Cavity antenna circuit integrated metamaterial and preparation method thereof

Abstract

The invention belongs to the technical field of antenna and radio frequency circuit integration, and discloses a cavity antenna circuit integrated metamaterial and a preparation method thereof. By removing part of the dielectric substrate to construct the artificial cavity, space is provided for a radio frequency functional circuit, and efficient coplanar integration of the antenna and the radio frequency circuit is realized. According to the invention, the mutual restriction of the thickness of the dielectric substrate on the antenna bandwidth and radio frequency circuit design can be overcome, the design flexibility and stability are improved, and the application scene is expanded. Through cavity and space stacking integration, the problem that in the prior art, an antenna and a radio frequency circuit are machined on the same layer of substrate at the same time, and consequently the design requirements of the antenna and the radio frequency circuit are contradictory is solved, the artificial cavity is formed in the bottom of the antenna medium, and the radio frequency function circuit executing the electromagnetic function is arranged in the artificial cavity, so that the antenna efficiency is improved. The prepared cavity antenna circuit integrated metamaterial can simultaneously exert the optimal performance of the two parts of an antenna and a radio frequency circuit, and the design flexibility is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of antenna and radio frequency circuit integration technology, specifically relating to a cavity antenna circuit integration metamaterial and its preparation method. Background Technology

[0002] With the rapid development of electromagnetic metamaterials technology, its application in field-circuit integration is becoming increasingly widespread, and the demand for the integration of radio frequency (RF) circuits and antennas is becoming more prominent. However, in existing technical solutions, there are significant contradictions in the integration of antennas and RF circuits. Specifically, if the dielectric substrate is too thick, the design of the RF circuit is limited, making it difficult to achieve high performance; while if the dielectric substrate is too thin, the bandwidth performance of the antenna will be significantly restricted. These conflicting design requirements make it extremely difficult to simultaneously optimize the performance of antennas and RF circuits on the same substrate.

[0003] To address the aforementioned issues, common solutions currently include two main approaches: one is to select a dielectric substrate of moderate thickness to accommodate the design requirements of both the antenna and the RF circuitry, but this obviously limits the performance of both; the other is to introduce an air layer between the antenna and the RF circuitry, placing the RF circuitry below the antenna, but this approach leads to unstable connections between the antenna and the RF circuitry, affecting the overall reliability. Therefore, achieving efficient integration of the antenna and RF circuitry without sacrificing their performance has become a pressing technical challenge in the field of metamaterials design. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides a cavity antenna circuit integrated metamaterial and its fabrication method. The technical problem to be solved by this invention is achieved through the following technical solution: In a first aspect, the present invention provides a method for fabricating a cavity antenna circuit integrated metamaterial, the method comprising: Obtain a dielectric substrate, divide the dielectric substrate into several antenna dielectrics at equal intervals, set a radiating patch on the upper surface of the antenna dielectric, and set connection pads on both sides of the lower surface of the antenna dielectric. For each antenna medium, the portion of the substrate between two connecting pads in the antenna medium is removed to obtain an artificial cavity; Cut the adjacent antenna media and use the cut antenna media as independent cavity antennas; Prepare several radio frequency (RF) functional circuits and arrange all the RF functional circuits into an RF array; A cavity antenna is used as a cover and placed above each radio frequency functional circuit in the radio frequency array, serving as a metamaterial integrated into the cavity antenna circuit; wherein the radio frequency functional circuit is disposed within an artificial cavity.

[0005] In one embodiment of the present invention, connecting the pads includes: Fixing pads for mechanical connection of the carrier board and electrical pads for connection between RF functional circuits and antenna media.

[0006] In one embodiment of the present invention, a portion of the dielectric substrate between two connecting pads in the antenna dielectric is removed to obtain an artificial cavity, comprising: The antenna dielectric is placed on a drilling platform, and the part of the dielectric substrate between the two connecting pads is removed by controlled-depth drilling to obtain an artificial cavity.

[0007] In one embodiment of the present invention, the radio frequency functional circuit includes: an amplifier, a phase shifter, a power divider, an attenuator, and a transmission line.

[0008] In a second aspect, the present invention provides a cavity antenna circuit integrated metamaterial, comprising: Several cavity antennas and radio frequency arrays; among them, All cavity antennas are positioned above each radio frequency functional circuit in the radio frequency array, acting as covers; each cavity antenna corresponds to a radio frequency functional circuit.

[0009] In one embodiment of the present invention, the cavity antenna includes: The components arranged from top to bottom are: a radiating patch, an antenna medium, connecting pads on both sides of the lower surface of the antenna medium, and an artificial cavity between the two connecting pads.

