the short pin toward the power supply line.

[0011] The plurality of inductors may include a first inductor, a second inductor, and a third inductor arranged sequentially in the direction from the short pin toward the power supply line.

[0012] The inductance of the second inductor is greater than the inductance of the first inductor by 1.5 nH or more and less than or equal to 2.5 nH, and the inductance of the third inductor may be greater than the inductance of the second inductor by 1.5 nH or more and less than or equal to 2.5 nH.

[0013] The difference between the inductance of the first inductor and the inductance of the second inductor may be the same as the difference between the inductance of the second inductor and the inductance of the third inductor.

[0014] The above plurality of passive elements may include a plurality of capacitors.

[0015] The above plurality of passive elements may include at least one capacitor and at least one inductor.

[0016] The above-mentioned radiator extends in a first direction, the above-mentioned short pin extends toward the ground plane in a second direction different from the first direction, and the above-mentioned feed line may extend toward the ground plane in the second direction.

[0017] The end of the above power supply line may be spaced apart from the ground plane.

[0018] The above radiator may be a linear pattern.

[0019] The size of the interior angle formed by the radiator and the short pin is 90°±5°, and the size of the interior angle formed by the short pin and the ground plane may be 90°±5°.

[0020] The length of the first direction of the above-mentioned radiator may be longer than the length of the second direction of the above-mentioned short pin.

[0021] The above power supply line can be extended in a direction parallel to the above short pin.

[0022] The above plurality of passive elements can be connected in parallel between the short pin and the ground plane.

[0023] The difference between the inductance of the second inductor and the inductance of the first inductor, and the difference between the inductance of the third inductor and the inductance of the second inductor, may be 0.15 times or more and 0.35 times or less the inductance of the second inductor.

[0024] A communication device according to one embodiment of the present invention comprises an antenna device, an IC chip disposed on the antenna device, and a shield member covering the IC chip. The antenna device comprises a substrate, a ground plane disposed on the substrate, a radiator disposed on the substrate, a short pin disposed on the substrate and connected to the radiator between the ground plane and the radiator, and a feed line disposed on the substrate and drawn from the radiator. The short pin and the ground plane are connected by a plurality of passive elements, and the IC chip is connected to the end of the feed line.

[0025] According to an embodiment of the present invention, the bandwidth of an Inverted-F antenna device can be expanded. In particular, according to an embodiment of the present invention, the bandwidth of an Inverted-F antenna device can be expanded with a simple structure without complex design, such as adjusting the length of the radiator or changing the position of the short pin. Furthermore, according to an embodiment of the present invention, the resonant frequency of an Inverted-F antenna device can be optimized with a simple structure without complex design, such as adjusting the length of the radiator or changing the position of the short pin.

[0026] FIG. 1 is a perspective view of an antenna device according to an embodiment of the present invention.

[0027] FIG. 2 is a top view of an antenna device according to an embodiment of the present invention.

[0028] FIG. 3 is an enlarged perspective view of a part of an antenna device according to an embodiment of the present invention.

[0029] FIG. 4 is an enlarged top view of a part of an antenna device according to an embodiment of the present invention.

[0030] Figures 5 to 7 are simulation graphs showing the frequency bandwidth according to the number of passive components between the short pin and the ground plane.

[0031] Figures 8 and 9 are simulation graphs showing the frequency bandwidth according to the difference in component values ​​when the number of passive components between the short pin and the ground plane is 3.

[0032] Figures 10 to 12 are simulation graphs showing the frequency bandwidth according to the arrangement order of the component values ​​when the number of passive components between the short pin and the ground plane is 3.

[0033] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[0034] However, the technical concept of the present invention is not limited to some of the described embodiments but can be implemented in various different forms, and within the scope of the technical concept of the present invention, one or more of the components among the embodiments may be selectively combined or substituted.

[0035] In addition, terms used in the embodiments of the present invention (including technical and scientific terms) may be interpreted in a sense that is generally understood by those skilled in the art to which the present invention belongs, unless explicitly and specifically defined otherwise. Terms that are commonly used, such as terms defined in advance, may be interpreted in consideration of their meaning in the context of the relevant technology.

[0036] Furthermore, the terms used in the embodiments of the present invention are for the purpose of describing the embodiments and are not intended to limit the present invention.

[0037] In this specification, the singular form may include the plural form unless specifically stated otherwise in the text, and when described as "at least one of A and B and C (or more than one)," it may include one or more of all combinations that can be formed from A, B, and C.

