This application claims the priority benefit of Taiwan application serial no. 110100210, filed on Jan. 5, 2021. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.
Technical Field
The disclosure relates to an antenna structure and an array antenna module, and more particularly, to a liquid crystal antenna structure and an array antenna module.
Description of Related Art
With the ever-increasing demand for the functions and performance of wireless devices, coupled with the lack of electromagnetic spectrum, the demand for adjustable operating frequencies of antennas is gradually increasing. At present, frequency modulated antennas generally use micro-electromechanical systems, diodes, field-effect transistor switches, etc. to achieve adjustable functions. However, the above adjustable methods are all discrete adjustments, which means that they may only hop between specific frequency points. In order for the frequency change of the modulation process to be continuous, a feasible method is to use the anisotropy of the liquid crystal material to realize electrical adjustment and achieve continuous modulation capability.
However, in the current antenna combination using a patch antenna and a liquid crystal layer, the liquid crystal layer is required to have a certain thickness, which will increase the manufacturing cost, while the response speed of the liquid crystal is also relatively slow, and the liquid crystal has more power consumption.
The disclosure provides an antenna structure, which may have a relatively thin liquid crystal layer.
The disclosure provides an array antenna module, which has the antenna structure.
The antenna structure of the disclosure includes a patch antenna, a microstrip line, two first radiation assemblies, two second radiation assemblies, a liquid crystal layer, and a ground plane. The patch antenna includes two opposite edges. The microstrip line is connected to the patch antenna. The two first radiation assemblies are respectively disposed on two sides of the patch antenna. The patch antenna, the microstrip line, and the two first radiation assemblies are located on a first plane, and each of the first radiation assemblies includes multiple separated first conductors. The two second radiation assemblies are disposed under the two first radiation assemblies and located on a second plane, and each of the second radiation assemblies includes multiple separated second conductors. A projection of the two second radiation assemblies on the first plane, the two first radiation assemblies, and the two edges of the patch antenna collectively form two loops. The liquid crystal layer is disposed between the first plane and the second plane. The ground plane is disposed under the two second radiation assemblies.
In an embodiment of the disclosure, an extending direction of the two edges of the patch antenna extends toward a first extending direction of the microstrip line, and the loop has a long side extending toward the first extending direction of the microstrip line.
In an embodiment of the disclosure, a width of the first conductor in an extending direction of a short side is less than a width of the second conductor in the extending direction.
In an embodiment of the disclosure, the two second radiation assemblies are connected to each other through two conducting wires. The two second radiation assemblies are divided into an inner zone and two outer zones located at two sides of the inner zone by a second extending direction of the two conducting wires, and the second conductors of the second radiation assemblies are only located in the two outer zones.
In an embodiment of the disclosure, the first conductors are staggered from the second conductors.
In an embodiment of the disclosure, the antenna structure further includes a thin film transistor and multiple first circuits connected to the thin film transistor and the first conductors. The first conductors are electrically connected to the thin film transistor through the first circuits. The thin film transistor supplies a voltage to the first conductors to adjust a dielectric constant of the liquid crystal layer.
In an embodiment of the disclosure, the first circuits are respectively perpendicular to the connected first conductors.
In an embodiment of the disclosure, the antenna structure further includes multiple second circuits connected to the ground plane and the second conductors, and the second conductors are electrically connected to the ground plane through the second circuits.
In an embodiment of the disclosure, the second circuits are respectively perpendicular to the connected second conductors.
In an embodiment of the disclosure, the antenna structure further includes a first substrate and a second substrate which are disposed up and down, and separated from each other. The patch antenna, the microstrip line, and the two first radiation assemblies are disposed on the first substrate, and the two second radiation assemblies are disposed on the second substrate. The first plane is a surface of the first substrate facing the second substrate, and the second plane is a surface of the second substrate facing the first substrate. The liquid crystal layer is located between the first substrate and the second substrate.
In an embodiment of the disclosure, the ground plane is disposed on a surface of the second substrate away from the first substrate.
In an embodiment of the disclosure, the ground plane is disposed on a third substrate, and the ground plane is attached to the surface of the second substrate away from the first substrate.
In an embodiment of the disclosure, the antenna structure resonates in a frequency band, and a thickness of the liquid crystal layer is less than 0.005 times a wavelength of the frequency band.