[0010] In one embodiment of the present invention, the radio frequency functional circuit is connected to the connection pad via solder pads.

[0011] In one embodiment of the present invention, the diameter of the solder pad is 1 mm.

[0012] In one embodiment of the present invention, the shape of the radiating patch is rectangular.

[0013] The beneficial effects of this invention are: The solution provided by this invention overcomes the problem of conflicting design requirements caused by the simultaneous fabrication of antennas and radio frequency circuits on the same substrate layer in the prior art through cavity and space stacking integration. By setting an artificial cavity at the bottom of the antenna medium and setting the radio frequency functional circuit that performs electromagnetic functions in the artificial cavity, the fabricated cavity antenna circuit integrated metamaterial can simultaneously exert the best performance of both the antenna and radio frequency circuits, greatly improving the design flexibility. Attached Figure Description

[0014] Figure 1 This is a schematic diagram illustrating the steps of a method for fabricating a cavity antenna circuit integrated metamaterial according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the cavity antenna structure in a method for fabricating a cavity antenna circuit integrated metamaterial provided in an embodiment of the present invention; Figure 3 This is a simulation diagram of the S11 parameters of a cavity antenna circuit integrated metamaterial provided in an embodiment of the present invention; Figure 4 The images show the bottom and front views of the cut cavity antenna in the fabrication method of a cavity antenna circuit integrated metamaterial provided in an embodiment of the present invention. Figure 5 This is a physical diagram of the radio frequency functional circuit in the fabrication method of a cavity antenna circuit integrated metamaterial provided in an embodiment of the present invention; Figure 6 This is a physical image of a cavity antenna circuit integrated metamaterial provided in an embodiment of the present invention; Figure 7 The far-field radiation pattern of a cavity antenna circuit integrated in a metamaterial provided in an embodiment of the present invention. Detailed Implementation

[0015] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0016] This invention addresses the problem of efficient integration of antennas and radio frequency (RF) circuits on the same substrate in existing technologies by providing a cavity antenna circuit integration metamaterial and its fabrication method. This technical problem stems from the mutual constraint between the dielectric substrate thickness and antenna bandwidth and RF circuit design: if the dielectric substrate is thick, the design space for the RF circuit is limited; if the dielectric substrate is thin, the antenna bandwidth performance degrades. Furthermore, traditional methods that partially resolve this contradiction by introducing an air layer suffer from unstable connections and increased structural complexity. Therefore, this invention aims to provide a technical solution that overcomes the limitations of dielectric substrate thickness while achieving efficient integration of antennas and RF circuits.

[0017] Below, we will first introduce a method for fabricating a cavity antenna circuit integrated metamaterial provided in the embodiments of the present invention.

[0018] The present invention provides a method for fabricating a cavity antenna circuit integrated metamaterial, such as... Figure 1 As shown, it may include the following steps: S1. Obtain a dielectric substrate, divide the dielectric substrate into several antenna dielectrics at equal intervals, set a radiating patch on the upper surface of the antenna dielectric, and set connection pads on both sides of the lower surface of the antenna dielectric.

[0019] S2, For each antenna medium, remove the portion of the dielectric substrate between the two connecting pads in the antenna medium to obtain an artificial cavity; S3, cut the adjacent antenna media and use the cut antenna media as an independent cavity antenna; S4, Prepare several radio frequency functional circuits and form a radio frequency array by combining all the radio frequency functional circuits; S5 uses a cavity antenna as a cover and places it above each radio frequency functional circuit in the radio frequency array, serving as a metamaterial integrated into the cavity antenna circuit; wherein, the radio frequency functional circuit is placed inside the artificial cavity.

[0020] Understandably, during the cavity antenna design phase, the size and shape of the radiating patch are designed based on the target frequency, and the overall antenna performance is optimized by combining the depth and area of ​​the artificial cavity. A schematic diagram of a cavity antenna structure is shown below. Figure 2 As shown, the core structure of a cavity antenna includes: a radiating patch, an antenna dielectric, an artificial cavity, and connecting pads. The radiating patch is responsible for the radiation and reception of microwave energy, and its size and shape are determined by the target frequency. For example, at a working frequency of 5 GHz, the radiating patch can adopt a rectangular design with a length and width of 15 mm and 10 mm, respectively, to meet the resonance condition. The thickness of the antenna dielectric can be set to 1.5 mm. This thickness takes into account both the antenna bandwidth and the space requirements of the RF circuit. The artificial cavity is located at the bottom of the antenna dielectric, formed by removing part of the dielectric substrate, and its depth can be 0.8 mm. Its area is slightly larger than the projected area of ​​the radiating patch to ensure sufficient installation space for the RF circuit. Connecting pads are distributed in the edge area of ​​the antenna dielectric to achieve a stable connection between the antenna and the RF circuit. The connecting pads can include: fixed pads for mechanical connection to the carrier board and electrical pads for connection between the RF functional circuit and the antenna dielectric. Among them, the fixed pads for mechanical connection are relatively densely packed pad points. Solder mask rings can be covered around the pads to ensure good electrical connection. Specifically, considering the presence of the artificial cavity from the initial design stage, this embodiment of the invention optimizes the structural parameters of the radiating patch so that even with the introduction of the artificial cavity, the antenna's S11 parameters can still maintain good matching characteristics. The simulation diagram of the S11 parameters is shown below. Figure 3 As shown, the S11 curve reaches below -20dB at 5GHz, indicating that the antenna has excellent impedance matching performance.

