Antenna structure

Abstract

An antenna structure includes a first substrate, a second substrate, a first liquid crystal layer, a first electrode layer, a second electrode layer, and a reflective layer. The first substrate and the second substrate are disposed opposite to each other. The first liquid crystal layer is disposed between the first substrate and the second substrate. The first electrode layer is disposed on the first substrate and located between the first liquid crystal layer and the first substrate. The second electrode layer is disposed on the second substrate and located between the first liquid crystal layer and the second substrate. The reflective layer is disposed on a side of the second substrate facing away from the second electrode layer. The first electrode layer, the second electrode layer, and the reflective layer overlap each other, and the first electrode layer has at least one annular electrode or at least one annular opening.

Description

Technical Field

[0001] The present invention relates to a mobile communication technology, and particularly to an antenna structure. Background Art

[0002] With the commercialization of the fifth-generation mobile communication technology (5G), applications such as telemedicine over long distances, VR live streaming, 4K video quality live streaming, and smart homes have new development opportunities. Since 5G has high data rates, reduced latency, energy savings, cost reduction, increased system capacity, and large-scale device connection capabilities, operators in different fields can also form cross-border alliances to jointly build a new generation of 5G ecosystem chains. In order to increase the coverage of 5G millimeter waves, a reflective antenna is widely used.

[0003] Common reflective antennas can be further divided into passive array antennas and active array antennas. Passive array antennas have fixed electromagnetic wave reception angles and emission angles due to their fixed antenna sizes. On the contrary, since active array antennas have the ability to modulate the phase of electromagnetic waves, they can adjust the reception angles and emission angles of electromagnetic waves. However, such active array antennas generally use phase shifters to modulate the phase of electromagnetic waves. For larger array antennas, the cost of using phase shifters will be higher. Summary of the Invention

[0004] The present invention provides an antenna structure that can be used to modulate the reflection frequency and phase of electromagnetic waves and has a lower production cost.

[0005] The antenna structure of the present invention includes a first substrate, a second substrate, a first liquid crystal layer, a first electrode layer, a second electrode layer, and a reflective layer. The first substrate and the second substrate are disposed opposite to each other. The first liquid crystal layer is disposed between the first substrate and the second substrate. The first electrode layer is disposed on the first substrate and is located between the first liquid crystal layer and the first substrate. The second electrode layer is disposed on the second substrate and is located between the first liquid crystal layer and the second substrate. The reflective layer is disposed on a side of the second substrate facing away from the second electrode layer. The first electrode layer, the second electrode layer, and the reflective layer overlap each other, and the first electrode layer has at least one annular electrode or at least one annular opening.

[0006] Based on the above, in the antenna structure of an embodiment of the present invention, the capacitive coupling effect generated by the partial overlapping relationship between the first electrode layer and the second electrode layer can be changed via the liquid crystal layer sandwiched between these two electrode layers. That is, the resonance frequency and phase of the induction circuit (or induction loop) formed by these electrode layers can be modulated. Since the antenna structure of the present invention has the function of phase modulation without the need to be equipped with a phase shifter, it has more cost advantages. In addition, the antenna structure of the present invention has a smaller size and is more suitable for dense arrangement and forming an antenna array that can effectively suppress the formation of sidelobes. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1A and Figure 1B are top view schematic diagrams of the antenna structure according to the first embodiment of the present invention in different directions.

[0008] Figure 2 is Figure 1A a cross-sectional schematic diagram of the antenna structure.

[0009] Figure 3 is Figure 1A a graph of the reflection coefficient S11 and phase versus frequency of the antenna structure in different operating modes.

[0010] Figure 4 is a schematic diagram of an antenna array according to an embodiment of the present invention.

[0011] Figure 5A and Figure 5B are top view schematic diagrams of the antenna structure according to the second embodiment of the present invention in different directions.

[0012] Figure 6 is a cross-sectional schematic diagram of the antenna structure according to the third embodiment of the present invention.

[0013] Figure 7 is Figure 6 a graph of the reflection coefficient S11 and phase versus frequency of the antenna structure in different operating modes.

[0014] Figure 8 is a cross-sectional schematic diagram of the antenna structure according to the fourth embodiment of the present invention.

[0015] Figure 9 is Figure 8 a graph of the reflection coefficient S11 and phase versus frequency of the antenna structure in different operating modes.

