EP4697496A1

EP4697496A1 - Antenna substrate and front end module including same

Info

Publication number: EP4697496A1
Application number: EP24788940.5A
Authority: EP
Inventors: Chan Woo Yang; Kyung Ho Lim; Sang Kil Kim; Do Hyun Kim
Original assignee: University Industry Cooperation Foundation of Pusan National University; LG Innotek Co Ltd
Current assignee: University Industry Cooperation Foundation of Pusan National University; LG Innotek Co Ltd
Priority date: 2023-04-13
Filing date: 2024-03-28
Publication date: 2026-02-18
Also published as: KR20240152565A; CN121100447A; WO2024214997A1

Abstract

An antenna substrate of an embodiment comprises: multiple antenna layers stacked on each other and vertically spaced apart from each other; an antenna insulation layer disposed between the multiple antenna layers; and a transmission line, wherein the multiple antenna layers comprise a high-frequency antenna layer radiating a first signal of a first wireless frequency band and a low-frequency antenna layer radiating a second signal of a second wireless frequency band lower than the first wireless frequency band, the transmission line comprises a capacitive feeding part that faces and feeds power to each of the high-frequency and low-frequency antenna layers in a state where the antenna insulation layer is interposed therebetween and a via extending through the low-frequency antenna layer, and the capacitive feeding part overlaps the high-frequency antenna layer.

Description

[Technical Field]

Embodiments relate to an antenna substrate and a front end module including the same.

[Background Art]

Recently, efforts have been made to develop an improved 5^th generation (5G) or pre-5G communication system in order to meet the demand for wireless data traffic.
To achieve a high data transfer rate, the 5G communication system uses millimeter wave (mmWave) bands. This high frequency band is called mmWave due to the wavelength thereof.
In order to reduce path loss of radio waves and increase a transmission distance of radio waves in the ultra-high frequency band, integration technologies such as beamforming, massive multiple-input multiple-output (MIMO), and array antennas have been developed in the 5G communication system. The size of antenna systems may increase because hundreds of active antennas are required to cover the above frequency bands.
However, an antenna needs to be reduced in size in order to be mounted in smartphones or the like, and therefore, various research with the goal of increasing the bandwidth of an antenna without increasing the size thereof is underway.

[Disclosure]

[Technical Problem]

Embodiments provide an antenna substrate having a reduced size and a wide bandwidth and a front end module including the same.

[Technical Solution]

An antenna substrate according to an embodiment may include a plurality of antenna layers stacked so as to be spaced apart from each other in a vertical direction, an antenna insulating layer disposed between the plurality of antenna layers, and a transmission line. The plurality of antenna layers may include a high-frequency antenna layer configured to radiate a first signal in a first radio frequency band and a low-frequency antenna layer configured to radiate a second signal in a second radio frequency band lower than the first radio frequency band. The transmission line may include a capacitive power feeding unit disposed to face each of the high-frequency and low-frequency antenna layers with the antenna insulating layer interposed therebetween and configured to feed power to each of the high-frequency and low-frequency antenna layers and a via disposed to pass through the low-frequency antenna layer. The capacitive power feeding unit may overlap the high-frequency antenna layer.
In an example, the via may include first and second vias passing through the low-frequency antenna layer, and the capacitive power feeding unit may include a first power feeding plate extending in a horizontal direction from an end of the first via so as to face the high-frequency antenna layer disposed above the first power feeding plate and to face the low-frequency antenna layer disposed below the first power feeding plate and a second power feeding plate extending in the horizontal direction from an end of the second via so as to face the high-frequency antenna layer disposed above the second power feeding plate and to face the low-frequency antenna layer disposed below the second power feeding plate.
In an example, the first power feeding plate may have a planar area greater than the planar area of the end of the first via, and the second power feeding plate may have a planar area greater than the planar area of the end of the second via.
In an example, the plurality of antenna layers may further include a feeding antenna layer disposed between the high-frequency antenna layer and the low-frequency antenna layer, and the first and second power feeding plates may belong to the feeding antenna layer.
In an example, the feeding antenna layer may be disposed closer to the high-frequency antenna layer than to the low-frequency antenna layer.
In an example, the first power feeding plate may be located on a virtual first horizontal line passing through the center of the feeding antenna layer, the second power feeding plate may be located on a virtual second horizontal line passing through the center of the feeding antenna layer and orthogonal to the first horizontal line, and the center of the feeding antenna layer may correspond to an intersection point between an axis passing through the center of the first antenna layer in the vertical direction and a virtual horizontal plane having the first and second power feeding plates disposed thereon.
In an example, each of the first and second power feeding plates may have at least one of a circular planar shape or a polygonal planar shape.
In an example, each of the first and second power feeding plates may have a region gradually increasing in width in a direction away from the center of the feeding antenna layer.
In an example, each of the first and second power feeding plates may have a droplet-shaped planar shape.
A front end module according to another embodiment may include a plurality of antenna areas spaced apart from each other in a horizontal direction, and each of the plurality of antenna areas may include an antenna unit. The antenna unit may include a plurality of antenna layers stacked so as to be spaced apart from each other in a vertical direction, an antenna insulating layer disposed between the plurality of antenna layers, and a transmission line. The plurality of antenna layers may include a high-frequency antenna layer configured to radiate a first signal in a first radio frequency band and a low-frequency antenna layer configured to radiate a second signal in a second radio frequency band lower than the first radio frequency band. The transmission line may include a capacitive power feeding unit disposed to face each of the high-frequency and low-frequency antenna layers with the antenna insulating layer interposed therebetween and configured to feed power to each of the high-frequency and low-frequency antenna layers and a via disposed to pass through the low-frequency antenna layer. The capacitive power feeding unit may overlap the high-frequency antenna layer.

