Thin film microstrip reflective array unit and layout method for avoiding creases of microstrip reflective array

Abstract

The application discloses a thin film microstrip reflective array unit, which is sequentially and closely arranged and comprises a metal patch layer, a polyimide film layer, an air layer and a metal ground plate supporting layer; the application designs the microstrip reflective array antenna unit by taking the thin film as a medium, and has the advantages of simple structure, easy folding, light weight and the like, and can meet the folding and unfolding requirements of a large-aperture spaceborne antenna; considering that the thin film reflective array antenna is formed, there is a folding mark in the folding process, the application further discloses a microstrip reflective array layout method for avoiding the folding mark, analyzes layout conditions under square, triangular and circular grids, then calculates the number of units intersected with the folding mark under different layouts according to the folding mark position, and the folding mark is avoided by rotating or removing the units, and by adjusting the antenna units, the application first proposes a thin film microstrip reflective array unit layout scheme for avoiding the influence of the folding mark.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wireless communication and space deployable antenna, and relates to a thin film microstrip reflectarray unit.

[0002] The application also relates to a microstrip reflectarray layout method for avoiding folds. BACKGROUND

[0003] With the wide application of satellite technology in the fields of communication, radio astronomy observation, earth and space exploration, military reconnaissance and the like, the demand for high-gain antennas of satellite-borne systems is becoming more and more urgent; in order to meet the demand for high gain, the antenna aperture is usually several meters to more than one hundred meters, and due to the volume limitation of the satellite carrying space, the large-aperture antenna of the satellite-borne system needs to be folded and stored in the fairing of the carrier with relatively light mass.

[0004] The implementation of the satellite-borne deployable antenna mainly includes two types of reflector antennas and array antennas; the parabolic antenna has a large volume and heavy mass, and has limited electrical design freedom, which is difficult to match multiple purposes; the feed network of the phased array antenna is relatively complex, resulting in low radiation efficiency, high cost and heavy weight, and the folding and unfolding is limited.

[0005] The microstrip reflectarray antenna overcomes the disadvantages of large volume of the reflector antenna and high cost of the phased array antenna while achieving high gain; by using the characteristics of the planar structure of the microstrip reflectarray antenna and selecting a thin film material as the dielectric, an effective way to meet the demand for future large-aperture satellite-borne communication antennas is provided.

[0006] However, for the deployable thin film microstrip reflectarray unit, a large number of folds will be generated in the thin film structure during the folding and storage process, resulting in irreversible plastic deformation of the thin film structure; in the array layout design of the microstrip reflectarray antenna, the regular grid form is usually adopted for layout at a fixed interval, resulting in a large number of intersections between the antenna unit and the folds; when the antenna unit is located at the fold of the thin film, the plastic deformation generated will affect the electrical performance of the antenna. SUMMARY

[0007] The purpose of the present application is to provide a thin film microstrip reflectarray unit, which solves the problem of a large number of intersections between the unit and the folds caused by the regular grid layout of the array, thereby affecting the electrical performance of the antenna.

[0008] Another purpose of the present application is to provide a microstrip reflectarray layout method for avoiding folds.

[0009] The technical solution adopted by the present application is that the thin film microstrip reflectarray unit is sequentially and closely attached to a metal patch layer, a polyimide film layer, an air layer and a metal ground plate support layer.

[0010] The present application is also characterized in that:

[0011] The metal patch layer comprises two concentrically arranged equilateral triangle ring radiation patches.

[0012] The length of the side of the two concentrically arranged equilateral triangle ring radiation patches satisfies the mathematical formula L1=0.5*L, wherein L1 is the length of the side of the smaller equilateral triangle on the inside, and L is the length of the side of the larger equilateral triangle on the outside.

[0013] The width of the two concentrically arranged equilateral triangle ring radiation patches respectively satisfies the mathematical formula W1=0.1*L and W2=0.05*L, wherein W1 is the width of the larger equilateral triangle ring on the outside, and W2 is the width of the smaller equilateral triangle ring on the inside.

