PATCH ANTENNA AND ANTENNA ARRAY

A patch antenna includes a first substrate, a second substrate and a substrate module that are stacked from top to bottom, a driving radiative element that is disposed below the second substrate, and a parasitic radiative element that is disposed above the first substrate. The patch antenna further includes a first feed-in line and a second feed-in line that are disposed below the substrate module. The patch antenna further includes a first feed-out probe and a second feed-out probe, each of which extends from below the driving radiative element from top to bottom, and penetrates the substrate module. When the driving radiative element receives an electromagnetic wave, a portion of the electromagnetic wave is sequentially and electromagnetically coupled to the first feed-out probe and the first feed-in line, and another portion of the electromagnetic wave is sequentially and electromagnetically coupled to the second feed-out probe and the second feed-in line.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Taiwanese Invention Patent Application No. 113115077, filed on Apr. 23, 2024, the entire disclosure of which is incorporated by reference herein.

FIELD

The disclosure relates to a patch antenna and an antenna array, and more particularly to a patch antenna and an antenna array that are adapted for low-earth orbit satellite communication.

BACKGROUND

As communication technology and integrated circuit technology advances, components of consumer electronic products are gradually being miniaturized. With the growing demands in wireless communication, consumers will be demanding for an antenna that has advantages such as a lower cost, a smaller size, and better performance. Among various antenna technologies, patch antennas not only hold the abovementioned advantages, but are also easy to manufacture, are easily integrated into other circuits, and have a high level of design diversity. As such, patch antennas are widely applied to various electronic products.

FIG. 1 shows a patch antenna disclosed in Taiwanese Invention Patent Publication No. TWI783595B. The patch antenna includes a dielectric substrate 95, a radiating metal arm 91, a U-shaped slot 92, a ground metal plate (not shown), two parasitic metal arms 94, and two feed-in slots 93. The dielectric substrate 95 includes a first surface, a second surface, and a plurality of side surfaces arranged circumferentially between the first surface and the second surface. The radiating metal arm 91 is disposed on the first surface, and may be in a shape of a regular rectangle or polygon, or an irregular ellipse, loop, or fan shape. The U-shaped slot 92 is formed within the radiating metal arm 91. The ground metal plate is disposed on the second surface. The parasitic metal arms 94 extend from the ground metal plate to the first surface through one of the side surfaces, and are adjacent to but not connected to the radiating metal arm 91. The feed-in slots 93 are disposed between the radiating metal arm 91 and the parasitic metal arms 94. Since the patch antenna only has one substrate (i.e., the dielectric substrate 95), the radiating metal arm 91 and the parasitic metal arms 94 need to be disposed on the same surface (i.e., the first surface) of the dielectric substrate 95. The U-shaped slot 92 and the parasitic metal arms 94 are capable of broadening an operating frequency band of the patch antenna, which is 98 MHz, but there is still space for improvements.

SUMMARY

Therefore, an object of the disclosure is to provide a patch antenna and an antenna array that can alleviate at least one of the drawbacks of the prior art.

According to an aspect of the disclosure, a patch antenna includes a first substrate, a second substrate, a substrate module, a driving radiative element, a parasitic radiative element, a first feed-in line, a second feed-in line, a first feed-out probe and a second feed-out probe. The first substrate, the second substrate and the substrate module are stacked from top to bottom. The driving radiative element is disposed on a lower surface of the second substrate. The parasitic radiative element is disposed on an upper surface of the first substrate. The first feed-in line and the second feed-in line are disposed on a lower surface of the substrate module. Each of the first feed-out probe and the second feed-out probe extends from a lower surface of the driving radiative element from top to bottom, and penetrates the substrate module. The first feed-out probe is electrically connected to the first feed-in line, and the second feed-out probe is electrically connected to the second feed-in line. In response to the driving radiative element receiving an input electromagnetic wave, a portion of the input electromagnetic wave is sequentially and electromagnetically coupled to the first feed-out probe and the first feed-in line, and another portion of the input electromagnetic wave is sequentially and electromagnetically coupled to the second feed-out probe and the second feed-in line.