[0016] Figure 10A and Figure 10B are top view schematic diagrams of the antenna structure according to the fifth embodiment of the present invention in different directions.

[0017] Figure 11 is Figure 10A a cross-sectional schematic diagram of the antenna structure.

[0018] Figure 12 is Figure 10A a graph of the reflection coefficient S11 and phase versus frequency of the antenna structure in different operating modes.

[0019] DESCRIPTION OF REFERENCE NUMERALS:

[0020] 1: Antenna array

[0021] 10, 10A, 10B, 20, 30: Antenna structures

[0022] 50: Drive circuit board

[0023] 101: First substrate

[0024] 102: Second substrate

[0025] 102s: Surface

[0026] 103: Third substrate

[0027] 104: Fourth substrate

[0028] 110, 110A: First electrode layer

[0029] 112, 132: First ring electrode

[0030] 112O: First ring opening

[0031] 114, 134: Second ring electrode

[0032] 114O: Second ring opening

[0033] 116, 136: Third ring electrode

[0034] 120, 120A, 120B: Second electrode layer

[0035] 120e: Extension part

[0036] 120oe: Opening extension part

[0037] 120m: Main part

[0038] 120om: Opening main part

[0039] 122, 122A, 142: First strip electrode

[0040] 122O: First strip opening

[0041] 124, 124A, 144: Second strip electrode

[0042] 124O: Second strip opening

[0043] 130: Third electrode layer

[0044] 140: Fourth electrode layer

[0045] 150: Reflective layer

[0046] AG: Air layer

[0047] AU1, AU2: Antenna units

[0048] G, G'': Gap

[0049] LC1: First liquid crystal layer

[0050] LC2: Second liquid crystal layer

[0051] OW1: First opening width

[0052] OW2: Second opening width

[0053] S: Spacing

[0054] W: Width

[0055] W1: First width

[0056] W2: Second width

[0057] X, Y, Z: Directions

[0058] A - A', B - B': Section lines Detailed implementation manners

[0059] As used herein, "about", "approximately", "essentially", or "substantially" includes the stated value and the average within an acceptable deviation range of a specific value determined by a person of ordinary skill in the art, taking into account the specific amount of the measurement being discussed and the errors associated with the measurement (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations of the stated value, or, for example, within ±30%, ±20%, ±15%, ±10%, or ±5%. Furthermore, "about", "approximately", "essentially", or "substantially" as used herein can be selected according to the nature of the measurement, the nature of the cutting, or other properties, to select a more acceptable deviation range or standard deviation, rather than applying one standard deviation to all properties.

[0060] In the drawings, for clarity, the thicknesses of layers, films, panels, regions, etc. are exaggerated. It should be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" or "connected to" another element, it can be directly on or connected to the other element, or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or "directly connected to" another element, no intervening elements are present. As used herein, "connected" can refer to physical and / or electrical connection. Furthermore, "electrically connected" can mean that other elements are present between two elements.

[0061] Reference will now be made in detail to the exemplary embodiments of the present invention, examples of the exemplary embodiments being illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used in the drawings and the description to refer to the same or like parts.

[0062] Figure 1Aand Figure 1B is a top view schematic diagram of the antenna structure according to the first embodiment of the present invention in different directions. Figure 2 is Figure 1A a cross-sectional schematic diagram of the antenna structure. Figure 2 corresponding to Figure 1A the section line A-A'. Figure 3 is Figure 1A a graph of the reflection coefficient S11 and phase of the antenna structure against frequency in different operating modes. Figure 4 is a schematic diagram of an antenna array according to an embodiment of the present invention.

[0063] Figure 5A and Figure 5B is a top view schematic diagram of the antenna structure according to the second embodiment of the present invention in different directions. For the sake of clear presentation, Figure 1A and Figure 1B only show Figure 2 the first electrode layer 110 and the second electrode layer 120.

[0064] Please refer to Figure 1A , Figure 1B and Figure 2 , the antenna structure 10 includes a first substrate 101, a second substrate 102, a first liquid crystal layer LC1, a first electrode layer 110, and a second electrode layer 120. The first substrate 101 and the second substrate 102 are disposed opposite to each other. The first liquid crystal layer LC1 is disposed between the first substrate 101 and the second substrate 102. The first electrode layer 110 is disposed on the first substrate 101 and is located between the first liquid crystal layer LC1 and the first substrate 101. The second electrode layer 120 is disposed on the second substrate 102 and is located between the first liquid crystal layer LC1 and the second substrate 102. In this embodiment, the materials of the first substrate 101 and the second substrate 102 are, for example, glass.

