Conformal array antenna with reconfigurable frequency and preparation method thereof

Abstract

The invention discloses a frequency reconfigurable conformal array antenna and a preparation method thereof, an antenna metal radiation layer comprises a power distribution network and a reconfigurable antenna unit, a main radiation patch of the reconfigurable antenna unit is a rectangular metal patch, feed is carried out in a side feed mode, and the main radiation patch is a rectangular metal patch. The variable capacitance diode is arranged in the middle of the U-shaped groove between the main radiation patch and the parasitic patch; the 4 * 4 equidistantly arranged reconfigurable antenna units are connected with the T-junction power divider, and the input port of the power divider is connected with an external direct current bias device. By controlling the external bias voltage, the junction capacitance of the variable capacitance diode can be changed, and the reconstruction of the current on the surface of the patch is realized, so that the reconfigurable frequency is realized. The invention also discloses a processing method of the antenna. The antenna disclosed by the invention has the characteristics of low profile, simple structure, low cost, continuously reconfigurable frequency and the like, and the conformal preparation of the antenna can be realized according to the preparation scheme, so that the antenna has a conformal characteristic, and the influence of the antenna on the aerodynamic configuration of a carrier is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of antennas and relates to a frequency reconfigurable conformal array antenna and a preparation method thereof. Background Art

[0002] With the rapid development of wireless communication systems, the number of antennas required on aircraft platforms for communication, positioning, and navigation is increasing. This leads to issues such as high cost, increased size, and electromagnetic compatibility. To reduce the weight and cost of antennas on platforms, while also ensuring good electromagnetic compatibility, it is desirable to utilize a single antenna to perform the functions of multiple antennas. Frequency-reconfigurable antennas can flexibly switch operating frequencies based on different application scenarios, improving antenna anti-interference capabilities and spectrum efficiency. Conventional aircraft antennas protrude from the aircraft body, significantly impacting aerodynamic performance. Conformal antennas have a minimal impact on the aerodynamic shape of the vehicle, require less installation space, and provide greater airspace coverage. Combining frequency reconfigurability with conformal properties can reduce system cost and enhance anti-interference capabilities. It can also improve antenna performance without compromising the overall design, reducing system load and increasing overall aircraft profitability.

[0003] Existing frequency reconfigurable antennas can be reconfigured in various ways, including loading PIN diodes, varactor diodes, MEMS switches, optical switches, microfluidic control, or material tuning. However, most reconfigurable antennas have a small number of switchable frequency states, use too many switching devices on the antenna unit, and have a complex adjustment mechanism. The antenna forms used are mostly difficult to integrate into conformal arrays. Summary of the Invention

[0004] In response to the deficiencies of the above-mentioned background technology, the present invention provides a frequency-reconfigurable conformal array antenna and a preparation method thereof. Only two lumped elements are used on each antenna unit, and adjusting a bias voltage can control the state of the entire array antenna, thereby achieving continuous frequency reconstruction within a certain frequency range. According to the preparation method, conformal preparation of the antenna on a carrier can be achieved, solving the technical problems of previous frequency-reconfigurable antennas, such as a large number of lumped elements, a small number of reconstruction states, a complex adjustment mechanism, and the inability to form an array conformally.

[0005] The present invention adopts the following technical solutions to achieve the above-mentioned purpose.

[0006] A frequency reconfigurable conformal array antenna comprises: a metal radiation layer, the metal radiation layer comprising: a power distribution network and at least one reconfigurable antenna unit; the power distribution network is used to receive radio frequency signals and evenly distribute them to each reconfigurable antenna unit; The reconfigurable antenna unit is used to achieve continuous reconstruction of the resonant frequency by adjusting the DC bias voltage.

[0007] Optionally, the power distribution network is a one-to-sixteen T-junction power divider in a microstrip form; its output port is connected to the microstrip feeder, and its input port is connected to an external DC bias device using an SMA connector.

[0008] Optionally, the reconfigurable antenna unit includes a main radiation patch and a microstrip feed line, the main radiation patch is a rectangular metal patch, and the microstrip feed line feeds power to the main radiation patch from the side.

[0009] Optionally, slots are formed on both sides of the connection between the microstrip feed line and the main radiation patch to achieve impedance matching of the antenna.

[0010] Optionally, the reconfigurable antenna unit further includes a parasitic patch, and a U-shaped slot is provided between the main radiation patch and the parasitic patch, with the opening of the U-shaped slot facing the side where the microstrip feed line is located.

[0011] Optionally, the frequency reconfigurable conformal array antenna further includes: a lumped device; the lumped device includes a varactor diode, the varactor diode is overlapped at a symmetrical position in the middle of the U-shaped groove, and connects the main radiation patch and the parasitic patch.