[Advantageous Effects]

An antenna substrate and a front end module including the same according to the embodiments may have a small volume and a wide bandwidth and may cover both a frequency band of 24 GHz to 29.5 GHz and a frequency band of 36 GHz to 43.5 GHz.

[Description of Drawings]

FIG. 1 is a plan view of an antenna substrate according to an embodiment.
FIG. 2 is a perspective view of the antenna substrate shown in FIG. 1.
FIG. 3 is a cross-sectional view taken along line I-I' shown in FIG. 1.
FIG. 4 is a schematic perspective view of an antenna unit according to an embodiment.
FIG. 5 is a perspective view of the antenna substrate according to the embodiment.
FIGs. 6A to 6D are plan views of embodiments of first and second power feeding plates shown in FIG. 5.
FIG. 7 is a cross-sectional view of an antenna substrate according to a comparative example.
FIG. 8 is a graph indicating return loss in the antenna substrate according to the comparative example.
FIG. 9 is a graph indicating return loss in the antenna substrate according to the embodiment.
FIG. 10 is a block diagram of a front end module according to an embodiment.

[Best Mode]

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.
The technical spirit of the disclosure is not limited to the embodiments to be described, and may be implemented in various other forms, and one or more of the components may be selectively combined and substituted for use without exceeding the scope of the technical spirit of the disclosure.
In addition, terms (including technical and scientific terms) used in the embodiments of the disclosure, unless specifically defined and described explicitly, are to be interpreted as having meanings that may be generally understood by those having ordinary skill in the art to which the disclosure pertains, and meanings of terms that are commonly used, such as terms defined in a dictionary, should be interpreted in consideration of the context of the relevant technology.
Further, the terms used in the embodiments of the disclosure are for explaining the embodiments and are not intended to limit the disclosure. In this specification, the singular forms may also include plural forms unless otherwise specifically stated in a phrase, and in the case in which "at least one (or one or more) of A, B, or C" is stated, it may include one or more of all possible combinations of A, B, and C.
In addition, in describing the components of the embodiments of the disclosure, terms such as "first," "second," "A," "B," "(a)," and "(b)" can be used. Such terms are only for distinguishing one component from another component, and do not determine the nature, sequence, or procedure of the corresponding constituent elements.
In addition, when it is described that a component is "connected," "coupled" or "joined" to another component, the description may include not only being directly "connected," "coupled" or "joined" to the other component but also being "connected," "coupled" or "joined" by another component between the component and the other component.
In addition, in the case of being described as being formed or disposed "above (on)" or "below (under)" another component, the description includes not only the case where the two components are in direct contact with each other, but also the case where one or more other components are formed or disposed between the two components. In addition, when expressed as "above (on)" or "below (under)," it may refer to a downward direction as well as an upward direction with respect to one element.
Hereinafter, an antenna substrate according to an embodiment will be described with reference to the accompanying drawings. Here, the antenna substrate refers to a hybrid antenna substrate, an antenna in package (AIP), an antenna array substrate, an antenna array, etc.
The antenna substrate 100 will be described using the Cartesian coordinate system (x-axis, y-axis, z-axis) for convenience of description, but may also be described using other coordinate systems. In the Cartesian coordinate system, the x-axis, the y-axis, and the z-axis are perpendicular to each other, but the embodiments are not limited thereto. That is, the x-axis, the y-axis, and the z-axis may intersect each other obliquely. Hereinafter, for convenience of description, the x-axis direction will be referred to as a "first direction," the y-axis direction will be referred to as a "second direction," the z-axis direction will be referred to as a "third direction" or a "vertical direction," and at least one of the x-axis direction or the y-axis direction will be referred to as a "horizontal direction."
FIG. 1 is a plan view of the antenna substrate 100 according to an embodiment, and FIG. 2 is a perspective view of the antenna substrate 100 shown in FIG. 1.
The antenna substrate 100 according to the embodiment may include a plurality of antenna areas arranged to be spaced apart from each other in the horizontal direction. For example, as shown in FIGs. 1 and 2, the antenna substrate 100 may include first to fourth antenna areas A1, A2, A3, and A4 arranged in the y-axis direction, which is the horizontal direction. However, the embodiments are not limited thereto. That is, according to another embodiment, the antenna substrate 100 may include more or less than four antenna areas.
FIG. 3 is a cross-sectional view taken along line I-I' shown in FIG. 1.
Hereinafter, the configuration of the third antenna area A3 (hereinafter referred to as an "antenna area") will be described with reference to FIG. 3. Because each of the other antenna areas A1, A2, and A4 has the same configuration as the third antenna area A3, a duplicate description thereof will be omitted.
The antenna area 200 according to an embodiment may include an antenna unit ANT and a routing unit ROT. According to another embodiment, the antenna area 200 may further include a core unit CO. That is, the core unit CO may be omitted from the antenna area 200.
According to one embodiment, as shown in FIG. 3, the antenna unit ANT may be disposed on the core unit CO, the routing unit ROT may be disposed under the core unit CO, and the core unit CO may be disposed between the antenna unit ANT and the routing unit ROT.
According to another embodiment, the antenna unit ANT and the routing unit ROT may be disposed on the same horizontal plane.
