Low-temperature ceramic-based liquid crystal phased-array antenna and manufacturing process thereof

Abstract

The invention provides a low-temperature ceramic-based liquid crystal phased-array antenna and a manufacturing process thereof, the low-temperature ceramic-based liquid crystal phased-array antenna comprises an antenna array surface layer, a first coupling layer, a liquid crystal phase shifter layer, a second coupling layer and a feed network layer which are stacked in sequence, and the antenna array surface layer, the first coupling layer, the second coupling layer and the feed network layer all adopt low-temperature ceramic substrates; the liquid crystal phase shifter layer is composed of two layers of glass substrates etched with microwave circuits and liquid crystals poured between the two layers of glass substrates, and the low-temperature ceramic substrates of the first coupling layer and the second coupling layer are bonded with the glass substrates of the liquid crystal phase shifter layer through solid glue. According to the invention, the low-temperature ceramic substrate and the glass substrate of the liquid crystal phase shifter are adhered, so that the problems of warping and tearing of the liquid crystal phased-array antenna are prevented, and the service life of the antenna is prolonged; moreover, the loss is reduced, and the performance of the phased-array antenna is improved.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a low-temperature ceramic-based liquid crystal phased array antenna and a manufacturing process thereof. Background Art

[0002] Phased array antenna is an antenna composed of multiple antenna units, which mainly include antenna units, phase shifter units and feed network units. The relative phase difference between each antenna unit is controlled by the phase shifter, thereby changing the direction of the entire array transmitting or receiving beam. Liquid crystal phased array antenna is a type of phased array antenna. Its phase shifter unit uses liquid crystal material. The dielectric constant of liquid crystal material can be changed according to the voltage applied to it, which allows liquid crystal to exhibit different electromagnetic properties under different voltages. For example, different dielectric constants have different time delay characteristics for the phase of microwaves.

[0003] At present, there are four main forms of liquid crystal phased array antennas:

[0004] 1. Add liquid crystal material directly to the radiating element of the antenna unit to form a holographic phased array antenna;

[0005] 2. The antenna unit adopts a PCB board, which is combined with a glass liquid crystal phase shifter;

[0006] 3. The antenna unit adopts metal waveguide, which is combined with metal waveguide and glass liquid crystal phase shifter;

[0007] 4. As in patent CN10600874A, the antenna unit uses low-temperature ceramic as a substrate, digs a hole in the low-temperature ceramic substrate, and fills a small amount of liquid crystal into the hole.

[0008] The above four liquid crystal phased array antennas have the following disadvantages:

[0009] 1. For the first type of liquid crystal phased array antenna, the processing accuracy requirements of the holographic radiation unit are too high, resulting in very high costs; in addition, the basic structure of the holographic radiation unit is a resonant structure, and its bandwidth is too narrow to meet the needs of today's broadband communications.

[0010] 2. For the fourth type of liquid crystal phased array, a cavity is opened on the ceramic to seal the liquid crystal. Since the ceramic is opaque, the currently mature processing technology of liquid crystal displays cannot be used to encapsulate the liquid crystal. In addition, low-temperature (co-fired) ceramics inherently have an uncontrollable shrinkage error of 0.3%. The more radiating units there are, the larger the size and area of ​​the antenna array, which makes the alignment accuracy of the fourth type of liquid crystal phased array antenna lower, and it is basically in a state that cannot be controlled and produced.

[0011] 3. For the second and third liquid crystal antennas using PCB and metal waveguide, due to the large difference in thermal expansion coefficients between PCB or metal and glass, in the actual working environment, due to temperature changes, the second and third liquid crystal phased array antennas are prone to antenna surface warping and stress tearing at the junction of PCB or metal waveguide and glass, which seriously affects the electrical performance and life of the antenna. Summary of the invention

[0012] In view of this, an object of the present invention is to provide a low temperature ceramic-based liquid crystal phased array antenna and a manufacturing process thereof to solve the above-mentioned problems.

