Patent Publication Number: US-2023163459-A1

Title: Phase shifter, antenna circuit and antenna device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Taiwan Application Serial Number 110143251, filed Nov. 19, 2021, which is herein incorporated by reference in its entirety. 
     BACKGROUND 
     Field of Invention 
     The present disclosure relates to a phase array antenna technology. More particularly, the present disclosure relates to a phase shifter of changing a rotation angle of a liquid crystal to adjust a phase of a radio frequency signal, a related antenna circuit, and an antenna device. 
     Description of Related Art 
     The array antenna can change its beam synthesis mode through electronic components, thereby adjusting the scanning direction. Compared with the antenna that rotates in a mechanical structure, the array antenna has the advantages of small size and high scanning rate. The key elements of an array antenna are the phase shifter and the antenna electrodes, and the phase shifter is used to feed the radio frequency signal into the antenna electrodes. By using a plurality of phase shifters to set a plurality of radio frequency signals to different phases, constructive interference of the plurality of radio frequency signals in a specific direction can be achieved, so that the scanning direction of the array antenna can be adjusted to the specific direction. 
     SUMMARY 
     The present disclosure provides a phase shifter. The phase shifter comprises a first substrate, a second substrate, a liquid crystal layer, a plurality of first ring-shaped electrodes, and a plurality of second ring-shaped electrodes. The first substrate and the second substrate are disposed opposite to each other. The liquid crystal layer is disposed between the first substrate and the second substrate. The plurality of first ring-shaped electrodes are disposed sequentially and in interval on a side of the first substrate which is close to the liquid crystal layer. The plurality of second ring-shaped electrodes are disposed sequentially and in interval on a side of the second substrate which is close to the liquid crystal layer. A plurality of vertical projections projected by the plurality of first ring-shaped electrodes on the second substrate are at least partially overlapped with a plurality of second ring-shaped electrodes respectively. 
     The present disclosure provides an antenna circuit. The antenna circuit comprises an antenna electrode, a first substrate, a second substrate, a liquid crystal layer, and a phase shifter. The first substrate and the second substrate are disposed opposite to each other. The liquid crystal layer is disposed between the first substrate and the second substrate. The phase shifter is configured to feed a radio frequency signal into the antenna electrode, and comprises a plurality of first ring-shaped electrodes and a plurality of second ring-shaped electrodes. The plurality of first ring-shaped electrodes are disposed sequentially and in interval on a side of the first substrate which is close to the liquid crystal layer. The plurality of second ring-shaped electrodes are disposed sequentially and in interval on a side of the second substrate which is close to the liquid crystal layer. A plurality of vertical projections projected by the plurality of first ring-shaped electrodes on the second substrate are at least partially overlapped with a plurality of second ring-shaped electrodes respectively. 
     The present disclosure provides an antenna device. The antenna device comprises a first substrate, a second substrate, a liquid crystal layer, and a plurality of antenna circuits. The first substrate and the second substrate are disposed opposite to each other. The liquid crystal layer is disposed between the first substrate and the second substrate. The plurality of antenna circuits are arranged in an antenna matrix having a plurality of rows and a plurality of columns. Each of the antenna circuit comprises an antenna electrode and a phase shifter. The phase shifter is configured to feed a radio frequency signal into the antenna electrode, and comprises a plurality of first ring-shaped electrodes and a plurality of second ring-shaped electrodes. The plurality of first ring-shaped electrodes are disposed sequentially and in interval on a side of the first substrate which is close to the liquid crystal layer. The plurality of second ring-shaped electrodes are disposed sequentially and in interval on a side of the second substrate which is close to the liquid crystal layer. A plurality of vertical projections projected by the plurality of first ring-shaped electrodes on the second substrate are at least partially overlapped with the plurality of second ring-shaped electrodes respectively. 
     One of the advantages of the above-mentioned phase shifter is that a circuit layout with a small area can make the radio frequency signal generate a phase shift with a wide range. 
     One of the advantages of the above-mentioned antenna circuit is that a circuit layout with a small area can make the radio frequency signal generate a phase shift with a wide range. 
     One of the advantages of the antenna device is that it is thin and has a wide scanning angle. 
