A low profile composite material stripline antenna unit, Ku band array antenna

Abstract

The present application relates to a kind of low profile composite material strip line antenna unit, Ku band array antenna, belong to radar and communication antenna field.Antenna unit includes polyimide single-sided copper-clad plate, PMI polymethacrylimide foam, polyimide single-sided copper-clad plate, PMI polymethacrylimide foam and polytetrafluoroethylene glass cloth double-sided copper-clad plate, six layers of different thickness plane material are made by bag pressure high temperature gluing.The upper layer polyimide copper-clad layer corrosion octagonal hole is used as the aperture of antenna unit radiation, polytetrafluoroethylene glass cloth double-sided copper-clad layer and metallized via array constitute the radiation cavity of antenna unit, the middle layer polyimide copper-clad plate is used as antenna feeder, and pentagonal patch is stretched into radiation cavity resonance, and electromagnetic wave is radiated through the aperture of upper layer.The present application has the characteristics of light weight, low profile, wide bandwidth, small loss, easy processing and the like by composite material strip line feed.

Description

Technical Field

[0001] The present invention relates to a low-profile composite material stripline antenna unit. The antenna adopts composite material stripline technology and is very suitable for use as a unit of a Ku-band array antenna with high requirements on profile, weight, bandwidth and efficiency. The antenna belongs to the field of radar and communication antennas. Background Art

[0002] Regarding the design requirements of high-gain and high-efficiency array antennas, microstrip array antennas can be directly used in frequency bands below the X-band, and waveguide slot array antennas can be used above the Ka-band. However, the Ku-band high-gain and high-efficiency array antenna is in a dilemma in terms of solution selection. The traditional microstrip antenna has low efficiency, and the waveguide slot array antenna has high processing cost and large volume and weight. It is necessary to develop a lightweight and efficient Ku-band array antenna.

[0003] Composite strip lines have the characteristics of light weight and low loss. If a composite strip line-fed radiating antenna unit can be designed, this problem will inevitably be solved in terms of structure and electricity. The existing antenna radiating unit uses composite strip line feeding, but the radiation direction is parallel to the plane structure direction. Figure 1 The radiation direction shown is along the X-axis or Y-axis. Assuming that the radiation direction is along the Y-axis, then this antenna unit is combined into an array antenna, and the radiation units can only be arranged along the X-axis and the Z-axis. Then the cross-section of the antenna (Y-direction dimension) is relatively high, and if the radiation units are arranged along the Z-direction, the entire array antenna is discrete and cannot be processed as a whole. An additional frame is required for installation and fixation, and the volume and weight will also increase. Summary of the Invention

[0004] The technical problems to be solved by the present invention are:

[0005] To address the technical issues of existing composite stripline antennas, which have high profiles and cannot be manufactured in one piece, the present invention provides a low-profile composite stripline antenna unit and a Ku-band array antenna composed of these low-profile composite stripline antenna units. However, during the design process, it was discovered that the symmetry of the antenna pattern was not symmetrical. To address this issue, the present invention further optimized the structure and added a reflective patch.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A low-profile composite stripline antenna unit, comprising, from top to bottom, a first polyimide single-sided copper-clad laminate, a first PMI polymethacrylimide foam, a second polyimide single-sided copper-clad laminate, a second PMI polymethacrylimide foam, a first polytetrafluoroethylene glass cloth double-sided copper-clad laminate, and a second polytetrafluoroethylene glass cloth double-sided copper-clad laminate. Epoxy film is laid between the layers and the layers are bonded together by bag pressing and high-temperature gluing. The unit is characterized by:

[0008] A first octagonal hole is etched out of the upper copper layer of the first polyimide single-sided copper-clad laminate to serve as an aperture for radiation of the antenna unit;

[0009] A feeder is provided on the upper copper layer of the second imide single-sided copper-clad laminate, and the feeder terminal is a pentagonal patch that extends into the first octagonal hole and the second octagonal hole. The pentagonal patch is transformed into a universal 50-ohm impedance port through a step;

[0010] The upper copper clad layer of the first polytetrafluoroethylene glass cloth double-sided copper clad laminate has a second octagonal hole etched away, while the lower copper clad layer is intact. The side length of the second octagonal hole is smaller than the first octagonal hole on the first copper clad layer. A first metallized through-hole array is provided along the edge of the second octagonal hole on the first polytetrafluoroethylene glass cloth double-sided copper clad laminate. The first metallized through-hole array does not penetrate into the second octagonal hole. The metallized through-hole array connects the first polytetrafluoroethylene glass cloth double-sided copper clad laminate and the second polytetrafluoroethylene glass cloth double-sided copper clad laminate.

