Waveguide structure of liquid crystal phased-array antenna

Abstract

The utility model relates to a waveguide structure of a liquid crystal phased-array antenna, the liquid crystal phased-array antenna comprises a liquid crystal antenna and a waveguide part, the waveguide part is provided with an electromagnetic wave cavity channel, the electromagnetic wave cavity channel is provided with a feed port and a plurality of output ends, the liquid crystal antenna is arranged on the front surface of the waveguide part, and the plurality of output ends are connected with a coupler on the back surface of the liquid crystal antenna; the waveguide part comprises a metal waveguide plate with an electromagnetic wave cavity channel, and a plurality of output ends are distributed on the front surface of the metal waveguide plate in an array manner; the liquid crystal antenna is attached to the front surface of the metal waveguide plate; the left side and the right side of each column of output ends on the front face of the metal waveguide plate are provided with grooves A, the front end and the rear end of each output end are provided with grooves B, and the width and the depth of the grooves A and the grooves B are both 1 / 4 wavelength. The beneficial effects of the utility model are that under the condition that the normal performance of the liquid crystal phased-array antenna is maintained, the waveguide structure is compact, miniaturized and light, the cost is reduced, and the requirements of civil liquid crystal phased-array antenna equipment are met.

Description

TECHNICAL FIELD

[0001] The utility model relates to liquid crystal phased array technical field especially a waveguide structure of liquid crystal phased array antenna. BACKGROUND

[0002] For the phased array fed by microstrip power divider, the transmission loss of microstrip power divider is more obvious with the expansion of array, the gain increases less when further expanding the array, and the antenna efficiency is too low.

[0003] And for waveguide power divider, it has good wideband and low loss characteristics in Ka band, the transmission loss is generally about 0.1dB, and the loss does not increase obviously with the expansion of array size. Therefore, the waveguide structure of Ka band is a more common way for liquid crystal phased array.

[0004] At present, some liquid crystal phased arrays adopt electromagnetic wave channel structure design of one-to-sixteen waveguide power dividers, the cross section of electromagnetic wave channel (cavity) is rectangular, the width of standard Ka band waveguide aperture size (cross section rectangle) is 4.318mm, the depth is 8.636mm, and the transmission loss is less than 0.1dB in the range of 21.7GHz-33GHz.

[0005] Since the traditional liquid crystal phased array is mostly used in military, the liquid crystal phased array technology is gradually adopted in civil equipment at present, but the current civil equipment mostly adopts some design ideas of military - such design ideas are not particularly suitable, for example, the civil equipment requires miniaturization, light weight, and the performance cannot be reduced too much.

[0006] Therefore, the scheme mainly aims at civil liquid crystal phased array equipment, designs a miniaturized and light weight waveguide structure, and after miniaturization and reduction of structure, the waveguide structure also has excellent performance. SUMMARY

[0007] The utility model discloses a liquid crystal phased array antenna's waveguide structure, solve the problem of miniaturization, light weight of waveguide structure under the condition of guaranteeing excellent performance.

[0008] The utility model discloses a liquid crystal phased array antenna's waveguide structure, solve the problem of miniaturization, light weight of waveguide structure under the condition of guaranteeing excellent performance.

[0009] The waveguide part includes a metal waveguide plate, and the electromagnetic wave cavity is integrally arranged on the back surface of the metal waveguide plate; the electromagnetic wave cavity is a T-shaped cavity, and the plurality of output ends are arranged in an array on the front surface of the metal waveguide plate.

[0010] The liquid crystal antenna is attached to the front surface of the metal waveguide plate;

[0011] The left and right sides of each column of output ends at the front surface of the metal waveguide plate are provided with slots A, and the front and rear ends of each output end are provided with slots B, the width and depth of the slots A and B are each one quarter of a wavelength, and a compact structure of a back wave suppression coupler is formed.

[0012] As a preferred technical solution of the present application, the cross section of the electromagnetic wave cavity is rectangular, the left and right widths of the cross section are 1.8 mm, and the upper and lower depths are 8.636 mm, forming a miniaturized structure of a Ka wave band waveguide.

[0013] As a preferred technical solution of the present application, the electromagnetic wave cavity is a T-shaped cavity divided into sixteen parts, which has one feeding port and sixteen output ends.