[0012] Optionally, the reconfigurable antenna unit further includes a bias pad, a bias lead and a ground pad, wherein the bias pad is located at an edge of the parasitic patch and is connected to the ground pad via the bias lead.

[0013] Optionally, the frequency reconfigurable conformal array antenna further includes: a metal ground layer and a metallized through hole penetrating the dielectric layer; the ground pad is provided with a metallized through hole and is connected to the metal ground layer via the metallized through hole.

[0014] Optionally, the frequency reconfigurable conformal array antenna further includes a DC bias device; the DC bias device is connected to the RF feed line and an adjustable DC bias power supply, and is used to provide a bias voltage to multiple varactor diodes while providing an RF input signal.

[0015] A method for preparing a frequency reconfigurable conformal array antenna, the method comprising the following steps: S1: Prepare the antenna substrate. According to the conformal requirements of the aircraft surface, use the stereolithography technology to prepare a flat or curved substrate and polish it. S2: Prepare the metal ground layer by conformally inkjet printing silver nano-ink on the substrate using a five-axis CNC machine; S3: Prepare the dielectric layer by using a five-axis CNC machine to conformally write dielectric resin on the metal layer. Multiple layers are stacked to meet the required thickness of the reconfigurable antenna dielectric layer. S4: Prepare the metal radiation layer by conformally inkjet printing silver nano-ink on the dielectric layer using a five-axis CNC machine according to the designed reconfigurable antenna surface shape; S5: Prepare metal vias, laser-etch holes according to the designed reconfigurable antenna via positions, and fill the vias with conductive silver paste; S6: Device bonding: Use conductive silver glue to bond the varactor diode and inductor on the antenna into place.

[0016] The present invention adopts the above technical solution and has the following beneficial effects: (1) The present invention arranges parasitic patches around the rectangular patch antenna and connects a variable capacitance diode with adjustable junction capacitance between the parasitic patch and the main radiation patch. Only one variable capacitance diode and one inductor are used on each antenna unit, and the continuous adjustment of the antenna frequency is achieved with a minimum number of lumped elements. The various states of the frequency reconfigurable conformal array antenna of the present invention are well matched, and can meet the frequency requirements of various communication modes in wireless communication systems. It has the advantages of a small number of lumped elements and a simple adjustment mechanism.

[0017] (2) The antenna structure described in the present invention is simple and only involves a DC grounding hole, which reduces the difficulty of antenna manufacturing. The use of the preparation method can achieve conformal preparation of the antenna on the surface of the carrier, reducing the impact of the antenna on the aerodynamic shape of the carrier.

[0018] (3) The present invention has both frequency reconfiguration function and conformal characteristics, and has a wide range of applications. It is suitable for wireless communication systems with diverse frequency requirements and limited installation space. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 1. It is a schematic diagram of the structure of a frequency reconfigurable conformal array antenna according to an embodiment of the present invention; Figure 2 is a schematic structural diagram of an antenna unit in one embodiment of the present invention; Figure 3 This is a detailed diagram of the dimensions of each part of the antenna unit structure in one embodiment of the present invention; Figure 4 is the reflection characteristic curve S of each state of the frequency reconfigurable conformal array antenna in one embodiment of the present invention. 11 Simulation results; Figure 5 This is a simulation result of the far-field pattern of the frequency reconfigurable conformal array antenna at a center frequency of 4.448 GHz when the bias voltage is 0 V in one embodiment of the present invention; Figure 6 This is a simulation result of the far-field pattern of the frequency reconfigurable conformal array antenna at a center frequency of 5.756 GHz when the bias voltage is 20 V in one embodiment of the present invention; Figure 7 It is a curved surface base model required for an antenna receiving substrate in one embodiment of the present invention; Figure 8 is a flow chart of a method for preparing an antenna in one embodiment of the present invention; Description of the drawings: 1. Lumped device, 2. Metal radiation layer, 3. Dielectric layer, 4. Metal ground layer, 5. Metalized via, 6. First T-junction, 7. Second T-junction, 8. Third T-junction, 9. Fourth T-junction, 11. Varactor diode, 12. Inductor, 21. Main radiation patch, 22. Microstrip feed line, 23. Parasitic patch, 24. Bias pad, 25. Bias lead, 26. Ground pad, 201. Power distribution network, 202. Output port, 203. Input port, 204. Main microstrip line, 205a. Second-level branch line, 206a. Third-level branch line, 207a. Fourth-level branch line. DETAILED DESCRIPTION

[0020] The following is combined with Figures 1 to 8 The present invention will be further described in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the relevant content and are not intended to limit the present invention. It should also be noted that for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings.