     It is to be understood that both the foregoing general description and the following detailed description are by examples, and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure can be more fully understood by reading the following detailed description of the embodiment, with reference made to the accompanying drawings as follows: 
         FIG.  1    is an exploded view of a phase shifter according to an embodiment of the present disclosure. 
         FIG.  2    is an enlarged schematic view of the microstrip line and the first ring-shaped electrode shown in  FIG.  1   . 
         FIG.  3    is an enlarged schematic view of the second ring-shaped electrode, the third ring-shaped electrode, and the fourth ring-shaped electrode shown in  FIG.  1   . 
         FIG.  4    is a schematic top view of the phase shifter shown in  FIG.  1   . 
         FIG.  5    is an enlarged schematic view of a microstrip line and a first ring-shaped electrode according to an embodiment of the present disclosure. 
         FIG.  6    is an enlarged schematic view of a microstrip line and a first ring-shaped electrode according to an embodiment of the present disclosure. 
         FIG.  7    is an enlarged schematic view of a second ring-shaped electrode, a third ring-shaped electrode, and a fourth ring-shaped electrode according to an embodiment of the present disclosure. 
         FIG.  8 A  is a schematic diagram of a maximum phase offset provided by a phase shifter according to some embodiments of the present disclosure. 
         FIG.  8 B  is a schematic diagram of a maximum phase offset provided by a phase shifter according to some embodiments of the present disclosure. 
         FIG.  8 C  is a schematic diagram of a maximum phase offset provided by a phase shifter according to some embodiments of the present disclosure. 
         FIG.  9    is a schematic top view of an antenna circuit according to an embodiment of the present disclosure. 
         FIG.  10    is a schematic cross-sectional view along the line shown in  FIG.  9   . 
         FIG.  11    is a schematic top view of an antenna device according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
       FIG.  1    is an exploded view of a phase shifter  10  according to an embodiment of the present disclosure. The phase shifter  10  includes a first substrate  11 , a second substrate  12 , a liquid crystal layer  13 , first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4 , second ring-shaped electrodes  15 _ 1 ˜ 15 _ 4 , third ring-shaped electrodes  16 _ 1 ˜ 16 _ 4 , fourth ring-shaped electrodes  17 _ 1 ˜ 17 _ 4 , and a microstrip line  18 . The first substrate  11  and the second substrate  12  are disposed opposite to each other, and the liquid crystal layer  13  is disposed between the first substrate  11  and the second substrate  12 . The first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4  are disposed sequentially and in interval on a side of the first substrate  11  which is close to the liquid crystal layer  13 . The second ring-shaped electrodes  15 _ 1 ˜ 15 _ 4  are disposed sequentially and in interval on a side of the second substrate  12  which is close to the liquid crystal layer  13 . The third ring-shaped electrodes  16 _ 1 ˜ 16 _ 4  and the fourth ring-shaped electrodes  17 _ 1 ˜ 17 _ 4  are disposed on a side of the second substrate  12  which is close to the liquid crystal layer  13 , and the third ring-shaped electrodes  16 _ 1 ˜ 16 _ 4  and the fourth ring-shaped electrodes  17 _ 1 ˜ 17 _ 4  are respectively disposed on opposite sides of the second ring-shaped electrodes  15 _ 1 ˜ 15 _ 4 . 
     The microstrip line  18  is disposed on a side of the first substrate  11  which is close to the liquid crystal layer  13 . The microstrip line  18  is used to transmit the radio frequency signal from the transmitter circuit (Tx, not shown) to the antenna electrode (such as the antenna electrode  95  in  FIG.  9    described later) through the phase shifter  10 . The first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4 , the second ring-shaped electrodes  15 _ 1 ˜ 15 _ 4 , the third ring-shaped electrodes  16 _ 1 ˜ 16 _ 4 , and the fourth ring-shaped electrodes  17 _ 1 ˜ 17 _ 4  are used to form an electric field to deflect the liquid crystal layer  130 , thereby changing the dielectric constant of the liquid crystal layer  130 , so as to change the phase of the radio frequency signal passing through the phase shifter  10 . 