[0038] In addition, terms such as first, second, A, B, (a), (b), etc. may be used when describing the components of the embodiments of the present invention.

[0039] These terms are intended merely to distinguish a component from other components and are not limited by the nature, order, sequence, etc., of the said component.

[0040] And, where it is stated that a component is 'connected', 'combined', or 'joined' to another component, this may include not only cases where the component is directly connected, combined, or joined to the other component, but also cases where it is 'connected', 'combined', or 'joined' due to another component located between the component and the other component.

[0041] Furthermore, when described as being formed or placed "above or below" each component, "above" or "below" includes not only cases where two components are in direct contact with each other, but also cases where one or more other components are formed or placed between the two components. Additionally, when expressed as "above or below," it may include the meaning of a downward direction as well as an upward direction relative to a single component.

[0042] Hereinafter, embodiments will be described in detail with reference to the attached drawings, provided that identical or corresponding components are given the same reference number regardless of the drawing symbols, and redundant descriptions thereof will be omitted.

[0043] FIG. 1 is a perspective view of an antenna device according to an embodiment of the present invention, FIG. 2 is a top view of an antenna device according to an embodiment of the present invention, FIG. 3 is an enlarged perspective view of a part of an antenna device according to an embodiment of the present invention, and FIG. 4 is an enlarged top view of a part of an antenna device according to an embodiment of the present invention.

[0044] Referring to FIGS. 1 to 4, the antenna device (100) includes a substrate (110), a ground plane (120), a radiator (130), a shorting pin (140), and a feed line (150). The antenna device (100) according to an embodiment of the present invention may be an Inverted-F antenna (IFA). The IFA has the advantages of being miniaturizable, easy to impedance match, providing high gain and efficiency, and enabling single-plane implementation. Accordingly, the IFA can be applied to various wireless communication devices such as smartphones, tablets, laptops, IoT devices, vehicles, wearable devices, and wireless sensors.

[0045] The substrate (110) has insulating performance and dielectric properties and supports a ground plane (120), a radiator (130), a short pin (140), and a feed line (150). For example, the substrate (110) may include at least one of a ceramic material, a glass-reinforced epoxy laminated material, PI (polyimide), PTFE (polytetrafluoroethylene), and LCP (liquid crystal polymer). Depending on the dielectric constant of the substrate (110), the resonant frequency, bandwidth, and efficiency of the antenna device (100) may vary. The substrate (110) may be a printed circuit board (PCB).

[0046] A ground plane (120) is disposed on a substrate (110). Although the ground plane (120) is depicted as being disposed on the upper surface of the substrate (110), it is not limited thereto, and the ground plane (120) may be disposed on the lower surface of the substrate (110) or between the upper and lower surfaces of the substrate (110). In order for the ground plane (120) to be disposed between the upper and lower surfaces of the substrate (110), the substrate (110) includes an upper insulating layer comprising the upper surface of the substrate (110) and a lower insulating layer comprising the lower surface of the substrate (110), and the ground plane (120) may be disposed between the upper insulating layer and the lower insulating layer. The ground plane (120) may be in the form of a planar plane parallel to the upper surface of the substrate (110). Accordingly, the ground plane (120) may be referred to as a ground plane. The ground plane (120) may be made of a conductive metal. For example, the ground plane (120) may include copper. The ground plane (120) provides a reference potential and can affect the radiation characteristics and matching impedance of the antenna device (100).

[0047] A radiator (130) is placed on a substrate (110). The radiator (130) may be placed in a planar form on the upper surface of the substrate (110). The radiator (130) may be made of a conductive metal. For example, the radiator (130) may be made of a conductive metal comprising at least one of copper, nickel, silver, and aluminum. The radiator (130) may be patterned on the substrate (110) by photolithography or etching, etc., or implemented as a metal pin or wire. As illustrated, the radiator (130) may be a linear pattern. The linear pattern may have a length of λ / 4. Although not illustrated, the radiator (130) may be implemented in a U shape, Z shape, step shape, spiral shape, meander shape, etc. The length of the radiator (130) may affect the resonant frequency of the antenna device (100). When the pattern of the radiator (130) is implemented as a U shape, Z shape, step shape, spiral shape, meander shape, etc., the length of the radiator (130) can be extended even within a narrow area, and the resonance frequency can be finely adjusted.