According to still another embodiment, the antenna unit ANT may be stacked on the routing unit ROT.
According to still another embodiment, the routing unit ROT and the antenna unit ANT may be disposed to be spaced apart from each other, and may be electrically connected to each other via a connection member, e.g., a flexible printed circuit board (FPCB).
According to still another embodiment, the routing unit ROT and the antenna unit ANT may be disposed to be spaced apart from each other, and may be electrically connected to each other via a connection member, e.g., a solder ball or a metal bump.
Hereinafter, the antenna unit ANT and the routing unit ROT of the antenna area 200 according to the embodiment will be described as being disposed in the structure shown in FIG. 3. However, the embodiments are not limited to any specific arrangement structure of the antenna unit ANT and the routing unit ROT.
The antenna unit ANT may include a plurality of wiring layers (hereinafter referred to as "antenna layers") stacked so as to be spaced apart from each other in the vertical direction and an insulating layer (hereinafter referred to as an "antenna insulating layer"). In this case, the wiring layer may mean an antenna patch, a patch antenna, or a patch layer.
The plurality of antenna layers may be sequentially stacked on the core unit CO, and the antenna insulating layer may be disposed between the plurality of antenna layers.
In addition, although not shown in FIG. 3, the antenna unit ANT may include a transmission line. A current supplied through a port is fed to a corresponding antenna layer among the plurality of antenna layers through the transmission line disposed in each of the routing unit ROT and the antenna unit ANT.
For example, the plurality of antenna layers may include first to M^th antenna layers AL1 to ALM sequentially stacked from above to below in the vertical direction on the core unit CO. In this case, M is a positive integer of 2 or greater.
The first antenna layer AL1 may correspond to each of the uppermost layers 120-1, 120-2, 120-3, and 120-4 of the first to fourth antenna areas A1, A2, A3, and A4 shown in FIGs. 1 and 2.
First to (M-1)^th antenna insulating layers DL11 to DL1 (M-1) may be disposed between the first to M^th antenna layers AL1 to ALM.
For example, if M is 7, the antenna unit ANT may include first to seventh antenna layers AL1 to AL7 and first to sixth antenna insulating layers DL11 to DL16 sequentially stacked in the vertical direction from the top thereof to the core unit CO. That is, the first antenna insulating layer DL11 may be disposed between the first antenna layer AL1 and the second antenna layer AL2, the second antenna insulating layer DL12 may be disposed between the second antenna layer AL2 and the third antenna layer AL3, the third antenna insulating layer DL13 may be disposed between the third antenna layer AL3 and the fourth antenna layer AL4, the fourth antenna insulating layer DL14 may be disposed between the fourth antenna layer AL4 and the fifth antenna layer AL5, the fifth antenna insulating layer DL15 may be disposed between the fifth antenna layer AL5 and the sixth antenna layer AL6, and the sixth antenna insulating layer DL16 may be disposed between the sixth antenna layer AL6 and the seventh antenna layer AL7.
Meanwhile, the routing unit ROT may include the aforementioned transmission line, and the plurality of wiring layers included in the routing unit ROT may include a signal pattern, a power pattern, or a resistance pattern. In addition, the routing unit ROT may have combinations of various routing characteristics such as power/data, input/output, and radio frequency (RF) routing.
Similar to the antenna unit ANT, the routing unit ROT may include a plurality of wiring layers (hereinafter referred to as "routing layers") and an insulating layer (hereinafter referred to as a "routing insulating layer").
The routing insulating layer may be disposed between the plurality of routing layers.
First to N^th routing layers RL1 to RLN may be sequentially disposed in the vertical direction from the core unit CO to below. In this case, N is a positive integer of 2 or greater. N may be identical to M. In this case, first to (N-1)^th routing insulating layers DL21 to DL2(N-1) may be disposed between the first to N^th routing layers RL1 to RLN.
The first routing layer RL1 may be a main ground GND formed in a ground GND pattern.
Alternatively, the antenna unit ANT may be formed on the routing unit ROT without the core unit CO. In this case, the antenna unit ANT may be formed on the first routing layer RL1, which is the main ground.
For example, if N is identical to M, i.e., 7, the routing unit ROT may include first to seventh routing layers RL1 to RL7 and first to sixth routing insulating layers DL21 to DL26 sequentially stacked in the vertical direction from the core unit CO. That is, the first routing insulating layer DL21 may be disposed between the first routing layer RL1 and the second routing layer RL2, the second routing insulating layer DL22 may be disposed between the second routing layer RL2 and the third routing layer RL3, the third routing insulating layer DL23 may be disposed between the third routing layer RL3 and the fourth routing layer RL4, the fourth routing insulating layer DL24 may be disposed between the fourth routing layer RL4 and the fifth routing layer RL5, the fifth routing insulating layer DL25 may be disposed between the fifth routing layer RL5 and the sixth routing layer RL6, and the sixth routing insulating layer DL26 may be disposed between the sixth routing layer RL6 and the seventh routing layer RL7.
The material of each of the first to M^th antenna layers AL1 to ALM, the core unit CO, and the first to N^th routing layers RL1 to RLN described above may include metal, such as copper (Cu), aluminum (Al), silver (Ag) , tin (Sn), gold (Au), nickel (Ni), lead (Pb), titanium (Ti), or alloys thereof.
