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

Abstract

The application provides a low-temperature ceramic-based liquid crystal phased array antenna and a manufacturing process thereof, comprising an antenna array 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 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 engraved with microwave circuits and liquid crystal filled 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. The low-temperature ceramic substrate and the glass substrate of the liquid crystal phase shifter are bonded in the application, which prevents the warping and tearing problems of the liquid crystal phased array antenna, prolongs the service life of the antenna, reduces the loss and improves the performance of the phased array antenna.

Description

TECHNICAL FIELD

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

[0002] A phased array antenna is an antenna composed of multiple antenna elements, which mainly includes antenna elements, phase shifter units and feed network units. The relative phase difference between each antenna element is controlled by the phase shifter, so as to change the direction of the entire array transmitting or receiving beam. The liquid crystal phased array antenna is a kind of phased array antenna, in which the phase shifter unit adopts liquid crystal material. The dielectric constant of the liquid crystal material can be changed according to the voltage applied thereon, which makes the liquid crystal exhibit different electromagnetic properties under different voltages, such as different time delay characteristics of the phase of microwave caused by different dielectric constants.

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

[0004] 1. The liquid crystal material is directly added to the radiating element of the antenna element to form a holographic mode phased array antenna;

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

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

[0007] 4. As disclosed in patent CN10600874A, the antenna element adopts low-temperature ceramic as a base material, a hole is dug in the low-temperature ceramic base material, and a small amount of liquid crystal is filled in the hole.

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

[0009] 1. For the first kind of liquid crystal phased array antenna, the processing precision requirement of the holographic radiating element is too high, resulting in a very high cost. In addition, the basic structure of the holographic radiating element belongs to a resonant structure, and the bandwidth is too narrow, which is difficult to meet the demand of current wideband communication.

[0010] 2. For the fourth kind of liquid crystal phased array, a cavity is opened on the ceramic to store the liquid crystal. Since the ceramic is opaque, the mature processing technology of the liquid crystal display cannot be used to encapsulate the liquid crystal. In addition, the low-temperature (co-fired) ceramic has an uncontrollable shrinkage error of 0.3% by nature. The more the radiating elements are, the larger the size and area of the antenna array are, so that the positioning accuracy of the fourth kind of liquid crystal phased array antenna is lower, and it is basically in an uncontrollable and unproducible state.

[0011] 3. For the second and third liquid crystal antenna using PCB and metal waveguide, due to the large difference in thermal expansion coefficient between PCB or metal and glass, in actual working environment, due to the change of temperature, the second and third liquid crystal phased array antenna is prone to antenna surface warping and stress tearing of the combination part of PCB or metal waveguide and glass, which seriously affects the electrical performance and service life of the antenna. SUMMARY

[0012] Therefore, the present application aims to provide a low-temperature ceramic-based liquid crystal phased array antenna and a manufacturing process thereof to solve the above problems.

[0013] In a first aspect, a low-temperature ceramic-based liquid crystal phased array antenna is provided, comprising: an antenna array 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 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 layers of glass substrates engraved with microwave circuits and liquid crystal filled between the two layers of glass substrates, 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 by solid glue, and the sintering temperature of the low-temperature ceramic substrate is 850-900℃.

[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 layer is composed of a plurality of antenna units, each antenna unit comprising a radiation surface and a back plate surface, and an active radio frequency device is mounted on the back plate surface of each antenna array unit.

[0016] Optionally, the back plate surface of each antenna array unit is provided with a gold-plated solder pad, the gold-plated solder pad is formed by co-firing with the antenna array layer, and the active radio frequency device is connected with the gold-plated solder pad by gold wire bonding.

[0017] Optionally, the first coupling layer is provided with metal cavities equal in number to the antenna units, and the active radio frequency device on the back plate surface of each antenna unit is embedded in a metal cavity.