[0021] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0022] Unless otherwise stated, the exemplary embodiments / examples shown are to be understood as providing exemplary features of various details of some ways in which the technical concept of the present invention can be implemented in practice. Therefore, unless otherwise stated, the features of the various embodiments / examples may be further combined, separated, interchanged, and / or rearranged without departing from the technical concept of the present invention.

[0023] The use of cross hatching and / or shading in the accompanying drawings is generally used to make the boundaries between adjacent components clear. As such, unless otherwise indicated, the presence or absence of cross hatching or shading does not convey or indicate any preference or requirement for the specific materials, material properties, dimensions, proportions, commonalities between the components shown, and / or any other characteristics, attributes, properties, etc. of the components. In addition, in the accompanying drawings, the sizes and relative sizes of the components may be exaggerated for clarity and / or descriptive purposes. When the exemplary embodiments can be implemented differently, the specific process sequence can be performed in a different order than described. For example, two successively described processes can be performed substantially simultaneously or in an order opposite to the order described. In addition, the same figure numbers represent the same components.

[0024] When a component is referred to as being “on,” “over,” “connected to,” or “coupled to” another component, the component may be directly on, directly connected to, or directly coupled to the other component, or intervening components may be present. However, when a component is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another component, there are no intervening components present. For this purpose, the term “connected” may refer to a physical connection, an electrical connection, etc., with or without intervening components.

[0025] For descriptive purposes, the present disclosure may use spatially relative terms such as "below," "beneath," "under," "down," "above," "upper," "above," "higher," and "side (e.g., as in "sidewall")," to describe the relationship of one component to another (other) component as shown in the accompanying drawings. The spatially relative terms are intended to encompass different orientations of the device in use, operation, and / or manufacture in addition to the orientation depicted in the accompanying drawings. For example, if the device in the drawings is turned over, a component described as "below" or "beneath" another component or feature would then be oriented "above" the other component or feature. Thus, the exemplary term "below" can encompass both the "above" and "below" orientations. Furthermore, the device may be otherwise oriented (e.g., rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0026] The terms used herein are for the purpose of describing specific embodiments and are not intended to be restrictive. As used herein, unless the context clearly indicates otherwise, the singular forms "one (kind, person)" and "said (the)" are also intended to include plural forms. In addition, when the terms "comprise" and / or "include" and their variations are used in this specification, the features, integral bodies, steps, operations, parts, assemblies and / or their groups stated are explained, but the presence or addition of one or more other features, integral bodies, steps, operations, parts, assemblies and / or their groups is not excluded. It should also be noted that, as used herein, the terms "substantially", "approximately" and other similar terms are used as approximate terms and not as degree terms, so that they are used to explain the inherent deviations of the measured values, calculated values ​​and / or the values ​​provided that will be recognized by those of ordinary skill in the art.

[0027] In one embodiment, the present invention discloses a frequency reconfigurable conformal array antenna, comprising: a metal radiation layer, the metal radiation layer comprising: a power distribution network and at least one reconfigurable antenna unit; the power distribution network is used to receive radio frequency signals and evenly distribute them to each reconfigurable antenna unit; The reconfigurable antenna unit is used to achieve continuous reconstruction of the resonant frequency by adjusting the DC bias voltage.

[0028] Optionally, the power distribution network is a one-to-sixteen T-junction power divider in a microstrip form; its output port is connected to the microstrip feeder, and its input port is connected to an external DC bias device using an SMA connector.

[0029] Optionally, the reconfigurable antenna unit includes a main radiation patch and a microstrip feed line, the main radiation patch is a rectangular metal patch, and the microstrip feed line feeds power to the main radiation patch from the side.

[0030] Optionally, slots are formed on both sides of the connection between the microstrip feed line and the main radiation patch to achieve impedance matching of the antenna.

[0031] Optionally, the reconfigurable antenna unit further includes a parasitic patch, and a U-shaped slot is provided between the main radiation patch and the parasitic patch, with the opening of the U-shaped slot facing the side where the microstrip feed line is located.

[0032] Optionally, the frequency reconfigurable conformal array antenna further includes: a lumped device; the lumped device includes a varactor diode, the varactor diode is overlapped at a symmetrical position in the middle of the U-shaped groove, and connects the main radiation patch and the parasitic patch.

[0033] Optionally, the reconfigurable antenna unit further includes a bias pad, a bias lead and a ground pad, wherein the bias pad is located at an edge of the parasitic patch and is connected to the ground pad via the bias lead.

[0034] Optionally, the frequency reconfigurable conformal array antenna further includes: a metal ground layer and a metallized through hole penetrating the dielectric layer; the ground pad is provided with a metallized through hole and is connected to the metal ground layer via the metallized through hole.