In addition, each of the first to (M-1)^th antenna insulating layers DL11 to DL1(M-1) and the first to (N-1)^th routing insulating layers DL21 to DL2(N-1) may be made of a material having insulating properties (hereinafter referred to as an "insulative material"). For example, a thermosetting resin such as an epoxy resin, a thermoplastic resin such as polyimide, or a material containing a reinforcing material such as a glass fiber and/or an inorganic filler together with a thermosetting resin or a thermoplastic resin, e.g., ABF, PID, BCC, or prepreg (PPG), may be used as the insulative material. However, the insulative material is not limited to a resin. For example, a glass plate or a ceramic plate may be used. However, the embodiments are not limited to any specific material of each of the first to (M-1)^th antenna insulating layers DL11 to DL1(M-1) and the first to (N-1)^th routing insulating layers DL21 to DL2(N-1).
Hereinafter, an embodiment of the antenna unit ANT shown in FIG. 3 will be described with reference to FIG. 4.
FIG. 4 is a schematic perspective view of the antenna unit according to the embodiment.
The antenna unit shown in FIG. 4 may include a high-frequency band (HB) antenna layer (hereinafter referred to as a "high-frequency antenna layer") 210, a low-frequency band (LB) antenna layer (hereinafter referred to as a "low-frequency antenna layer") 212, a transmission line, and an antenna insulating layer.
In FIG. 4, the white background between the high-frequency antenna layer 210 and the low-frequency antenna layer 212 may correspond to the antenna insulating layer.
The high-frequency antenna layer 210 may radiate a first signal (or HB signal) in a first radio frequency band. The high-frequency antenna layer 210 may correspond to the first antenna layer AL1 shown in FIG. 3.
The high-frequency antenna layer 210 may radiate a signal having a frequency belonging to the millimeter wave (mmWave) frequency band.
The low-frequency antenna layer 212 serves to radiate a second signal (or LB signal) in a second radio frequency band lower than the first radio frequency band. The low-frequency antenna layer 212 may correspond to the third antenna layer AL3 shown in FIG. 3.
The transmission line disposed in the antenna unit ANT may include a capacitive power feeding unit 300 and a via VA.
The capacitive power feeding unit 300 is disposed to face each of the high-frequency antenna layer 210 and the low-frequency antenna layer 212 with the antenna insulating layer interposed therebetween, and serves to feed power to each of the high-frequency antenna layer 210 and the low-frequency antenna layer 212. In general, a capacitor is a device in which carriers move between two metal plates opposing each other with a dielectric material interposed therebetween. Using this principle, the capacitive power feeding unit 300 may feed power to the high-frequency antenna layer 210 with a dielectric material interposed therebetween. Furthermore, in the embodiment, the capacitive power feeding unit 300 may also feed power to the low-frequency antenna layer 212. That is, the single capacitive power feeding unit 300 may feed power to both the high-frequency antenna layer 210 and the low-frequency antenna layer 212. In detail, the single capacitive power feeding unit 300 may supply current to the high-frequency antenna layer 210 while facing the high-frequency antenna layer 210 with the antenna insulating layer interposed therebetween, and simultaneously may supply current to the low-frequency antenna layer 212 while facing the low-frequency antenna layer 212 with the antenna insulating layer interposed therebetween.
As described above, the capacitive power feeding unit 300 is spaced apart from the high-frequency antenna layer 210 and the low-frequency antenna layer 212 with a dielectric material interposed therebetween without physical contact with the high-frequency antenna layer 210 or the low-frequency antenna layer 212.
The capacitive power feeding unit 300 overlaps the high-frequency antenna layer 210 in the vertical direction. For example, the capacitive power feeding unit 300 may entirely overlap the high-frequency antenna layer 210 in the vertical direction.
The capacitive power feeding unit 300 may be disposed to be spaced apart from the high-frequency antenna layer 210 with the antenna insulating layer interposed therebetween in the overlapping area with the high-frequency antenna layer 210.
The capacitive power feeding unit 300 may be disposed to be spaced apart from the high-frequency antenna layer 210 with a dielectric material interposed therebetween in the overlapping area with the high-frequency antenna layer 210.
The capacitive power feeding unit 300 may be disposed to be physically spaced apart from the high-frequency antenna layer 210 in the overlapping area with the high-frequency antenna layer 210.
As such, according to the embodiment, the single capacitive power feeding unit 300 may feed power to both the high-frequency antenna layer 210 and the low-frequency antenna layer 212.
The via VA may be connected to the transmission line of the routing unit ROT via the core unit CO and may pass through the low-frequency antenna layer 212 to be connected to the capacitive power feeding unit 300. To this end, the low-frequency antenna layer 212 includes a through-hole TH through which the via VA passes.
The material of the via VA may be identical to the material of the first to M^th antenna layers AL1 to ALM and the first to N^th routing layers RL1 to RLN. For example, the material of the via VA may include metal, such as copper (Cu), aluminum (Al), silver (Ag), tin (Sn), gold (Au), nickel (Ni), lead (Pb), titanium (Ti), or alloys thereof. However, the embodiments are not limited thereto.
In this case, the diameter of the through-hole TH may be greater than the diameter of the via VA. The reason for this is to prevent the via VA passing through the through-hole TH from contacting the low-frequency antenna layer 212.
In some cases, a ring RI (or via connection part) may be disposed on a portion of the outer surface of the via VA that is located in the through-hole TH in order to efficiently connect the via VA disposed in each insulating layer to the via VA disposed in another insulating layer. In addition, because the ring RI has a larger planar area than the via VA, the ring RI may perform a role similar to that of the power feeding unit 300 of the high-frequency antenna layer 210 and the low-frequency antenna layer 212.
