Phased array antenna based on light-operated liquid crystal

Abstract

The invention provides a phased-array antenna based on light-operated liquid crystal, which sequentially comprises a power division shifting layer, a liquid crystal layer and a grounding radiation layer from bottom to top, and the liquid crystal is the light-operated liquid crystal; the phase of the antenna is controlled by a light field, and the dielectric constant of the light-operated liquid crystal is adjusted by applying the light field, so that the emission angle of the antenna is changed; different phase distributions can be realized on the phase shifter through different UV light fields, so that the radiation unit is controlled to emit millimeter wave beams with different spatial morphologies; electric field control is not used, so that light field control is fully utilized to reduce the weight of the whole antenna; according to the phased-array antenna disclosed by the invention, by applying 365nm illumination, the beam transmitting direction of the antenna can be differently regulated and controlled, and the beam of the antenna can be regulated and controlled within + / -16 degrees through UV light fields with different patterns; and the resonant frequency of the antenna is 10.2 GHz, and the resonant depth reaches-27dB.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a phased array antenna based on light-controlled liquid crystal. Background Art

[0002] As functions such as communication, navigation, guidance, and surveillance are increasingly integrated into platforms such as aircraft, ships, and satellites, traditional fixed-function antennas can no longer meet these needs. Therefore, the introduction of reconfigurable antennas provides a new way to solve these problems. A reconfigurable antenna is an antenna system that can dynamically change its operating frequency, radiation characteristics, or polarization state. It emerged to cope with the frequently changing needs of modern communication and radar systems, as well as the requirement to realize multifunctional antennas in a limited space. By dynamically changing its physical structure or size, a reconfigurable antenna can realize the functions of multiple antennas, thereby meeting a variety of communication and radar requirements in a limited space.

[0003] Traditional optically controlled antennas are all reconfigurable by loading photodiodes or optically controlled microwave switches. In addition, the current technology using liquid crystal materials for adjustment mainly adjusts the dielectric constant of liquid crystal materials by applying an external electric field to achieve dynamic and continuous adjustment of the operating frequency. Secondly, the current liquid crystal antennas that meet the requirements of electric field regulation are mostly implemented with complex feeding structures, which not only reduces the antenna communication efficiency and bandwidth, but also makes the equipment heavy and not light enough. At the same time, the antenna stability and anti-interference performance also decrease, making it difficult to meet user needs. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a phased array antenna based on light-controlled liquid crystal. The present invention can achieve different radiations on the antenna through different light intensities and can emit millimeter-wave beams with different spatial morphologies.

[0005] The technical solution of the present invention is: a phased array antenna based on light-controlled liquid crystal, which includes a power division shifting layer, a liquid crystal layer and a ground radiation layer from bottom to top, wherein the power division shifting layer includes a first transparent PET substrate and a T-shaped power divider and a phase shifter arranged on the first transparent PET substrate; the liquid crystal layer includes a second transparent PET substrate and a light-controlled liquid crystal arranged on the second transparent PET substrate; the ground radiation layer includes an FR-4 substrate, a ground layer is arranged on the lower surface of the FR-4 substrate, and two symmetrically arranged rectangular grooves are opened on the ground layer; and two radiation patches are symmetrically arranged on the upper surface of the FR-4 substrate corresponding to the rectangular grooves; and the antenna beam emission direction is controlled by applying light fields of different modes.

[0006] Preferably, the T-shaped power divider has an input port and two output ports, wherein the two output ports are respectively connected to corresponding phase shifters, and the other ends of the two phase shifters are respectively connected to a ground layer containing a gap to form a coupled feeding structure.

[0007] Preferably, the T-shaped power divider comprises a first transmission line, a second transmission line and a third transmission line; the first transmission line and the second transmission line are connected to form a T-shaped structure, and both ends of the second transmission line are connected to the third transmission line;

[0008] The first transmission line is a transmission line with impedances Z0, Z1, and Z2, and Z2=Z0||Z0; Z1 is matched with a quarter-wavelength impedance transformation branch, that is, Z1=(Z0*Z2) 1 / 2 ; The impedance of the third transmission line is Z0.

[0009] Preferably, the phase shifter is a serpentine microstrip line, on which a number of equally spaced through holes are arranged, and the other end of the serpentine microstrip line is connected to the ground layer to form a coupled feeding structure to transfer energy to the radiation patch through the rectangular groove.

[0010] Preferably, the light-controlled liquid crystal is prepared by mixing liquid crystal E7 and azo dye, wherein the mass proportion of the azo dye is 1%.