[0011] The upper copper clad pattern of the second polytetrafluoroethylene glass cloth double-sided copper clad laminate has one more rectangular pattern than the upper copper clad pattern of the first polytetrafluoroethylene glass cloth double-sided copper clad laminate, and the lower copper clad layer is complete. A second rectangularly arranged metalized blind hole array is provided on the second polytetrafluoroethylene glass cloth double-sided copper clad laminate to connect the rectangular pattern with the lower copper clad layer.

[0012] A further technical solution of the present invention is that the feed line and the rectangular figure are on the same vertical line.

[0013] A further technical solution of the present invention: the hole diameters of the first metallized through-hole array and the second metallized through-hole array are 0.9 mm, and the center-to-center distance between adjacent holes is 1.5 mm.

[0014] A further technical solution of the present invention is as follows: the base material thickness of the first polyimide single-sided copper-clad laminate and the second polyimide single-sided copper-clad laminate is 0.035 mm, and the copper foil thickness is 1 OZ.

[0015] A further technical solution of the present invention: the first PMI polymethacrylimide foam and the second PMI polymethacrylimide foam are of model ROHACELL HF31, with a thickness of 1 mm.

[0016] A further technical solution of the present invention is as follows: the model of the polytetrafluoroethylene glass cloth double-sided copper clad laminate is Shengyi SG5220, the base material thickness is 3mm, and the copper foil thickness is 1OZ;

[0017] A further technical solution of the present invention is as follows: the thickness of the epoxy film is 0.05 mm, and the temperature of the bag pressing high-temperature bonding is controlled at 130°C.

[0018] A Ku-band array antenna is characterized by comprising a plurality of the above-mentioned low-profile composite material stripline antenna units, wherein the antenna units are arranged in two dimensions in a non-radiating direction.

[0019] A method for adjusting the symmetry of a directional pattern of a low-profile composite material stripline antenna unit is characterized in that the symmetry of the directional pattern is adjusted by adjusting the size of a rectangular pattern (6a-1).

[0020] The beneficial effects of the present invention are:

[0021] The present invention provides a low-profile composite stripline antenna unit, which uses composite stripline feeding to meet the requirements of lightness and low loss, and the antenna radiation direction is perpendicular to the plane structure. Figure 1 If the radiation direction shown is along the Z axis, then this antenna unit is combined into an array antenna, and the radiating units are arranged along the X and Y axes. The cross-section of the antenna (Z-direction dimension) is relatively low, and the entire array antenna can be processed as a whole, without the need for an additional frame for installation and fixation, and the volume and weight are relatively small. The present invention also provides a method for adjusting the symmetry of the directional pattern, which makes the directional pattern symmetrical by designing a reflective patch. Compared with the prior art, it has the following technical effects:

[0022] 1. Lightweight and low loss: The composite stripline technology used for processing and feeding is lightweight and has low loss. The composite stripline and printed circuit board lamination are combined to achieve lower loss and higher efficiency after array formation.

[0023] 2. Low profile: The radiation direction of the antenna unit is perpendicular to the plane structure, and the profile height is only the unit thickness.

[0024] 3. Bandwidth: The antenna bandwidth is widened by opening octagonal holes, punching metalized through-hole arrays, pentagonal patches at the feeder terminals, and step transformation.

[0025] 4. Symmetrical pattern: The feed line penetrating into the radiation cavity from one side can easily cause the E-plane pattern of the antenna to be asymmetric. The symmetry of the antenna pattern can be ensured by adjusting the size of the grounded rectangular reflective patch.

[0026] 5. Easy to assemble: By arranging the antenna units in two dimensions and processing them in one piece using composite stripline technology, it is easy to realize an array antenna with light weight, low profile and low loss.