[0035] Optionally, the frequency reconfigurable conformal array antenna further includes a DC bias device; the DC bias device is connected to the RF feed line and an adjustable DC bias power supply, and is used to provide a bias voltage to multiple varactor diodes while providing an RF input signal.

[0036] In one embodiment, if Figure 1 and Figure 2 As shown, the present invention discloses a frequency reconfigurable conformal array antenna, comprising: a lumped device, a metal radiation layer, a dielectric layer, a metal ground layer, and a metallized through hole penetrating the dielectric layer; The metal radiation layer includes: a power distribution network and at least one reconfigurable antenna unit; the power distribution network is used to receive radio frequency signals and evenly distribute them to each reconfigurable antenna unit; The reconfigurable antenna unit realizes continuous reconstruction of the resonant frequency by adjusting the DC bias voltage across the varactor diode; Specifically including: main radiation patch, microstrip feed line, parasitic patch, varactor diode, inductor, bias pad, bias lead and ground pad.

[0037] The main radiation patch 21, as a basic radiation unit, is laterally connected to the power distribution network via a microstrip feeder 22; The parasitic patch 23 is decoupled from the main radiation patch 21 through a U-shaped slot, wherein the opening of the U-shaped slot faces the side where the microstrip feed line 22 is located; The varactor diode 11 is symmetrically connected to the middle of the U-shaped groove, connecting the main radiating patch 21 and the parasitic patch 23. Its junction capacitance is dynamically adjusted with the change of the external bias voltage to change the current distribution on the patch surface and adjust the equivalent electrical length of the antenna; The bias pad 24, the bias lead 25 and the ground pad 26 constitute a DC bias loop. The bias pad 24 is located at the edge of the parasitic patch 23 and is connected to the ground pad 26 through the bias lead 25. The ground pad 26 is conductively connected to the metal ground layer 4 through the metallized via 5. The inductor 12 is connected between the bias pad 24 and the parasitic patch 23 to block the radio frequency signal and form an LC resonant circuit to enhance the tuning sensitivity.

[0038] In one embodiment, if Figure 1 As shown, the present invention discloses a frequency-reconfigurable conformal array antenna. From the top to the bottom, a lumped device 1, a metal radiating layer 2, a dielectric layer 3, a metal grounding layer 4, and metalized vias 5 extending through the dielectric layer are sequentially arranged. The metal radiating layer includes a power distribution network 201 and 4×4 reconfigurable antenna elements arranged at equal intervals.

[0039] like Figure 2As shown, the reconfigurable antenna unit includes a main radiating patch 21, a microstrip feed line 22, a parasitic patch 23, a bias pad 24, a bias lead 25, and a ground pad 26. The main radiating patch 21 is a rectangular metal patch that serves as a basic radiating element and determines the highest resonant frequency (e.g., 5.756 GHz). The microstrip feed line 22 feeds the main radiating patch 21 from the side. Slots are cut on both sides of the connection between the microstrip feed line 22 and the main radiating patch 21 to achieve impedance matching for the antenna. A U-shaped slot is located between the main radiating patch 21 and the parasitic patch 23, with the slot opening facing the side where the microstrip feed line 22 is located. The parasitic patch is decoupled from the main radiating patch by the U-shaped slot and functions as a parasitic element at low bias voltages. At high bias voltages, it is turned on by a varactor diode and merged into the main radiator. The parasitic patch is directly connected to the varactor diode to dynamically adjust the radiation area in response to capacitance changes. The varactor diode 11 is symmetrically connected in the middle of the U-shaped slot, connecting the main radiating patch 21 and the parasitic patch 23. The varactor diode adjusts the equivalent capacitance through an external bias voltage, changing the equivalent electrical length of the antenna unit, thereby dynamically adjusting the resonant frequency and enabling continuous frequency modulation. The varactor diode cooperates with the parasitic patch and the U-shaped slot to change the radiation characteristics of the parasitic patch through capacitance changes, transforming it from a "parasitic" to a "main radiating" part, thereby extending the effective length of the antenna. The bias pad 24 is located at the edge of the parasitic patch 23 and is connected to the ground pad 26 via a bias lead 25. The ground pad 26 is provided with a metalized via 5 and connected to the metal ground layer 4. The inductor 12 is connected between the bias pad 24 and the parasitic patch 23. The inductor and the bias pad form a DC circuit to ensure that the bias voltage is stably applied to the varactor diode. It is used to block RF signals to ensure that the DC bias voltage acts only on the varactor diode, preventing RF signal leakage. It also forms an LC resonant circuit with the varactor diode to enhance tuning sensitivity.