[0011] Preferably, in the absence of light, the liquid crystal molecules of the light-controlled liquid crystal are arranged according to the orientation direction of the orientation layer. After UV light is applied, the azo molecules undergo cis-trans isomerization, disturbing the arrangement of the liquid crystal molecules. If the external UV light field is removed, the azo dye molecules return to the reverse state, presenting a long rod-like molecular structure, and the liquid crystal molecules also return to their initial orientation.

[0012] Preferably, the N=N double bond in the azo molecule undergoes cis-trans isomerization transformation between trans-cis and cis-trans under the action of light and heat, wherein trans-azobenzene is converted to cis under 365nm ultraviolet light irradiation;

[0013]

[0014] Here, hv and kT represent light and heat, respectively.

[0015] Preferably, the distance between the two radiation patches is 20 mm.

[0016] Preferably, the ground layer is a copper-clad layer with gaps etched on the lower surface of the FR-4 substrate.

[0017] The beneficial effects of the present invention are:

[0018] 1. The present invention uses a light field to control the phase of the antenna. Different phase distributions can be achieved on the phase shifter through different UV light fields, thereby controlling the radiation unit to emit millimeter wave beams with different spatial morphologies;

[0019] 2. The present invention manufactures light-controlled liquid crystal materials by mixing liquid crystal and azo, and adjusts the dielectric constant of the light-controlled liquid crystal by applying a light field, thereby changing the resonant frequency or emission angle of the antenna; since electric field control is not used, complex electrical connections and fixed electrode structures are abandoned, and remote and non-contact control of the light field is fully utilized to reduce the weight of the entire system;

[0020] 3. The present invention changes the state of azo molecules through UV light field to disturb the arrangement of liquid crystal molecules and thus change their dielectric constant, and obtains a light-controlled liquid crystal material with continuously adjustable dielectric constant and low dielectric loss by adjusting the external light intensity;

[0021] 4. The phased array antenna of the present invention can achieve different adjustments in the antenna operating frequency or the transmission beam direction by applying 365nm light. Through UV light fields of different patterns, the antenna beam can be adjusted between ±16°; and the antenna resonant frequency is 10.2GHz, and the resonance depth reaches -27dB. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of the phased array antenna of the present invention;

[0023] Figure 2 It is a schematic diagram of the working state of the phased array antenna of the present invention;

[0024] Figure 3 It is a schematic diagram of the structure of the power divider and the phase shifter of the present invention;

[0025] Figure 4 is a response schematic diagram of the light-controlled liquid crystal of the present invention;

[0026] Figure 5 is a curve diagram of the S parameters of the phased array antenna of the present invention;

[0027] Figure 6 The yoz plane radiation pattern of the phased array antenna of the present invention at 10.5 GHZ;

[0028] In the figure, 1-power distribution layer; 2-liquid crystal layer; 3-ground radiation layer;

[0029] 11-first transparent PET substrate; 12-T-shaped power divider; 13-phase shifter;

[0030] 121 - input port; 122 - output port; 123 - first transmission line; 124 - second transmission line; 125 - third transmission line;

[0031] 21-second transparent PET substrate; 22-light-controlled liquid crystal;

[0032] 31-FR-4 substrate; 32-ground layer; 33-radiation patch; 34-rectangular groove. DETAILED DESCRIPTION

[0033] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings:

[0034] like Figure 1 As shown, this embodiment provides a phased array antenna based on light-controlled liquid crystal, which includes a power division shifting layer 1, a liquid crystal layer 2 and a ground radiation layer 3 from bottom to top.

[0035] The power division and shifting layer 1 includes a first transparent PET substrate 11 and a T-shaped power divider 12 and a phase shifter 13 arranged on the first transparent PET substrate 11 .

[0036] The liquid crystal layer 2 includes a second transparent PET substrate 21 and a light-controlled liquid crystal 22 disposed on the second transparent PET substrate 21 .

[0037] The ground radiation layer 3 includes a FR-4 substrate 31, a ground layer 32 is provided on the lower surface of the FR-4 substrate 31, and two symmetrically arranged rectangular grooves 34 are provided on the ground layer 32; and two radiation patches 33 are symmetrically arranged on the upper surface of the FR-4 substrate 31 corresponding to the rectangular grooves 34; the spacing between the two radiation patches 33 is 20 mm. And the ground layer 32 is a copper-clad layer with gaps etched on the lower surface of the FR-4 substrate 31.