[0018] Optionally, the metal cavity is composed of a metal side wall, an upper and lower metal mesh ground and a cavity, the metal side wall is arranged around the outer periphery of the cavity, and the metal side wall is composed of a plurality of metal through holes; the upper and lower metal mesh grounds are respectively composed of a metal mesh ground at the bottom of the antenna array layer and a metal mesh ground at the bottom of the cavity.

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

[0020] Optionally, the metal side wall and the cavity are separated by a preset distance.

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

[0022] welding active radio frequency devices corresponding to the number of antenna units on the back plate of the low-temperature ceramic substrate of the antenna array layer;

[0023] pre-setting cavities on the low-temperature ceramic substrate of the first coupling layer, the number of which is the same as that of the active radio frequency devices, and forming sealed metal cavities based on the cavities, and embedding each active radio frequency device in a metal cavity;

[0024] welding the side of the low-temperature ceramic substrate of the antenna array layer with the active radio frequency devices to the side of the low-temperature ceramic substrate of the first coupling layer with the metal cavities;

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

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

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

[0029] filling metal in each through hole to form a metal through hole, and a plurality of metal through holes form a metal side wall around the cavity, and the metal side wall and the metal mesh ground at the bottom of the antenna array layer and the metal mesh 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 the manufacturing process thereof provided by the application comprise an antenna array 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 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 filled between the two glass substrates, and the low-temperature ceramic substrates of the first coupling layer and the second coupling layer are bonded to the glass substrates of the liquid crystal phase shifter layer by solid glue.

[0031] Since the thermal expansion coefficients of low-temperature ceramics and glass are basically the same, this invention allows for bonding the low-temperature ceramic substrate to the glass substrate of the liquid crystal phase shifter, preventing warping and tearing of the liquid crystal phased array antenna and extending its lifespan. The dielectric constant of the low-temperature ceramic material is close to that of glass, enabling smooth transmission of electromagnetic waves from the antenna array 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 manufacturing of liquid crystal phase shifters uses mature liquid crystal display technology, the manufacturing cost has been significantly reduced compared to traditional phased array antennas, and has reached a cost range acceptable to customers using satellite communication.

[0033] Meanwhile, the innovative design of embedding a large number of active radio frequency components individually, planarly, and one-to-one in a metal cavity minimizes the transmission distance between electromagnetic signals and active radio frequency components, effectively improving the performance of the phased array antenna. It also makes the phased array antenna more planar and ultra-thin. The combination of ultra-thinness and the excellent heat dissipation performance of low-temperature ceramics gives the phased array antenna of this invention a significant advantage in heat dissipation compared to other phased array antennas.

[0034] Furthermore, the unique design of the metal cavity, compared to the traditional separate ceramic packaging for each RF chip, not only further reduces the cost of this phased array antenna, but also makes it more integrated, more aesthetically pleasing, and more efficient.

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This diagram illustrates the layered structure of the low-temperature ceramic-based liquid crystal phased array antenna provided in an embodiment of the present invention.

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

[0039] Figure 3A plan view of a radiation surface of an antenna array layer provided by an embodiment of the present application is shown.

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

[0041] Figure 5 A structural schematic diagram of a structure in which a source radio frequency device is embedded between an antenna array layer and a first coupling layer of a low-temperature ceramic-based liquid crystal phased array antenna provided by an embodiment of the present application is shown.

[0042] Figure 6 A structural schematic diagram of a first coupling layer provided by an embodiment of the present application is shown.

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

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

[0045] Main element symbol explanations: 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 green ceramic tape; 101, antenna array unit; 102, gold-plated solder pad; 103, active radio frequency device; 104, microwave circuit; 105, gold wire; 201, metal cavity; 2011, cavity; 2012, metal side wall; 202, metal mesh ground; 301, glass substrate; 302, liquid crystal. DETAILED DESCRIPTION

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will describe the technical solutions in the embodiments of the present application in a clear and complete manner with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application but only represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0047] An embodiment of the present application provides a low-temperature ceramic-based liquid crystal phased array antenna, as shown in Figure 1 and Figure 2 is an 8*8 array low-temperature ceramic-based liquid crystal phased array antenna,Figure 1 is a schematic diagram of the low-temperature ceramic-based liquid crystal phased array antenna in layers; Figure 2 is a schematic diagram of the finished low-temperature ceramic-based liquid crystal phased array antenna.