[0014] Further, the electromagnetic wave cavity comprises a cavity a. The cavity a is provided along the front and rear directions, the front end of the cavity a is the feeding port, and the rear end is communicated with the middle point of the left and right provided cavities b; the two ends of the cavity b are respectively communicated with the middle points of the corresponding front and rear provided cavities c, and the two ends of the cavity c are respectively communicated with the middle points of the left and right provided cavities d. The two ends of the cavity d are respectively communicated with the corresponding front and rear provided cavities e, and the two ends of the cavity e are output ends; the length from one end of the cavity e to the end of the cavity d is L1, and the length from the other end of the cavity e to the end of the cavity d is L2; L1 is 7.94 mm longer than L2.

[0015] Further, the electromagnetic wave cavity is provided with a trapezoidal gradual change structure at each T-shaped branch position; the trapezoidal gradual change structure has a first step and a second step at the center position on the first step; the width of the corresponding cavity at the first step is 1.35 mm, and the width of the corresponding cavity at the second step is 0.9 mm; the upper and lower depths of the first step and the second step are 6.5 mm; the length of the second step along the corresponding cavity is 1.8 mm, and the length of the first step along the corresponding cavity is 5.56 mm.

[0016] As a preferred technical solution of the present application, the back surface of the metal waveguide plate is welded with a reinforcing rib and a bending groove body; the bending groove body has a bending groove, and the groove wall thickness at each position is consistent; after the bending groove body is welded on the back surface of the metal waveguide plate, the bending groove is closed to form an electromagnetic wave cavity.

[0017] The utility model has the following advantages:

[0018] I. Lightweight design: thinner metal waveguide plate is used, and then reinforcing ribs are welded on the back of the metal waveguide plate to form support in strength; then the bending groove body with bending grooves is welded on the back of the waveguide plate, so that the bending grooves are encapsulated into electromagnetic wave cavities; such design can ensure that the entire waveguide structure is relatively light in weight and can maintain a certain strength.

[0019] II. Compact and miniaturized design:

[0020] It should be noted that the liquid crystal antenna has a coupler on the back, which is connected to the output end on the waveguide part, and the coupler is a component that generates a large amount of radiation, which may have an adverse effect on the electromagnetic waves in the electromagnetic wave channel; therefore, in traditional designs, a certain distance is required between the coupler and the surface of the waveguide part, which increases the size of the entire liquid crystal phased array;

[0021] In this scheme, the liquid crystal antenna is directly attached to the metal waveguide plate (becoming compact), and slots A are provided on the left and right sides of the output end and slots B are provided at both ends - the output end is isolated, and the width and depth of slots A and slots B are both one-quarter of a wavelength - which can also suppress the back radiation of the coupler, i.e., maintaining the compactness of the liquid crystal phased array antenna while avoiding the impact of electromagnetic waves in the electromagnetic wave cavity;

[0022] It should be noted that in the electromagnetic wave channel of the existing one-to-sixteen waveguide power divider, the standard Ka-band waveguide aperture size (rectangular cross-section) is 4.318mm in width and 8.636mm in depth, and its transmission loss is less than 0.1dB within the range of 21.7GHz-33GHz;

[0023] In this scheme, in order to achieve waveguide miniaturization, in the electromagnetic wave channel of the one-to-sixteen waveguide power divider, the Ka-band waveguide aperture size (rectangular cross-section) is 1.8mm in width and 8.636mm in depth, which also has excellent results.

[0024] III. Others: T-shaped branches are used in the electromagnetic wave channel of the one-to-sixteen waveguide power divider, and stepped tapered waveguides are used at the nodes of the T-shaped branches for matching and transition to reduce reflection; in addition, the design of different branch arm lengths L1 and L2 compensates for the 180° phase difference caused by the e-plane T-branch, ensuring consistent phase of transmission to each port; through some simple structural design, the normal performance of the miniaturized liquid crystal phased array antenna is ensured.

[0025] IV. Therefore, this scheme makes the waveguide structure compact, miniaturized, and lightweight while maintaining the normal performance of the liquid crystal phased array antenna, meeting the needs of civilian liquid crystal phased array antenna equipment. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 Structure schematic view of the utility model;

[0027] Figure 2 Structure schematic view of the front of the metal waveguide plate;

[0028] Figure 3 Structure schematic view of the back of the metal waveguide plate;

[0029] Figure 4 Structure schematic view of the electromagnetic wave cavity;

[0030] Figure 5 Structure schematic view of the cavity e;

[0031] Figure 6 Waveguide power divider simulation S parameter amplitude value of the utility model;

[0032] Figure 7 Waveguide power divider simulation S parameter phase value of the utility model;

[0033] In the figure: 10-liquid crystal antenna, 20-metal waveguide plate, 21-groove A, 22-groove B, 30-electromagnetic wave cavity, 31-feed port, 32-output end, 40-stiffener, 50-bent groove body. DETAILED DESCRIPTION

[0034] The utility model will be further described below in combination with the drawings, but the protection scope of the utility model is not limited to the following.