[0014] The thickness of the polyimide film layer is 0.1 mm, and the dielectric constant is 2.5.

[0015] The thickness h of the air layer is 2 mm.

[0016] The second technical solution of the present application is a microstrip reflectarray layout method for avoiding folds, which adopts a thin film microstrip reflectarray unit and is implemented according to the following steps:

[0017] Step 1: According to the basic period size determined in the unit analysis, the spacing between the array units in the full array layout of the unit grid is determined according to a certain period.

[0018] Step 2: The number of units arranged in the selected aperture of the antenna under the unit grid is calculated according to the period size determined in step 1.

[0019] Step 3: According to the selected fold form, the fold position is determined, and then the unit position intersecting with the fold is determined. The units at these positions are analyzed, and then the fold avoidance processing is performed.

[0020] The second technical solution of the present application is also characterized in that:

[0021] The unit grid in step 1 specifically includes a square, triangular, and circular grid.

[0022] In step 3, when the sizes of the microstrip reflectarray units are calculated according to the compensation phase, the reference phase is different, the layout of the microstrip reflectarray is different, the number of microstrip reflectarray units intersecting with the fold is different, and the fold avoidance processing is specifically: the unit positions intersecting with the fold are determined, the units at these positions are analyzed, it is determined whether the number of units can be adjusted to avoid the fold, if not, the units at the positions are removed, and finally the number of units that can be arranged after adjustment is obtained.

[0023] The present application has the advantages of

[0024] The foldable thin film microstrip reflectarray unit of the application has simple structure, is convenient to fold and light in quality, can meet the needs of large-aperture spaceborne antenna folding and unfolding, and after considering the existence of folding marks in the folding process after forming the thin film reflectarray antenna, the antenna unit is adjusted to first propose a thin film microstrip reflectarray unit layout scheme for avoiding the influence of folding marks. BRIEF DESCRIPTION OF DRAWINGS

[0025] Fig. 1(a) is a top view of the unit structure of the thin film microstrip reflectarray unit of the application;

[0026] Fig. 1(b) is a side view of the unit structure of the thin film microstrip reflectarray unit of the application;

[0027] Figure 2 is a phase shift curve of the thin film microstrip reflectarray unit of the application at different frequencies;

[0028] Figure 3 is a phase shift curve of the thin film microstrip reflectarray unit of the application at different incident angles;

[0029] Figure 4 is a reflection phase change curve of the thin film microstrip reflectarray unit of the application at different rotation angles;

[0030] Figure 5 is a winding folding mark schematic diagram of the thin film microstrip reflectarray unit of the application;

[0031] Figure 6 is a layout situation diagram of the microstrip reflectarray of the thin film microstrip reflectarray unit of the application;

[0032] Figure 7 is a full array layout schematic diagram of the thin film microstrip reflectarray unit of the application;

[0033] Figure 8 is a rotation after layout schematic diagram of the thin film microstrip reflectarray unit of the application;

[0034] Figure 9 is a unit layout schematic diagram of the thin film microstrip reflectarray unit of the application after removing the folding mark;

[0035] Figures 10-11 is an antenna gain pattern of the thin film microstrip reflectarray unit of the application;

[0036] Figure 12 is a gain change curve with frequency of the thin film microstrip reflectarray unit of the application.

[0037] In the figure, 1 is a metal patch layer, 101 is an outer larger equilateral triangle ring, 102 is an inner smaller equilateral triangle ring, 2 is a polyimide film layer, 3 is an air layer, and 4 is a metal floor support layer. DETAILED DESCRIPTION

[0038] The application will be described in detail below in combination with the drawings and specific embodiments.