According to another aspect of the disclosure, an antenna array includes a first antenna, a second antenna, a third antenna and a fourth antenna, each of which includes a patch antenna described above. A center of the second antenna is aligned with a center of the first antenna in a first direction, and the second antenna is offset from the first antenna in a counterclockwise orientation by 90 degrees. A center of the third antenna is aligned with the center of the second antenna in a second direction, and the third antenna is offset from the second antenna in a counterclockwise orientation by 90 degrees. A center of the fourth antenna is aligned with the center of the third antenna in the first direction, and the fourth antenna is offset from the third antenna in a counterclockwise orientation by 90 degrees.

DETAILED DESCRIPTION

Referring to FIGS. 2 to 6, a patch antenna according to an embodiment of the disclosure includes a first substrate 11, a first adhesive layer 21, a second substrate 12, a substrate module 120, a driving radiative element 41, a parasitic radiative element 42, a parasitic resonator 43, a first feed-in line 521, a second feed-in line 522, a first feed-out probe 511 and a second feed-out probe 512.

The first substrate 11, the first adhesive layer 21, the second substrate 12 and the substrate module 120 are stacked from top to bottom in the given order along a direction that is reverse to a Z-direction pointing from bottom to top.

The substrate module 120 includes a second adhesive layer 22, a third substrate 13, a third adhesive layer 23, a fourth substrate 14, a fourth adhesive layer 24, a ground layer 3 and a fifth substrate 15 that are stacked from a lower surface of the second substrate 12 from top to bottom in the given order along the direction that is reverse to the Z-direction.

Each of the first substrate 11, the first adhesive layer 21, the second substrate 12, the second adhesive layer 22, the third substrate 13, the third adhesive layer 23, the fourth substrate 14, the fourth adhesive layer 24 and the fifth substrate 15 is made of a dielectric material. The ground layer 3 is made of metal.

The driving radiative element 41 is disposed on the lower surface of the second substrate 12, and includes a driving patch 411 and four driving stubs 412. The driving patch 411 is a square metal sheet with four borders. Each of the driving stubs 412 is a rectangular metal sheet, and the driving stubs 412 are connected to the four borders of the driving patch 411, respectively. Two centers respectively of two of the driving stubs 412 are aligned with a center of the driving patch 411 in a Y-direction that is, for example, perpendicular to the Z-direction. Two centers respectively of another two of the driving stubs 412 are aligned with the center of the driving patch 411 in an X-direction that is, for example, perpendicular to the Y-direction and the Z-direction. The driving stubs 412 are used for broadening an operating frequency band of the patch antenna of this embodiment.

The parasitic radiative element 42 is disposed on an upper surface of the first substrate 11, and includes a parasitic patch 421 and four parasitic stubs 422. The parasitic patch 421 is a square metal sheet with four borders. Each of the parasitic stubs 422 is a rectangular metal sheet, and the parasitic stubs 422 are connected to the four borders of the parasitic patch 421, respectively. Two centers respectively of two of the parasitic stubs 422 are aligned with a center of the parasitic patch 421 in the Y-direction, and two centers respectively of another two of the parasitic stubs 422 are aligned with the center of the parasitic patch 421 in the X-direction. The parasitic stubs 422 are used for broadening the operating frequency band of the patch antenna of this embodiment.

A projection, in the Z-direction, of a center of the driving radiative element 41 on the parasitic radiative element 42 coincides with a center of the parasitic radiative element 42.

The parasitic resonator 43 is disposed on the lower surface of the second substrate 12, and is a sheet that is made of metal and that has an L shape. The parasitic resonator 43 includes two arms 431, where an angle between the two arms 431 of the parasitic resonator 43 faces the driving radiative element 41. The parasitic resonator 43 is used for suppressing interference between a first signal that passes through the first feed-in line 521 and a second signal that passes through the second feed-in line 522.