[0035] It should be noted that the orientation or positional relationship indicated by "left", "right" and the like is based on the orientation or positional relationship shown in the drawings, or is the orientation or positional relationship commonly used when the utility model product is used, or is the orientation or positional relationship commonly understood by those skilled in the art. Such terms are only used to facilitate the description of the utility model and simplify the description, and do not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the utility model.

[0036] It should be noted that the embodiments in the utility model and the features and technical solutions in the embodiments can be combined with each other without conflict.

[0037] It should be noted that the general liquid crystal phased array antenna includes a liquid crystal antenna, a waveguide part, the liquid crystal antenna has a coupler, and the liquid crystal antenna is fixed on the waveguide part; the waveguide part has an electromagnetic wave cavity, the inlet of the electromagnetic wave cavity is a feed port, and the outlet is an output end connected with the coupler on the liquid crystal antenna. When working, the electromagnetic wave generated at the feed port is transmitted along the electromagnetic wave cavity and transmitted to the liquid crystal antenna through the coupler after coupling, and the liquid crystal antenna emits the electromagnetic wave signal (the liquid crystal antenna also has the function of phase shift control).

[0038] At present, in some liquid crystal phased array antennas, there is a design idea of designing the electromagnetic wave cavity into one sixteenth, and there is also a design idea of using T-shaped shunt when shunting. Such liquid crystal phased array antennas are mostly used in military, and if the design idea of military is still used in civilian liquid crystal phased array antenna equipment, the cost will soar.

[0039] Therefore, the embodiment provides a waveguide structure of a liquid crystal phased array antenna, which further makes the waveguide structure of the liquid crystal phased array antenna more compact, miniaturized and lightweight on the basis of the existing design idea of military liquid crystal phased array antenna, and reduces the cost without seriously affecting the performance.

[0040] Specifically, as shown in Figures 1-3 A waveguide structure of a liquid crystal phased array antenna is provided, the liquid crystal phased array antenna includes a liquid crystal antenna 10 and a waveguide part, and the waveguide part includes a metal waveguide plate 20.

[0041] Among them, the back of the metal waveguide plate 20 has an integral electromagnetic wave cavity 30, the electromagnetic wave cavity 30 is a T-shaped cavity and has an inlet and multiple outlets, the inlet of the electromagnetic wave cavity 30 is a feed port 31, and the outlet is an output end 32;

[0042] Among them, multiple output ends 32 are arranged in an array on the front surface of the metal waveguide plate 20, slots A21 are opened on the left and right sides of each column of output ends 32, and slots B22 are opened at the front and rear end positions of each output end 32, so that the output ends 32 are isolated; and the width and depth of the slots A21 and the slots B22 are both one fourth of the wavelength;

[0043] Among them, the back of the liquid crystal antenna 10 is arranged in close contact with the front surface of the metal waveguide plate 20, and multiple couplers are arranged on the back of the liquid crystal antenna 10, and the multiple couplers are connected with the corresponding output ends 32.

[0044] In operation, electromagnetic waves generated by the feeding port 31 are transmitted to the liquid crystal antenna 10 through the electromagnetic wave cavity 30, the output end 32 and the coupler. Electromagnetic radiation is also generated at the coupler, but the radiation is suppressed in the backward direction by the slot A 21 and the slot B 22, thereby avoiding the influence of the electromagnetic waves in the electromagnetic wave cavity 30. Since the back of the liquid crystal antenna 10 is attached to the front of the metal waveguide plate 20, the structure realizes the compact design of the waveguide structure while suppressing the radiation of the coupler.

[0045] The electromagnetic wave cavity 30 is described in further detail below.

[0046] The electromagnetic wave cavity 30 has a rectangular cross section with a left-right width of 1.8 mm and an up-down depth of 8.636 mm, so as to facilitate the feeding of the liquid crystal phased array without affecting the waveguide cutoff frequency, thereby forming a miniaturized structure of the Ka-band waveguide.

[0047] Referring to Figure 3 , the electromagnetic wave cavity 30 is a T-shaped cavity divided into sixteen parts, which has one feeding port 31 and sixteen output ends 32.