[0048] A short pin (140) is placed on a substrate (110) and positioned between a ground plane (120) and a radiator (130). The short pin (140) is a conductive structure that electrically connects the ground plane (120) and the radiator (130). The resonant frequency can be adjusted by the length of the short pin (140) and the radiator (130) connected to the ground plane (120). The short pin (140) may be made of a conductive metal. For example, the short pin (140) may be made of a conductive metal comprising at least one of copper, nickel, silver, and aluminum. The short pin (140) may be patterned on the substrate (110) by photolithography or etching, etc., or implemented as a metal pin or wire. The short pin (140) is connected to the radiator (130) and extends in a direction from the radiator (130) toward the ground plane (120).

[0049] A feed line (150) is placed on a substrate (110) and positioned between a ground plane (120) and a radiator (130). The feed line (150) may be made of a conductive metal. For example, the feed line (150) may be made of a conductive metal comprising at least one of copper, nickel, silver, and aluminum. The feed line (150) may be patterned on the substrate (110) by photolithography or etching, etc., or implemented as a metal pin or wire. The feed line (150) is connected to the radiator (130) and extends from the radiator (130) toward the ground plane (120). The end of the feed line (150) may be referred to as a feeding point. The feeding point is a point where an RF signal is input or output, and is a location where an external circuit is electrically connected to the radiator (130). Although not illustrated, a pad or connector for connecting an external circuit may be placed at the power point, which is the end of the power supply line (150). The power point may be placed spaced apart from the ground plane (120). Although not illustrated, a pad or connector for connecting an external circuit may be placed at the power point, which is the end of the power supply line (150), and an IC chip may be placed at the pad or connector, and the IC chip may be connected to the ground plane (120).

[0050] According to an embodiment of the present invention, a radiator (130) may extend in a first direction on a substrate (110), and a short pin (140) may extend from the radiator (130) toward a second direction different from the first direction. The second direction may mean a direction toward the ground plane (120) from the radiator (130). According to an embodiment of the present invention, the size of the interior angle formed by the radiator (130) and the short pin (140) may be 90°±5°, and the size of the interior angle formed by the short pin (140) and the ground plane (120) may be 90°±5°. The size of the interior angle formed by the radiator (130) and the short pin (140) affects the length of the current path between the radiator (130) and the short pin (140) and the resonance frequency. When the size of the internal angle formed by the ground plane (120), the radiator (130), and the short pin (140) satisfies this numerical range, the current distribution is stabilized, the radiation pattern of the radiator (130) maintains symmetry, and optimal impedance matching can be achieved. According to an embodiment of the present invention, the first directional length of the radiator (130) may be longer than the second directional length of the short pin (140). Accordingly, the radiation efficiency and gain of the antenna device (100) can be increased, and since it is easy to adjust the relative position between the feed point and the short pin (140), it is possible to adjust the input impedance.

[0051] According to an embodiment of the present invention, the power supply line (150) may be extended in a direction toward the ground plane (120) from the radiator (130). For example, the power supply line (150) may be extended toward the ground plane (120) in a second direction. That is, the power supply line (150) may be extended in a direction parallel to the short pin (140). At this time, the power supply line (150) may be extended parallel to the short pin (140) but spaced apart by a predetermined distance, and a current path may be formed by a loop structure between the short pin (140), the radiator (130), and the power supply line (150).

[0052] The resonant frequency of the antenna device (100) can be precisely adjusted according to the dielectric constant of the substrate (110), the length of the radiator (130), the area of ​​the ground plane (120), and the distance between the short pin (140) and the feed line (150). In order to form a predetermined resonant frequency, various such factors must be considered, and accordingly, the design complexity of the antenna device (100) increases. Furthermore, when designing the antenna device (100) by considering these various factors, a predetermined resonant frequency can be formed, but it may be difficult to expand the bandwidth.

[0053] According to an embodiment of the present invention, the short pin (140) and the ground plane (120) are connected by at least one passive element (160). Depending on the location, number, and element value of the at least one passive element (160) connecting the short pin (140) and the ground plane (120), the current path between the short pin (140), the radiator (130), and the feed line (150) can be diversified, the formed resonant frequency can be diversified, and the bandwidth can be expanded.

[0054] Here, the passive component (160) may be used in combination with a chip component and may be a capacitor or an inductor. Also, the component value of the passive component (160) may be a capacitance or an inductance. Depending on the component value of the passive component (160) connecting the short pin (140) and the ground plane (120), the capacitance of the loop structure for the short pin (140), the radiator (130), and the feed line (150) varies, and accordingly, the resonant frequency of the antenna device (100) can be adjusted. That is, according to an embodiment of the present invention, the short pin (140) and the ground plane (120) are connected by at least one passive component (160), and the target resonant frequency can be easily obtained by adjusting the component value of the at least one connected passive component (160).