[0040] Combine Figure 3For the reconfigurable antenna unit, a U-shaped slot is used to isolate the main radiating patch from the parasitic patch, with the varactor diode 11 lapped in the middle of the slot. The ratio of the length (LHF) of the main radiating patch 21 to the U-shaped slot width is 34:1; the ratio of the length (LLF) of the parasitic patch 23 to the U-shaped slot width is 46:1. This ratio is designed to ensure proper lap connection of the varactor diode and adjust the coupling strength between the two through capacitance changes. Slots are cut on both sides of the microstrip feed line 22 where it connects to the main radiating patch 21. The slot width is the distance between the feed line and the patch edge, and the slot length (Lslot) to slot width (Wslot) ratio is 10:1. The microstrip feed line width (Wfeed) to slot width ratio is 3:1, which is used to achieve impedance matching and reduce signal reflections. A bias pad 24 is located at the edge of the parasitic patch 23. The two are connected by conductive silver glue. The spacing is negligible (considered a direct connection), but must meet soldering process requirements and is typically less than 0.1mm. Bias lead 25 is a microstrip line connecting bias pad 24 to ground pad 26. Its length, depending on the layout design, should be kept as short as possible to minimize losses. The lead length is typically 3-5 times the ground pad diameter (approximately 1-2 mm) to ensure a clean current path. Metallized via 5 is located at the center of ground pad 26, with no spacing between them (the via extends directly through the pad), ensuring low-impedance grounding.

[0041] The feed slot's aspect ratio (10:1) and the ratio of microstrip line width to slot width (3:1) are calculated based on 50Ω impedance matching to ensure efficient RF signal transmission. The large ratios of U-shaped slot width (0.5mm) to main / parasitic patch lengths (34:1 and 46:1) reduce the patch's capacitive interference with the diode and improve frequency tuning sensitivity. All spacing designs must adapt to the five-axis CNC printing process to ensure dimensional consistency on flat or curved surfaces and avoid spacing distortion due to conformal bending.

[0042] The power distribution network 201 is a microstrip-type, one-to-sixteen T-junction power divider. Its output port 202 is connected to the microstrip feeder 22 of the reconfigurable antenna unit, and its input port 203 is connected to an external DC bias source via an SMA connector. The external DC bias source is connected to the RF feeder and an adjustable DC bias power supply, providing bias voltage to multiple varactors while providing the RF input signal. The power distribution network evenly distributes the RF signal to the 16 antenna units, ensuring phase consistency. It receives external bias voltage via SMA connectors to synchronously control all varactors. In conjunction with the external DC bias source, a single voltage controls the entire array, simplifying system design.

[0043] A microstrip line-based, one-to-sixteen T-junction power splitter expands from one input port 203 through multiple stages of T-branching to 16 output ports 202, achieving uniform distribution of RF signals. Specifically, the tree-like branches of the one-to-sixteen T-junction power splitter exhibit a multi-stage T-shaped bifurcation structure, starting from input port 203 and gradually expanding through four stages of T-branching to 16 output ports. Taking the four reconfigurable antenna elements in the upper left corner as an example, the specific hierarchy is as follows: The input port 203 is connected to a main microstrip line 204. The end of the main microstrip line 204 is divided into two branch lines through the first T-junction 6: the second level 205a and 205b (only 205a and 205b are marked in the figure, and the same marking method is used for similar branch lines below); The end of the second-level branch line 205a is further divided into two by a T-junction 7 to form a branch line 206a, for a total of four branch lines at the same level; The end of the third-level branch line 206a is divided into two by a T-junction 8, forming a branch line 207a, with a total of eight branch lines of the same level; Each end of the fourth-level branch line 207 a is divided into two by a T-junction 9 , ultimately forming 16 output branch lines, that is, 16 output ports 202 .

[0044] All branch lines at each level are in the form of microstrip lines, and the line width is designed according to the impedance matching requirements to ensure that the RF signal has minimal loss and consistent amplitude and phase during the distribution process.

[0045] The metal ground layer and metallized vias are used to provide a low-impedance ground path, suppress electromagnetic interference (EMI), and stabilize the radiation direction; the metallized vias ensure that the DC bias loop is closed, that is, the loop formed by the varactor diode → parasitic patch → ground pad → via → ground layer.

[0046] In this embodiment, a DC bias voltage enters the reconfigurable antenna element through an external DC bias device, an SMA connector, and a power distribution network. It then passes through a microstrip feed line, a primary radiating patch, a varactor diode, a parasitic patch, an inductor, a bias pad, a bias lead, a ground pad, a metalized via, and a metal ground layer to form a closed loop. Increasing the bias voltage of the external DC bias device simultaneously increases the bias voltage of the varactor diodes in the sixteen reconfigurable antenna elements, reducing the varactor diodes' equivalent capacitance and altering the current distribution on the patch. This causes the parasitic patch to gradually become part of the primary radiating patch, thereby increasing the antenna's effective length and lowering its resonant frequency, thereby enabling continuous reconfiguration of the antenna's resonant frequency.