[0013] In a first aspect, a low-temperature ceramic-based liquid crystal phased array antenna is provided, comprising: an antenna array surface layer, a first coupling layer, a liquid crystal phase shifter layer, a second coupling layer and a feed network layer stacked in sequence, wherein the antenna array surface layer, the first coupling layer, the second coupling layer and the feed network layer all adopt a low-temperature ceramic substrate, the liquid crystal phase shifter layer is composed of two glass substrates engraved with microwave circuits and liquid crystal poured between the two glass substrates, the low-temperature ceramic substrates of the first coupling layer and the second coupling layer are bonded to the glass substrate of the liquid crystal phase shifter layer by solid glue, and the sintering temperature of the low-temperature ceramic substrate is 850-900°C.

[0014] Optionally, the antenna array layer, the first coupling layer, the liquid crystal phase shifter layer, the second coupling layer and the feed network layer all adopt a planar structure.

[0015] Optionally, the antenna array surface layer is composed of a plurality of antenna units, each antenna unit includes a radiation surface and a back panel surface, and an active radio frequency device is installed on the back panel surface of each antenna array unit.

[0016] Optionally, a gold-plated welding pad is provided on the back panel surface of each antenna array unit, the gold-plated welding pad is co-fired with the antenna array surface layer, and the active radio frequency device is connected to the gold-plated welding pad by gold wire welding.

[0017] Optionally, the first coupling layer is provided with metal cavities having the same number as the antenna units, and the active radio frequency device on the back panel surface of each antenna unit is buried in a metal cavity.

[0018] Optionally, the metal cavity consists of a metal sidewall, an upper and lower layer of metal grid ground and a cavity, the metal sidewall is arranged around the periphery of the cavity, and the metal sidewall consists of a plurality of metal through holes; the upper and lower layers of metal grid ground are respectively composed of a metal grid ground at the bottom of the antenna array layer and a metal grid ground at the bottom of the cavity.

[0019] Optionally, the metal through holes are arranged according to a preset arrangement rule.

[0020] Optionally, a preset distance is provided between the metal sidewall and the cavity.

[0021] In a second aspect, a manufacturing process of a low-temperature ceramic-based liquid crystal phased array antenna is provided, comprising:

[0022] Active radio frequency devices corresponding to the number of antenna units are welded on the back surface of the low-temperature ceramic substrate of the antenna array layer;

[0023] Preset cavities on the low-temperature ceramic substrate of the first coupling layer, the same number as the active radio frequency devices, and form sealed metal cavities based on the cavities, and bury each active radio frequency device in a corresponding metal cavity;

[0024] Welding together the side of the low-temperature ceramic substrate of the antenna array layer on which the active radio frequency device is welded and the side of the low-temperature ceramic substrate of the first coupling layer on which the metal cavity is welded;

[0025] bonding the upper glass substrate of the liquid crystal phase shifter layer to the other side of the low temperature ceramic substrate of the first coupling layer;

[0026] One side of the low-temperature ceramic substrate of the second coupling layer is bonded to the lower glass substrate of the liquid crystal phase shifter layer; wherein the second coupling layer and the feeding network layer are co-fired together.

[0027] Optionally, presetting cavities on the low-temperature ceramic substrate of the first coupling layer, which have the same number as the number of active radio frequency devices, and forming sealed metal cavities based on the cavities comprises:

[0028] Punching a plurality of through holes along the periphery of the cavity;

[0029] Metal is poured into each through hole to form a metal through hole. Several metal through holes form a metal side wall around the cavity. The metal side wall, the metal grid ground at the bottom of the antenna array layer and the metal grid ground at the bottom of the cavity together form a sealed metal cavity.