[0055] According to an embodiment of the present invention, a short pin (140) and a ground plane (120) are connected by a plurality of passive elements (160). Accordingly, a plurality of resonant frequencies are formed by the element values ​​of each passive element at the connection point between the short pin (140) and the ground plane (120), and as a result, the antenna bandwidth can be expanded. Accordingly, the plurality of passive elements (160) may be a plurality of passive elements of the same type or a plurality of passive elements of different types. For example, the plurality of passive elements (160) may include a plurality of inductors. For another example, the plurality of passive elements (160) may include a plurality of capacitors. For yet another example, the plurality of passive elements (160) may include at least one inductor and at least one capacitor. In the following description, the plurality of passive elements (160) are described as an example of including a plurality of inductors, but they are not limited thereto and may include a combination of inductors, capacitors, and other passive elements.

[0056] According to an embodiment of the present invention, a plurality of passive elements (160) are arranged to be spaced apart from each other between a short pin (140) and a ground plane (120), and one end of each passive element is connected to the ground plane (120), and the other end of each passive element can be connected to the short pin (140). That is, a plurality of passive elements (160) can be connected in parallel between the short pin (140) and the ground plane (120). Accordingly, a plurality of resonant frequencies are formed by the element value of each passive element at the connection point between the short pin (140) and the ground plane (120), and as a result, the frequency bandwidth can be expanded.

[0057] According to an embodiment of the present invention, a plurality of passive elements (160) may have different element values. For example, if the plurality of passive elements (160) include a plurality of inductors, the plurality of inductors may have different inductances. If the plurality of passive elements (160) include a plurality of capacitors, the plurality of capacitors may have different capacitances. Accordingly, a plurality of different resonant frequencies are formed by the element values ​​of each passive element at the connection point between the short pin (140) and the ground plane (120), and as a result, the frequency bandwidth can be expanded.

[0058] Hereinafter, more specifically, an embodiment in which a plurality of passive elements (160) include a first inductor (161), a second inductor (162), and a third inductor (163) is described as an example. According to an embodiment of the present invention, the first inductor (161), the second inductor (162), and the third inductor (163) may be sequentially arranged so as to be spaced apart from each other in the direction from the short pin (140) toward the power supply line (150), that is, in the first direction in which the radiator (130) extends. At this time, the inductance of the first inductor (161), the second inductor (162), and the third inductor (163) may increase sequentially. Accordingly, a plurality of different resonant frequencies are formed by the element values ​​of each passive element at the connection point between the short pin (140) and the ground plane (120), and as a result, the frequency bandwidth may be expanded.

[0059] According to an embodiment of the present invention, the inductance of the second inductor (162) may be greater than the inductance of the first inductor (161) by 1.5 nH or more and 2.5 nH or less, preferably 1.7 nH or more and 2.3 nH or less, more preferably 1.9 nH or more and 2.1 nH or less, and the inductance of the third inductor (163) may be greater than the inductance of the second inductor (162) by 1.5 nH or more and 2.5 nH or less, preferably 1.7 nH or more and 2.3 nH or less, more preferably 1.9 nH or more and 2.1 nH or less. When the inductances of the first inductor (161), the second inductor (162), and the third inductor (163) are within these numerical ranges, the effect of expanding the frequency bandwidth can be maximized. At this time, the difference between the inductance of the second inductor (162) and the inductance of the first inductor (161), and the difference between the inductance of the third inductor (163) and the inductance of the second inductor (162) may be 0.15 times or more and 0.35 times or less of the inductance of the second inductor (162), preferably 0.2 times or more and 0.3 times or less, and more preferably 0.225 times or more and 0.275 times or less. According to this, the effect of expanding the frequency bandwidth can be maximized.

[0060] According to an embodiment of the present invention, the difference between the inductance of the first inductor (161) and the inductance of the second inductor (162) may be the same as the difference between the inductance of the second inductor (162) and the inductance of the third inductor (163). Here, being the same may include a difference within ±10%, preferably within ±5%, and more preferably within ±1%. Accordingly, the resonant frequency formed by the loop structure centered on the first inductor (161), the resonant frequency formed by the loop structure centered on the second inductor (162), and the resonant frequency formed by the loop structure centered on the third inductor (163) are finely adjusted, and accordingly, the effect of expanding the frequency bandwidth may be increased.