[0021] After completing the cavity antenna design, the antenna carrier board fabrication stage begins. Based on the designed antenna structure, the board is fabricated to form a metal structure including radiating patches, metal vias, and connecting pads. The metal vias penetrate the antenna dielectric to connect the radiating patches to the connecting pads, ensuring the integrity of the signal transmission path. During fabrication, the thickness and surface roughness of the metal layers must be strictly controlled to reduce high-frequency signal loss. Simultaneously, the overall dimensions of the antenna carrier board are designed to conform to standard FR-4 sheet metal specifications, facilitating subsequent processing and assembly.

[0022] For S2, removing the portion of the dielectric substrate between the two connecting pads in the antenna dielectric to obtain an artificial cavity can include: The antenna dielectric is placed on a drilling platform, and the part of the dielectric substrate between the two connecting pads is removed by controlled-depth drilling to obtain an artificial cavity.

[0023] Specifically, in step S2, during the removal of a portion of the dielectric substrate, this embodiment of the invention employs controlled-depth drilling technology to remove a portion of the dielectric at the bottom of the antenna carrier board, forming an artificial cavity. Controlled-depth drilling technology ensures that the dimensions of the artificial cavity match the design by precisely controlling the drill bit's feed depth. In practice, the circuit board carrying the metal structure is first fixed on the drilling platform, and then controlled-depth drilling can be performed using a 5mm diameter drill bit. The drilling depth can be set to 0.8mm, and the drilling process is monitored in real time using a laser rangefinder to avoid damage to other areas of the antenna carrier board. Understandably, the formation of the artificial cavity not only provides ample installation space for the RF functional circuitry within the cavity but also significantly reduces the impact of the dielectric substrate thickness on the antenna bandwidth performance.

[0024] After completing the fabrication of the artificial cavity, the process proceeds to the cutting and panelization stage corresponding to step S3. Since the fabrication of cavity antennas often involves processing multiple antennas simultaneously on a large circuit board, it is necessary to cut the continuous cavity antenna panels into independent units. During cutting, a high-precision CNC cutting machine is used to divide the antennas along predetermined cutting lines, ensuring that the edges of each cavity antenna are neat and burr-free. The bottom and front views of the cut cavity antennas are shown below. Figure 4 As shown, the bottom surface of the cut cavity antenna clearly shows the outline of the artificial cavity, while the front surface displays the distribution of the radiating patch and connecting pads.

[0025] After completing the cutting and board-splitting stage corresponding to step S3, in the RF functional circuit manufacturing stage corresponding to step S4, specific RF functional circuits can be flexibly designed and manufactured according to the functional requirements of the metamaterial. The RF functional circuits may include amplifiers, phase shifters, power dividers, attenuators, and transmission lines. Their array size generally ranges from 6×6 to 64×64. In this embodiment, a bidirectional amplifier circuit is used as an example, whose core components include a low-noise amplifier and a power amplifier, used to enhance the strength of the received and transmitted signals, respectively. During circuit design, the position and size of the solder pads connected to the cavity antenna must be considered to ensure the reliability of signal transmission. The solder pads adopt a circular design with a diameter of 1mm and are firmly connected to the connecting pads using a hot air soldering process. Furthermore, the layout of the RF circuit must make full use of the space of the artificial cavity to avoid electromagnetic interference between components. A physical diagram of the RF functional circuit is shown below. Figure 5 As shown, it can be seen Figure 5The solder pads and solder joints are clearly visible. The radio frequency functional circuit integrates phase shifting, amplification and switching functional modules into the cavity base plate to realize the corresponding functions of metamaterials.