In this case, a first spacing distance Z1 in the vertical direction between the capacitive power feeding unit 300 and the high-frequency antenna layer 210 may be less than a second spacing distance Z2 in the vertical direction between the capacitive power feeding unit 300 and the low-frequency antenna layer 212. This is because a frequency radiated from the high-frequency antenna layer 210 is higher than a frequency radiated from the low-frequency antenna layer 212. As such, since a higher frequency is more sensitive to capacitance, the capacitive power feeding unit 300 is disposed closer to the high-frequency antenna layer 210 than to the low-frequency antenna layer 212 in order to perform coupling mainly for the high frequency.
In addition, in order to secure a height of the low-frequency antenna layer 212 from the ground layer (RL1 in FIG. 3) located below the low-frequency antenna layer 212, the capacitive power feeding unit 300 is disposed between the high-frequency antenna layer 210 and the low-frequency antenna layer 212, closer to the high-frequency antenna layer 210, rather than being disposed below the low-frequency antenna layer 212.
Hereinafter, an antenna unit according to an embodiment connected to two ports Port1 and Port2 will be described with reference to FIG. 5.
FIG. 5 is a perspective view of the antenna substrate according to the embodiment.
The antenna substrate shown in FIG. 5 may include the antenna unit shown in FIG. 4.
The antenna substrate may include first to seventh antenna layers 410, 412, 414, 416, 418, 420, and 422 and a ground layer 424, which are stacked so as to be spaced apart from each other in the vertical direction, and may include a via VA and a capacitive power feeding unit 300A. In this case, the ground layer 424 may correspond to the first routing layer RL1 shown in FIG. 3.
The via VA may correspond to an embodiment of the via VA shown in FIG. 4, and the capacitive power feeding unit 300A may correspond to an embodiment of the capacitive power feeding unit 300 shown in FIG. 4.
In addition, the first antenna layer 410 may correspond to the high-frequency antenna layer 210 shown in FIG. 4, and the third antenna layer 414 may correspond to the low-frequency antenna layer 212 shown in FIG. 4. The second antenna layer 412, which is an antenna layer (hereinafter referred to as a "feeding antenna layer") in which the capacitive power feeding unit 300A is disposed, may be disposed between the first antenna layer 410 and the third antenna layer 414.
In addition, at least one antenna layer may be further disposed between the third antenna layer 414 and the ground layer 424. For example, as shown in FIG. 5, at least one of the fourth to seventh antenna layers 416 to 422 may be further disposed between the third antenna layer 414 and the ground layer 424.
Each of the fourth to seventh antenna layers 416 to 422 may be omitted or may be added in order to perform various functions such as impedance matching, via VA connection, bandwidth adjustment, or S-parameter tuning. The embodiments are not limited as to the presence or absence of the additional antenna layers or the number thereof.
Hereinafter, the capacitive power feeding unit 300A and the via VA will be described with reference to FIG. 5. The following description of the capacitive power feeding unit 300A and the via VA is applicable regardless of the presence or absence of the additional antenna layers or the number thereof.
The via VA may include first and second vias VA1 and VA2 that extend from the ground plate 424 and pass through the third to seventh antenna layers 414 to 422. To this end, each of the third to seventh antenna layers 414 to 422 may include a through-hole through which the first and second vias VA1 and VA2 pass, similar to the low-frequency antenna layer 212 shown in FIG. 4.
The capacitive power feeding unit 300A may include first and second power feeding plates 312 and 314. For example, the first and second power feeding plates 312 and 314 may belong to the second antenna layer 412, which is the feeding antenna layer. Although the second antenna layer 412 is illustrated in FIG. 5 as having a planar shape including an outer frame having therein a hollow portion and the first and second power feeding plates 312 and 314 disposed in the hollow portion in the outer frame, the embodiments are not limited thereto. In another embodiment, the outer frame may be omitted from the second antenna layer 412.
The first power feeding plate 312 may extend in the horizontal direction from an end of the first via VA1 so as to face the first antenna layer 410 disposed thereabove and to face the third antenna layer 414 disposed therebelow. To this end, one of both ends of the first via VA1 may be connected to the first power feeding plate 312, and the other of both ends thereof may be connected to the first port Port1 via the ground layer 424.
The second power feeding plate 314 may extend in the horizontal direction from an end of the second via VA2 so as to face the first antenna layer 410 disposed thereabove and to face the third antenna layer 414 disposed therebelow, and may be spaced apart from the first power feeding plate 312. To this end, one of both ends of the second via VA2 may be connected to the second power feeding plate 314, and the other of both ends thereof may be connected to the second port Port2 via the ground layer 424.
Due to the configuration described above with reference to FIG. 4, in which the first spacing distance Z1 is less than the second spacing distance Z2, the first and second power feeding plates 312 and 314 may be disposed within the second antenna layer 412, closer to the first antenna layer 410 than to the third antenna layer 414.
Hereinafter, various embodiments of the first and second power feeding plates 312 and 314 shown in FIG. 5 will be described with reference to FIGs. 6A to 6D.
FIGs. 6A to 6D are plan views showing embodiments of the first and second power feeding plates 312 and 314 shown in FIG. 5. FIGs. 6A and 6B show the second antenna layer 412 including the outer frame, and FIGs. 6C and 6D show the second antenna layer 412 without the outer frame.
In this case, CP represents the center of the second antenna layer 412 and is defined as a point at which an axis passing through the center of the first antenna layer 410 in the vertical direction meets a virtual horizontal plane on which the first and second power feeding plates 312 and 314 are disposed.