[0048] The low-temperature ceramic-based liquid crystal phased 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 low-temperature ceramic substrates, the liquid crystal phase shifter layer 300 is composed of two layers of glass substrates 301 engraved with microwave circuits and liquid crystal 302 filled 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 are bonded with the glass substrates 301 of the liquid crystal phase shifter layer 300 by solid glue. The solid glue can be glass glue, which is applied on the surface of the glass substrate 301 to form a glue bonding layer 600. The sintering temperature of the low-temperature ceramic substrate is 850-900°C.

[0049] The antenna array layer 100 mainly functions to receive and radiate electromagnetic waves and is formed by co-firing multiple layers of low-temperature ceramic green ceramic tapes and metal circuits. In a feasible implementation, the co-firing process is as follows: first, a plurality of low-temperature ceramic green ceramic tape pieces 700 are cut, a number of antenna array units 101 designed on each layer of green ceramic tape piece is punched, silver paste is filled in each hole, and then a pre-designed metalized microwave circuit 104 is printed on the silver paste area. The green ceramic tape pieces are stacked and sintered at one time to obtain the antenna array layer 100. Figure 3 As shown in FIG. 2, the radiation surface of the antenna array layer 100 is shown, and each circular area is the corresponding radiation surface of each antenna array unit. Of course, other metal holes can be punched according to the needs of circuit design.

[0050] The first coupling layer 200 functions 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 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 surface wave beam and the change of the beam pointing. Through the control of 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 filling the radio frequency liquid crystal between the two layers of glass substrates 301 with the mature liquid crystal panel production process 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 and control of the electromagnetic wave phase.

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

[0053] The feed network layer 400 functions to synthesize the electromagnetic wave signals of all the antenna array units 101, amplify and frequency-convert the electromagnetic wave signals into intermediate frequency signals and then output the signals, or conversely convert the electrical signals into electromagnetic wave signals and then radiate the signals.

[0054] Wherein, when receiving the antenna signal, the signal is 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, and when transmitting the antenna signal, the signal is 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 the reverse order.

[0055] Since the low-temperature ceramic is a glass ceramic based on quartz, the low-temperature ceramic and the glass itself have a thermal expansion coefficient basically consistent, about 8.9x10-6(dL / L), thus the low-temperature ceramic substrate and the glass substrate of the liquid crystal phase shifter are bonded to prevent the warping and tearing of the liquid crystal phased array antenna, and meanwhile the various shortcomings of the traditional PCB substrate of the liquid crystal phased array are overcome. Compared with the PCB substrate, the low-temperature ceramic substrate has the following advantages:

[0056] 1. In the microwave and millimeter wave frequency band, the low-temperature ceramic material with a dielectric constant of 5.5 has better radio frequency performance than the PCB substrate with the same dielectric constant;

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

[0058] 3. Suitable for use in the environment with large temperature change (such as aerospace), facilitating the heat dissipation of the antenna and effectively prolonging the service life of the antenna;

[0059] 4. The electromagnetic wave can be smoothly transmitted from the antenna array layer 100 to the liquid crystal phase shifter layer 300, thus effectively reducing the loss and improving the performance of the phased array antenna itself.

[0060] On the basis of 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 the planar structure, the complexity of micro-assembly is greatly simplified, and mass production is facilitated.

[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 achieve active operation. Taking a PCB substrate as an example, the specific reasons are explained below:

[0063] To achieve active antennas, the T / R module needs to be soldered onto the surface of the PCB substrate, and a separate T / R module needs to be designed and manufactured for each transmit and receive channel of the antenna array element 101. This results in a significant increase in antenna thickness and weight. Furthermore, in the millimeter-wave band, the area of ​​the antenna array element 101 is relatively small, making it difficult to implement complex T / R modules.