[0038] like Figure 2 As shown, by applying light fields of different modes, the emission direction of the antenna beam can be controlled. Figure 2 In the figure, (a) is a waveform diagram of mode 0 transmission; (b) is a waveform diagram of mode 1 transmission; (c) is a waveform diagram of mode 2 transmission, wherein mode 0 is the initial state of the antenna, that is, the no-light state, and the antenna radiation angle does not change; mode 1 represents illuminating the right liquid crystal to achieve positive angle control of the antenna radiation; mode 2 represents illuminating the left liquid crystal to achieve negative angle control of the antenna radiation.

[0039] As preferred in this embodiment, Figure 3 As shown, the T-shaped power divider 12 has an input port 121 and two output ports 122, wherein the two output ports 122 are respectively connected to corresponding phase shifters 13, and the other ends of the two phase shifters 13 are respectively connected to a grounding layer 32 containing a rectangular groove 34 to form a coupled feeding structure.

[0040] As preferred in this embodiment, Figure 3 As shown, the T-shaped power divider 12 includes a first transmission line 123, a second transmission line 124 and a third transmission line 125; the first transmission line 123 and the second transmission line 124 are connected to form a T-shaped structure, and the two ends of the second transmission line 124 are connected to the third transmission line 125; wherein the first transmission line 123 adopts a transmission line with impedances Z0, Z1, and Z2, and Z2=Z0||Z0; Z1 adopts a quarter-wavelength impedance transformation branch for matching, that is, Z1=(Z0*Z2) 1 / 2 The impedance of the third transmission line 125 is Z0. That is, in this embodiment, Z0 is 50 ohms; Z2 = Z0 || Z0 = 25 ohms; Z1 = (Z0*Z2) 1 / 2 =35.35 ohms.

[0041] As preferred in this embodiment, Figure 3 As shown, the phase shifter 13 is a serpentine microstrip line, on which a number of equally spaced through holes are arranged. The other end of the serpentine microstrip line is connected to the ground layer 32 to form a coupled feeding structure, which transfers energy to the radiation patch 33 through the rectangular groove 34.

[0042] As a preferred embodiment of the present invention, the light-controlled liquid crystal 22 is prepared by mixing liquid crystal E7 with an azo dye, wherein the mass proportion of the azo dye is 1%.

[0043] As preferred in this embodiment, Figure 4 As shown, in the absence of light, the liquid crystal molecules of the light-controlled liquid crystal 22 are arranged according to the orientation direction of the orientation layer. After UV light is applied, the azo molecules undergo cis-trans isomerization, disturbing the arrangement of the liquid crystal molecules. If the external UV light field is removed, the azo dye molecules return to the reverse state, presenting a long rod-like molecular structure, and the liquid crystal molecules also return to their initial orientation.

[0044] The N=N double bond in the azo molecule undergoes cis-trans isomerization transformation between trans-cis and cis-trans under the action of light and heat, wherein trans-azobenzene is converted to cis under 365nm ultraviolet light irradiation;

[0045]

[0046] Herein, hv and kT represent applied light and heat, respectively. In this embodiment, hv is light with a wavelength of 365 nm.

[0047] In this embodiment, the entire control process is completed by remote control using a light field, without the need to use an electric field to achieve it using electrodes and leads; different light intensities can achieve different radiation on the antenna, can produce different resonant frequencies, and emit millimeter-wave beams of different spatial morphologies. In other words, by irradiating an external light field, the orientation of the liquid crystal mixture can be modulated, thereby changing the dielectric constant of the system in the millimeter-wave band. On the antenna, this change is reflected as a shift in the resonant frequency or radiation direction.

[0048] like Figure 5 As shown, the antenna resonant frequency of this embodiment is 10.2 GHz, and the resonance depth reaches -27 dB. Figure 6 As shown, in different working modes of the antenna, applying UV light of different intensities can realize the beam scanning of the antenna. When the UV light field distribution is modulated, the change of the dielectric constant of the light-controlled liquid crystal can be controlled, and multiple small radiation units will be formed in the antenna radiation area. The RF electromagnetic waves emitted by multiple radiation units will be superimposed on each other. By changing the size, number and distribution of the radiation units, the amplitude and phase distribution of the emitted electromagnetic waves can be effectively adjusted to obtain the desired electromagnetic wave shape. Through UV light fields of different patterns, the antenna beam can be regulated between ±16°.

[0049] In short, the entire phase control process is completed by remote control using light fields, without the need to use electrodes and leads with the help of electric fields; by customizing different UV light fields online, different phase distributions can be achieved on the phase shifter, thereby controlling the radiation unit to emit millimeter-wave beams with different spatial morphologies. In this embodiment, the state of azo molecules is changed by UV light fields to disturb the arrangement of liquid crystal molecules and thus change their dielectric constants, and a light-controlled liquid crystal material with a continuously adjustable dielectric constant and low dielectric loss is obtained by adjusting the external light intensity. The dielectric constant of the light-controlled liquid crystal is 2.7 to 3.3, which is lower than that of glass fiber epoxy resin, and has excellent dielectric properties. This type of light-controlled liquid crystal can be used in antennas, phase shifters, etc., and this type of radio frequency device has the advantages of light weight, small size, low power consumption, low manufacturing cost, easy implementation, and high reliability.