[0030] The low-temperature ceramic-based liquid crystal phased array antenna and its manufacturing process provided by the present invention include an antenna array surface layer, a first coupling layer, a liquid crystal phase shifter layer, a second coupling layer and a feed network layer which are stacked in sequence, wherein the antenna array surface layer, the first coupling layer, the second coupling layer and the feed network layer all adopt a low-temperature ceramic substrate, the liquid crystal phase shifter layer is composed of two glass substrates engraved with microwave circuits and liquid crystal poured between the two glass substrates, and the low-temperature ceramic substrates of the first coupling layer and the second coupling layer and the glass substrate of the liquid crystal phase shifter layer are bonded by solid glue.

[0031] In the present invention, since the thermal expansion coefficients of low-temperature ceramics and glass are substantially the same, the low-temperature ceramic substrate is bonded to the glass substrate of the liquid crystal phase shifter, thereby preventing the warping and tearing of the liquid crystal phased array antenna and extending the life of the antenna; the dielectric constant of the low-temperature ceramic material itself is close to that of glass, and can achieve smooth transmission of electromagnetic waves from the antenna array surface to the liquid crystal phase shifter, thereby effectively reducing losses and improving the performance of the phased array antenna itself.

[0032] In addition, in terms of application value, since the production of liquid crystal phase shifters uses mature liquid crystal display technology, the manufacturing cost has been greatly reduced compared to traditional phased array antennas, and has reached a cost range acceptable to customers using satellite communications.

[0033] At the same time, the design of burying active RF components in metal cavities in large quantities, individually, planarly, and one-to-one correspondence, which is the first of its kind in the present invention, shortens the transmission distance between electromagnetic signals and active RF components to the maximum extent, effectively improving the performance of the phased array antenna; it also makes the overall phased array antenna more planar and ultra-thin; the combination of ultra-thinness and good heat dissipation performance of low-temperature ceramics makes the phased array antenna of the present invention have a greater advantage in heat dissipation processing than other phased array antennas.

[0034] Furthermore, the unique design of the metal cavity, compared with the traditional ceramic packaging of each RF chip, not only further reduces the cost of this phased array antenna, but also makes its overall integration higher, more beautiful and more efficient.

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 A schematic diagram showing the layered structure of a low-temperature ceramic-based liquid crystal phased array antenna provided by an embodiment of the present invention is shown;

[0038] Figure 2 A schematic diagram of the finished product structure of a low-temperature ceramic-based liquid crystal phased array antenna provided by an embodiment of the present invention is shown;

[0039] Figure 3A schematic plan view of the radiation surface of the antenna array layer provided in an embodiment of the present invention is shown;

[0040] Figure 4 A circuit diagram of a conventional T / R module in the prior art is shown;

[0041] Figure 5 A schematic structural diagram showing an active radio frequency device buried between the antenna array surface layer and the first coupling layer of a low-temperature ceramic-based liquid crystal phased array antenna provided by an embodiment of the present invention;

[0042] Figure 6 A schematic diagram of the structure of a first coupling layer provided in an embodiment of the present invention is shown;

[0043] Figure 7 A schematic diagram showing a process flow of a low-temperature ceramic-based liquid crystal phased array antenna manufacturing process provided by an embodiment of the present invention;

[0044] Figure 8 A schematic diagram of the layered structure of the first coupling layer provided by an embodiment of the present invention is shown.

[0045] Explanation of the main component symbols: 100, antenna array layer; 200, first coupling layer; 300, liquid crystal phase shifter layer; 400, feed network layer; 500, second coupling layer; 600, adhesive layer; 700, low-temperature ceramic raw porcelain tape; 101, antenna array unit; 102, gold-plated welding pad; 103, active RF device; 104, microwave circuit; 105, gold wire; 201, metal cavity; 2011, cavity; 2012, metal sidewall; 202, metal grid ground; 301, glass substrate; 302, liquid crystal. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention.

[0047] The embodiment of the present invention provides a low temperature ceramic-based liquid crystal phased array antenna, such as Figure 1 and Figure 2 As shown, it is an 8*8 array of low-temperature ceramic-based liquid crystal phased array antenna. Figure 1 This is a layered schematic diagram of the low-temperature ceramic-based liquid crystal phased array antenna; Figure 2 This is a schematic diagram of the finished product of the low-temperature ceramic-based liquid crystal phased array antenna.