[0065] In this embodiment, the first electrode layer 110 may include three ring electrodes separated from each other, namely a first ring electrode 112, a second ring electrode 114, and a third ring electrode 116. The second ring electrode 114 is disposed around the first ring electrode 112. The third ring electrode 116 is disposed around the first ring electrode 112 and the second ring electrode 114. That is to say, the first ring electrode 112, the second ring electrode 114, and the third ring electrode 116 can be respectively regarded as the inner ring electrode, the middle ring electrode, and the outer ring electrode of the first electrode layer 110 (as Figure 1AAs shown. It should be particularly noted that the orthographic projection profiles of these annular electrodes on the first substrate 101 are all rectangular. More specifically, in this embodiment, the outer contour of the orthographic projection of the first annular electrode 112 on the first substrate 101 is a long rectangular shape, while the outer contours of the orthographic projections of the second annular electrode 114 and the third annular electrode 116 on the first substrate 101 are both square, but not limited thereto.

[0066] On the other hand, the distances between the first annular electrode 112 and the second annular electrode 114 in different directions are different. For example, the distance between the first annular electrode 112 and the second annular electrode 114 in the Y direction (i.e., the width W of the gap G) is less than the distance S between the first annular electrode 112 and the second annular electrode 114 in the X direction, where the X direction intersects the Y direction. More specifically, the X direction can be substantially perpendicular to the Y direction, but not limited thereto. In this embodiment, the second annular electrode 114 has a first width W1 and a second width W2 in the Y direction and the X direction respectively, and the first width W1 is greater than the second width W2. However, the present invention is not limited thereto. In other embodiments, the first width W1 can also be less than or substantially equal to the second width W2.

[0067] On the other hand, the second electrode layer 120 can include two strip electrodes, namely the first strip electrode 122 and the second strip electrode 124. These two strip electrodes are respectively arranged on the opposite sides of the first annular electrode 112 along the Y direction, and each overlaps the first annular electrode 112, the second annular electrode 114, and the gap G between the first annular electrode 112 and the second annular electrode 114. More specifically, each of these two strip electrodes of the second electrode layer 120 has a connected main part 120m and an extension part 120e, where the main part 120m overlaps the first annular electrode 112, the second annular electrode 114, and the gap G between the first annular electrode 112 and the second annular electrode 114, and the extension part 120e extends on the opposite sides of the main part 120m along the X direction.

[0068] In this embodiment, the extension parts 120e of these strip electrodes can selectively partially overlap the second annular electrode 114 of the first electrode layer 110, but not limited thereto. In other embodiments, the extension parts 120e of the strip electrodes (such as the first strip electrode 122A and the second strip electrode 124A) of the second electrode layer 120A of the antenna structure 10A can also completely overlap (as Figure 5A and Figure 5B shown) or not overlap (not shown) with the second annular electrode 114 of the first electrode layer 110. It should be noted that the overlapping relationship here refers to the projections of the two components along the Z direction overlapping. Unless otherwise specifically mentioned in the following paragraphs, the overlapping relationship between the two components is also defined by the Z direction and will not be elaborated further.

[0069] Due to the capacitive coupling effect formed by the overlapping relationship between the main part 120m of the strip-shaped electrode of the second electrode layer 120 and the first ring electrode 112 and the second ring electrode 114 of the first electrode layer 110, two induction loops can be formed on the opposite sides of the first ring electrode 112 along the direction X. Since the first liquid crystal layer LC1 can be driven by an electric field to change its effective dielectric constant between the first electrode layer 110 and the second electrode layer 120, the resonance frequency and phase of the resonance circuit of the equivalent capacitance and equivalent inductance formed among the first electrode layer 110, the second electrode layer 120, and the first liquid crystal layer LC1 can be modulated.