[0050] The above embodiments and descriptions are only for illustrating the principles and best embodiments of the present invention. Without departing from the spirit and scope of the present invention, the present invention may be subject to various changes and improvements, all of which fall within the scope of the present invention to be protected.

Claims

1. A phased array antenna based on light-controlled liquid crystal, characterized in that: It includes, from bottom to top, a power distribution transfer layer (1), a liquid crystal layer (2) and a ground radiation layer (3); The power division and shifting layer (1) comprises a first transparent PET substrate (11) and a T-shaped power divider (12) and a phase shifter (13) arranged on the first transparent PET substrate (11); The liquid crystal layer (2) comprises a second transparent PET substrate (21) and a light-controlled liquid crystal (22) arranged on the second transparent PET substrate (21); The ground radiation layer (3) comprises an FR-4 substrate (31), a ground layer (32) is arranged on the lower surface of the FR-4 substrate (31), and two symmetrically arranged rectangular grooves (34) are opened on the ground layer (32); and two radiation patches (33) are symmetrically arranged on the upper surface of the FR-4 substrate (31) corresponding to the rectangular grooves (34); and the emission direction of the antenna beam is controlled by applying light fields of different modes.

2. The phased array antenna based on light-controlled liquid crystal according to claim 1, characterized in that: The T-shaped power divider (12) has an input port (121) and two output ports (122), wherein the two output ports (122) are respectively connected to corresponding phase shifters (13), and the other ends of the two phase shifters (13) are respectively connected to a grounding layer (32) containing a rectangular groove (34) to form a coupled feeding structure.

3. The phased array antenna based on light-controlled liquid crystal according to claim 2, characterized in that: The T-shaped power divider (12) comprises a first transmission line (123), a second transmission line (124) and a third transmission line (125); the first transmission line (123) and the second transmission line (124) are connected to form a T-shaped structure, and the third transmission line (125) is connected to both ends of the second transmission line (124).

4. The phased array antenna based on light-controlled liquid crystal according to claim 3, characterized in that: The first transmission line (123) is a transmission line with impedances Z0, Z1, and Z2, and Z2=Z0||Z0; Z1 is matched by a quarter-wavelength impedance transformation branch, that is, Z1=(Z0*Z2) 1 / 2 ; The impedance of the third transmission line (125) is Z0.

5. The phased array antenna based on light-controlled liquid crystal according to claim 2, characterized in that: The phase shifter (13) is a serpentine microstrip line, on which a plurality of through holes arranged at equal intervals are arranged, and the other end of the serpentine microstrip line is connected to a grounding layer (32) with a rectangular groove (34) to form a coupled feeding structure, which transmits energy to a radiation patch (33) through the rectangular groove (34).

6. The phased array antenna based on light-controlled liquid crystal according to claim 1, characterized in that: The light-controlled liquid crystal (22) is prepared by mixing liquid crystal E7 and azo dye, wherein the mass proportion of the azo dye is 1%.

7. The phased array antenna based on light-controlled liquid crystal according to claim 6, characterized in that: In the absence of light, the liquid crystal molecules of the light-controlled liquid crystal (22) are arranged according to the orientation direction of the orientation layer. After UV light is applied, the azo molecules undergo cis-trans isomerization, disturbing the arrangement of the liquid crystal molecules. If the external UV light field is removed, the azo dye molecules return to the reverse state, presenting a long rod-shaped molecular structure, and the liquid crystal molecules also return to their initial orientation.

8. The phased array antenna based on light-controlled liquid crystal according to claim 7, characterized in that: The N=N double bond in the azo molecule undergoes cis-trans isomerization transformation between trans-cis and cis-trans under the action of light and heat, wherein trans-azobenzene is converted to cis under 365nm ultraviolet light irradiation; Here, hv and kT represent light and heat, respectively.

9. The phased array antenna based on light-controlled liquid crystal according to claim 1, characterized in that: The distance between the two radiation patches (33) is 20 mm.

10. The phased array antenna based on light-controlled liquid crystal according to claim 1, characterized in that: The grounding layer (32) is a copper-clad layer with gaps etched on the lower surface of the FR-4 substrate (31), and two rectangular grooves (34) are provided on the copper-clad layer.

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