[0048] The low-temperature ceramic-based liquid crystal linear array antenna comprises: an antenna array layer 100, a first coupling layer 200, a liquid crystal phase shifter layer 300, a second coupling layer 500 and a feed network layer 400 stacked in sequence, wherein the antenna array layer 100, the first coupling layer 200, the second coupling layer 500 and the feed network layer 400 all adopt a low-temperature ceramic substrate, the liquid crystal phase shifter layer 300 is composed of two layers of glass substrates 301 engraved with microwave circuits and liquid crystal 302 poured between the two layers of glass substrates 301, and the low-temperature ceramic substrates of the first coupling layer 200 and the second coupling layer 500 and the glass substrate 301 of the liquid crystal phase shifter layer 300 are bonded by solid glue. The solid glue can be glass glue, which is applied on the surface of the glass substrate 301 to form an adhesive layer 600. The sintering temperature of the low-temperature ceramic substrate is 850-900°C.

[0049] The antenna array surface layer 100 mainly functions to receive and radiate electromagnetic waves, and is formed by co-firing multiple layers of low-temperature ceramic raw tape and metal circuits. In a feasible implementation, the co-firing process is to first cut a number of low-temperature ceramic raw tape sheets 700, punch holes on each layer of raw tape sheets according to the number of antenna array units 101 designed, pour silver paste into each hole, and then print the pre-designed metallized microwave circuit 104 on the silver paste area, stack the layers of raw tape sheets, and sinter them once to obtain the antenna array surface layer 100. Figure 3 The figure shows the radiation surface of the antenna array layer 100. Each circular area is the radiation surface corresponding to each antenna unit. Of course, other metal holes can be punched according to the circuit design requirements.

[0050] The function of the first coupling layer 200 is to transmit the electromagnetic waves received by the antenna array layer 100 to the glass liquid crystal phase shifter in a field coupling manner or to output the signal of the phase shifter to the antenna array layer 100 .

[0051] The main function of the liquid crystal phase shifter layer 300 is to adjust the amplitude and phase of the input signal of each antenna array unit 101, so as to realize the synthesis of the entire antenna array beam and the change of the beam direction. By controlling the liquid crystal material, the continuous adjustment of the signal phase can be realized, so as to realize the continuous scanning of the beam. The phase shifter is made by engraving the corresponding microwave circuit between the two layers of glass substrates 301, and using the mature liquid crystal panel production process, the radio frequency liquid crystal is poured between the two layers of glass substrates 301 with the microwave circuit to form a glass liquid crystal phase shifter. Finally, by adjusting the bias voltage, the dielectric constant of the liquid crystal 302 itself is changed to realize the regulation of the electromagnetic wave phase.

[0052] The function of the second coupling layer 500 is to output the signal of the liquid crystal phase shifter layer 300 to the feeding network layer 400 in a field coupling manner or to input the signal of the feeding network layer 400 into the liquid crystal phase shifter layer 300 .

[0053] The function of the feed network layer 400 is to synthesize the electromagnetic wave signals of all antenna array units 101, amplify and frequency-convert them, and convert the electromagnetic wave signals into intermediate frequency electrical signals for output, or vice versa, convert electrical signals into electromagnetic wave signals and radiate them out.

[0054] When receiving antenna signals, the signals are transmitted along the antenna array layer 100, the first coupling layer 200, the liquid crystal phase shifter layer 300, the second coupling layer 500 and the feed network layer 400. When transmitting antenna signals, the signals are transmitted along the feed network layer 400, the second coupling layer 500, the liquid crystal phase shifter layer 300, the first coupling layer 200 and the antenna array layer 100 in reverse.