[0026] In the assembly and integration stage corresponding to step S6, the cavity antenna is used as a cover for the radio frequency (RF) functional circuit and installed on the large-scale RF functional circuit to form a complete metamaterial assembly. During assembly, the RF functional circuit is first fixed inside the artificial cavity, and then the cavity antenna is fixed to the RF functional circuit using screws or adhesive. The specific assembly method follows the connection method of the shielding cover, mainly including: solder paste printing, cover placement, and reflow soldering. In this process, the cavity antenna not only physically covers the RF functional components but also electrically connects to the RF functional circuit, constituting a complete metamaterial function. After assembly, the connection pads and solder joints between the cavity antenna and the RF functional circuit are in close contact to ensure the stability of the signal transmission path. A physical diagram of the assembled cavity antenna circuit integrated metamaterial is shown below. Figure 6 As shown, the integrated structure of the cavity antenna and the radio frequency functional circuit is clearly visible. The overall structure of the metamaterial is compact, which is conducive to system-level integration and packaging. In the metamaterial, the periodic radio frequency functional circuit and the periodic cavity antenna are neatly arranged.

[0027] Secondly, corresponding to the above-described preparation method embodiments, this invention also provides a cavity antenna circuit integrated metamaterial, such as... Figure 2 As shown, it may include: Several cavity antennas and radio frequency arrays; among them, All cavity antennas are placed above each radio frequency functional circuit in the radio frequency array as covers; each cavity antenna corresponds to a radio frequency functional circuit.

[0028] Specifically, a cavity antenna may include: The components arranged from top to bottom are: a radiating patch, an antenna medium, connecting pads on both sides of the lower surface of the antenna medium, and an artificial cavity between the two connecting pads.

[0029] The radio frequency functional circuit is connected to the connection pad via solder pads.

[0030] Preferably, the diameter of the solder pad can be 1 mm.

[0031] Preferably, the shape of the radiating patch can be rectangular.

[0032] The far-field radiation pattern of the cavity antenna circuit integrated in the metamaterial provided in the embodiments of the present invention is as follows: Figure 7 As shown, it can be seen from Figure 7As can be seen, the red and purple lines represent typical spherical slices corresponding to azimuth angles of 0 and 90 degrees respectively. It can be seen that the radiation direction of the integrated metamaterial of the cavity antenna circuit is mainly the radiation direction, with a maximum gain of 4dBi, showing a wide radiation coverage range.

[0033] Understandably, the cavity antenna circuit integrated metamaterial proposed in this invention constructs an artificial cavity by removing part of the dielectric substrate, providing space for the radio frequency (RF) functional circuit within the cavity. This overcomes the limitation imposed by the dielectric substrate thickness on the performance of the antenna and RF circuit in traditional methods. Designed specialized connection pads or connection methods (such as screw connections) ensure a stable connection between the antenna and the RF functional circuit, avoiding the connection instability problems found in traditional air-layer solutions. Placing the RF functional circuit performing electromagnetic functions within the cavity achieves spatial stacking integration of the antenna and RF circuit, maximizing their performance. In particular, the integrated design of the cavity antenna and RF circuit allows for separate optimization, fully leveraging their respective optimal performance.

[0034] The cavity antenna circuit integrated metamaterial proposed in this invention overcomes the problem of conflicting design requirements caused by the simultaneous fabrication of antennas and radio frequency circuits on the same substrate in existing technologies through cavity and spatial stacking integration. By setting an artificial cavity at the bottom of the antenna medium and setting the radio frequency functional circuit that performs electromagnetic functions in the artificial cavity, the prepared cavity antenna circuit integrated metamaterial can simultaneously exert the optimal performance of both the antenna and radio frequency circuits, greatly improving design flexibility.

[0035] Specifically, the key aspects of this invention are as follows: First, by removing part of the dielectric substrate to construct an artificial cavity, space is provided for the radio frequency (RF) functional circuit within the cavity, overcoming the limitations imposed by the thickness of the traditional dielectric substrate on the performance of the antenna and RF circuit. Second, specialized connection pads or connection methods (such as screw connections) are designed to ensure a stable connection between the antenna and the RF circuit, avoiding the connection instability problems found in traditional air-layer solutions. Third, the RF functional circuit performing electromagnetic functions is placed within the cavity, achieving spatial stacking and integration of the antenna and the RF functional circuit, maximizing their performance. In particular, the integrated design of the cavity antenna and the RF functional circuit allows for separate optimization, fully leveraging their respective optimal performance.