According to the embodiment, as illustrated in FIGs. 6A to 6D, the first power feeding plates 312A to 312D may be located on a virtual first horizontal line HL1 passing through the center CP of the second antenna layer 412, and the second power feeding plates 314A to 314D may be located on a virtual second horizontal line HL2 passing through the center CP of the second antenna layer 412 and orthogonal to the first horizontal line HL1. In this manner, the first power feeding plates 312A to 312D and the second power feeding plates 314A to 314D may be disposed orthogonal to each other with respect to the center CP of the second antenna layer 412.
In addition, the first power feeding plates 312A to 312D and the second power feeding plates 314A to 314D may be disposed so as not to be symmetrical to each other with respect to the center CP.
In addition, the first power feeding plates 312A to 312D and the second power feeding plates 314A to 314D may be disposed to form various angles therebetween, such as 60°, 45°, or 30°, with respect to the center CP. That is, an angle θ formed by the first horizontal line HL1 and the second horizontal line HL2 may be 90°, 60°, 45°, or 30°.
In addition, each of the first and second power feeding plates 312 and 314 may have various planar shapes.
According to one embodiment, as shown in FIG. 6A, each of the first and second power feeding plates 312A and 314A may have a circular planar shape.
According to another embodiment, each of the first and second power feeding plates may have a polygonal planar shape. For example, as shown in FIG. 6B, each of the first and second power feeding plates 312B and 314B may have a rectangular planar shape.
According to still another embodiment, each of the first and second power feeding plates may have a tapered planar shape having a region that gradually increases in width in a direction away from the center CP of the second antenna layer 412, i.e., a region that gradually decreases in width in a direction toward the center CP of the second antenna layer 412.
Alternatively, each of the first and second power feeding plates may have a region that gradually increases in width and then gradually decreases in width in a direction away from the center CP. In this case, the region that decreases in width may have a curvature.
For example, as shown in FIG. 6C, each of the first and second power feeding plates 312C and 314C may have a droplet-shaped planar shape, and as shown in FIG. 6D, each of the first and second power feeding plates 312D and 314D may have a planar shape in which a portion located farthest from the center CP is cut out from the droplet-shaped plane shown in FIG. 6C or may have a trapezoidal sectional shape.
In FIGs. 6B to 6D, the centers of the first power feeding plates 312B, 312C, and 312D and the second power feeding plates 314B, 314C, and 314D may be closer to the center CP of the second antenna layer 412 than the centers of first and second vias VA1 and VA2. This may contribute to dual-band antenna design and tuning using only single power feeding, and may also contribute to improvement in bandwidth performance, as will be described later with reference to FIGs. 8 and 9.
In each of FIGs. 6A to 6D, it can be seen that the planar area of the first power feeding plate 312 is greater than the planar area of the end of the first via VA1 and the planar area of the second power feeding plate 314 is greater than the planar area of the end of the second via VA2.
Hereinafter, an antenna substrate according to a comparative example and the antenna substrate according to the embodiment will be described with reference to the accompanying drawings.
FIG. 7 is a cross-sectional view of an antenna substrate according to a comparative example.
The antenna substrate shown in FIG. 7 includes first to seventh antenna layers 10 to 22, first to fourth vias 42 to 48, and a ground layer 24.
The second and sixth antenna layers 12 and 20 perform the same role as the first and third antenna layers 410 and 414 shown in FIG. 5, respectively, and the ground layer 24 corresponds to the ground layer 424 shown in FIG. 5. Thus, a duplicate description thereof will be omitted.
The first antenna layer 10 corresponds to a high-frequency stack patch, the third antenna layer 14 corresponds to a high-frequency feeding patch, the fourth antenna layer 16 corresponds to a high-frequency impedance matching patch, the fifth antenna layer 18 corresponds to a low-frequency stack patch, and the seventh antenna layer 22 corresponds to a low-frequency impedance matching patch.
Ends of the first and second vias 42 and 44 are directly coupled to the sixth antenna layer 20 in order to feed power to the sixth antenna layer 20. In addition to the first and second vias 42 and 44, ends of the third and fourth vias 46 and 48 are directly coupled to the second antenna layer 12 in order to feed power to the second antenna layer 12.
In this way, according to the comparative example, a total of four vias 42 to 48 is required to feed power to the second and sixth antenna layers 12 and 20, and each of the four vias is directly coupled to the antenna layer corresponding thereto.
In contrast, according to the embodiment, as shown in FIG. 5, power may be fed to the first and third antenna layers 410 and 414 using a total of two vias VA1 and VA2. This is possible because the power feeding unit 300 or 300A feeds power to the first and third antenna layers 410 and 414 in a capacitive manner without being directly coupled thereto.
Therefore, according to the embodiment, a smaller number of vias than in the comparative example is used to feed power to the high-frequency antenna layer 410 and the low-frequency antenna layer 414. Accordingly, the antenna substrate according to the embodiment may have simple configuration, may reduce manufacturing costs, and may simplify a manufacturing process. Further, because the lengths thereof in the first, second, and third directions are reduced, the antenna substrate according to the embodiment may have a smaller size and volume than the comparative example.
In addition, the size of the capacitive power feeding unit 300 or 300A that feeds power to the high-frequency antenna layer 410 and the low-frequency antenna layer 414 in a capacitive manner in the embodiment is greater than the size of the vias 42 to 48 directly coupled to the high-frequency antenna layer 12 and the low-frequency antenna layer 20 in the comparative example.