[0055] Since low-temperature ceramics are glass ceramics based on quartz, the thermal expansion coefficients of low-temperature ceramics and glass itself are basically the same, about 8.9x10-6 (dL / L), so the low-temperature ceramic substrate is bonded to the glass substrate of the liquid crystal phase shifter to prevent the warping and tearing of the liquid crystal phased array antenna, while overcoming the various shortcomings of the PCB substrate in the traditional liquid crystal phased array. Compared with the PCB substrate, it has the following advantages:

[0056] 1. In the microwave and millimeter wave frequency band, when an antenna is made of low-temperature ceramic material with a dielectric constant of 5.5, its RF performance is better than that of a PCB substrate with the same dielectric constant;

[0057] 2. The ceramic substrate has high mechanical strength and bending resistance, and has high reliability and stability in severe environments with large temperature changes and other harsh environments, avoiding the problem of antenna warping caused by temperature changes;

[0058] 3. Suitable for applications in environments with large temperature changes (such as aerospace), which facilitates the heat dissipation of the antenna and can effectively extend the life of the antenna;

[0059] 4. It can realize smooth transmission of electromagnetic waves from the antenna array layer 100 to the liquid crystal phase shifter layer 300, which can effectively reduce losses and improve the performance of the phased array antenna itself.

[0060] Based on the above embodiment, the antenna array layer 100, the first coupling layer 200, the liquid crystal phase shifter layer 300, the second coupling layer 500 and the feed network layer 400 all adopt a planar structure.

[0061] By adopting a planar structure, the complexity of micro-assembly is greatly simplified, making it easier to produce on a large scale.

[0062] In the background technology, the second and third types of liquid crystal phased array antennas are both passive liquid crystal phased arrays and cannot be active. Taking the PCB substrate as an example, the specific reasons are as follows:

[0063] To achieve active antenna, the T / R module needs to be soldered on the surface of the PCB substrate, and a T / R module needs to be designed and produced for the transmit and receive channels of each antenna array unit 101. This also causes a sharp increase in the thickness and weight of the antenna. In addition, in the millimeter wave frequency band, the area of ​​the antenna array unit 101 is small, and it is difficult to realize a complex T / R module.

[0064] And because the phased array antenna is composed of thousands of channels, each channel requires a T / R module, which is expensive and difficult to promote to the communications industry, especially the civilian communications industry.

[0065] like Figure 4 The figure shows a schematic diagram of a conventional T / R module, through which one can roughly understand its complexity. It is also understandable that the price of a conventional phased array antenna composed of tens of thousands of such T / R modules is high.

[0066] At the same time, in order to avoid cross-interference of signals between adjacent channels, a metal shielding cavity needs to be set up for each T / R module and each T / R module needs to be buried inside it.

[0067] There are two ways to set a metal cavity for each T / R module on the PCB:

[0068] One way is to dig a cavity on the PCB and keep the bottom of the cavity flat; then print the circuit on the bottom plane of the cavity, and finally plate copper on the four walls of the cavity to form a metal cavity. The cost of this processing method will be astronomical. Therefore, it is not feasible to dig a large number of cavities on PCB.

[0069] Another way is to pre-make a metal cavity made of low-temperature ceramic or high-temperature ceramic with a metal surface inside for each T / R module, encapsulate the T / R module inside, and then weld it to the PCB antenna backplane. However, the cost of making thousands of such ceramic metal cavities is also very high. As a result, it is not feasible.

[0070] The method of using metal waveguide has the same problem as that of PCB substrate, and because glass cannot form through holes, it is also impossible to make holes on the glass substrate 301 of the glass liquid crystal phase shifter and bury the active RF device 103 in the glass to achieve active operation. Therefore, the second and third liquid crystal phased arrays in the background technology cannot achieve active working mode. The gain of the passive liquid crystal phased array antenna is small, resulting in the G / T value cannot meet the requirements, and the antenna receiving rate is difficult to meet the needs of modern communications.