[0061] Hereinafter, experimental results for verifying the frequency bandwidth expansion effect according to an embodiment of the present invention will be described.

[0062] A ground plane, a radiator, a short pin, and a feed line were arranged on a substrate with a first direction length of 20 mm and a second direction length of 48 mm. The radiator extends in the first direction, and the short pin and feed line extend in the second direction, with the length of the short pin configured to be 8.7 mm. The frequency bandwidth expansion effect was experimented upon by varying the number of passive components and the component values ​​of the passive components between the short pin and the ground plane.

[0063] Table 1 and Figures 5 to 7 are simulation graphs showing the frequency bandwidth according to the number of passive components between the short pin and the ground plane.

[0064] No. Passive Component Inductance (nH) Bandwidth (GHz) 1 Inductor 18 1.13 2 Inductor 18 1.2 Inductor 210 3 Inductor 16 1.27 Inductor 28 Inductor 310

[0065] Inductors 1, 2, and 3 were arranged sequentially in the direction from the short pin toward the power supply line. In the graphs of FIGS. 5 to 7, the horizontal axis represents frequency and the vertical axis represents return loss, and a return loss of -6 or less was determined to be a meaningful bandwidth. As the bandwidth was 1.13 GHz in the graph simulated with only one inductor (8 nH inductor), 1.2 GHz in the graph simulated with two inductors (8 nH inductor and 10 nH inductor), and 1.27 GHz in the graph simulated with three inductors (6 nH inductor, 8 nH inductor, and 10 nH inductor), it can be seen that the bandwidth increases as the number of passive components connecting the short pin and the ground plane increases. In addition, as the number of passive components connecting the short pin and the ground plane increases, the return loss decreases, which also has the effect of improving antenna performance.

[0066] Table 2 and Figures 7 to 9 show the results of frequency bandwidth according to the difference in component values ​​when the number of passive components between the short pin and the ground plane is 3.

[0067] No. Passive Component Inductance (nH) Bandwidth (GHz) 3 Inductor 16 1.27 Inductor 28 Inductor 310 4 Inductor 16 1.06 Inductor 27 Inductor 38 5 Inductor 16 1.09 Inductor 29 Inductor 312

[0068] Inductors 1, 2, and 3 were arranged sequentially in the direction from the short pin toward the power supply line. In the graphs of FIGS. 7 to 9, the horizontal axis represents frequency and the vertical axis represents return loss; a return loss of -6 or less was determined to be a meaningful bandwidth. It can be seen that the bandwidth increases further when the difference in inductance between adjacent inductors is 2nH compared to 1nH and 3nH. Table 3 and FIGS. 7, 10 to 12 show the results representing the frequency bandwidth according to the arrangement order of the component values ​​when there are three passive components between the short pin and the ground plane.

[0069] No. Passive Component Inductance (nH) Bandwidth (GHz) 3 Inductor 16 1.27 Inductor 28 Inductor 3 106 Inductor 18 1.07 Inductor 26 Inductor 3 107 Inductor 18 1.07 Inductor 210 Inductor 368 Inductor 1 101.08 Inductor 28 Inductor 36

[0070] Inductors 1, 2, and 3 were arranged sequentially in the direction from the short pin toward the power supply line. In the graphs of FIGS. 7 and FIGS. 10 to 12, the horizontal axis represents frequency and the vertical axis represents return loss; a return loss of -6 or less was determined to be a meaningful bandwidth. It can be seen that the greatest bandwidth expansion effect is obtained when the inductances of inductors 1, 2, and 3 are arranged to increase sequentially in the direction from the short pin toward the power supply line. The antenna device according to an embodiment of the present invention can be applied to a communication device. A communication device according to an embodiment of the present invention can be applied to a mobile terminal, smartphone, tablet, wearable device, TV, home appliance, vehicle, etc.

[0071] A communication device according to an embodiment of the present invention comprises an antenna device, an IC chip disposed on the antenna device, and a shield member covering the IC chip. The antenna device comprises a substrate, a ground plane disposed on the substrate, a radiator disposed on the substrate, a short pin disposed on the substrate and connected to the radiator between the ground plane and the radiator, and a feed line disposed on the substrate and drawn from the radiator. The short pin and the ground plane are connected by a plurality of passive elements. The IC chip is connected to the end of the feed line, and the IC chip is connected to the ground plane.

[0072] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as described in the following claims.

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