[0070] That is to say, the modifiable property of the effective dielectric constant of the first liquid crystal layer LC1 enables the antenna structure 10 to modulate the frequency and phase of the main electromagnetic waves (such as millimeter waves) it reflects. Please also refer to Figure 3 , when the first liquid crystal layer LC1 is not driven (i.e., the first electrode layer 110 and the second electrode layer 120 are not energized), the curve C1a of the reflection coefficient S11 of the antenna structure 10 against frequency and the curve C2a of the electromagnetic wave phase against frequency are significantly different from those when the first liquid crystal layer LC1 is driven, namely, the curve C1b of the reflection coefficient S11 of the antenna structure 10 against frequency and the curve C2b of the electromagnetic wave phase against frequency. For example, for electromagnetic waves with a phase falling near -100 degrees, whether the first liquid crystal layer LC1 is driven or not can change the main reflection frequency of the electromagnetic waves, such as switching between a frequency of 26.2 GHz and a frequency of 26.8 GHz. From another perspective, for electromagnetic waves with a frequency falling near 26.5 GHz, the maximum phase modulation amount ΔP1 that can be generated when the first liquid crystal layer LC1 is driven or not is approximately 200 degrees.

[0071] Since the antenna structure 10 of this embodiment can have the ability of phase modulation without being equipped with a phase shifter, it has a greater cost advantage compared with traditional antenna structures and is conducive to the large-scale sizing of the antenna structure. On the other hand, the size of the antenna structure 10 of this embodiment is also smaller. For example, the length of the antenna structure 10 along the direction X or the direction Y is about 0.3 times the wavelength of the electromagnetic waves to be reflected. Therefore, it is more suitable for being densely arranged on the driving circuit board 50 to form an antenna array 1 (as Figure 4 shown) that can effectively suppress the formation of side lobes.

[0072] Furthermore, in order to increase the reflectivity of the antenna structure 10 to target electromagnetic waves (such as millimeter waves), the antenna structure 10 further includes a reflection layer 150, which is disposed on the side of the second substrate 102 facing away from the second electrode layer 120. In this embodiment, the reflection layer 150 is, for example, a metal conductive layer with a ground potential, and integrally covers the surface 102s of the second substrate 102 away from the second electrode layer 120, but is not limited thereto.

[0073] Some other embodiments will be listed below to illustrate the present disclosure in detail. The same components will be denoted by the same reference numerals, and the description of the same technical content will be omitted. For the omitted part, please refer to the foregoing embodiments and will not be repeated hereinafter.

[0074] Figure 6 is a cross-sectional schematic view of an antenna structure according to a third embodiment of the present invention. Figure 7 is Figure 6 a graph of the reflection coefficient S11 and phase of the antenna structure against frequency in different operating modes. Please refer to Figure 6 , the difference between the antenna structure 20 of this embodiment and Figure 2 the antenna structure 10 is that the number of electrode layers and liquid crystal layers is different.

[0075] Specifically, the antenna structure 20 further includes a third substrate 103, a fourth substrate 104, a second liquid crystal layer LC2, a third electrode layer 130, and a fourth electrode layer 140. The third substrate 103 is disposed on a side of the first substrate 101 away from the second substrate 102. The fourth substrate 104 is disposed between the third substrate 103 and the first substrate 101. The second liquid crystal layer LC2 is disposed between the third substrate 103 and the fourth substrate 104. The third electrode layer 130 is disposed on the third substrate 103 and is located between the second liquid crystal layer LC2 and the third substrate 103. The fourth electrode layer 140 is disposed on the fourth substrate 104 and is located between the second liquid crystal layer LC2 and the fourth substrate 104. In this embodiment, the materials of the third substrate 103 and the fourth substrate 104 are, for example, glass.

[0076] Similar to the first electrode layer 110, the third electrode layer 130 also includes three separated ring electrodes, namely a first ring electrode 132, a second ring electrode 134, and a third ring electrode 136. The second ring electrode 134 is disposed around the first ring electrode 132. The third ring electrode 136 is disposed around the first ring electrode 132 and the second ring electrode 134. That is to say, the first ring electrode 132, the second ring electrode 134, and the third ring electrode 136 can be regarded as the inner ring electrode, the middle ring electrode, and the outer ring electrode of the third electrode layer 130, respectively.

[0077] On the other hand, similar to the second electrode layer 120, the fourth electrode layer 140 also includes two strip electrodes, namely a first strip electrode 142 and a second strip electrode 144. These two strip electrodes are respectively disposed on opposite sides of the first ring electrode 132 along the direction Y, and each overlaps the first ring electrode 132, the second ring electrode 134, and the gap G” between the first ring electrode 132 and the second ring electrode 134.