[0071] However, the above problems can be solved by combining the low-temperature ceramic substrate of the embodiment of the present invention with the glass liquid crystal phase shifter, and an active liquid crystal phased array can be realized. The antenna array surface layer 100 of the embodiment of the present invention is composed of a plurality of antenna array units 101, each antenna array unit 101 including a radiation surface and a backplane surface. A metal grid ground is arranged on the back of the antenna array surface layer.

[0072] The way to realize active liquid crystal phased array is as follows:

[0073] Step 1: If Figure 5 As shown, firstly, an active radio frequency device 103 is welded on the back surface of each antenna array unit 101 .

[0074] In a preferred embodiment, the active RF device 103 uses LNA (Low Noise Amplifier). By replacing the traditional T / R module with LNA, the active function is realized, the antenna gain is improved, and the G / T value of the liquid crystal phased array is improved. And compared with the traditional T / R module, the cost is reduced. The temperature generated by the working current of the LNA itself can also be used to effectively heat the liquid crystal 302 to prevent the liquid crystal 302 from crystallizing at low temperature, so that the liquid crystal 302 can work within its effective range (10-40°C), which can increase the working environment of the liquid crystal 302 by about 20°C.

[0075] like Figure 1 As shown, a gold-plated soldering pad 102 is provided on the back surface of each antenna array unit 101 . The gold-plated soldering pad 102 is co-fired with the antenna array surface layer 100 . The active RF device 103 is soldered to the gold-plated soldering pad 102 via a gold wire 105 .

[0076] The second step is, Figure 6 As shown, metal cavities 201 having the same number as the active RF devices 103 are preset on the low-temperature ceramic substrate on the first coupling layer 200, and the active RF device 103 on the back surface of each antenna array unit 101 is buried in a metal cavity 201. The required raw low-temperature ceramic tape can be cut by laser and then co-fired.

[0077] In an embodiment of the present invention, the metal cavity 201 is composed of a metal sidewall 2012 and a cavity 2011. The metal sidewall 2012 is disposed around the outer periphery of the cavity 2011, and the metal sidewall 2012 is composed of a plurality of metal through-holes.

[0078] The traditional method is to directly brush a layer of metal on the inner sidewall of the cavity 201 to avoid the interference of electromagnetic waves between the mutual channels. However, due to the structure of the cavity 2011, it is impossible to brush the metal one by one. Therefore, in the embodiment of the present invention, by arranging the metal sidewall 201 on the outer periphery of the cavity 2011, the electromagnetic wave interference between adjacent channels can be realized.

[0079] In a feasible embodiment, the metal through-holes are arranged according to a preset arrangement rule to ensure that there is no leakage of electromagnetic waves.

[0080] Among them, when designing, a preset distance is provided between the metal sidewall 201 and the cavity 2011 to prevent the collapse caused by too many layers of low-temperature ceramic green tapes.

[0081] In the present invention, by arranging the metal cavity 201 on the low-temperature ceramic substrate of the first coupling layer 200 and embedding the active radio frequency device 103 in the metal cavity 201, the active working mode of the low-temperature ceramic-based liquid crystal phased array is realized.

[0082] Based on the same inventive concept, a manufacturing process of a low-temperature ceramic-based liquid crystal phased array antenna is provided, as Figure 7 shown, including the following steps:

[0083] Step S701: Weld a plurality of active radio frequency devices 103 corresponding to the number of antenna array units 101 on the back surface of the low-temperature ceramic substrate of the antenna array layer 100.

[0084] In this step, the welding is a one-time welding, and the one-time welding temperature is higher than 223°C. According to the number of antenna array units 101, weld the same number of active radio frequency devices 103 as the number of antenna array units 101.

[0085] Step S702: Preset the same number of metal cavities 201 as the number of active radio frequency devices 103 on the low-temperature ceramic substrate of the first coupling layer 200, and bury each active radio frequency device 103 in a corresponding metal cavity 201.