     In some embodiments, the phase shifter  10  further includes a first ground electrode  19  and a second ground electrode  20 . The first ground electrode  19  is disposed on a side of the first substrate  11  away from the liquid crystal layer  13 , that is the first ground electrode  19  and the first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4  are disposed on opposite sides of the first substrate  11 . The second ground electrode  20  is disposed on a side of the second substrate  12  away from the liquid crystal layer  13 , that is the second ground electrode  20  and each of the second ring-shaped electrodes  15 _ 1 ˜ 15 _ 4 , the third ring-shaped electrodes  16 _ 1 ˜ 16 _ 4 , and the fourth ring-shaped electrodes  17 _ 1 ˜ 17 _ 4  is disposed on opposite sides of the second substrate  12 . 
     In some embodiments, the first substrate  11  and the second substrate  12  can be made of suitable dielectric materials such as glass or ceramic materials. 
     In some embodiments, the first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4 , the second ring-shaped electrodes  15 _ 1 ˜ 15 _ 4 , the third ring-shaped electrodes  16 _ 1 ˜ 16 _ 4 , and the fourth ring-shaped electrodes  17 _ 1 ˜ 17 _ 4  can be realized by a composite coating of copper, aluminum, silver, titanium, molybdenum, chromium or the above metal materials; or the first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4 , the second ring-shaped electrodes  15 _ 1 ˜ 15 _ 4 , the third ring-shaped electrodes  16 _ 1 ˜ 16 _ 4 , and the fourth ring-shaped electrodes  17 _ 1 ˜ 17 _ 4  can also be realized by a conductive metal oxide material such as indium oxide (ITO) , indium zinc oxide (IZO), or zinc oxide (ZnO). 
       FIG.  2    is an enlarged schematic view of the microstrip line  18  and the first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4  shown in  FIG.  1   . The microstrip line  18  includes a first conductive segment  21  and a second conductive segment  22 , wherein the first conductive segment  21  and the second conductive segment  22  can have the same length direction DL and the width direction DW. In some embodiments, the first conductive segment  21  is used to receive the radio frequency signal from the transmitter circuit (Tx, not shown), and the second conductive segment  22  is used to feed the radio frequency signal to the antenna electrode (such as the antenna electrode  95  in  FIG.  9    described later). The first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4  are sequentially arranged between the first conductive segment  21  and the second conductive segment  22  in the length direction DL. Any two adjacent ones of the first ring-shaped electrode  14 _ 1 ˜ 14 _ 4  have a first distance Sa, that is the first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4  are DC insulated from each other, and can be arranged at the same interval. In some embodiments, the first distance Sa can be 10˜20 μm. 
     There is a space between the first conductive segment  21  and the first ring-shaped electrode  14 _ 1 , and there is also a space between the second conductive segment  22  and the first ring-shaped electrode  14 _ 4 , that is the first conductive segment  21  and the second conductive segment  22  are not electrically connected to the first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4  directly. In other words, the first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4  are used to transmit an AC radio frequency signal from the first conductive segment  21  to the second conductive segment  22  under the condition that the first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4  are DC insulated from the first conductive segment  21  and the second conductive segment  22 . 
       FIG.  3    is an enlarged schematic view of the second ring-shaped electrodes  15 _ 1 ˜ 15 _ 4 , the third ring-shaped electrodes  16 _ 1 ˜ 16 _ 4 , and the fourth ring-shaped electrodes  17 _ 1 ˜ 17 _ 4  shown in  FIG.  1   . The second ring-shaped electrodes  15 _ 1 ˜ 15 _ 4  are arranged in sequence and at intervals in the length direction DL. Similarly, the third ring-shaped electrodes  16 _ 1 ˜ 16 _ 4  and the fourth ring-shaped electrodes  17 _ 1 ˜ 17 _ 4  are arranged in sequence and at intervals in the length direction DL. Any two adjacent ones of the second ring-shaped electrodes  15 _ 1 ˜ 15 _ 4  have a second distance Sb, that is the second ring-shaped electrodes  150 _ 1 ˜ 150 _ 4  are DC insulated from each other, and can be arranged at the same interval. Similarly, any two adjacent ones of the third ring-shaped electrodes  16 _ 1 ˜ 16 _ 4  have the second distance Sb, and any two adjacent ones of the fourth ring-shaped electrode  17 _ 1 ˜ 17 _ 4  have the second distance Sb. In some embodiments, the second distance Sb can be 10˜20 μm. 