[0027] 6. It has the characteristics of high processing precision and low cost, and is suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0029] Figure 1 This is an exploded view of the structure of a low-profile composite material stripline antenna unit of the present invention;

[0030] Figure 2 The stacking order and structural diagram of the planar materials of the low-profile composite material stripline antenna unit of the present invention;

[0031] Figure 3 A top view of a low-profile composite stripline antenna unit according to the present invention;

[0032] Figure 4 The metal pattern on the copper clad layer (1a) of the polyimide single-sided copper clad laminate (1) of the present invention;

[0033] Figure 5 The metal pattern on the copper clad layer (3a) of the polyimide single-sided copper clad laminate (3) of the present invention;

[0034] Figure 6 The metal pattern on the upper copper clad layer (5a) of the polytetrafluoroethylene glass cloth double-sided copper clad plate (5) of the present invention;

[0035] Figure 7 The metal pattern on the upper copper clad layer (6a) of the polytetrafluoroethylene glass cloth double-sided copper clad plate (6) of the present invention;

[0036] Figure 8 VSWR curve of the antenna according to the embodiment of the present invention;

[0037] Figure 9 is the directional pattern curve of the antenna according to the embodiment of the present invention.

[0038] 1-first polyimide single-sided copper-clad laminate, 2-first PMI polymethacrylimide foam, 3-second polyimide single-sided copper-clad laminate, 4-second PMI polymethacrylimide foam, 5-first polytetrafluoroethylene glass cloth double-sided copper-clad laminate, 1a-first copper clad layer, 1a-1-first octagonal hole, 3a-second copper clad layer, 3a-1-pentagonal patch, 3a-2-step, 3a-3-50 ohm impedance port, 5a-1-second octagonal hole, 5a-third copper clad layer, 5b-fourth copper clad layer, 5c-first metallized through-hole array, 6-second polytetrafluoroethylene glass cloth double-sided copper clad laminate, 6a-fifth copper clad layer, 6a-1-rectangular pattern, 6b-sixth copper clad layer, 6c-second metallized blind hole array. DETAILED DESCRIPTION

[0039] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0040] A low-profile composite stripline antenna unit provided in an embodiment of the present invention is composed of six layers of planar materials of different thicknesses, namely, from top to bottom, a first polyimide single-sided copper-clad laminate 1, a first PMI polymethacrylimide foam 2, a second polyimide single-sided copper-clad laminate 3, a second PMI polymethacrylimide foam 4, a first polytetrafluoroethylene glass cloth double-sided copper-clad laminate 5, and a second polytetrafluoroethylene glass cloth double-sided copper-clad laminate 6. Epoxy film is laid between the layers, and the layers are bonded together by bag pressing and high-temperature gluing.

[0041] Preferably, the base material thickness of the first polyimide single-sided copper clad laminate 1 and the second polyimide single-sided copper clad laminate 3 is 0.035 mm, and the copper foil thickness is 1 OZ; the model of the first PMI polymethacrylimide foam 2 and the second PMI polymethacrylimide foam 4 is ROHACELL HF31, with a thickness of 1 mm; the model of the first polytetrafluoroethylene glass cloth double-sided copper clad laminate 5 is Shengyi SG5220, with a base material thickness of 3 mm and a copper foil thickness of 1 OZ; the model of the second polytetrafluoroethylene glass cloth double-sided copper clad laminate 6 is Shengyi SG5220, with a base material thickness of 1 mm and a copper foil thickness of 1 OZ; the thickness of the epoxy film is 0.05 mm; and the temperature of the bag pressing high-temperature bonding is controlled at 130°C.

[0042] Specifically, the first octagonal hole 1a-1 of the first polyimide copper clad corrosion layer 1 serves as the aperture for radiation of the antenna unit. The size of the aperture determines the main resonant frequency of the antenna. The first octagonal hole 1a-1 can increase the adjustment amount to broaden the antenna bandwidth and ensure the symmetry of the radiation pattern.

[0043] The copper layer 3a of the second polyimide single-sided copper-clad laminate 3 faces upward, and the feeder terminal on the copper layer 3a is a pentagonal patch 3a-1, which extends into the first octagonal hole 1a-1 and the second octagonal hole 5a-1. The pentagonal patch 3a-1 is transformed into a universal 50-ohm impedance port 3a-3 through a step 3a-2.

[0044] The upper copper clad layer 5a of the first polytetrafluoroethylene glass cloth double-sided copper clad laminate 5 has the second octagonal hole 5a-1 corroded away, while the lower copper clad layer is intact. The side length of the second octagonal hole 5a-1 is slightly smaller than that of the first octagonal hole 1a-1 on the polyimide single-sided copper clad laminate.