[0086] In this step, as Figure 8 shown, it is a schematic diagram of the layering of the first coupling layer 200. The specific manufacturing process of the first coupling layer 200 is as follows:

[0087] Step S7021: First, determine the number of low-temperature ceramic green tape pieces 700 to be cut according to the depth of the metal cavity 201 to be preset.

[0088] Step S7022: cutting a plurality of cavities 2011 on the low-temperature ceramic green tape sheet 700 to be cut, with the positions of the cavities 2011 between the layers corresponding to each other.

[0089] Step S7023: Punch a plurality of through holes along the periphery of the side wall of the cavity 2011; pour metal into each through hole to form a metal through hole. The plurality of metal through holes form a metal side wall 2012 around the cavity 2011. The metal side wall 2012, the metal grid ground at the bottom of the antenna array layer and the metal grid ground at the bottom of the cavity together form a sealed metal cavity.

[0090] It should be noted that the shielding effect achieved by the metal cavity is equivalent to that achieved by coating the inner wall of the cavity with metal.

[0091] Step S7024: designing a metal grid ground 202 on the next layer of low-temperature ceramic green tape sheet 700 of the last cut low-temperature ceramic green tape sheet 700.

[0092] The gridded metal ground helps to produce a smoother surface during low-temperature ceramic sintering, which is beneficial to improving the overall processing and manufacturing accuracy of the antenna.

[0093] Step S7025: sintering the cut low-temperature ceramic green tape piece 700, the low-temperature ceramic green tape piece 700 where the metal grid is located, and other uncut low-temperature ceramic green tape pieces 700 together.

[0094] For example, when using a 100um low-temperature ceramic green tape 700, if a 500um deep cavity is required, five low-temperature ceramic green tapes 700 need to be laser cut in the same manner. Holes are punched around each layer of cut cavity to obtain a metal sidewall 2012, which is then co-fired with the sixth layer of metal grid 202 and other required low-temperature ceramic green tapes 700.

[0095] Step S703: welding the low-temperature ceramic substrate of the antenna array layer 100 and one side of the low-temperature ceramic substrate of the first coupling layer 200 together.

[0096] In this step, the welding is secondary welding, and the welding temperature of the secondary welding is about 180° C. After the secondary welding, the cavity becomes a metal cavity sealed by a metal grid.

[0097] By cutting metal cavities corresponding to all active RF devices in the first coupling layer of microwave signals, a large number of unpackaged active RF devices can be effectively buried in a planar manner between the antenna array surface layer and the first coupling layer. The electromagnetic wave signal can be amplified by the active RF devices, and the mutual interference of microwave signals between different channels can be avoided by the metal cavity, thus avoiding the technical difficulty of not being able to punch holes in glass, making it possible to use liquid crystal to make active phased array antennas. In addition, the active RF components welded in the metal cavity are all bare chips, reducing the complex and expensive packaging costs of packaging each active RF device.

[0098] Step S704 : bonding the upper glass substrate 301 of the liquid crystal phase shifter layer 300 and the other surface of the low-temperature ceramic substrate of the first coupling layer 200 together.

[0099] Step S705 : bonding one side of the low-temperature ceramic substrate of the second coupling layer 500 to the lower glass substrate 301 of the liquid crystal phase shifter layer 300 ; wherein the second coupling layer 500 and the feed network layer 400 are co-fired together.

[0100] In the embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of devices or units can be electrical, mechanical or other forms.

[0101] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0102] In addition, each functional unit in the embodiment provided by the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0103] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0104] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0105] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0106] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0107] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, those skilled in the art should understand that any person skilled in the art can still modify the technical solutions described in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or perform equivalent replacements on some of the technical features thereof; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. They should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A low temperature ceramic-based liquid crystal phased array antenna, characterized in that: include: The antenna array layer, the first coupling layer, the liquid crystal phase shifter layer, the second coupling layer and the feed network layer are stacked in sequence, wherein the antenna array layer, the first coupling layer, the second coupling layer and the feed network layer all adopt low-temperature ceramic substrates, the liquid crystal phase shifter layer is composed of two glass substrates engraved with microwave circuits and liquid crystal poured between the two glass substrates, the low-temperature ceramic substrates of the first coupling layer and the second coupling layer are bonded to the glass substrate of the liquid crystal phase shifter layer by solid glue, wherein the sintering temperature of the low-temperature ceramic substrate is 850-900°C.