     The third ring-shaped electrodes  16 _ 1 ˜ 16 _ 4  are respectively disposed on a first side (such as a left side) of the second ring-shaped electrodes  15 _ 1 ˜ 15 _ 4  in the width direction DW. The fourth ring-shaped electrodes  17 _ 1 ˜ 17 _ 4  are respectively disposed on a second side (such as a right side) of the second ring-shaped electrodes  15 _ 1 ˜ 15 _ 4  relative to the first side in the width direction DW. For example, both sides of the second ring-shaped electrode  15 _ 1  in the width direction DW are respectively adjacent to the third ring-shaped electrode  16 _ 1  and the fourth ring-shaped electrode  17 _ 1 . For another example, both sides of the second ring-shaped electrode  15 _ 2  in the width direction DW are respectively adjacent to the third ring-shaped electrode  16 _ 2  and the fourth ring-shaped electrode  17 _ 2 , and so on. 
       FIG.  4    is a schematic top view of the phase shifter  10  shown in  FIG.  1   . In order to simplify the drawing,  FIG.  4    omits the first substrate  11 , the liquid crystal layer  13 , the first ground electrode  19 , and the second ground electrode  20  in  FIG.  1   . A plurality of vertical projections projected by the first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4  on the second substrate  12  will be ( 1 ) at least partially overlapped with second ring-shaped electrodes  15 _ 1 ˜ 15 _ 4  respectively, ( 2 ) at least partially overlapped with third ring-shaped electrode  16 _ 1 ˜ 16 _ 4  respectively, and ( 3 ) at least partially overlapped with fourth ring-shaped electrode  17 _ 1 ˜ 17 _ 4  respectively. For example, the vertical projection projected by the first ring-shaped electrode  14 _ 1  on the second substrate  12  are at least partially overlapped with the second ring-shaped electrode  15 _ 1 , the third ring-shaped electrode  16 _ 1 , and the fourth ring-shaped electrode  17 _ 1 , and can not overlap other ring-shaped electrode. For another example, the vertical projection projected by the first ring-shaped electrode  14 _ 2  on the second substrate  12  are at least partially overlapped with the second ring-shaped electrode  15 _ 2 , the third ring-shaped electrode  16 _ 2 , and the fourth ring-shaped electrode  17 _ 2 , and can not overlap other ring-shaped electrode, and so on. 
     The area of one ring electrode that overlaps with the other ring electrode forms a capacitive element in the phase shifter  10 , and the part that does not overlap with the other ring electrode forms an inductive element in phase shifter  10 . The dielectric constant of the liquid crystal layer  13  can be changed by changing the DC bias voltages received by the first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4 , the second ring-shaped electrodes  15 _ 1 ˜ 15 _ 4 , the third ring-shaped electrodes  16 _ 1 ˜ 16 _ 4 , and the fourth ring-shaped electrodes  17 _ 1 ˜ 17 _ 4 , so as to change the capacitance value of the phase shifter  10 , thereby changing the phase of the radio frequency signal passing through the phase shifter  10 . 
       FIG.  5    is an enlarged schematic view of a microstrip line  18  and first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4  according to an embodiment of the present disclosure. The phase shifter  10  can includes the microstrip line  18  and the first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4 , and includes the second ring-shaped electrodes  15 _ 1 ˜ 15 _ 4 , the third ring-shaped electrodes  16 _ 1 ˜ 16 _ 4 , and the fourth ring-shaped electrodes  17 _ 1 ˜ 17 _ 4  in  FIG.  3   , that is the corresponding elements in  FIG.  2    are replaced by the elements in  FIG.  5   . Since the embodiment of  FIG.  5    is similar to the embodiment of  FIG.  2   , only the differences are described in detail below. In the embodiment shown in  FIG.  5   , the microstrip line  18  further includes a plurality of sub-electrodes  23  arranged in sequence in the length direction DL, and each sub-electrode  23  is disposed between two adjacent ones of the first ring-shaped electrodes  14 _ 1 ˜ 14   4 . The plurality of sub-electrodes  23  are not electrically connected to the first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4  directly, that is the plurality of sub-electrodes  23  can be DC insulated from the first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4 . In some embodiments, the plurality of sub-electrodes  23  and the first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4  are used to receive the same DC bias voltage. 