[0036] Understandably, the technical effects of this invention are manifested in the following ways: First, it overcomes the mutual constraint between the thickness of the dielectric substrate and the performance of the antenna and RF functional circuits. Through the design of the artificial cavity, the antenna can maintain good bandwidth performance on a relatively thick dielectric substrate, while providing sufficient design space for the RF functional circuits. Second, it improves design flexibility. The integrated design of the cavity antenna and the RF functional circuits allows for separate optimization, fully leveraging their respective best performance. Third, it enhances stability. Through a specific connection port design, it ensures a stable connection between the antenna and the RF functional circuits, avoiding the connection instability problems found in traditional air-layer solutions. Finally, it expands application scenarios. This technical solution is applicable to various antenna types (such as microstrip antennas, slot antennas, etc.) and various RF circuit functions (such as amplification, filtering, etc.), and has broad application prospects.

[0037] Furthermore, this invention provides various alternatives to meet the needs of different application scenarios. The antenna form is not limited to microstrip antennas; other antenna forms (such as slot antennas, dipole antennas, etc.) can also be integrated with RF circuits by constructing cavities. For example, a slot antenna can be integrated with RF functional circuits by creating a radiating structure through slots in the antenna medium and combining this with the design of an artificial cavity. The connection method is not limited to pad connections; other connection methods (such as screw connections, pin connections, etc.) can also be used to connect the antenna and the RF circuit. For example, a screw connection can be used by setting threaded holes in the edge region of the antenna medium to fix the cavity antenna to the RF functional circuit, while achieving electrical connection through conductive pads. The RF functional circuit can be designed with any function (such as amplification, filtering, modulation / demodulation, etc.) according to actual needs, as long as space allows. For example, a filtering circuit can achieve selective signal transmission within a specific frequency range by arranging an LC resonator within an artificial cavity.

[0038] In summary, the embodiments of the present invention create an artificial cavity by removing part of the dielectric substrate, providing space for the radio frequency (RF) functional circuits within the cavity, thus achieving efficient integration of the antenna and the RF circuit. This technical solution not only solves the problem of the mutual constraint between the dielectric substrate thickness and the performance of the antenna and the RF circuit, but also significantly improves design flexibility, stability, and the diversity of application scenarios, providing important technical support for the development of the field of electromagnetic metamaterials.

[0039] It should be noted that, in the description of this invention, the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A method for fabricating a cavity antenna circuit integrated metamaterial, characterized in that, include: Obtain a dielectric substrate, divide the dielectric substrate into several antenna dielectrics at equal intervals, set a radiating patch on the upper surface of the antenna dielectric, and set connection pads on both sides of the lower surface of the antenna dielectric. For each antenna medium, the portion of the substrate between two connecting pads in the antenna medium is removed to obtain an artificial cavity; Cut the adjacent antenna media and use the cut antenna media as independent cavity antennas; Prepare several radio frequency (RF) functional circuits and arrange all the RF functional circuits into an RF array; A cavity antenna is used as a cover and placed above each radio frequency functional circuit in the radio frequency array, serving as a metamaterial integrated into the cavity antenna circuit; wherein the radio frequency functional circuit is disposed within an artificial cavity.

2. The method for fabricating a cavity antenna circuit integrated metamaterial according to claim 1, characterized in that, The connection pads include: Fixing pads for mechanical connection of the carrier board and electrical pads for connection between RF functional circuits and antenna media.

3. The method for fabricating a cavity antenna circuit integrated metamaterial according to claim 1, characterized in that, The step of removing a portion of the dielectric substrate between two connecting pads in the antenna dielectric to obtain an artificial cavity includes: The antenna dielectric is placed on a drilling platform, and the part of the dielectric substrate between the two connecting pads is removed by controlled-depth drilling to obtain an artificial cavity.

4. The method for fabricating a cavity antenna circuit integrated metamaterial according to claim 1, characterized in that, The radio frequency functional circuitry includes: an amplifier, a phase shifter, a power divider, an attenuator, and a transmission line.

5. A cavity antenna circuit integrated metamaterial, characterized in that, include: Several cavity antennas and radio frequency arrays; among them, All cavity antennas are positioned as covers above each radio frequency functional circuit in the radio frequency array; The cavity antenna corresponds one-to-one with the radio frequency functional circuit.

6. The cavity antenna circuit integrated metamaterial according to claim 5, characterized in that, The cavity antenna includes: The components arranged from top to bottom are: a radiating patch, an antenna medium, connecting pads on both sides of the lower surface of the antenna medium, and an artificial cavity between the two connecting pads.

7. The cavity antenna circuit integrated metamaterial according to claim 6, characterized in that, The radio frequency functional circuit is connected to the connection pad via solder pads.

8. The cavity antenna circuit integrated metamaterial according to claim 7, characterized in that, The diameter of the solder pad is 1 mm.

9. The cavity antenna circuit integrated metamaterial according to claim 6, characterized in that, The radiating patch is rectangular in shape.

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