[0048] Further, the electromagnetic wave cavity 30 includes a cavity a; the cavity a is opened along the front-rear direction, the front end of the cavity a is the feeding port 31, and the rear end is connected to the middle point of the left-right arranged cavity b; the two ends of the cavity b are respectively connected to the middle points of the corresponding front-rear arranged cavity c, and the two ends of the cavity c are respectively connected to the middle points of the left-right arranged cavity d; the two ends of the cavity d are respectively connected to the corresponding front-rear arranged cavity e, and the two ends of the cavity e are the output ends 32; the length from one end of the cavity e to the end of the cavity d is L1, and the length from the other end of the cavity e to the end of the cavity d is L2; L1 is 7.92 mm longer than L2.

[0049] It should be noted that L1 is 7.94 mm longer than L2, i.e. ΔL = 7.94 mm, which mainly compensates for the difference of 180º between the two output ports of the ET waveguide power divider;

[0050] According to the TE10 mode of the waveguide, ΔL = π / β,

[0051] wherein: the phase constant:

[0052] Waveguide wavelength:

[0053] Free space wavelength:

[0054] Cutoff frequency:

[0055] c' is the speed of light, and a' is the width of the rectangular waveguide.

[0056] Further, in the electromagnetic wave cavity 30, a trapezoidal taper structure is arranged at each T-shaped branch position. Figure 5 As shown, the T-shaped branch of the electromagnetic wave cavity 30 refers to: one cavity (referred to as the front cavity) is divided into two cavities (referred to as the rear cavity) to the two sides, and the width (the width between the two walls) of the front cavity and the rear cavity is 1.8 mm (i.e. the width of W in the middle) and the depth is 8.636 mm. Figure 5 As shown, the trapezoidal taper structure arranged at each T-shaped branch position refers to: the wall of the rear cavity corresponding to the outlet of the front cavity has a first step, and the second step has a first step. Figure 5

[0057] Further, the width between the first step, the second step and the other wall of the corresponding electromagnetic wave cavity 30 is described. The width W1 between the first step and the other wall corresponding to the rear cavity is 1.35 mm, and the width W2 between the second step and the other wall corresponding to the rear cavity is 0.9 mm.

[0058] It should be noted that the design principle of the width between the first step, the second step and the other wall of the corresponding electromagnetic wave cavity 30 is: taking the width W between the two walls of the electromagnetic wave cavity 30 as the reference, the width of each step to the other wall of the electromagnetic wave cavity 30 is taken as the change amount of the equal difference data, for example, W1= (W-W / 4)=3W / 4=1.35, for example, W2= (W-W / 4-W / 4)=W / 2=0.9 mm.

[0059] It should be noted that the left and right width of the above T-shaped taper structure is a smooth transition dominant mode (TE10), which can avoid the excitation of high-order modes, thereby ensuring the stability of power distribution.

[0060] Further, the position and size of the first step and the second step are further described. The depth size is described, and the up and down depth of the first step and the second step is 6.5 mm. The up and down depth position is described, since the up and down depth of the electromagnetic cavity channel 30 is 8.636 mm, the spacing between the first step and the second step and the top wall of the electromagnetic wave cavity 30 is ((8.636-6.5) / 2) mm, and the spacing between the first step and the second step and the bottom wall of the electromagnetic wave cavity 30 is ((8.636-6.5) / 2) mm.

[0061] ​Further, the first step and the second step along the length direction of the electromagnetic wave cavity 30 are described. In the present scheme, the length W2 of the second step is consistent with the width of the electromagnetic wave cavity 30, that is, Y2=1.8mm. In the present scheme, the length Y1 of the first step is ((1.8+(1.8+0.08)X2)=5.56mm, because the second step is located at the middle of the first step, and the second step extends (1.8+0.8)mm to the left and right.

[0062] It should be noted that in some ordinary designs, the length of the second step is designed to be 2.75mm, and the length of the corresponding second step is designed to be (2.75X3)mm. The second step is located at the middle of the first step, and the second step extends 2.72mm to the left and right.

[0063] The entire waveguide structure is further described below.

[0064] Referring to Figure 3 , the back of the metal waveguide plate 20 is welded with a reinforcing rib 40 to enhance the stability and reliability of the structure. In addition, a bending groove body 50 is also welded on the back of the metal waveguide plate 20, and the bending groove body 50 has a bending groove with consistent groove wall thickness at each position. After the bending groove body 50 is welded on the back of the metal waveguide plate 20, the bending groove is closed to form the electromagnetic wave cavity 30. This design can reduce the thickness of the metal waveguide plate 20 as much as possible while ensuring the strength of the entire waveguide structure, making it lightweight and saving costs.