[0039] The application provides a thin film microstrip antenna patch unit in the form of an equilateral triangle ring, as shown in Figure 1a and Figure 1b The unit structure diagram of the reflective array antenna unit is shown; the unit of the application is composed of four layers, namely a metal patch layer 1, a polyimide film layer 2, an air layer 3 and a metal ground plate support layer 4, and the unit of the application works at 30 GHz; the size of the basic period unit is 6 mm, the thickness of the polyimide film layer 2 is 0.1 mm, and the dielectric constant is 2.5; 101 and 102 are two concentrically arranged equilateral triangle ring radiation patches, wherein the side length relationship of the two equilateral triangle ring radiation patches is: L1=0.5×L, the width W1 of the larger triangle ring 101 located on the outside is 0.1×L, the width W2 of the smaller triangle ring 102 located on the inside is 0.05×L, and the coupling strength between the two resonant structures is adjusted by adjusting the size of the triangle side length L to control the unit phase; the thickness h of the air layer is 2 mm, and the introduction of the air layer makes the change of the unit reflection phase with the size more smooth, and a larger phase shift range is obtained.

[0040] The application also mentions a microstrip reflective array layout method for avoiding folds, which is implemented according to the following steps:

[0041] Step 1: According to the basic period size determined during unit analysis, the spacing between the array units in the full array layout of square, triangular and circular grids is determined according to a certain period.

[0042] Step 2: The number of units that can be arranged in the selected aperture (200 mm) under the three kinds of grids is calculated according to the period size determined above.

[0043] Step 3: According to the analysis, when the size of each microstrip reflective unit is calculated according to the compensation phase, due to the difference in reference phase, the layout of the microstrip reflective array will change, which will further lead to different numbers of microstrip reflective units intersecting with the folds. According to the selected fold form, the fold position is determined, the number of units intersecting with the folds under different reference phases in the full array of triangular, circular and square grids is calculated, the positions of the units intersecting with the folds are determined, and the units at these positions are analyzed to determine the number of units that can avoid the folds by adjusting (rotating). If the folds cannot be avoided by rotation, the units at the positions are removed, and finally the number of units that can be arranged after adjustment under different reference phases in the triangular, circular and square grids is obtained.

[0044] The advantages of the application will be described in combination with specific experiments.

[0045] As Figure 2 shown is Y polarization incident wave irradiation to the unit, change of the unit at different frequencies under the change of L; change L, the unit can achieve a phase change range of 399° at 30GHz; at the same time from Figure 2 It can also be seen that the phase shift curve remains good parallelism and changes relatively smoothly at different frequencies, with good wideband characteristics; high linearity and no phase sharp decline point occurs;

[0046] As Figure 3 shown is the change of the unit phase with size L under different incident angles; when the incident angle is between 0-20°, the reflected phase changes little with the incident angle, indicating that the unit is angle stable, and reasonable control of the position of the feed source can make the error of the unit at the edge of the array due to oblique incidence smaller;

[0047] As Figure 4 shown is the change curve of the reflected phase at 30GHz under different rotation angles; when L is fixed, the reflected phase of the unit is basically unchanged when the unit is rotated, which ensures that the adjustment of the unit does not affect the gain, sidelobe and other electrical properties of the antenna;

[0048] As Figure 5 shown is the antenna of the application, which is a winding fold line schematic diagram, under the known fold line distribution, the number of units intersecting with the fold line is calculated based on triangular grid, square grid and circular grid as reference, the units intersecting with the fold line are adjusted by rotating the units, and the final layout is obtained as Figure 6 shown; in the example analysis, the array aperture is 200mm, the microstrip reflective array antenna adopts the mode of offset feeding, the feed horn antenna is placed in the direction of 10° offset-X axis of the normal line of the reflective array surface, the main beam is in the positive direction of Z axis, and the focal ratio is 0.9;