For example, the size of the vias 42 to 48 directly coupled to the high-frequency antenna layer 12 and the low-frequency antenna layer 20 shown in FIG. 7 is equal to the size of the ends of the vias VA1 and VA2 shown in FIGs. 6A to 6D, whereas the planar area of the first and second power feeding plates 312 and 314 is greater than the size of the ends of the first and second vias VA1 and VA2.
As such, since the power-feeding portions for the high-frequency antenna layer 410 and the low-frequency antenna layer 414 in the embodiment are larger than in the comparative example, the paths through which feeding current flows may become more diversified, thereby increasing the bandwidth and enabling compatibility with global networks.
In addition, the bandwidth and performance may be improved by adjusting at least one of the length between the high-frequency antenna layer 410 and the feeding antenna layer 412 in the vertical direction (e.g., first spacing distance Z1), the planar area or length of the first and second power feeding plates 312 and 314, or a degree of inclination of the tapered shape of the first and second power feeding plates 312 and 314.
In addition, when the power feeding plates have a tapered planar shape, for example, a droplet shape as shown in FIG. 6C, tuning may be enabled according to an initial impedance value, thereby achieving wideband impedance matching performance.
FIG. 8 is a graph indicating return loss (or reflection coefficient) in the antenna substrate according to the comparative example, and FIG. 9 is a graph indicating return loss in the antenna substrate according to the embodiment. In each of FIGs. 8 and 9, the horizontal axis represents frequency, and the vertical axis represents return loss. Return loss is a ratio of reflected voltage to input voltage.
If the antenna substrate according to the comparative example is implemented as shown in FIG. 7 and a first height H1 in the vertical direction from the ground layer 24 to the fifth antenna layer 18 is 0.36 mm, return loss characteristics for the first to fourth ports Port1, Port2, Port3, and Port4, to which the first to fourth vias 42 to 48 are respectively connected, are obtained as shown in FIG. 8.
In addition, if the antenna substrate according to the embodiment is implemented as shown in FIG. 5 and a second height H2 in the vertical direction from the ground layer 424 to the low-frequency antenna layer 414 is 0.7 mm, return loss characteristics for the first and second ports Port1 and Port2, to which the first and second vias VA1 and VA2 are respectively connected, are obtained as shown in FIG. 9.
Referring to FIGs. 8 and 9, based on -10 dB, the bandwidth in the low-frequency band in the comparative example is BW1, and the bandwidth in the low-frequency band in the embodiment is BW2. It can be seen that the low-frequency bandwidth in the embodiment is increased by 203% compared to the comparative example, and the bandwidth in the high-frequency band in the embodiment is BW3. As such, according to the embodiment, it can be seen that both an operating frequency band of 24 GHz to 29.5 GHz and an operating frequency band of 36 GHz to 43.5 GHz are covered.
According to the embodiment, since the virtual first horizontal line HL1 on which the first power feeding plates 312A to 312D are located and the virtual second horizontal line HL2 on which the second power feeding plates 314A to 314D are located are disposed so as not to be symmetrical to each other, influence of one port upon another port may be reduced, and isolation between the high-frequency band and the low-frequency band may be improved, thereby improving the performance of the antenna.
Hereinafter, a front end module according to an embodiment will be described with reference to the accompanying drawings.
FIG. 10 is a block diagram of a front end module 500 according to an embodiment.
The front end module 500 according to the embodiment shown in FIG. 10 may include an antenna 510, first and second amplifiers 520 and 540, a multilayer filter 530, and a switch 550.
The first amplifier 520 may amplify a signal received through the antenna 510 and may provide a result of amplification to the multilayer filter 530. For example, the first amplifier 520 may be a low noise amplifier (LNA).
The multilayer filter 530 may filter the signal amplified by the first amplifier 520 and may output the filtered signal through an output terminal OUT.
The second amplifier 540 may amplify a signal input through an input terminal IN and may transmit a result of amplification through the antenna 510. For example, the second amplifier 540 may be a power amplifier (PA).
The switch 550 may be disposed between the antenna 510 and each of the input terminal of the first amplifier 520 and the output terminal of the second amplifier 540 to select signal paths therebetween.
The antenna 510 may correspond to the antenna substrate 100 according to the above-described embodiment, and thus a duplicate description thereof will be omitted.
The configuration shown in FIG. 10 is merely illustrative of an embodiment of the front end module 500, and the antenna substrate 100 according to the above-described embodiment may be employed as a substrate for a front end module having various configurations without being limited to the configuration shown in FIG. 10.
The antenna substrate and the front end module according to the above-described embodiments may be applied to modules for mobile devices, base stations, repeaters, etc. to enable short-range or medium-range ultra-high-speed broadband communication for mobile devices and mobility devices. However, the embodiments are not limited to any specific application.
While the present disclosure has been particularly shown and described with reference to exemplary embodiments thereof, these embodiments are only proposed for illustrative purposes, and do not restrict the present disclosure, and it will be apparent to those skilled in the art that various changes in form and detail may be made without departing from the essential characteristics of the embodiments set forth herein. For example, respective configurations set forth in the embodiments may be modified and applied. Further, differences in such modifications and applications should be construed as falling within the scope of the present disclosure as defined by the appended claims.