The first feed-in line 521 and the second feed-in line 522 are disposed on a lower surface of the fifth substrate 15. Each of the first feed-out probe 511 and the second feed-out probe 512 extends from a lower surface of the driving patch 411 from top to bottom in the direction that is reverse to the Z-direction, and penetrates the substrate module 120. The first feed-out probe 511 is electrically connected to the first feed-in line 521, and the second feed-out probe 512 is electrically connected to the second feed-in line 522.

When the driving radiative element 41 receives an input electromagnetic wave, a portion of the input electromagnetic wave is sequentially and electromagnetically coupled to the first feed-out probe 511 and the first feed-in line 521, and another portion of the input electromagnetic wave is sequentially and electromagnetically coupled to the second feed-out probe 512 and the second feed-in line 522. In such a case, the parasitic resonator 43 is used for suppressing interference between the portion of the input electromagnetic wave that passes through the first feed-in line 521, and the another portion of the input electromagnetic wave that passes through the second feed-in line 522.

In this embodiment, the patch antenna is configured to operate in a frequency band from 17.7 GHz to 20.2 GHz (i.e., the operating frequency band of the patch antenna is from 17.7 GHz to 20.2 GHz), and can be used in a low-earth orbit satellite communication system.

FIG. 7 is a plot illustrating scattering parameters (S11, S22, and S21) of the patch antenna of this embodiment in a frequency range of 17 GHz to 21 GHz. Referring to FIGS. 5 and 7, the scattering parameter (S11) is a reflection coefficient at the first feed-in line 521, and is smaller than a target value of the scattering parameter (S11) (e.g., −10 dB) in the operating frequency band of the patch antenna. The scattering parameter (S22) is a reflection coefficient at the second feed-in line 522, and is smaller than a target value of the scattering parameter (S22) (e.g., −10 dB) in the operating frequency band of the patch antenna. The scattering parameter (S21) is a transmission coefficient that is related to isolation between the first feed-in line 521 and the second feed-in line 522, and is smaller than a target value of the scattering parameter (S21) (e.g., −20 dB) in the operating frequency band of the patch antenna.

Referring to FIG. 8, an antenna array according to an embodiment of the disclosure includes a first antenna 61, a second antenna 62, a third antenna 63 and a fourth antenna 64, each of which includes the patch antenna as mentioned above. The second antenna 62 includes a first input port 71 and a second input port 72 (respectively corresponding to the first feed-in line 521 (see FIG. 5) and the second feed-in line 522 (see FIG. 5) of the patch antenna); the first antenna 61 includes a third input port 73 and a fourth input port 74 (respectively corresponding to the second feed-in line 522 (see FIG. 5) and the first feed-in line 521 (see FIG. 5) of the patch antenna); the third antenna 63 includes a fifth input port 75 and a sixth input port 76 (respectively corresponding to the second feed-in line 522 (see FIG. 5) and the first feed-in line 521 (see FIG. 5) of the patch antenna); and the fourth antenna 64 includes a seventh input port 77 and an eighth input port 78 (respectively corresponding to the second feed-in line 522 (see FIG. 5) and the first feed-in line 521 (see FIG. 5) of the patch antenna).

A center of the second antenna 62 is aligned with a center of the first antenna 61 in an X′-direction (also referred to as a first direction), and the second antenna 62 is offset from the first antenna 61 in a counterclockwise orientation by 90 degrees. A center of the third antenna 63 is aligned with the center of the second antenna 62 in a Y′-direction (also referred to as a second direction) that is, for example, perpendicular to the X′-direction, and the third antenna 63 is offset from the second antenna 62 in a counterclockwise orientation by 90 degrees. A center of the fourth antenna 64 is aligned with the center of the third antenna 63 in the X′-direction, and the fourth antenna 64 is offset from the third antenna 63 in a counterclockwise orientation by 90 degrees.