The array antenna module of the disclosure includes multiple antenna structures, which are arranged in an array.
In an embodiment of the disclosure, the antenna structures include multiple first antenna structures. The microstrip lines of the first antenna structures have a variety of lengths. A phase difference of the first antenna structures is non-zero. Phases of the first antenna structures along the second extending direction are an arithmetic series.
In an embodiment of the disclosure, a difference between the lengths of any two adjacent ones of the microstrip lines of the first antenna structures is λg*(P/360), where λg is an effective wavelength of a feeding signal in the antenna structure, and P is a phase difference (°) between the two adjacent microstrip lines.
In an embodiment of the disclosure, the phase difference of the first antenna structures is P=(360*d*sin θ)/λ, where θ is a radiation angle, while λ is a radiation wavelength, and d is a distance between any two adjacent ones of the first antenna structures.
In an embodiment of the disclosure, the antenna structures further include multiple second antenna structures. A phase difference of the second antenna structures is 0. The first antenna structures and the second antenna structures are successively arranged along the second extending direction or the first extending direction, and an antenna radiation direction is adjusted by operating at different timings.
In an embodiment of the disclosure, a third extending direction is perpendicular to the first extending direction and the second extending direction. When the first antenna structures have radiation signals (ON), and the second antenna structures do not have the radiation signals (OFF), an angle is included between the antenna radiation direction and the third extending direction, and the angle is greater than 0 and less than 90 degrees. When the first antenna structures do not have the radiation signals (OFF), and the second antenna structures have the radiation signals (ON), the antenna radiation direction is parallel to the third extending direction.
In an embodiment of the disclosure, lengths of the microstrip lines of the first antenna structures are greater than lengths of the microstrip lines of the second antenna structures.
Based on the above, in the antenna structure of the disclosure, the two first radiation assemblies are respectively disposed on the two sides of the patch antenna, and the two second radiation assemblies are disposed under the two first radiation assemblies. The projection of the two second radiation assemblies on the first plane, the two first radiation assemblies, and the two edges of the patch antenna collectively form the two loops. The liquid crystal layer is disposed between the first plane and the second plane. The ground plane is disposed under the two second radiation assemblies. In the disclosure, the first conductors and the second conductors are disposed above and below the liquid crystal layer to generate a multi-capacitance path of a signal. In the conventional technology, the antenna structure using the liquid crystal layer determines a radiation frequency offset by the thickness of the liquid crystal layer, and thus the thick liquid crystal layer is required. In the antenna structure of the disclosure, through the above multi-capacitance path, a fringe radiation field of the patch antenna may change the radiation frequency according to the capacitance change generated by the multi-capacitance path. Therefore, the thickness of the liquid crystal layer of the antenna structure in the disclosure may be greatly reduced, thereby reducing the cost and power consumption.
Referring to
As shown in
The two first radiation assemblies 130 are symmetrically disposed on two sides of the patch antenna 110, respectively. Each of the first radiation assemblies 130 includes multiple separated first conductors 132. The two second radiation assemblies 140 are disposed under the two first radiation assemblies 130, and are symmetrical to the two sides of the patch antenna 110. Each of the second radiation assemblies 140 includes multiple separated second conductors 142. The first conductors 132 are at least partially staggered from the second conductors 142.
In this embodiment, a shape and size of the first conductor 132 and the second conductor 142 are different, and a width W1 of the first conductor 132 in an extending direction of a short side is less than a width W2 of the second conductor 142 in the extending direction. The two second radiation assemblies 140 are connected to each other through two conducting wires 146. As shown in
The patch antenna 110, the microstrip line 120, and the two first radiation assemblies 130 are located on a first plane P1. The two second radiation assemblies 140 are disposed under the two first radiation assemblies 130 and located on a second plane P2. Specifically, the antenna structure 100 further includes a first substrate 160 and a second substrate 162 disposed up and down and separated from each other. The first substrate 160 and the second substrate 162 may be glass plates or plastic plates. Materials of the first substrate 160 and the second substrate 162 are not limited, as long as a tangent loss in an operating frequency band of an antenna is less than 0.05.