[0078] Since the configuration relationship of the third electrode layer 130, the fourth electrode layer 140, and the second liquid crystal layer LC2 and the technical effects generated are similar to the combination of the first electrode layer 110, the second electrode layer 120, and the first liquid crystal layer LC1, for the detailed description, please refer to the relevant paragraphs of the foregoing embodiments, and will not be repeated herein.

[0079] It should be particularly noted that both the third electrode layer 130 and the fourth electrode layer 140 overlap the first electrode layer 110, the second electrode layer 120, and the reflective layer 150. In this embodiment, the third electrode layer 130 and the fourth electrode layer 140 can be respectively aligned with the first electrode layer 110 and the second electrode layer 120 along the direction Z. From another perspective, the antenna structure of the present invention can also be a stacked structure of multiple antenna units. For example: the antenna structure 20 of this embodiment can be formed by stacking the antenna unit AU1 and the antenna unit AU2. Among them, the antenna unit AU1 is the Figure 2 antenna structure 10, and the other antenna unit AU2 is Figure 2 the antenna structure 10 after removing the reflective layer 150.

[0080] By overlapping multiple antenna units, a larger phase modulation amount or frequency modulation amount can be further achieved. Please also refer to Figure 7 , when the first liquid crystal layer LC1 and the second liquid crystal layer LC2 are not driven (that is, the first electrode layer 110, the second electrode layer 120, the third electrode layer 130, and the fourth electrode layer 140 are not energized), the curve C3a of the reflection coefficient S11 of the antenna structure 20 with respect to frequency and the curve C4a of the electromagnetic wave phase with respect to frequency are significantly different from the curve C3b of the reflection coefficient S11 of the antenna structure 20 with respect to frequency and the curve C4b of the electromagnetic wave phase with respect to frequency when the first liquid crystal layer LC1 and the second liquid crystal layer LC2 are driven.

[0081] For example, for electromagnetic waves with a phase falling near -110 degrees, whether the first liquid crystal layer LC1 and the second liquid crystal layer LC2 are driven can significantly change the main reflection frequency of the electromagnetic wave, for example, switching between the frequency of 24.8 GHz and the frequency of 25.9 GHz. From another perspective, for electromagnetic waves with a frequency falling near 25.3 GHz, the maximum phase modulation amount ΔP2 that can be generated when the first liquid crystal layer LC1 and the second liquid crystal layer LC2 are driven or not is about 310 degrees. Since the antenna structure 20 of this embodiment can have the ability of phase modulation without being equipped with a phase shifter, it has a greater cost advantage compared with the traditional antenna structure and helps to increase the size of the antenna structure.

[0082] Figure 8 is a cross-sectional schematic view of the antenna structure according to the fourth embodiment of the present invention. Figure 9 is Figure 8Graph of the reflection coefficient S11 and phase of the antenna structure against frequency under different operating modes. Please refer to Figure 8 and Figure 9 In this embodiment, the difference between the antenna structure 10B and the Figure 2 antenna structure 10 is that an air layer AG is provided between the reflective layer 150 and the second substrate 102 of the antenna structure 10B. By providing this air layer AG, the dependence of the maximum phase modulation amount ΔP3 that the antenna structure 10B can generate for electromagnetic waves near a specific frequency on frequency can be reduced.

[0083] When the first liquid crystal layer LC1 is not driven (i.e., the first electrode layer 110 and the second electrode layer 120 are not energized), the curve C5a of the reflection coefficient S11 of the antenna structure 10B against frequency and the curve C6a of the electromagnetic wave phase against frequency are significantly different from those when the first liquid crystal layer LC1 is driven, namely, the curve C5b of the reflection coefficient S11 of the antenna structure 10B against frequency and the curve C6b of the electromagnetic wave phase against frequency. For example, for electromagnetic waves with a frequency falling near 16.9 GHz, whether the first liquid crystal layer LC1 is driven or not, the maximum phase modulation amount ΔP3 that can be generated is approximately 200 degrees, and for electromagnetic waves with a frequency range between 16.7 GHz and 17.1 GHz, the dependence of this maximum phase modulation amount ΔP3 on frequency is less obvious. That is to say, the antenna structure 10B of this embodiment can generate a considerable maximum phase modulation amount ΔP3 for electromagnetic waves with a frequency range between 16.7 GHz and 17.1 GHz, which helps to increase the operating flexibility of the antenna structure 10B.