In this embodiment, the antenna array is configured to operate in the frequency band from 17.7 GHz to 20.2 GHz (i.e., an operating frequency band of the antenna array is from 17.7 GHz to 20.2 GHz).

FIGS. 9 to 12 are plots illustrating scattering parameters (S21, S43, S65, and S87) of the antenna array of this embodiment in a frequency range of 17 GHz to 21 GHz. Specifically, FIGS. 9 to 12 illustrate polarization isolation between different two of the input ports 71-78 that are of the same one of the antennas 61-64. Referring to FIGS. 8 to 12, the scattering parameter (S21) is a transmission coefficient that is related to isolation between the second input port 72 and the first input port 71, and is smaller than a target value of the scattering parameter (S21) (e.g., −20 dB) in the operating frequency band of the antenna array. The scattering parameter (S43) is a transmission coefficient that is related to isolation between the fourth input port 74 and the third input port 73, and is smaller than a target value of the scattering parameter (S43) (e.g., −20 dB) in the operating frequency band of the antenna array. The scattering parameter (S65) is a transmission coefficient that is related to isolation between the sixth input port 76 and the fifth input port 75, and is smaller than a target value of the scattering parameter (S65) (e.g., −20 dB) in the operating frequency band of the antenna array. The scattering parameter (S87) is a transmission coefficient that is related to isolation between the eighth input port 78 and the seventh input port 77, and is smaller than a target value of the scattering parameter (S87) (e.g., −20 dB) in the operating frequency band of the antenna array.

FIG. 13 is a plot illustrating scattering parameters (S31, S51, and S71) of the antenna array of this embodiment in a frequency range of 17 GHz to 21 GHz. Specifically, FIG. 13 illustrate polarization isolation between two of the input ports 71-78 that are respectively of two different ones of the antennas 61-64. Referring to FIGS. 8 and 13, the scattering parameter (S31) is a transmission coefficient that is related to isolation between the third input port 73 and the first input port 71, and is smaller than a target value of the scattering parameter (S31) (e.g., −15 dB) in the operating frequency band of the antenna array. The scattering parameter (S51) is a transmission coefficient that is related to isolation between the fifth input port 75 and the first input port 71, and is smaller than a target value of the scattering parameter (S51) (e.g., −15 dB) in the operating frequency band of the antenna array. The scattering parameter (S71) is a transmission coefficient that is related to isolation between the seventh input port (S77) and the first input port 71, and is smaller than a target value of the scattering parameter (S71) (e.g., −15 dB) in the operating frequency band of the antenna array.

FIG. 14 is a plot illustrating an axial ratio of circular polarization of the antenna array of this embodiment in a frequency range of 17.5 GHz to 20.5 GHz. As shown in FIG. 14, the axial ratio of this embodiment is smaller than a predetermined value of 0.1 dB in the operating frequency band of the antenna array.

Referring back to FIG. 3, in summary, according to the disclosure, the patch antenna includes multiple substrates 11-15 so that the driving radiative element 41 and the parasitic radiative element 42 may be disposed on different substrates (i.e., the second substrate 12 and the first substrate 11) of the patch antenna. As such, more space are available for the driving radiative element 41 to include the driving stubs 412, and for the parasitic radiative element 42 to include the parasitic stubs 422, so as to broaden the operating frequency band of the patch antenna. When the driving radiative element 41 receives an input electromagnetic wave, a portion of the input electromagnetic wave is sequentially and electromagnetically coupled to the first feed-out probe 511 and the first feed-in line 521, and another portion of the input electromagnetic wave is sequentially and electromagnetically coupled to the second feed-out probe 512 and the second feed-in line 522, thus achieving the function of signal transmission using the patch antenna. Moreover, the operating frequency band of the patch antenna ranges from 17.7 GHz to 20.2 GHz, which has a bandwidth of 2.5 GHz. Multiple patch antennas may be combined to form the antenna array, while the effect of circular polarization can be obtained without obvious cracking of the scattering parameters in the operating frequency band of the antenna array.