[0064] Furthermore, since phased array antennas consist of thousands of channels, each channel requires a T / R module, resulting in high costs and making it difficult to promote them in the communications industry, especially the civilian communications industry.

[0065] like Figure 4 The diagram shown illustrates a traditional T / R module, providing a general understanding of its complexity. This also explains the high price of a traditional phased array antenna composed of thousands upon thousands of such T / R modules.

[0066] Meanwhile, to avoid cross-interference between adjacent channels, each T / R module needs to be equipped with a metal shielding cavity, and each T / R module needs to be buried inside.

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

[0068] One method involves carving out cavities on the PCB, ensuring the bottom of the cavity remains flat; then printing circuitry on the bottom plane of the cavity; finally, copper plating is applied to the four walls of the carved-out cavity to form a metal cavity. This manufacturing process would be astronomically expensive. Therefore, the process of carving out numerous cavities on PCBs is not feasible.

[0069] Another approach is to prefabricate a metal cavity for each T / R module, made of low-temperature or high-temperature ceramic with an entirely metal surface inside. The T / R module is then encapsulated within this cavity and soldered onto the PCB antenna backplane. However, manufacturing thousands upon thousands of such ceramic-metal cavities would be extremely costly, making this approach impractical.

[0070] The method of using metal waveguides suffers from the same problems as PCB substrates. Furthermore, since glass cannot form through-holes, it is impossible to embed the active RF device 103 within the glass by creating holes in the glass substrate 301 of the glass liquid crystal phase shifter. Therefore, the second and third types of liquid crystal phased arrays in the background art cannot achieve active operation. Moreover, the passive liquid crystal phased array antenna has a low gain, resulting in an insufficient G / T value, making it difficult to meet the requirements of modern communication.

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

[0072] The following are methods for implementing an active liquid crystal phased array:

[0073] Step 1: As Figure 5 As shown, an active radio frequency device 103 is first soldered onto the backplane of each antenna array unit 101.

[0074] In a preferred embodiment, the active RF device 103 employs an LNA (Low Noise Amplifier). Replacing the traditional T / R module with an LNA achieves active operation, improves antenna gain, and consequently increases the G / T value of the liquid crystal phased array. Furthermore, it reduces costs compared to traditional T / R modules. The heat generated by the LNA's own operating current can also effectively heat the liquid crystal 302, preventing crystallization at low temperatures and allowing the liquid crystal 302 to operate within its effective operating range (10-40°C), thus raising the operating temperature of the liquid crystal 302 by approximately 20°C.

[0075] like Figure 1 As shown, each antenna array unit 101 has a gold-plated solder pad 102 on its back panel. The gold-plated solder pad 102 is co-fired with the antenna array surface layer 100. The active radio frequency device 103 is soldered to the gold-plated solder pad 102 by gold wire 105.

[0076] The second step, as Figure 6 As shown, a number of metal cavities 201, the same number as the number of active radio frequency devices 103, are pre-set on a low-temperature ceramic substrate on the first coupling layer 200. The active radio frequency devices 103 on the backplane of each antenna array unit 101 are embedded in a metal cavity 201. The required low-temperature ceramic strip can be obtained by laser cutting and then co-firing.

[0077] In the embodiment of the present application, the metal cavity 201 is composed of the metal side wall 2012 and the cavity 2011, the metal side wall 2012 is arranged around the outer periphery of the cavity 2011, and the metal side wall 2012 is composed of a plurality of metal through holes.

[0078] The conventional way is to directly brush a layer of metal on the inner side wall of the cavity 2011 to avoid the electromagnetic wave interference between the mutual channels, but the structure of the cavity 2011 cannot realize the metal brushing one by one, therefore, in the embodiment of the present application, the metal side wall 2012 is arranged around the outer periphery of the cavity 2011, so that the electromagnetic wave interference between the adjacent channels can be realized.