     The plurality of sub-electrodes  23  can flatten the forward transmission coefficient (S 21 ) curve of the phase shifter  10  near the operating frequency of the radio frequency signal, so as to increase the bandwidth of the phase shifter  10 . 
       FIG.  6    is an enlarged schematic view of a microstrip line  68  and first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4  according to an embodiment of the present disclosure.  FIG.  7    is an enlarged schematic view of second ring-shaped electrodes  15 _ 1 ˜ 15 _ 4 , third ring-shaped electrodes  16 _ 1 ˜ 16 _ 4 , and fourth ring-shaped electrodes  17 _ 1 ˜ 17 _ 4  according to an embodiment of the present disclosure. The phase shifter  10  can include the microstrip line  68  and the first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4  in  FIG.  6   , and include the second ring-shaped electrodes  15 _ 1 ˜ 15 _ 4 , the third ring-shaped electrodes  16 _ 1 ˜ 16 _ 4 , and the fourth ring-shaped electrodes  17 _ 1 ˜ 17 _ 4  in  FIG.  7   , that is the corresponding elements in  FIG.  2    are replaced by elements in  FIG.  6   , and the corresponding elements in  FIG.  3    are replaced by elements in  FIG.  7   . Since the embodiments in  FIGS.  6  and  7    are respectively similar to the embodiments in  FIGS.  2  and  3   , only the differences will be described in detail below. 
     In the embodiment of  FIG.  6   , the microstrip line  68  further includes the plurality of sub-electrodes  63  arranged in sequence in the length direction DL, each of the sub-electrodes  63  is disposed between two adjacent ones of the first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4 , and the plurality of sub-electrodes  63  are not electrically connected to the first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4  directly. Any two adjacent ones of the first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4  have a first distance Sa′ , and the first distance Sa′ is substantially set to nλ 0 . n is a value between 0 and 1, and λ 0  is the wavelength in a free space after the radio frequency signal on the microstrip line  68  is transmitted through the antenna electrode (such as the antenna electrode  95  in  FIG.  9    described later). In some embodiments, the length of the sub-electrode  63  in the length direction DL is substantially set to nλ 0 . In the embodiment shown in  FIG.  7   , any two adjacent ones of the second ring-shaped electrodes  15 _ 1 ˜ 15 _ 4  have the second distance Sb′ , and any two adjacent ones of the third ring-shaped electrodes  16 _ 1 ˜ 16 _ 4  have the second distance Sb′ , and any two adjacent ones of the fourth ring-shaped electrodes  17 _ 1 ˜ 17 _ 4  have the second distance Sb′ . In order to enable the vertical projection projected by the first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4  on the second substrate  12  are at least partially overlapped with the second ring-shaped electrodes  15 _ 1 ˜ 15 _ 4  respectively, at least partially overlapped with third ring-shaped electrodes  16 _ 1 ˜ 16 _ 4  respectively, at least partially overlapped with fourth ring-shaped electrodes  17 _ 1 ˜ 17 _ 4  respectively, and the second distance Sb′ is also substantially set to nλ 0 . 
     The wider the first distance Sa′ and the second distance Sb′ are, the larger the impedance bandwidth of the antenna electrode (such as the antenna electrode  95  in  FIG.  9   ) will be. In addition, each of the ring-shaped electrode receives a DC bias from a bias trace (not shown), and the wider the first distance Sa′ are, the larger the second distance Sb′ of the distance between the bias traces will be, thus, it is avoided that the bias traces affect the coupling effect between the ring-shaped electrodes. 