[0047] In one embodiment, the present invention discloses a frequency reconfigurable conformal array antenna. Figure 1It is the overall structure of a frequency reconfigurable conformal array antenna. The overall dimensions in the planar state are 230mm×230mm×0.5mm, and the array cross-section is only 0.5mm. It has flexible bending conformal capability. The dielectric substrate is Rogers5880 material, and a one-to-sixteen T-junction power divider is used. The array element spacing is 60mm. Too large an array element spacing will cause the antenna beam angle to be too small, increasing the difficulty of aligning the transmitting and receiving antennas. Too small a spacing will cause insufficient directionality of the antenna array, and will also make the power divider and the antenna patch too close, resulting in severe coupling and even physical interference. Therefore, 60mm is selected as the array element spacing of the antenna array.

[0048] For example, Figure 3 Shown Figure 1 Detailed diagram of the dimensions of each part of the antenna unit structure. The values ​​of the antenna unit structure parameters are: L g = W g =45mm, L LF =23mm, W LF =26mm, L HF =17mm, W LF =18mm, L slot =5mm, W slot =0.5mm, W feed =1.5mm, g=0.5mm, inductance value is 15nH, and the varactor diode is MGV125-20-0805-2. L LF 、 W LF Determine the lowest resonant frequency of the frequency reconfigurable conformal array antenna. In this example, the lowest resonant frequency is 4.448 GHz. The size of the main radiating patch is L HF 、 W LF Determines the highest resonant frequency of the frequency reconfigurable conformal array antenna. In this example, the highest resonant frequency is 5.756 GHz. L slot 、 W slot and feeder size W feedTo determine the antenna matching state, it is necessary to ensure that the antenna input port impedance characteristic is around 50Ω to obtain good matching characteristics; the slot width g affects the coupling state between the parasitic patch and the main radiation patch. During design, the slot width must be limited to ensure that the varactor diode can be properly connected. The MGV125-20-0805-2 varactor diode has an adjustable junction capacitance. In electromagnetic simulation, it can be equivalent to an RLC series circuit model. This circuit model includes parasitic inductance ( L p =0.40nH)、parasitic resistance( R =1.60Ω), parasitic capacitance ( C p =0.06pF) and junction capacitance ( C j ). When the bias voltage changes between 0~20V, the junction capacitance C j It will vary between 1.1 and 0.1 pF, thus achieving continuous frequency adjustment. In the optimization design of frequency reconfigurable conformal array antennas, it is necessary to prioritize increasing the highest resonant frequency of the reconfigurable antenna to compensate for the effect of the capacitance of the varactor diode on the overall shift of the reconfigured frequency band to low frequencies; optimize the patch size and the size of the feed slot to improve the matching of the antenna at low frequencies; prioritize matching the high frequency of the antenna, shifting limited resources more to high frequencies, and giving full play to the antenna's advantage of high radiation efficiency at high frequencies; and change the main radiating patch. L HF The length of the antenna should be set to avoid extra frequency points from entering the main reconstruction frequency band of the antenna; the size of the parasitic patch should be limited to avoid the difficulty of antenna array design caused by the parasitic patch being too large.

[0049] Figure 4 is the reflection characteristic curve S of each state of the frequency reconfigurable conformal array antenna 11 Simulation results. Figure 5 This is the simulation result of the far-field radiation pattern of the frequency reconfigurable conformal array antenna at a center frequency of 4.448 GHz when the bias voltage is 0 V. At this time, the variable capacitance of the varactor diode is 1.1 pF and the maximum gain of the antenna is 13.31 dBi. Figure 6 This is the simulation result of the far-field pattern of the frequency-reconfigurable conformal array antenna at a center frequency of 5.756 GHz, with a bias voltage of 20 V. At this point, the variable capacitance of the varactor diode is 0.1 pF, and the antenna's maximum gain is 18.92 dBi. The external bias voltage can be continuously adjusted between 0 and 20 V, and the antenna frequency can be continuously adjusted between 4.448 and 5.756 GHz. Table 1 shows some of the antenna's reconfigurable states and frequencies.

[0050] Table 1

[0051] When the antenna operates in a planar state or has a cylindrical bending conformal requirement, it can be made of Rogers 5880 material with a thickness of 0.508 mm, a dielectric constant of 2.2, and a dielectric loss of 0.0009. When there is a requirement for non-developable surface conformal, the preparation method proposed in the present invention can be used to complete the preparation. In this case, the dielectric substrate uses a photocurable resin with a dielectric constant of 2.65 and a dielectric loss of 0.0135. The antenna size parameters need to be changed accordingly according to the dielectric constant of the material.