[Mode for Disclosure]

Various embodiments have been described in the best mode for carrying out the disclosure.

[Industrial Applicability]

The antenna substrate according to the embodiment may be used for wireless communication.

Claims

An antenna substrate, comprising:
a plurality of antenna layers stacked so as to be spaced apart from each other in a vertical direction;

an antenna insulating layer disposed between the plurality of antenna layers; and

a transmission line,

wherein the plurality of antenna layers includes:
a high-frequency antenna layer configured to radiate a first signal in a first radio frequency band; and

a low-frequency antenna layer configured to radiate a second signal in a second radio frequency band lower than the first radio frequency band,

wherein the transmission line includes:
a capacitive power feeding unit disposed to face each of the high-frequency and low-frequency antenna layers with the antenna insulating layer interposed therebetween, the capacitive power feeding unit being configured to feed power to each of the high-frequency and low-frequency antenna layers; and

a via disposed to pass through the low-frequency antenna layer, and

wherein the capacitive power feeding unit overlaps the high-frequency antenna layer.
The antenna substrate according to claim 1, wherein the via includes first and second vias passing through the low-frequency antenna layer, and
wherein the capacitive power feeding unit includes:
a first power feeding plate extending in a horizontal direction from an end of the first via so as to face the high-frequency antenna layer disposed above the first power feeding plate and to face the low-frequency antenna layer disposed below the first power feeding plate; and

a second power feeding plate extending in the horizontal direction from an end of the second via so as to face the high-frequency antenna layer disposed above the second power feeding plate and to face the low-frequency antenna layer disposed below the second power feeding plate.
The antenna substrate according to claim 2, wherein the first power feeding plate has a planar area greater than a planar area of the end of the first via, and
wherein the second power feeding plate has a planar area greater than a planar area of the end of the second via.
The antenna substrate according to claim 2, wherein the plurality of antenna layers further includes a feeding antenna layer disposed between the high-frequency antenna layer and the low-frequency antenna layer, and
wherein the first and second power feeding plates belong to the feeding antenna layer.
The antenna substrate according to claim 4, wherein the feeding antenna layer is disposed closer to the high-frequency antenna layer than to the low-frequency antenna layer.
The antenna substrate according to claim 4, wherein the first power feeding plate is located on a virtual first horizontal line passing through a center of the feeding antenna layer,
wherein the second power feeding plate is located on a virtual second horizontal line passing through the center of the feeding antenna layer and orthogonal to the first horizontal line, and

wherein the center of the feeding antenna layer corresponds to an intersection point between an axis passing through a center of the first antenna layer in the vertical direction and a virtual horizontal plane having the first and second power feeding plates disposed thereon.
The antenna substrate according to claim 4, wherein each of the first and second power feeding plates has at least one of a circular planar shape or a polygonal planar shape.
The antenna substrate according to claim 4, wherein each of the first and second power feeding plates has a region gradually increasing in width in a direction away from a center of the feeding antenna layer.
The antenna substrate according to claim 8, wherein each of the first and second power feeding plates has a droplet-shaped planar shape.
A front end module, comprising:
a plurality of antenna areas spaced apart from each other in a horizontal direction,

wherein each of the plurality of antenna areas includes an antenna unit,

wherein the antenna unit includes:
a plurality of antenna layers stacked so as to be spaced apart from each other in a vertical direction;

an antenna insulating layer disposed between the plurality of antenna layers; and

a transmission line,

wherein the plurality of antenna layers includes:
a high-frequency antenna layer configured to radiate a first signal in a first radio frequency band; and

a low-frequency antenna layer configured to radiate a second signal in a second radio frequency band lower than the first radio frequency band,

wherein the transmission line includes:
a capacitive power feeding unit disposed to face each of the high-frequency and low-frequency antenna layers with the antenna insulating layer interposed therebetween, the capacitive power feeding unit being configured to feed power to each of the high-frequency and low-frequency antenna layers; and

a via disposed to pass through the low-frequency antenna layer, and

wherein the capacitive power feeding unit overlaps the high-frequency antenna layer.