[0084] Figure 10A and Figure 10B are top view schematic diagrams of the antenna structure according to the fifth embodiment of the present invention in different directions. Figure 11 is Figure 10A a cross-sectional schematic diagram of the antenna structure. Figure 11 corresponds to Figure 10A the section line B - B'. Figure 12 is Figure 10A a graph of the reflection coefficient S11 and phase of the antenna structure against frequency under different operating modes. For clear presentation, Figure 10A and Figure 10B only show Figure 2 the first electrode layer 110 and the second electrode layer 120.

[0085] Please refer to Figure 10A , Figure 10B and Figure 11 In this embodiment, the antenna structure 30 and the Figure 1AThe difference in the antenna structure 10 lies in the different configurations of the electrode patterns of the electrode layers. Specifically, the first electrode layer 110A of the antenna structure 30 has a first annular opening 112O and a second annular opening 114O. The second annular opening 114O is disposed around the first annular opening 112O. In the present embodiment, the second annular opening 114O has a first opening width OW1 and a second opening width OW2 in the Y direction and the X direction, respectively, and the first opening width OW1 is greater than the second opening width OW2. However, the present invention is not limited thereto. In other embodiments, the first opening width OW1 may also be less than or substantially equal to the second opening width OW2.

[0086] On the other hand, the second electrode layer 120B has a first strip-shaped opening 122O and a second strip-shaped opening 124O. It should be particularly noted that the first strip-shaped opening 122O and the second strip-shaped opening 124O are respectively disposed on opposite sides of the first annular opening 112O along the Y direction, and each partially overlaps the first annular opening 112O and the second annular opening 114O. For example, the first strip-shaped opening 122O and the second strip-shaped opening 124O of the second electrode layer 120B each have an opening main portion 120om and an opening extension portion 120oe that are connected. The opening main portion 120om overlaps the first annular opening 112O and the second annular opening 114O. The opening extension portion 120oe extends on opposite sides of the opening main portion 120om along the X direction.

[0087] In the present embodiment, the opening extension portions 120oe of these strip-shaped openings may selectively partially overlap the second annular opening 114O of the first electrode layer 110A, but are not limited thereto. In other embodiments not shown, the opening extension portions 120oe of the strip-shaped openings of the second electrode layer of the antenna structure may also completely overlap or not overlap the second annular opening 114O of the first electrode layer 110A.

[0088] Through the capacitive coupling effect formed by the overlapping relationship between the opening main portion 120om of the strip-shaped opening of the second electrode layer 120B and the first annular opening 112O and the second annular opening 114O of the first electrode layer 110A, two induction loops can be formed on opposite sides of the first annular opening 112O along the X direction. Since the first liquid crystal layer LC1 can be driven by an electric field to change its effective dielectric constant between the first electrode layer 110A and the second electrode layer 120B, the resonance frequency and phase of the resonance circuit of the equivalent capacitance and equivalent inductance formed between the first electrode layer 110A, the second electrode layer 120B, and the first liquid crystal layer LC1 can be modulated.

[0089] That is to say, the modifiable performance of the effective dielectric constant of the first liquid crystal layer LC1 enables the antenna structure 30 to modulate the frequency and phase of the main electromagnetic waves (such as millimeter waves) it reflects. Please refer toFigure 12 When the first liquid crystal layer LC1 is not driven (i.e., the first electrode layer 110A and the second electrode layer 120B are not energized), the curve C7a of the reflection coefficient S11 of the antenna structure 30 versus frequency and the curve C8a of the electromagnetic wave phase versus frequency are significantly different from those when the first liquid crystal layer LC1 is driven, namely, the curve C7b of the reflection coefficient S11 of the antenna structure 30 versus frequency and the curve C8b of the electromagnetic wave phase versus frequency. For example, for an electromagnetic wave with a phase falling around -100 degrees, whether the first liquid crystal layer LC1 is driven or not can change the main reflection frequency of the electromagnetic wave, such as switching between a frequency of 18.1 GHz and a frequency of 18.9 GHz. From another perspective, for an electromagnetic wave with a frequency falling around 18.5 GHz, the maximum phase modulation amount ΔP4 that can be generated when the first liquid crystal layer LC1 is driven or not is approximately 170 degrees. That is to say, the antenna structure 30 of this embodiment has the ability of phase modulation without the need to be equipped with a phase shifter, which is more cost-effective than traditional antenna structures and helps to increase the size of the antenna structure.