The patch antenna 110, the microstrip line 120, and the two first radiation assemblies 130 are disposed on the first substrate 160, and the two second radiation assemblies 140 are disposed on the second substrate 162. The first plane P1 is a surface of the first substrate 160 facing the second substrate 162, and the second plane P2 is a surface of the second substrate 162 facing the first substrate 160. The liquid crystal layer 150 is located between the first substrate 160 and the second substrate 162, and located between the first plane P1 and the second plane P2. The liquid crystal layer 150 is used as a modulation layer of a radiation frequency.
As shown in
Returning to
In addition, the antenna structure 100 further includes multiple second circuits 144 connected to the ground plane 155 (
The thin film transistor 136 supplies a voltage to the first conductors 132, so that there is a voltage difference between the first conductors 132 and the second conductors 142 (equipotential to the ground plane 155). As a result, an electric field is formed to control an aligning direction of liquid crystal molecules in the liquid crystal layer 150, so as to adjust a dielectric constant of the liquid crystal layer 150.
It should be noted that the position, number, and size of the thin film transistor 136 are not limited by the drawing. In addition, the first conductor 132 and the second conductor 142 may be metal or non-metal conductors, and may also be transparent electrodes. The types of the first conductor 132 and the second conductor 142 are not limited thereto.
It should be noted that in this embodiment, the first circuits 134 are respectively perpendicular to the connected first conductors 132, and the second circuits 144 are respectively perpendicular to the connected second conductors 142. Such a design may enable a current direction (along an edge of the first conductor 132) on a surface of the first conductor 132 to be perpendicular to an extending direction of the connected first circuit 134, and a current direction (along an edge of the second conductor 142) on a surface of the second conductor 142 to be perpendicular to an extending direction of the connected second circuit 144, which may reduce an interference of a bias signal (a low frequency to 60 Hz) and a high frequency signal of an antenna (>1 GHz).
Referring to
In the antenna structure 100 of this embodiment, the two first radiation assemblies 130 and the two second radiation assemblies 140 are disposed above and below the liquid crystal layer 150. A projection of the second conductors 142 of the two second radiation assemblies 140 on the first plane P1, the first conductors 132 of the two first radiation assemblies 130, and the two edges 112 of the patch antenna 110 collectively form two loops. Such a design may enable the first conductors 132 and the second conductors 142 to be alternately arranged up and down to generate a multi-capacitance path of a radiation signal, so that the signal resonates between the first conductors 132 and the second conductors 142 alternately arranged up and down.
Therefore, a fringe radiation field of the patch antenna 110 located in the center may change the radiation frequency due to a capacitance change generated by alternately stacking the first conductors 132 and the second conductors 142. In other words, the antenna structure 100 of this embodiment is an antenna structure that generates radiation by using a resonance of high-frequency LC.
In the conventional technology, an antenna structure using a liquid crystal layer determines a radiation frequency offset by a thickness of the liquid crystal layer, and thus the thick liquid crystal layer is required. In this embodiment, the antenna structure 100 enhances an influence of the modulation of liquid crystal on a resonance of a radiator by using the multi-capacitance path, and achieves an adjustable capacitance by using an external voltage to change the dielectric constant of the liquid crystal layer 150. Therefore, the antenna structure 100 of this embodiment does not need to change the radiation frequency by applying a high voltage to the thick liquid crystal layer, so that a thickness of the liquid crystal layer 150 may be greatly reduced, thereby reducing the cost and power consumption.
For example, the antenna structure 100 resonates in the frequency band, and a thickness T (
Conversely, if the operating frequency is defined as 19.6 GHz, the dielectric constant ε of the liquid crystal layer 150 is 3.3 in the state where the voltage (9V) is supplied to the antenna structure 100. When the X coordinate is 19.6 GHz, I2 is taken as an example for S11 (the reflection coefficient) corresponding to the Y coordinate, which is close to −21 dB and means that most of the fed radiant energy is radiated, so that only a small amount of energy is reflected, which has a good radiation performance. Therefore, the antenna structure 100 may excite a radiation signal (ON) of 19.6 GHz. In the state where the antenna structure 100 is not supplied with the voltage, the dielectric constant ε of the liquid crystal layer 150 is 2.4. When the X coordinate is 19.6 GHz, I2′ of S11 (the reflection coefficient) corresponding to the Y coordinate is less than −1 dB, which means that most of the fed radiant energy is reflected back to the feeding end, and the radiation performance is pretty poor. Therefore, the antenna structure 100 may be said to have no radiation signal (OFF) of 19.6 GHz at this time.