2. The low temperature ceramic-based liquid crystal phased array antenna according to claim 1, characterized in that: The antenna array layer, the first coupling layer, the liquid crystal phase shifter layer, the second coupling layer and the feed network layer all adopt a planar structure.

3. The low temperature ceramic-based liquid crystal phased array antenna according to claim 1, characterized in that: The antenna array layer is composed of a plurality of antenna array units, each of which includes a radiation surface and a back panel surface, and an active radio frequency device is installed on the back panel surface of each antenna array unit.

4. The low temperature ceramic-based liquid crystal phased array antenna according to claim 3, characterized in that: A gold-plated welding pad is provided on the back surface of each antenna array unit. The gold-plated welding pad is co-fired with the antenna array surface layer. The active radio frequency device is connected to the gold-plated welding pad by gold wire welding.

5. The low temperature ceramic-based liquid crystal phased array antenna according to claim 3, characterized in that: The first coupling layer is provided with metal cavities having the same number as the antenna array units, and the active radio frequency device on the back panel of each antenna array unit is buried in a metal cavity.

6. The low temperature ceramic-based liquid crystal phased array antenna according to claim 5, characterized in that: The metal cavity is composed of a metal sidewall, an upper and lower layer of metal grid ground and a cavity. The metal sidewall is arranged around the periphery of the cavity and is composed of a plurality of metal through holes. The upper and lower layers of metal grid ground are respectively composed of a metal grid ground at the bottom of the antenna array layer and a metal grid ground at the bottom of the cavity.

7. The low temperature ceramic-based liquid crystal phased array antenna according to claim 6, characterized in that: The metal through holes are arranged according to a preset arrangement rule.

8. The low temperature ceramic-based liquid crystal phased array antenna according to claim 6, characterized in that: The metal side wall is spaced from the cavity by a preset distance.

9. A manufacturing process for a low-temperature ceramic-based liquid crystal phased array antenna, characterized in that: include: Active radio frequency devices corresponding to the number of antenna array units are welded on the back surface of the low-temperature ceramic substrate of the antenna array surface layer; Presetting cavities on the low-temperature ceramic substrate of the first coupling layer, the same number as the active radio frequency devices, and forming sealed metal cavities based on the cavities, and burying each of the active radio frequency devices in a corresponding metal cavity; Welding together the side of the low-temperature ceramic substrate of the antenna array layer on which the active radio frequency device is welded and the side of the low-temperature ceramic substrate of the first coupling layer on which the metal cavity is welded; bonding the upper glass substrate of the liquid crystal phase shifter layer to the other side of the low temperature ceramic substrate of the first coupling layer; One side of the low-temperature ceramic substrate of the second coupling layer is bonded to the lower glass substrate of the liquid crystal phase shifter layer; wherein the second coupling layer is co-fired with the feed network layer.

10. The manufacturing process of the low temperature ceramic-based liquid crystal phased array antenna according to claim 9, characterized in that: The method of presetting cavities on the low-temperature ceramic substrate of the first coupling layer, which have the same number as the active radio frequency devices, and forming a sealed metal cavity based on the cavities comprises: Cutting cavities on the low-temperature ceramic substrate of the first coupling layer, the same number as the active radio frequency devices; Punching a plurality of through holes along the periphery of the cavity; Metal is poured into each through hole to form a metal through hole. Several of the metal through holes form a metal side wall around the cavity. The metal side wall, the metal grid ground at the bottom of the antenna array layer and the metal grid ground at the bottom of the cavity together form a sealed metal cavity.

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