[0045] The upper copper clad layer 6a of the second PTFE glass cloth double-sided copper-clad laminate 6 has an additional rectangular pattern 6a-1 compared to the upper copper clad layer 5a of the first PTFE glass cloth double-sided copper-clad laminate 5. The lower copper clad layer 6b is intact. A second metallized blind via array 6c arranged in a rectangular pattern connects the rectangular pattern 6a-1 to the lower copper clad layer 6b. The vias have a diameter of 0.9 mm and a spacing of 1.5 mm between adjacent vias. Rectangular pattern 6a-1 forms a reflective patch. Adjusting the size of rectangle 6a-1 ensures antenna pattern symmetry.

[0046] A first metallized through-hole array 5c is punched along the edge of the first polytetrafluoroethylene glass cloth double-sided copper-clad laminate 5, penetrating the first polytetrafluoroethylene glass cloth laminate 5 and the first polytetrafluoroethylene glass cloth laminate 6. The first metallized through-hole array 5c cannot be punched into the second octagonal hole 5a-1. The first metallized through-hole array 5c connects the upper copper-clad layer 5a and the lower copper-clad layer 6b. The hole diameter is 0.9 mm, and the spacing between adjacent holes is 1.5 mm.

[0047] The double-sided copper clad layer of the polytetrafluoroethylene glass cloth board and the metallized through-hole array form the radiation cavity of the antenna unit, forming multiple parasitic resonant frequencies of the antenna, thereby widening the antenna's operating bandwidth. At the same time, it can suppress back-radiation interference and improve the antenna's radiation efficiency. The metallized through-hole array helps isolate surface waves in the feeder dielectric layer and reduce mutual interference after the antenna array is formed. The copper layer of the second polyimide single-sided copper-clad board faces upward. The feeder terminal on the copper layer is a pentagonal patch that extends into the radiation cavity. By adjusting the size and relative position of the patch and the radiation cavity, the antenna resonates and radiates electromagnetic waves through the upper octagonal aperture. The pentagonal patch and step transformation at the feeder terminal facilitate impedance matching and can be fine-tuned to further widen the antenna bandwidth.

[0048] The embodiment of the present invention also provides a Ku-band array antenna, comprising a plurality of the above antenna units, as shown in FIG. Figure 1If the radiation direction is along the Z axis, then this antenna unit is combined into an array antenna, with the antenna units arranged along the X and Y axes. This results in a relatively low antenna profile (Z-direction dimension), similar to that of a single antenna unit. Furthermore, the entire array antenna can be manufactured as a single piece, eliminating the need for additional mounting frames, resulting in a relatively small size and weight.

[0049] An embodiment of the present invention also provides a method for adjusting the symmetry of the directional pattern of a low-profile composite material stripline antenna unit. To address the asymmetric directional pattern of the above-mentioned antenna unit, the present invention provides a rectangular pattern 6a-1 as a reflective patch on the fifth copper clad layer 6a of the second polytetrafluoroethylene glass cloth double-sided copper clad laminate 6. The symmetry of the directional pattern is adjusted by adjusting the size of the pattern.

[0050] The metal layer pattern dimensions of the low-profile composite material stripline antenna unit of the present invention are shown in Table 1.

[0051] Table 1 Graphic dimensions of each metal layer of the antenna

[0052] W1(mm) W2(mm) W3(mm) W4(mm) W5(mm) W6(mm) W7(mm) 5 4.8 5 4.9 4.5 4.8 1.4 W8(mm) W9(mm) W10(mm) L1(mm) L2(mm) L3(mm) L4(mm) 2 2.8 4.8 2.8 3.4 2 5.6

[0053] The finished low-profile composite stripline antenna unit measures 28mm×28mm×6.4mm and weighs only 5g (excluding connectors).

[0054] Figure 8 is the standing wave curve of the antenna. It can be seen from the figure that the voltage standing wave ratio is less than 2 in the entire Ku band (12GHz~18GHz).

[0055] Figure 9 These are the E-plane radiation patterns of the antenna at 12 GHz, 15 GHz, and 18 GHz. It can be seen from the figure that the E-plane radiation patterns of the antenna are symmetrical at high, medium, and low frequencies.