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

[0080] In the design, a preset distance is arranged between the metal side wall 2012 and the cavity 2011 to prevent the collapse caused by too many layers of the low-temperature ceramic green tape.

[0081] In the embodiment of the present application, the metal cavity 201 is arranged on the low-temperature ceramic substrate of the first coupling layer 200, and the active radio frequency device 103 is buried in the metal cavity 201, so that the active working mode of the low-temperature ceramic substrate liquid crystal phased array is realized.

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

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

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

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

[0086] In this step, as shown in Figure 8 It is a layered schematic diagram of the first coupling layer 200, and the manufacturing process of the first coupling layer 200 is specifically as follows:

[0087] Step S7021: determining 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 cavities 2011 on the low-temperature ceramic green ceramic tape 700 that needs to be cut, and the positions of the cavities 2011 between layers correspond.

[0089] Step S7023: punching holes along the outer periphery of the side walls of the cavities 2011 to obtain a plurality of through holes; filling metal in each through hole to form a metal through hole, and a plurality of metal through holes form a metal side wall 2012 around the cavity 2011, and the metal side wall 2012 and the metal mesh ground at the bottom of the antenna array layer and the metal mesh 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 and the metal coating on the inner side wall is equivalent.

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

[0092] The meshed metal ground helps to produce a more flat plane during sintering of the low-temperature ceramic, which is conducive to improving the overall processing accuracy of the antenna.

[0093] Step S7025: sintering the cut low-temperature ceramic green ceramic tape 700, the low-temperature ceramic green ceramic tape 700 with the metal mesh ground, and other low-temperature ceramic green ceramic tapes 700 that have not been cut.

[0094] For example, when using a 100um low-temperature ceramic green ceramic tape 700, if a 500um deep cavity is needed, 5 pieces of low-temperature ceramic green ceramic tape 700 need to be cut by laser. Punching holes around the cavity cut in each layer to obtain a metal side wall 2012, and then sintering with the 6th layer of metal mesh ground 202 and other required low-temperature ceramic green ceramic tapes 700.

[0095] Step S703: welding one side of the low-temperature ceramic substrate of the antenna array layer 100 and 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 secondary welding, the cavity becomes a metal cavity sealed by a metal mesh ground.

[0097] By cutting the metal cavity corresponding to all active radio frequency devices in the first coupling layer of the microwave signal, the unpackaged active radio frequency devices are effectively buried in a large number of planes between the antenna array layer and the first coupling layer, the active radio frequency devices can amplify the electromagnetic wave signal, the metal cavity can avoid the mutual interference of microwave signals between different channels, the technical difficulty that glass cannot be punched through is avoided, and it is possible for liquid crystal to be used to manufacture active phased array antennas, and in addition, the active radio frequency devices welded in the metal cavity are all bare chips, which reduces the complex and expensive packaging cost of packaging each active radio frequency device.

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

[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 is co-fired with the feed network layer 400.

[0100] In the embodiments provided by the present application, it should be understood that the disclosed device and method 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, and there can be another division manner in actual implementation. For example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections between the units can be indirect couplings or communication connections through some interfaces, devices or units, and can be electrical, mechanical or in other forms.

[0101] The units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, that is, they can be located in one place, or can be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the embodiment scheme.

[0102] In addition, each functional unit in the embodiments provided by the present application can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit.