[0052] In one embodiment, the present invention discloses a method for preparing a frequency reconfigurable conformal array antenna, the method comprising the following steps: S1: Prepare the antenna substrate. According to the conformal requirements of the aircraft surface, use the stereolithography technology to prepare a flat or curved substrate and polish it. S2: Prepare the metal ground layer by conformally inkjet printing silver nano-ink on the substrate using a five-axis CNC machine; S3: Prepare the dielectric layer by using a five-axis CNC machine to conformally write dielectric resin on the metal layer. Multiple layers are stacked to meet the required thickness of the reconfigurable antenna dielectric layer. S4: Prepare the metal radiation layer by conformally inkjet printing silver nano-ink on the dielectric layer using a five-axis CNC machine according to the designed reconfigurable antenna surface shape; S5: Prepare metal vias, laser-etch holes according to the designed reconfigurable antenna via positions, and fill the vias with conductive silver paste; S6: Device bonding: Use conductive silver glue to bond the varactor diode and inductor on the antenna into place.

[0053] In one embodiment, the present invention discloses a method for preparing a frequency reconfigurable conformal array antenna, comprising the following steps: S1: Prepare the antenna substrate and design a flat or curved substrate according to the conformal requirements of the aircraft surface, such as Figure 7As shown, the non-developable surface on the ventral side of the fuselage below the wing was selected as the conformal location for the antenna. This area has moderate curvature and a large format, making it easy to install and secure. A corresponding curved substrate model was designed and fabricated using stereolithography 3D printing technology. The material used was high-temperature-resistant Rigid 10K photocurable resin, with a single layer printed at a thickness of 100μm. The substrate was cleaned twice with isopropyl alcohol. The substrate was cured at 70°C for 60 minutes to eliminate unreacted monomers remaining from the photocurable printing and initially improve the mechanical strength of the substrate. The temperature was gradually increased from 70°C to 90°C to prevent deformation caused by thermal stress. A post-curing process was performed at 90°C for 125 minutes to ensure sufficient cross-linking of the resin and achieve a higher heat distortion temperature. The substrate was then polished using 400-, 800-, 1500-, and 2000-grit sandpaper until the surface was smooth and free of visible scratches.

[0054] S2: Prepare the metal grounding layer. The preparation is completed by conformal inkjet printing on the S1 substrate using a five-axis CNC device. The material used is silver nano-ink. The substrate surface can be modified by plasma treatment or other methods before printing. During printing, the device is heated to 120°C to accelerate the drying speed of the ink, remove the dispersant and solvent, and form a silver nanoparticle accumulation. Multiple layers are repeatedly printed according to the planned reciprocating printing path to achieve ideal conductive performance and metal layer thickness. After printing, it is sintered at 180°C for 120 minutes to promote the melting of silver nanoparticles to form a dense conductive layer, further stabilizing the conductivity and adhesion of the metal formation.

[0055] S3: Prepare the dielectric layer. This is accomplished using conformal pneumatic direct writing on the S2 metal layer using a five-axis CNC machine. The material used is a photocurable resin. During printing, the device is heated to 60°C to reduce resin viscosity and improve material flow. A single layer is printed according to the planned printing path, with edge sealing followed by back-and-forth filling. Single-layer curing is performed using 365nm UV light. Multiple layers are printed and cured repeatedly until the dielectric layer reaches the desired thickness. The entire layer is then cured using 365nm UV light to ensure that the photocurable resin conversion efficiency meets the required standards. Step-by-step curing (single layer curing followed by overall curing) ensures interlayer adhesion and thickness uniformity. A contact probe is used to check if the dielectric thickness meets the design requirements.

[0056] S4: Prepare the metal radiation layer. According to the designed reconfigurable antenna surface shape, the metal radiation layer is prepared on the S3 dielectric layer using a five-axis CNC machine through conformal inkjet printing. The material used is silver nano-ink. During printing, the device is heated to 120°C. The printing path is planned according to the antenna surface shape and multiple layers are repeatedly printed to achieve the ideal conductive performance and metal layer thickness. After printing, it is sintered at 180°C for 120 minutes.

[0057] S5: Prepare metal vias, laser-etch holes according to the designed reconfigurable antenna via positions, fill the vias with conductive silver paste, and cure them at 175°C for 20 minutes to form a low-resistance conductive path. After curing, use a low-resistance multimeter to test the printed surface circuits and ground layers for continuity.

[0058] S6: Component bonding: Use a dispenser or needle to apply SINWE 3702 conductive silver glue to the pads where the components need to be bonded. Place the varactor diode and inductor in place. Cure at 175°C for 20 minutes to achieve mechanical fixation and electrical connection between the lumped component and the pads. After curing, use a low-resistance multimeter to test the printed surface circuits and ground layers for continuity.