[0090] In summary, in the antenna structure of an embodiment of the present invention, the capacitive coupling effect generated by the partial overlapping relationship between the first electrode layer and the second electrode layer can be changed via the liquid crystal layer sandwiched between these two electrode layers. That is to say, the resonance frequency and phase of the induction circuit (or induction loop) formed by these electrode layers can be modulated. Since the antenna structure of the present invention has the function of phase modulation without the need to be equipped with a phase shifter, it is more cost-effective. In addition, the antenna structure of the present invention has a smaller size and is more suitable for dense arrangement to form an antenna array that can effectively suppress the formation of sidelobes.

Claims

1. An antenna structure, comprising: A first substrate; A second substrate, disposed opposite to the first substrate; A first liquid crystal layer, disposed between the first substrate and the second substrate; A first electrode layer, disposed on the first substrate and between the first liquid crystal layer and the first substrate; A second electrode layer, disposed on the second substrate and between the first liquid crystal layer and the second substrate; and A reflective layer, disposed on a side of the second substrate away from the second electrode layer, wherein the first electrode layer, the second electrode layer, and the reflective layer overlap each other, and the first electrode layer has at least one annular electrode or at least one annular opening, The reflective layer increases the reflectivity of the antenna structure to a target electromagnetic wave.

2. The antenna structure according to claim 1, wherein the first electrode layer comprises: A first annular electrode; A second annular electrode, disposed around the first annular electrode; And A third annular electrode, disposed around the first annular electrode and the second annular electrode.

3. The antenna structure according to claim 2, wherein the first annular electrode and the second annular electrode have a gap in a first direction, and the second electrode layer overlaps the gap.

4. The antenna structure according to claim 3, wherein the width of the gap in the first direction is smaller than the distance between the first annular electrode and the second annular electrode in a second direction, and the first direction intersects the second direction.

5. The antenna structure according to claim 3, wherein the second electrode layer has a main portion and an extension portion connected thereto, the main portion overlaps the gap between the first annular electrode and the second annular electrode, the first annular electrode, and the second annular electrode, the extension portion extends along opposite sides of the main portion in a second direction, and the second direction intersects the first direction.

6. The antenna structure according to claim 2, wherein the second annular electrode has a first width and a second width in a first direction and a second direction respectively, the first direction intersects the second direction, and the first width is different from the second width.

7. The antenna structure according to claim 1, wherein the outer contour of the positive projection of the at least one annular electrode on the first substrate is rectangular.

8. The antenna structure according to claim 1, further comprising: A third substrate, disposed on a side of the first substrate away from the second substrate; A fourth substrate, disposed between the third substrate and the first substrate; A second liquid crystal layer, disposed between the third substrate and the fourth substrate; A third electrode layer, disposed on the third substrate and between the second liquid crystal layer and the third substrate; and A fourth electrode layer, disposed on the fourth substrate and between the second liquid crystal layer and the fourth substrate, wherein the third electrode layer and the fourth electrode layer overlap the first electrode layer, the second electrode layer, and the reflective layer, and the first electrode layer and the third electrode layer each have at least one annular electrode or at least one annular opening.

9. The antenna structure according to claim 1, wherein an air layer is provided between the reflective layer and the second substrate.

10. The antenna structure according to claim 1, wherein the first electrode layer has a first annular opening, the second electrode layer has a strip-shaped opening, and the strip-shaped opening partially overlaps the first annular opening.

11. The antenna structure according to claim 10, wherein the first electrode layer further has a second annular opening surrounding the first annular opening, and the strip-shaped opening of the second electrode layer further partially overlaps the second annular opening.

12. The antenna structure according to claim 11, wherein the second annular opening has a first opening width and a second opening width in a first direction and a second direction respectively, the first direction intersects the second direction, and the first opening width is different from the second opening width.

13. The antenna structure according to claim 12, wherein the strip-shaped opening has a main opening part and an opening extension part that are connected to each other, the main opening part overlaps the first annular opening and the second annular opening, the opening extension part extends along opposite sides of the main opening part in the second direction, and partially overlaps the second annular opening of the first electrode layer.

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