     It can be known from the above-mentioned embodiments that the first ring-shaped electrodes  14 _ 1 ˜ 14 _ 4 , the second ring-shaped electrodes  15 _ 1 ˜ 15 _ 4 , the third ring-shaped electrodes  16 _ 1 ˜ 16 _ 4 , and the fourth ring-shaped electrodes  17 _ 1 ˜ 17 _ 4  can have the same number (such as four), but the number of the ring-shaped electrodes in  FIG.  1   ˜ FIG.  7    is only an exemplary embodiment, the present disclosure is not limited to this. The number of the ring-shaped electrode can be adjusted according to the required phase offset. For convenience of description, an unspecified number of all first ring-shaped electrodes will be referred to below by reference numeral  14 ; an unspecified number of all second ring-shaped electrodes will be referred to below by reference numeral  15 ; an unspecified number of all third ring-shaped electrodes will be referred to below by reference numeral  16 ; and an unspecified number of all fourth ring-shaped electrodes will be referred to below by reference numeral  17 . 
     In some embodiments, the number of each of the first ring-shaped electrodes  14 , the second ring-shaped electrodes  15 , the third ring-shaped electrodes  16 , and the fourth ring-shaped electrodes  17  can be 2˜7. 
     In some embodiments, the number of the sub-electrodes  23  in  FIG.  5    can be adjusted with the number of the first ring-shaped electrodes  14 . For example, when the number of the first ring-shaped electrodes  14  is 2, the number of the sub-electrode  23  is 1, that is the microstrip line  18  can include at least one sub-electrode  23 . 
     In some embodiments, the shape of the first ring-shaped electrodes  14 , the second ring-shaped electrodes  15 , the third ring-shaped electrodes  16 , and the fourth ring-shaped electrodes  17  can be circular or square rings. 
     In some embodiments, the third ring-shaped electrodes  16  and the fourth ring-shaped electrodes  17  can be omitted from the phase shifter  10 . 
       FIGS.  8 A- 8 C  are schematic diagrams of a maximum phase offset provided by a phase shifter  10  according to some embodiments of the present disclosure. The maximum phase offset refers to the phase generated by the radio frequency signal passing through the phase shifter  10  with the smallest capacitance value and the phase shifter  10  with the largest capacitance value when the radio frequency signal has a specific operating frequency (such as 24.4 GHz). In the embodiment shown in  FIGS.  8 A- 8 C , the phase shifter  10  include the microstrip line  18  and the first ring-shaped electrodes  14  in  FIG.  5   , and include the second ring-shaped electrodes  15 , the third ring-shaped electrodes  16 , and the fourth ring-shaped electrodes  17  in  FIG.  3   . 
     In the embodiment of  FIG.  8 A , the number of each of the first ring-shaped electrodes  14 , the second ring-shaped electrodes  15 , the third ring-shaped electrodes  16 , and the fourth ring-shaped electrodes  17  is 2, and the total length of these ring-shaped electrodes arranged in the length direction DL is about 2.2 mm (that is, the width LE (marked in  FIG.  2   ) of each ring-shaped electrodes in the length direction DL is about 1.1 mm). At this time, the phase shifter  10  can generate a maximum phase shift of 135° for the phase of the radio frequency signal. In the embodiment shown in  FIG.  8 B , the number of each kind of ring-shaped electrodes is 3, and the total length of these ring-shaped electrodes arranged in the length direction DL is about 3.3 mm. At this time, the phase shifter  10  can generate a maximum phase shift of 170° for the phase of the radio frequency signal. In the embodiment shown in  FIG.  8 C , the number of each type of ring-shaped electrodes is 4, and the total length of these ring-shaped electrodes arranged in the length direction DL is about 4.4 mm. At this time, the phase shifter  10  can generate a maximum phase shift of 225° for the phase of the radio frequency signal. 
     In addition, according to the experimental results, when the number of each type of ring-shaped electrodes is 7, the phase shifter  10  can provide a maximum phase shift exceeding 360° (e.g., 395°). Al I in all, the advantage of the phase shifter  10  is that a wide range of phase shift can be generated for the radio frequency signal through a circuit layout with a small area. 