[0049] As Figure 6 can be seen, in the case of triangular grid, the number of units that can be arranged after adjustment at the intersection with the fold line is the most; therefore, in the case of triangular grid, the optimal reference unit size is selected, three cases of full unit arrangement, partial unit rotation and direct removal of units at the fold line are considered, and through calculation, it is obtained that 955, 777 and 631 units can be arranged in the three cases respectively, and the sheet rates are 100%, 81.36% and 66.07% respectively, and the layout schematic diagrams of the three cases are as Figures 7-9 shown;

[0050] Figures 10-11 The gain patterns of the microstrip reflective array antenna at 30GHz under the three layout conditions are given, Figure 12The gain-frequency variation trends of the three layouts; From the above results, the microstrip reflectarray realized the main beam of 10°, The gain of the unit realized at the center frequency of 30 GHz is 32.1 dB, which can realize high gain and obtain narrow beam, and the sidelobe level is below-15 dB; From the above results, the microstrip reflectarray realized the main beam of 10°, Figures 10-11 It can be seen that with the decrease of the number of units, the gain of the reflectarray antenna decreases, the beam width is basically unchanged, and the maximum sidelobe level of the two main planes increases; The directional patterns of the two main planes in the three cases are symmetrical; After rotating some units, the patch rate can be increased by 15.3%, and the gain can be increased by 1.4 dB. From the above results, the microstrip reflectarray realized the main beam of 10°, Figure 12 It can be seen that the gain-frequency variation trends in the three cases are the same, and the maximum gain basically appears near 30 GHz; The 1-dB gain bandwidth changes in the three cases, and after directly removing the units, the 1-dB gain bandwidth is widened by 3.4%.

[0051] From the above analysis, it can be seen that rotating the units has little effect on the reflection phase when the incident wave is a Y-polarized wave; Under the condition of the known folding method, it is feasible to adjust the units intersecting the folds by rotating to avoid the folds, which provides a guarantee for avoiding the folds without affecting the gain, sidelobe and other electrical properties of the antenna.

Claims

1. A method of meander-avoiding microstrip reflectarray layout employing thin-film microstrip reflectarray cells, characterized in that, The method is implemented according to the following steps: Step 1: according to the basic period size determined in the unit analysis, the spacing between the array units in the full array layout of the unit grid is determined according to a certain period; Step 2: the number of units arranged in the selected aperture of the antenna under the unit grid is calculated according to the period size determined in step 1; Step 3: according to the selected fold form, the fold position is determined, and then the unit position intersecting with the fold is determined, the units at these positions are analyzed, and then the fold avoidance processing is performed; The fold avoidance processing specifically includes: determining the unit position intersecting with the fold, analyzing the units at these positions, determining the number of units that can avoid the fold by rotation, and if the fold cannot be avoided by rotation, the units at the position are removed, and finally the number of units that can be arranged after adjustment is obtained; The thin film microstrip reflective array unit comprises: a metal patch layer (1), a polyimide film layer (2), an air layer (3) and a metal ground plate support layer (4) which are closely arranged in sequence. The metal patch layer (1) comprises two concentrically arranged equilateral triangle ring radiation patches, including an outer larger equilateral triangle ring (101) and an inner smaller equilateral triangle ring (102), the side length of the two concentrically arranged equilateral triangle ring radiation patches satisfies the mathematical formula L1=0.5×L, wherein L1 is the side length of the inner smaller equilateral triangle, L is the side length of the outer larger equilateral triangle, W1=0.1×L, W2=0.05×L, wherein W1 is the horizontal distance between the vertex of the outer edge angle of the outer larger equilateral triangle ring (101) and the vertex of the inner edge angle corresponding to the outer edge angle, and W2 is the horizontal distance between the vertex of the outer edge angle of the inner smaller equilateral triangle ring (102) and the vertex of the inner edge angle corresponding to the outer edge angle, the thickness of the polyimide film layer (2) is 0.1mm, and the dielectric constant is 2.5; The thickness h of the air layer (3) is 2mm.

2. The microstrip reflectarray layout method that evades folds of claim 1, wherein, The unit grid in step 1 specifically includes a square, triangular and circular grid.

Images