[0065] Further, the remaining blank positions on the back of the metal waveguide plate 20 after removing the reinforcing rib 40 and the bending groove body 50 can be used according to subsequent devices and hardware equipment.

[0066] Test experiment: as shown in Figure 6 and Figure 7 , simulation tests are performed on the present embodiment. The simulation data shows that the transmission coefficient S21 is about -12.05dB at 25.52GHz, and the insertion loss is very low. Within the working frequency band, the phase consistency is within 2°, and the design meets the expected requirements. This shows that even after compact design, miniaturization design and lightweight design, the waveguide structure of the liquid crystal antenna can still maintain normal performance.

[0067] The above embodiments only express the more preferred embodiments, and the description is more specific and detailed, but it cannot be understood as limiting the scope of the present utility model patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present utility model, a number of modifications and improvements can be made, which are within the protection scope of the present utility model.

Claims

1. A waveguide structure for a liquid crystal phased array antenna, the liquid crystal phased array antenna comprising a liquid crystal antenna (10) and a waveguide portion, the waveguide portion having an electromagnetic wave cavity (30), the electromagnetic wave cavity (30) having a feed port (31) and multiple output terminals (32), the liquid crystal antenna (10) being disposed on the front side of the waveguide portion, and the multiple output terminals (32) being connected to couplers on the back side of the liquid crystal antenna (10), characterized in that: The waveguide section includes a metal waveguide plate (20) and an integral electromagnetic wave cavity (30) on the back side of the metal waveguide plate (20); the electromagnetic wave cavity (30) is a T-shaped cavity, and multiple output terminals (32) are arrayed on the front side of the metal waveguide plate (20); The liquid crystal antenna (10) is attached to the front of the metal waveguide plate (20); The metal waveguide plate (20) has slots A (21) on the left and right sides of each column of output terminals (32) on the front side, and slots B (22) are opened at the front and rear ends of each output terminal (32). The width and depth of slots A (21) and B (22) are both quarter wavelengths, forming a compact structure for back-suppression of the coupler.

2. The waveguide structure of a liquid crystal phased array antenna according to claim 1, characterized in that: The electromagnetic wave cavity (30) has a rectangular cross-section with a width of 1.8 mm and a depth of 8.636 mm, forming a miniaturized structure of a Ka-band waveguide.

3. The waveguide structure of a liquid crystal phased array antenna according to claim 1 or 2, characterized in that: The electromagnetic wave channel (30) is a T-shaped channel divided into sixteen, which has a power supply port (31) and sixteen output terminals (32).

4. The waveguide structure of a liquid crystal phased array antenna according to claim 3, characterized in that: The electromagnetic wave cavity includes a cavity a; The cavity a is opened in the front-to-back direction. The front end of the cavity a is a power supply port (31), and the rear end is connected to the midpoint of the left and right cavities b. The two ends of the cavity b are respectively connected to the midpoint of the corresponding front and rear cavities c, and the two ends of the cavity c are respectively connected to the midpoint of the left and right cavities d. The two ends of the cavity d are respectively connected to the corresponding front and rear cavities e, and the two ends of the cavity e are output terminals (32). The length from one end of cavity e to the end of cavity d is L1, and the length from the other end of cavity e to the end of cavity d is L2; ​​L1 is 7.94 mm longer than L2.

5. The waveguide structure of a liquid crystal phased array antenna according to claim 3, characterized in that: In the electromagnetic wave cavity (30), a trapezoidal gradient structure is provided at each T-shaped branch position; The trapezoidal gradient structure has a first step and a second step at the center of the first step; the width of the corresponding cavity at the first step is 1.35 mm and the width of the corresponding cavity at the second step is 0.9 mm; the vertical depth of the first step and the second step is 6.5 mm; the length of the second step along the corresponding cavity is 1.8 mm and the length of the first step along the corresponding cavity is 5.56 mm.

6. The waveguide structure of a liquid crystal phased array antenna according to claim 1 or 2, characterized in that: The back of the metal waveguide plate (20) is welded with reinforcing ribs (40) and bending grooves (50). The bending groove (50) has a bending groove, and the wall thickness of the bending groove is consistent at each position; after the bending groove (50) is welded to the back of the metal waveguide plate (20), the bending groove is sealed into an electromagnetic wave cavity (30).

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