[0059] The advantages of the present invention are also: (1) The antenna structure is simple and easy to control. The operating frequency of the entire array antenna can be controlled by adjusting an external bias voltage.

[0060] (2) The operating frequency of the antenna changes continuously with the bias voltage, which can achieve continuous frequency modulation rather than discrete frequency modulation.

[0061] (3) The preparation method can realize the conformal preparation of the antenna on a flat or curved surface, reducing the impact of the antenna on the aerodynamic shape of the carrier.

[0062] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments / methods or examples. In addition, those skilled in the art may combine and combine different embodiments / methods or examples described in this specification and the features of different embodiments / methods or examples, unless they are contradictory.

[0063] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0064] It should be understood by those skilled in the art that the above embodiments are merely for the purpose of illustrating the present invention clearly, and are not intended to limit the scope of the present invention. For those skilled in the art, other changes or modifications may be made based on the above disclosure, and such changes or modifications are still within the scope of the present invention.

Claims

1. A frequency reconfigurable conformal array antenna, characterized in that: include: A metal radiation layer, the metal radiation layer comprising: a power distribution network and at least one reconfigurable antenna unit; the power distribution network is used to receive radio frequency signals and evenly distribute them to each reconfigurable antenna unit; The reconfigurable antenna unit is used to achieve continuous reconstruction of the resonant frequency by adjusting the DC bias voltage.

2. The frequency reconfigurable conformal array antenna according to claim 1, wherein: Preferably, the power distribution network is a one-to-sixteen T-junction power divider in microstrip form.

3. The frequency reconfigurable conformal array antenna according to claim 1, wherein: The reconfigurable antenna unit includes a main radiation patch and a microstrip feed line. The main radiation patch is a rectangular metal patch, and the microstrip feed line feeds power to the main radiation patch from the side.

4. The frequency reconfigurable conformal array antenna according to claim 3, wherein: Slots are formed on both sides of the connection between the microstrip feed line and the main radiation patch to achieve impedance matching of the antenna.

5. The frequency reconfigurable conformal array antenna according to claim 3, wherein: The reconfigurable antenna unit further includes a parasitic patch. A U-shaped slot is provided between the main radiation patch and the parasitic patch, and the opening of the U-shaped slot faces the side where the microstrip feed line is located.

6. The frequency reconfigurable conformal array antenna according to claim 5, characterized in that: The frequency reconfigurable conformal array antenna further includes: a lumped component; the lumped component includes a varactor diode, which is overlapped at a symmetrical position in the middle of the U-shaped groove and connects the main radiation patch and the parasitic patch.

7. The frequency reconfigurable conformal array antenna according to claim 5, characterized in that: The reconfigurable antenna unit further includes a bias pad, a bias lead and a ground pad. The bias pad is located at the edge of the parasitic patch and is connected to the ground pad through the bias lead.

8. The frequency reconfigurable conformal array antenna according to claim 7, wherein: The frequency reconfigurable conformal array antenna further includes: a metal ground layer and a metallized through hole penetrating the dielectric layer; the ground pad is provided with a metallized through hole and is connected to the metal ground layer via the metallized through hole.

9. The frequency reconfigurable conformal array antenna according to claim 1, wherein: The frequency reconfigurable conformal array antenna also includes a DC bias device; the DC bias device is connected to the radio frequency feed line and the adjustable DC bias power supply, and is used to provide a bias voltage for multiple varactor diodes while providing a radio frequency input signal.

10. A method for preparing a frequency reconfigurable conformal array antenna, characterized in that: The method comprises the following steps: S1: Prepare the antenna substrate. Based on the surface conformality requirements, use the stereolithography technology to prepare a flat or curved substrate and polish it. S2: Prepare the metal ground layer by conformally inkjet printing silver nano-ink on the substrate using a five-axis CNC machine; S3: Prepare the dielectric layer by using a five-axis CNC machine to conformally write dielectric resin on the metal layer. Multiple layers are stacked to meet the required thickness of the reconfigurable antenna dielectric layer. S4: Preparing a metal radiation layer by conformally inkjet printing silver nano-ink on the dielectric layer using a five-axis CNC machine according to the designed reconfigurable antenna surface shape; the reconfigurable antenna is configured to achieve continuous reconfiguration of the resonant frequency by adjusting the DC bias voltage; S5: Prepare metal vias, laser-etch holes according to the designed reconfigurable antenna via positions, and fill the vias with conductive silver paste; S6: Device bonding: Use conductive silver glue to bond the varactor diode and inductor on the antenna into place.

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