[0103] If the functions are realized in the form of software function units and sold or used as independent products, they can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application or the parts of the present application that essentially contribute to the prior art or the parts of the technical solutions of the present application can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in the various embodiments of the present application. The aforementioned storage medium includes a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0104] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present application is usually placed, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" and the like 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 must be absolutely horizontal or overhanging, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0106] In the description of the present application, it should also be noted that, unless otherwise explicitly specified and limited, the terms "arrangement", "installation", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0107] Finally, it should be noted that the above-described embodiments are merely specific embodiments of the present application, which are used to illustrate the technical solutions of the present application, but not to limit the present application, and the protection scope of the present application is not limited thereto. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily think of changes to the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to some technical features therein, within the technical scope disclosed by the present application, and these modifications, changes or replacements do not cause the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application. All should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A process for fabricating a low temperature co-fired ceramic based liquid crystal phased array antenna, characterized in that, The application relates to a low-temperature ceramic substrate for an antenna array. The back plate surface of the low-temperature ceramic substrate of the antenna array layer is welded with active radio frequency devices corresponding to the number of antenna array units; A cavity corresponding to the number of the active radio frequency devices is preset on the low-temperature ceramic substrate of the first coupling layer, and a sealed metal cavity is formed based on the cavity, and each active radio frequency device is correspondingly embedded in one metal cavity. The manufacturing process of the sealed metal cavity is as follows: Cutting cavities corresponding to the number of the active radio frequency devices on the low-temperature ceramic substrate of the first coupling layer; Punching a plurality of through holes along the periphery of the cavities; Filling metal in each through hole to form a metal through hole, and a metal side wall is formed around the cavities by the metal through holes, and the metal side wall and the metal mesh ground at the bottom of the antenna array layer and the metal mesh ground at the bottom of the cavity jointly form the sealed metal cavity; The low-temperature ceramic substrate of the antenna array layer with the active radio frequency devices is welded with the low-temperature ceramic substrate of the first coupling layer with the metal cavities; The upper glass substrate of the liquid crystal phase shifter layer is bonded with the other surface of the low-temperature ceramic substrate of the first coupling layer; One surface of the low-temperature ceramic substrate of the second coupling layer is bonded with the lower glass substrate of the liquid crystal phase shifter layer; wherein the second coupling layer is co-fired with the feed network layer; The temperature generated by the working current of the active radio frequency device is used to heat the liquid crystal in the liquid crystal phase shifter, so that the liquid crystal works in the effective range 10-40 DEG C.

2. A low temperature co-fired ceramic based liquid crystal phased array antenna made by the process of claim 1. The antenna array layer, the first coupling layer, the liquid crystal phase shifter layer, the second coupling layer and the feed network layer are sequentially stacked, 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 filled between the two 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, wherein the sintering temperature of the low-temperature ceramic substrate is 850-900 DEG C. 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 cryogenic ceramic-based liquid crystal phased array antenna of claim 2, wherein, The antenna array layer is composed of a plurality of antenna array units, each of which comprises a radiation surface and a back plate surface, and an active radio frequency device is installed on the back plate surface of each antenna array unit.

4. The cryogenic ceramic-based liquid crystal phased array antenna of claim 2, wherein, The back plate surface of each antenna array unit is provided with a gold-plated solder pad, the gold-plated solder pad is co-fired with the antenna array layer, and the active radio frequency device is connected with the gold-plated solder pad through gold wire bonding.

5. The cryogenic ceramic-based liquid crystal phased array antenna of claim 4, wherein, The first coupling layer is provided with metal cavities corresponding to the number of the antenna array units, and the active radio frequency device on the back plate surface of each antenna array unit is embedded in one metal cavity.

6. The cryogenic ceramic-based liquid crystal phased array antenna of claim 4, wherein, The metal cavity is composed of a metal side wall, upper and lower metal mesh grounds and a cavity, the metal side wall is arranged around the periphery of the cavity, and the metal side wall is composed of a plurality of metal through holes; the upper and lower metal mesh grounds are respectively composed of the metal mesh ground at the bottom of the antenna array layer and the metal mesh ground at the bottom of the cavity.

7. The cryogenic ceramic-based liquid crystal phased array antenna of claim 6, wherein, ​ 8. The cryogenic ceramic-based liquid crystal phased array antenna of claim 7, wherein, The metal through holes are arranged according to preset arrangement rules.

9. The cryogenic ceramic-based liquid crystal phased array antenna of claim 7, wherein, The metal side wall is spaced apart from the cavity by a preset distance.

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