[0056] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present invention, and these modifications or replacements should all be included in the scope of protection of the present invention.

Claims

1. A low-profile composite stripline antenna unit, comprising, from top to bottom, a first polyimide single-sided copper-clad laminate (1), a first PMI polymethacrylimide foam (2), a second polyimide single-sided copper-clad laminate (3), a second PMI polymethacrylimide foam (4), a first polytetrafluoroethylene glass cloth double-sided copper-clad laminate (5), and a second polytetrafluoroethylene glass cloth double-sided copper-clad laminate (6), epoxy films being laid between the layers and being formed by bag pressing and high-temperature gluing, characterized in that: The upper copper layer of the first polyimide single-sided copper-clad laminate (1) is etched to remove a first octagonal hole (1a-1) to serve as an aperture for radiation of the antenna unit; A feeder is provided on the upper copper layer of the second polyimide single-sided copper-clad laminate (3); the feeder terminal is a pentagonal patch (3a-1) extending into the first octagonal hole (1a-1) and the second octagonal hole (5a-1); the pentagonal patch (3a-1) is transformed into a universal 50-ohm impedance port (3a-3) via a step (3a-2); The upper copper layer of the first polytetrafluoroethylene glass cloth double-sided copper clad laminate (5) has the second octagonal hole (5a-1) corroded away, while the lower copper layer is intact. The side length of the second octagonal hole (5a-1) is smaller than the first octagonal hole (1a-1) on the first copper clad layer (1a). A first metallized through-hole array (5c) is provided along the edge of the second octagonal hole (5a-1) on the first polytetrafluoroethylene glass cloth double-sided copper clad laminate (5). The first metallized through-hole array (5c) does not penetrate into the second octagonal hole (5a-1). The first metallized through-hole array (5c) connects the first polytetrafluoroethylene glass cloth double-sided copper clad laminate (5) and the second polytetrafluoroethylene glass cloth double-sided copper clad laminate (6); The upper copper clad pattern of the second polytetrafluoroethylene glass cloth double-sided copper clad laminate (6) has an additional rectangular pattern compared to the upper copper clad pattern of the first polytetrafluoroethylene glass cloth double-sided copper clad laminate (5), and the lower copper clad layer is complete. A second metallized blind hole array (6c) arranged in a rectangular pattern is provided on the second polytetrafluoroethylene glass cloth double-sided copper clad laminate to connect the rectangular pattern (6a-1) with the lower copper clad layer.

2. The low-profile composite stripline antenna unit according to claim 1, characterized in that: The feed line and the rectangular figure (6a-1) are on the same vertical line.

3. The low-profile composite stripline antenna unit according to claim 1, characterized in that: The first metallized through-hole array (5c) and the second metallized blind hole array (6c) have a hole diameter of 0.9 mm, and a center-to-center distance between adjacent holes of 1.5 mm.

4. The low-profile composite stripline antenna unit according to claim 1, characterized in that: The base material thickness of the first polyimide single-sided copper-clad laminate (1) and the second polyimide single-sided copper-clad laminate (3) is 0.035 mm, and the copper foil thickness is 1 oz.

5. The low-profile composite stripline antenna unit according to claim 1, characterized in that: The first PMI polymethacrylimide foam (2) and the second PMI polymethacrylimide foam (4) are of model ROHACELLHF31, with a thickness of 1 mm.

6. The low-profile composite stripline antenna unit according to claim 1, characterized in that: The model of the polytetrafluoroethylene glass cloth double-sided copper clad laminate (5) is Shengyi SG5220, the base material thickness is 3mm, and the copper foil thickness is 1OZ.

7. The low-profile composite stripline antenna unit according to claim 1, characterized in that: The thickness of the epoxy film is 0.05 mm, and the temperature of the bag pressing high-temperature bonding is controlled at 130°C.

8. A Ku-band array antenna, characterized in that: The invention comprises a plurality of low-profile composite material stripline antenna units according to claim 1, wherein the antenna units are arranged in two dimensions in a non-radiating direction.

9. A method for adjusting the symmetry of the directional pattern of a low-profile composite stripline antenna unit according to claim 1, characterized in that: The symmetry of the directional pattern is adjusted by adjusting the size of the rectangular pattern (6a-1).

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