In other words, the antenna structure 100 of this embodiment may change the dielectric constant ε of the liquid crystal layer 150 between 2.4 and 3.3 through no voltage or the voltage of 9V, thereby achieving an effect of changing the radiation frequency between 21.3 GHz and 19.6 GHz.
According to a capacitance formula, C=ε*A/D, where C is a capacitance, and ε is a dielectric constant. A is an area of a conductor, and D is a distance between the first plane P1 and the second plane P2. When the dielectric constant ε changes, the capacitance changes accordingly. Furthermore, according to a frequency formula, f=1/(2π√(L*C)), where L is an inductance, and C is the capacitance. When the capacitance changes, the frequency also changes accordingly. Therefore, the antenna structure 100 of this embodiment changes the dielectric constant ε of the liquid crystal layer 150 by the multi-capacitance path, thereby achieving an effect of frequency modulation.
Compared with the conventional technology that requires the thick liquid crystal layer to achieve similar frequency modulation, the antenna structure 100 of this embodiment may have the thin liquid crystal layer 150, and the frequency modulation may be achieved by applying a lower voltage. In addition, at 21.3 GHz, the antenna structure 100 of this embodiment may obtain a switching ratio of about 9% (a radiation efficiency of the radiation signal (OFF)/a radiation efficiency of the radiation signal (ON)), and the radiation frequency of about 8% may be modulated (a difference between 21.3 GHz and 19.6 GHz/21.3 GHz), which may be applied to array antennas, and may effectively achieve an effect of beamforming.
Referring to
Referring to
In this embodiment, a phase change is adjusted by adjusting the lengths of the microstrip lines 120a, 120b, 120c, and 120d. A difference between the lengths of any two adjacent ones of the microstrip lines 120a, 120b, 120c, and 120d of the first antenna structures 30, 32, 34, and 36 is λg*(P/360), where λg is an effective wavelength of a feeding signal in the antenna structure 100. That is, the feeding signal is a wavelength when transmitted in media such as the patch antenna 110, the first conductor 132, the second conductor 142, the first substrate 160, the second substrate 162, and the liquid crystal layer 150 in
In addition, along the second extending direction D2, phases A1, A2, A3, and A4 of the first antenna structures 30, 32, 34, and 36 are an arithmetic series. For example, the phases A1, A2, A3, and A4 may be 20, 40, 60, and 80, but are not limited thereto.
As shown in
Referring to
In light of the above, the designer may achieve an effect of adjusting the antenna radiation direction by configuring the antenna structure 100 with different phases.
Referring to
The first antenna structures 30, 32, 34, and 36, and the second antenna structures 20 are successively arranged along the second extending direction D2, and the antenna radiation direction may be adjusted by operating at different timings. In an embodiment, the first antenna structures 30, 32, 34, and 36, and the second antenna structures 20 may also be successively arranged along the first extending direction D1.
Specifically, as shown in
As shown in
Of course, the angle of the antenna radiation direction varies according to the phase and antenna configuration. The designer may adjust the configuration of the antenna structure 100 and the switch settings of the antenna structure 100 according to requirements to control the phase difference (with/without phase difference), and then change the angle of the antenna radiation direction to achieve an effect of antenna radiation beam switching.
Based on the above, in the antenna structure of the disclosure, the two first radiation assemblies are respectively disposed on the two sides of the patch antenna, and the two second radiation assemblies are disposed under the two first radiation assemblies. The projection of the two second radiation assemblies on the first plane, the two first radiation assemblies, and the two edges of the patch antenna collectively form the two loops. The liquid crystal layer is disposed between the first plane and the second plane. The ground plane is disposed under the two second radiation assemblies. In the disclosure, the first conductors and the second conductors are disposed above and below the liquid crystal layer to generate the multi-capacitance path of the signal. In the conventional technology, the antenna structure using the liquid crystal layer determines the radiation frequency offset by the thickness of the liquid crystal layer, and thus the thick liquid crystal layer is required. In the antenna structure of the disclosure, through the above multi-capacitance path, the fringe radiation field of the patch antenna may change the radiation frequency according to the capacitance change generated by the multi-capacitance path. Therefore, the thickness of the liquid crystal layer of the antenna structure in the disclosure may be greatly reduced, thereby reducing the cost and power consumption.
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