       FIG.  9    is a schematic top view of an antenna circuit  90  according to an embodiment of the present disclosure.  FIG.  10    is a schematic cross-sectional view along the line AA′ shown in  FIG.  9   . Please refer to  FIG.  9    and  FIG.  10    at the same time, the antenna circuit  90  includes a first substrate  91 , a second substrate  92 , a third substrate  93 , a liquid crystal layer  94 , an antenna electrode  95 , a phase shifter  96 , a first ground electrode  97 , and a second ground electrode  98 . In the top view of  FIG.  9   , the phase shifter  96  is covered by the first substrate  91 . However, for the convenience of explaining the position of the phase shifter  96 , the phase shifter  96  is shown as visible in  FIG.  9   . 
     In some embodiments, the phase shifter  96  can be implemented by the phase shifter  10  of any of the foregoing embodiments. At this time, the first substrate  91 , the second substrate  92 , the liquid crystal layer  94 , the first ground electrode  97 , and the second ground electrode  98  in  FIG.  10    can be respectively used to form the first substrate  11 , the second substrate  12 , the liquid crystal layer  13 , the first ground electrode  19 , and the second ground electrode  20  of the phase shifter  10 . In other words, the arrangement of the first substrate  91 , the second substrate  92 , the liquid crystal layer  94 , the first ground electrode  97 , and the second ground electrode  98  in  FIG.  10    is similar to that of the first substrate  11 , the second substrate  12 , the liquid crystal layer  13 , the first ground electrode  19 , and the second ground electrode  20  in  FIG.  1   , therefore, the relevant content will not be repeated. 
     In this embodiment, the antenna electrode  95  is a patch antenna, but the present disclosure is not limited to this. In some embodiments, the antenna electrode  95  can also be implemented with other suitable types of antennas such as an inverted-F antenna or a microstrip antenna. The microstrip line of the phase shifter  96  extends below the antenna electrode  95  to feed the radio frequency signal into the antenna electrode  95 . That is, when the phase shifter  96  is implemented by the phase shifter  10 , the vertical projection projected by the antenna electrode  95  on the first substrate  91  is at least partially overlapped with the second conductive segment  22  of the phase shifter  10 . 
     The first ground electrode  97  is disposed on a side of the first substrate  91  away from the liquid crystal layer  94 , and is located between the antenna electrode  95  and the first substrate  91 . The first ground electrode  97  includes a slot SL, in the case where the phase shifter  96  is implemented with the phase shifter  10 , the vertical projection projected by the slot SL on the first substrate  91  will be at least partially overlapped with phase shifter  10  the second conductive segment  22 . The slot SL is used to prevent the first ground electrode  97  from interfering with the coupling effect between the antenna electrode  95  and the microstrip line of the phase shifter  96 . The third substrate  93  is disposed on a side of the first ground electrode  97  away from the first substrate  91 , and the third substrate  93  is located between the antenna electrode  95  and the first ground electrode  97 . In some embodiments, the third substrate  93  can be made of various suitable dielectric materials such as glass, ceramic or plastic materials. 
     All in all, the advantages of the antenna circuit  90  are that the circuit layout area is small, and the radio frequency signal it transmits can generate a wide range of phase shifts. 
       FIG.  11    is a schematic top view of an antenna device  110  according to an embodiment of the present disclosure. The antenna device  110  includes a plurality of antenna circuits  90  in  FIG.  9   , and the plurality of antenna circuits  90  are arranged in an antenna matrix  111  includes a plurality of rows and a plurality of columns. In other words, the antenna device  110  can include the aforementioned first substrate  91 , the aforementioned second substrate  92 , the aforementioned liquid crystal layer  94 , the aforementioned first ground electrode  97 , and the aforementioned second ground electrode  98 . The plurality of antenna circuits  90  can receive the radio frequency signal from the same transmitter circuit (not shown), that is the microstrip line of plurality of phase shifters  96  can be coupled to each other. The DC bias of each of the phase shifter  96  can be independently controlled, so that the radio frequency signal transmitted by the plurality of antenna circuits  90  have different phase offsets, so that the antenna device  110  can be operated as a phased array antenna. 
     As can be seen from the above, the antenna device  110  is thin and light and has a wide scanning angle, so that the antenna device  110  is suitable for tracking the moving care object in the application situation of home care, so as to obtain the physiological information of the care object in real time (for example, calculating the respiratory rate by measuring the frequency of chest rise and fall). 
     Although the present invention has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims.