A parameter optimization method for tightly coupled dipole antenna based on equivalent circuit model

Abstract

The present invention belongs to the field of antenna engineering technology, and provides a method for optimizing the parameters of a tightly coupled dipole antenna based on an equivalent circuit model, so as to solve the problems of low efficiency and poor effect of the design of tightly coupled dipole antennas based on full-wave simulation, as well as low precision and incompleteness of existing equivalent models. The present invention respectively establishes equivalent circuit models of the matching layer, radiator and feeder of the tightly coupled dipole antenna, and constructs an analytical relationship between the key structural parameters of the tightly coupled dipole antenna and the circuit parameters in its equivalent circuit model, thereby establishing a complete equivalent circuit model; by virtue of efficient parameter optimization of the complete equivalent circuit model, on the one hand, a coordinated optimization design of the performance of the tightly coupled dipole antenna, such as bandwidth, standing wave, and scanning range, is achieved, so that the antenna performance reaches the global optimum; on the other hand, the number of full-wave simulations required for parameter optimization is greatly reduced, thereby shortening the parameter optimization time and improving the design efficiency.

Description

Technical Field

[0001] The present invention belongs to the field of antenna engineering technology, and specifically provides a method for optimizing parameters of a tightly coupled dipole antenna based on an equivalent circuit model. Background Art

[0002] With the continuous development of modern communications, radar, and electronic warfare systems, the requirements for the bandwidth, efficiency, and beam coverage of their front-end phased array antennas are gradually increasing. Ultra-wideband, high-efficiency, wide-angle scanning phased array antennas covering multiple octaves can meet the signal reception and transmission requirements of different frequency bands and different functions under a single aperture, saving system space and cost, and gradually becoming an inevitable development trend of phased array antennas. Among various types of ultra-wideband antennas, the tightly coupled dipole array (TCDA) can achieve a range of less than λ due to the mutual coupling between array elements and the offset of floor reactance. high / 2(λ high Achieving an impedance bandwidth of no less than 8:1 at an array height of 100 nm (the wavelength corresponding to the highest operating frequency in a vacuum) is the preferred antenna solution for multifunctional integrated electronic platforms. However, the impedance difference between the tightly coupled dipole radiator and free space is large, and the radiator's own active impedance varies dramatically with frequency during ultra-wideband operation, making it difficult to optimize the in-band impedance matching. In addition, due to the complex structure and large number of parameters of the tightly coupled dipole unit, parameter optimization based on full-wave simulation not only requires a lot of time and computing resources, but also makes it difficult to achieve the overall optimal impedance matching of the matching layer, radiator and feed line. This results in low design efficiency and poor matching effect of the tightly coupled dipole antenna, which limits the development and application of tightly coupled dipole antennas.

[0003] The key to efficient parameter optimization of tightly coupled dipole antennas lies in high-precision equivalent modeling. For example, in the paper "Munk B A., "Broadband wire arrays in Finite Antenna Arrays and FSS," 1st ed. Hoboken, NJ, USA: Wiley-IEEE Press, 2003: 181-213," Professor B.A. Munk proposed a basic equivalent circuit model for a tightly coupled dipole. This model uses lumped inductors, capacitors, and resistors to represent the dipole's self-inductance, mutual coupling capacitance between elements, and free-space load impedance, respectively. A short-circuited transmission line stub is used to represent the reactance of the dipole looking toward the floor. While this model reveals how the impedance of the TCDA radiation source varies with frequency, its practical application is limited by the difficulty in obtaining the capacitance and inductance values ​​in the circuit. For example, in the document "ZHOU WY, CHEN YK, YANG SW, "Efficient Design of Tightly Coupled Dipole Array Using an Equivalent Circuit-Based Approach", IEEE Access, 2020, 8: 14013-14023.", Professor Yang Shi used an analytical formula to map the structural dimensions of the bowtie dipole with its capacitance and inductance parameters, and used circuits instead of full-wave simulation for parameter optimization. However, due to the variable shape of the actual dipole and the influence of the parasitic parameters of the feed line and dipole, the mapping relationship is less accurate, making the model only usable for preliminary parameter estimation. In addition to circuit models, rigorous analytical expressions have also been used to model tightly coupled dipoles; for example, in the literature "CAVALLOD, NETO A, GERINI G, "Green's Function Based Equivalent Circuits for Connected Arrays in Transmission and in Reception", IEEE Transactions on Antennas and Propagation, 2011, 59(5): 1535-1545," the spectral Green's function of the load or gap between dipole units is introduced to extend the analytical formula of the Green's function applicable to traditional connected arrays to tightly coupled dipole arrays, thereby achieving accurate prediction of the active impedance and surface current distribution of tightly coupled dipole units during broadband and wide-angle scanning. However, this formula fails when there is a wide-angle scanning impedance matching layer loading.

[0004] In summary, the existing technology still faces many challenges, mainly including: 1) Due to the variable shape of the radiator of the tightly coupled dipole antenna, the existing equivalent model is difficult to fully describe all the reactance components of the complex radiator, so it is difficult to accurately establish the mapping relationship between its structural parameters and S parameters; 2) Since the antenna as a whole usually consists of three parts: matching layer, radiator and feed line, each part has a significant impact on the impedance matching of the antenna as a whole. In order to achieve the best S 11 Parameters require adjusting all key structural parameters of each part at the same time. However, the existing technology fails to fully realize the joint equivalent modeling and parameter optimization of the matching layer, radiator and feeder. Only the radiator part is studied and modeled, so it is difficult to achieve the optimal impedance matching design of the entire antenna. Summary of the Invention

[0005] The purpose of the present invention is to provide a parameter optimization method for a tightly coupled dipole antenna based on an equivalent circuit model, so as to solve the problems of low efficiency and poor effect of the tightly coupled dipole antenna design based on full-wave simulation and low precision and incompleteness of the existing equivalent model.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for optimizing parameters of a tightly coupled dipole antenna based on an equivalent circuit model comprises the following steps:

[0008] Step 1. Establish an equivalent circuit model based on the physical structure of the matching layer, where the structural parameters of the matching layer are , the circuit parameters of the equivalent circuit model of the matching layer are ; At the same time, establish the circuit parameters and structural parameters The functional relationship f s1 : ;

[0009] Step 2: Establish an equivalent circuit model based on the physical structure of the radiator, where the structural parameters of the radiator are , the circuit parameters of the equivalent circuit model of the radiator are ; At the same time, establish the circuit parameters and structural parameters The functional relationship f s2 : ;

[0010] Step 3: Establish an equivalent circuit model based on the physical structure of the feeder, where the structural parameters of the feeder are: , the circuit parameters of the equivalent circuit model of the feeder are ; At the same time, establish the circuit parameters and structural parameters The functional relationship f s3 : ;

[0011] Step 4. Cascade the equivalent circuit models of the matching layer, radiator, and feeder in sequence to form the full antenna equivalent circuit model of the tightly coupled dipole antenna. The structural parameters of the tightly coupled dipole antenna are: , the circuit parameters of the full antenna equivalent circuit model are ; At the same time, establish the circuit parameters and structural parameters The functional relationship f s : ;

[0012] Step 5. Set the structural parameters As optimization parameters, the gradient descent algorithm is used to call the full antenna equivalent circuit model for simulation optimization until the S parameters output by the full antenna equivalent circuit model meet the design indicators, and the corresponding structural parameters are used as the optimal structural parameters of the tightly coupled dipole antenna.

[0013] Furthermore, in step 1, the structural parameters of the matching layer are specifically: ,in, represents the width of the rectangular matching patch, represents the gap between adjacent rectangular matching patches, represents the length of the rectangular matching patch;

[0014] The equivalent circuit model of the matching layer is composed of a transmission line T1, with the two ends of the transmission line T1 serving as the output and input ends of the equivalent circuit model respectively. The specific circuit parameters are: ,in, and They represent the relative permittivity and magnetic permeability of the transmission line T1, L fss1 Represents the electrical length of transmission line T1.

[0015] Furthermore, in step 1, the functional relationship f s1 Expressed as:

[0016] ,

[0017] ,

[0018] ,

[0019] ,

[0020] ,

[0021] in, 、 represents the S parameter obtained by full-wave simulation of the matching layer, k0 represents the wave number in vacuum, and k c is the electrostatic force constant.

[0022] Furthermore, in step 2, the structural parameters of the radiator are specifically: , where h, W d 、W s , L cp 、S f They represent the distance between the radiator and the floor, the width of the radiator, the length of the radiator, the length of the rectangular coupling patch, and the width of the central gap of the radiator;

[0023] The equivalent circuit model of the radiator consists of a lumped capacitor C p , lumped capacitance C1, lumped inductance L p , lumped inductor L1 and short-circuited transmission line T2, wherein the left end of the lumped inductor L1 serves as the input end of the equivalent circuit model, and the right end of the lumped inductor L1 is connected in series with the lumped inductor L p With the lumped capacitance C p , lumped capacitance C p The right end of is used as the output end of the equivalent circuit model, and the lumped capacitor C1 is connected in parallel with the lumped inductor L1 and the lumped inductor L p The common end of the equivalent circuit model is connected in parallel with the short-circuited transmission line T2. The specific circuit parameters are: , where L p , L1 is the inductance value, C p , C1 are capacitance values, Z0 and H represent the characteristic impedance and electrical length of the short-circuited transmission line T2.

[0024] Furthermore, in step 2, the functional relationship f s2 Expressed as:

[0025] ,

[0026] ,

[0027] ,

[0028] ,

[0029] ,

[0030] Where μ0 represents the magnetic permeability in vacuum, ε0 represents the dielectric constant in vacuum, c represents the speed of light in vacuum, ε1 represents the relative dielectric constant of the dielectric substrate, k0 is the wave number in vacuum, and k c is the electrostatic force constant, ts Indicates the thickness of the dielectric substrate.

[0031] Furthermore, in step 3, the structural parameters of the feeder are specifically: , where W op , s represent the conductor width of the open-circuit coplanar waveguide transmission line and the gap between the conductor and the ground, W sc 、S sc Respectively represent the conductor width of the short-circuited coplanar stripline and the distance between the two conductors; W st 、W et Indicates the starting width and the ending width of the gradient microstrip line;

[0032] The equivalent circuit model of the feeder consists of an open transmission line T3, a tapered width transmission line T4, a short-circuited transmission line T5, and an ideal transformer. The left ends of the tapered width transmission line T4 and the open transmission line T3 serve as the input ends of the equivalent circuit model, and the right ends of the tapered width transmission line T4 and the open transmission line T3 are connected to the two ends of the primary of the ideal transformer respectively; the two ends of the secondary of the ideal transformer serve as the output ends of the equivalent circuit model, and the short-circuited transmission line T5 is connected in parallel to the output end of the equivalent circuit model. The circuit parameters are as follows: , where Z st , Z et They represent the characteristic impedances of the starting and ending points of the tapered width transmission line T4, Z oc represents the characteristic impedance of the open transmission line T3, Z sc N represents the characteristic impedance of the short-circuited transmission line T5. t Represents the transformation ratio of an ideal transformer.

[0033] Furthermore, in step 3, the functional relationship f s3 Expressed as:

[0034] ,

[0035] ,

[0036] ,

[0037] ,

[0038] ,

[0039] ,

[0040] ,

[0041] Where ε1 represents the relative dielectric constant of the dielectric substrate, t s represents the thickness of the dielectric substrate, tc represents the thickness of the metal layer; K(·) represents the elliptic integral of the first kind, and tanh(·) represents the hyperbolic tangent function.

[0042] Furthermore, in step 4, the functional relationship f s Expressed as: .

[0043] Furthermore, in step 5, the full antenna equivalent circuit model is constructed using circuit simulation software, and the S output by the full antenna equivalent circuit model is 11 The parameters are expressed as:

[0044] ,

[0045] Among them, g s represents the transfer function of the full antenna equivalent circuit model;

[0046] Use gradient descent algorithm to adjust the structural parameters , until the full antenna equivalent circuit model outputs S 11 The parameters meet the design indicators, and the corresponding structural parameters of the output are the optimal structural parameters of the tightly coupled dipole antenna.

[0047] Based on the above technical solution, the beneficial effects of the present invention are:

[0048] The present invention provides a parameter optimization method for a tightly coupled dipole antenna based on an equivalent circuit model. Equivalent circuit models of a matching layer, a radiator, and a feeder of the tightly coupled dipole antenna are established respectively by using principles such as transmission line theory, equivalent medium theory, and virtual waveguide theory. Furthermore, an analytical relationship between key structural parameters of the tightly coupled dipole antenna and circuit parameters in its equivalent circuit model is constructed, thereby establishing a complete equivalent circuit model of the tightly coupled dipole antenna. By efficiently optimizing the parameters of the equivalent circuit model, on the one hand, a coordinated optimization design of the tightly coupled dipole antenna's performance, such as bandwidth, standing wave, and scanning range, is achieved, thereby achieving global optimization of the antenna performance. On the other hand, the number of full-wave simulations required for parameter optimization is significantly reduced, thereby shortening the parameter optimization time and improving design efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 Schematic diagram of the three-dimensional structure of the tightly coupled dipole antenna in the present invention.

[0050] Figure 2 Schematic diagram of the layered structure of the tightly coupled dipole antenna in the present invention.

[0051] Figure 3 Schematic diagram of the equivalent circuit model of the tightly coupled dipole antenna in the present invention.

[0052] Figure 4Schematic diagram of the structure of the matching layer of the tightly coupled dipole antenna in the present invention.

[0053] Figure 5 Schematic diagram of the structure of the radiator of the tightly coupled dipole antenna in the present invention.

[0054] Figure 6 Schematic diagram of the structure of the feeder of the tightly coupled dipole antenna in the present invention.

[0055] Figure 7 Schematic diagram of the flow of the gradient descent algorithm in the present invention.

[0056] Figure 8 This is a comparison diagram of the standing wave ratio of the tightly coupled dipole antenna in the present invention.

[0057] Figure 9 This is a gain comparison diagram of the tightly coupled dipole antenna in the present invention. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical solutions and beneficial effects of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0059] This embodiment provides a parameter optimization method for a tightly coupled dipole antenna based on an equivalent circuit model. First, the physical structure of the antenna is divided into three modules: a matching layer 1, a radiator 2, and a feeder 3. Each module is a two-port network. Then, two-port equivalent circuit models are established for each of the three modules, and the two-port equivalent circuit models of the three modules are cascaded to obtain an equivalent circuit model of the tightly coupled dipole antenna. Finally, an optimization algorithm is used to call the equivalent circuit model for parameter optimization. By replacing time-consuming full-wave simulation with efficient circuit simulation, optimization convergence is accelerated, and simultaneous optimization of multiple key structural parameters is achieved.

[0060] Specifically, the method for optimizing parameters of a tightly coupled dipole antenna based on an equivalent circuit model includes the following steps:

[0061] Step 1. Establish an equivalent circuit model of the matching layer;

[0062] The physical structure of the matching layer includes: 2×M rectangular matching patches 1-1 of the same size, where M ranges from 2 to 10; 2×M rectangular matching patches are symmetrically arranged on the front and back of the dielectric substrate, and the M rectangular matching patches on each side are arranged side by side at equal intervals, such as Figure 1 and Figure 2 As shown;

[0063] The structural parameters of the matching layer are: ,in, represents the width of the rectangular matching patch, represents the gap between adjacent rectangular matching patches, represents the length of the rectangular matching patch, such as Figure 4 As shown;

[0064] The equivalent circuit model of the matching layer is composed of the transmission line T1, as shown in Figure 3 As shown, the two ends of the transmission line T1 serve as the output and input ends of the equivalent circuit model respectively; the circuit parameters are ,in, and They represent the relative permittivity and magnetic permeability of the transmission line, L fss1 Represents the electrical length of the transmission line, L fss1 =k0×l fss1 , k0 is the wave number in vacuum;

[0065] The circuit parameters are functions to be solved for the structural parameters. and structural parameters The electromagnetic simulation software Ansys HFSS is used to perform full-wave simulation on the physical structure of the matching layer and the structural parameters Perform parameter sweeping and simulation to obtain the S parameters corresponding to each parameter combination, and calculate the relative dielectric constant and magnetic permeability of the transmission line based on the equivalent medium theory, specifically:

[0066] , ,

[0067] ,

[0068] ,

[0069] in, 、 、 and is the S parameter obtained by full-wave simulation, k c is the electrostatic force constant, k c =8.99×10 9 V;

[0070] The structural parameters As independent variables, the circuit parameters As the dependent variable, the curve fitting algorithm is used to obtain the functional relationship between the two s1 , expressed as: ;

[0071] Step 2: Establish an equivalent circuit model of the radiator;

[0072] The physical structure of the radiator is a tightly coupled dipole, comprising: a pair of rectangular radiating patches 2-1 and a pair of rectangular coupling patches 2-2, wherein the pair of rectangular radiating patches 2-1 is arranged on the back side of the dielectric substrate, and the pair of rectangular coupling patches 2-2 is arranged on the front side of the dielectric substrate. Figure 1 and Figure 2 As shown;

[0073] The structural parameters of the radiator are: , where h, W d 、W s , L cp 、S f They represent the distance between the radiator and the floor, the width of the radiator, the length of the radiator, the length of the rectangular coupling patch, and the width of the central gap of the radiator, respectively. Figure 5 As shown;

[0074] The equivalent circuit model of the radiator consists of a lumped capacitor C p , lumped capacitance C1, lumped inductance L p , lumped inductor L1 and short-circuited transmission line T2, as shown Figure 3 As shown, the left end of the lumped inductor L1 serves as the input end of the equivalent circuit model, and the right end of the lumped inductor L1 is connected in series with the inductor L p With the lumped capacitance C p , lumped capacitance C p The right end of is used as the output end of the equivalent circuit model, and the lumped capacitor C1 is connected in parallel with the lumped inductor L1 and the lumped inductor L p The common end of the equivalent circuit model is connected in parallel with the short-circuited transmission line T2. The circuit parameters are: , where L p , L1 is the inductance value, C p , C1 is the capacitance value, Z0 and H represent the characteristic impedance and electrical length of the short-circuited transmission line T2, Z0=377Ω, H=k0h, k0 is the wave number in vacuum;

[0075] The circuit parameters and structural parameters The functional relationship is obtained by calculating the metal strip inductance and parallel plate capacitance, which can be expressed as follows:

[0076] ,

[0077] ,

[0078] ,

[0079] ,

[0080] Where μ0 is the magnetic permeability in vacuum, μ0=4π×10 -7 H / m; ε0 is the dielectric constant in vacuum, ε0=8.85×10 -12 F / m; c is the speed of light in vacuum, c=3×10 8 m / s; ε1 represents the relative dielectric constant of the dielectric substrate, k c is the electrostatic force constant, t s Indicates the thickness of the dielectric substrate;

[0081] Therefore, the circuit parameters and structural parameters The functional relationship is simplified as f s2 : ;

[0082] Step 3: Establish an equivalent circuit model of the feeder;

[0083] The physical structure of the feed line is a Marchand balun, including: an open-circuit ground coplanar waveguide (GCPW) transmission line 3-1, a short-circuit coplanar strip line 3-2, a tapered bent microstrip line 3-3, and a microstrip line-slot line transition structure 3-4, wherein the short-circuit coplanar strip line structure constitutes the ground of the tapered bent microstrip line and the open-circuit ground coplanar waveguide transmission line; the end of the tapered bent microstrip line is connected to the open-circuit ground coplanar waveguide transmission line, and is connected in parallel with the short-circuit coplanar strip line through the microstrip line-slot line transition structure; the end of the short-circuit coplanar strip line is connected to the dipole, such as Figure 1 and Figure 2 As shown;

[0084] The structural parameters of the feeder are: , where W op , s represent the conductor width of the open-circuit coplanar waveguide transmission line and the gap between the conductor and the ground, W sc 、S sc Respectively represent the conductor width of the short-circuited coplanar stripline and the distance between the two conductors, W st 、W et Indicates the starting width and the ending width of the gradient microstrip line, such as Figure 6 As shown;

[0085] The equivalent circuit model of the feeder consists of an open transmission line T3, a width-varying transmission line T4, a short-circuited transmission line T5 and an ideal transformer; wherein the left ends of the width-varying transmission line T4 and the open transmission line T3 serve as the input ends of the equivalent circuit model respectively, and the right ends of the width-varying transmission line T4 and the open transmission line T3 are connected to the two ends of the primary of the ideal transformer respectively; the two ends of the secondary of the ideal transformer serve as the output ends of the equivalent circuit model, and the short-circuited transmission line T5 is connected in parallel to the output end of the equivalent circuit model; the circuit parameters are , where Z st , Zet They represent the characteristic impedances of the starting and ending points of the tapered width transmission line T4, Z oc represents the characteristic impedance of the open transmission line T3, Z sc N represents the characteristic impedance of the short-circuited transmission line T5. t Indicates the transformation ratio of an ideal transformer;

[0086] Circuit parameters and structural parameters The functional relationship is obtained by the calculation method of the transmission line characteristic impedance, which is specifically expressed as:

[0087] ,

[0088] ,

[0089] ,

[0090] ,

[0091] ,

[0092] ,

[0093] ,

[0094] Where ε1 represents the relative dielectric constant of the dielectric substrate, t s represents the thickness of the dielectric substrate, t c represents the thickness of the metal layer; K(x) represents the first kind of elliptic integral, and tanh(x) represents the hyperbolic tangent function, which is expressed as:

[0095] ,

[0096] ,

[0097] Where t represents the integral variable and x represents the independent variable of the function;

[0098] It should also be noted that the transformation ratio N of the ideal transformer is t is a constant; therefore, the circuit parameters and structural parameters The functional relationship is simplified as f s3 : ;

[0099] Step 4. Cascade the equivalent circuit models of the matching layer, radiator, and feeder in sequence to form the full antenna equivalent circuit model of the tightly coupled dipole antenna.

[0100] The structural parameters of the tightly coupled dipole antenna are expressed as , specifically:

[0101] ,

[0102] The circuit parameters of the full antenna equivalent circuit model are expressed as , specifically:

[0103] ,

[0104] Then the circuit parameters and structural parameters The functional relationship is expressed as f s , specifically:

[0105] , ;

[0106] Step 5. Use the gradient descent algorithm to call the full antenna equivalent circuit model for simulation until the S parameters output by the full antenna equivalent circuit model meet the design specifications. The corresponding structural parameters are used as the optimal structural parameters of the tightly coupled dipole antenna.

[0107] The circuit simulation software is used to build the equivalent circuit model of the full antenna, and the structural parameters are As the optimization parameter, the S output by the full antenna equivalent circuit model is 11 The parameters are expressed as:

[0108] ,

[0109] Among them, g s represents the transfer function of the full antenna equivalent circuit model;

[0110] Use gradient descent algorithm to adjust the structural parameters , until the full antenna equivalent circuit model outputs S 11 The parameters meet the design indicators, and the corresponding structural parameters are the optimal structural parameters of the tightly coupled dipole antenna, such as Figure 7 shown.

[0111] In this embodiment, the tightly coupled dipole antenna is as follows: Figure 1 、 Figure 2 As shown, its target operating frequency band is 0.8~6.6GHz, and the design indicators are: Voltage Standing Wave Ratio (VSWR) is not higher than 2.5 (S 11 <7.5dB; antenna printed on 0.6mm thick (t s=0.6mm) single-layer FR4 printed circuit board (PCB), dielectric constant ε1 = 4.2, the thickness of the metal layer t c =0.018mm; the structural parameters of the matching layer are initialized to: W fss1 =3, S fss1 =0.3mm, l fss1 =3.0mm; the structural parameters of the radiator are initialized to: W d =7.8mm, W s =20.0mm, h=21.0mm, S f =3.0mm, L cp =16.0mm; the structural parameters of the feeder are initialized to: W op =0.8mm, s=0.3mm, W sc =1.5mm, S sc =5.4mm, W st =0.3mm, W et =1.0mm; on this basis, the initial value of the circuit parameter is calculated to be: ε r =2.6, μ r =0.9, L fss1 =8°, C p =1.03pF, L p =6.85nH, C1=0.02pF, L1=2.05nH, Z o =377.0Ω,H=80.3°,Z oc =45.1Ω, Z sc =302.0Ω, Z st =120.4Ω, Z et =49.0Ω,N t =0.94; put the calculated circuit parameter values ​​into the full antenna equivalent circuit model simulation circuit to obtain S 11 Parameters, if S 11 If the parameters do not meet the design specifications, the gradient descent algorithm is used to generate new structural parameters, and the iteration is continued until S 11 The parameters meet the design indicators, and the optimal structural parameters are finally obtained as shown in Table 1.

[0112] Table 1

[0113]

[0114] The optimized tightly coupled dipole antenna of this embodiment is simulated and tested, and its standing wave is as follows: Figure 8 As shown, the gain is Figure 9As shown in the figure, it can be seen that the highest standing wave ratio of the tightly coupled dipole antenna before optimization is 3.1, while after optimization, the standing wave ratio in the full frequency band is less than 2.5; and the full frequency band gain of the tightly coupled dipole antenna is improved after optimization.

[0115] In addition, compared with the traditional full-wave simulation optimization method, the tightly coupled dipole antenna parameter optimization method based on the equivalent circuit model provided by the present invention can greatly shorten the time and improve the optimization efficiency; in this embodiment, the tightly coupled dipole antenna parameter optimization process takes about 4 hours, while the traditional full-wave simulation optimization method takes dozens of hours to several days.

[0116] The above description is only a specific embodiment of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes; all disclosed features, or all steps in the methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A method for optimizing parameters of a tightly coupled dipole antenna based on an equivalent circuit model, characterized in that: The following steps are involved: Step 1. Establish an equivalent circuit model based on the physical structure of the matching layer, where the structural parameters of the matching layer are , the circuit parameters of the equivalent circuit model of the matching layer are ; At the same time, establish the circuit parameters and structural parameters The functional relationship f s1 : ; Step 2: Establish an equivalent circuit model based on the physical structure of the radiator, where the structural parameters of the radiator are , the circuit parameters of the equivalent circuit model of the radiator are ; At the same time, establish the circuit parameters and structural parameters The functional relationship f s2 : ; Step 3: Establish an equivalent circuit model based on the physical structure of the feeder, where the structural parameters of the feeder are: , the circuit parameters of the equivalent circuit model of the feeder are ; At the same time, establish the circuit parameters and structural parameters The functional relationship f s3 : ; Step 4. Cascade the equivalent circuit models of the matching layer, radiator, and feeder in sequence to form the full antenna equivalent circuit model of the tightly coupled dipole antenna. The structural parameters of the tightly coupled dipole antenna are: , the circuit parameters of the full antenna equivalent circuit model are ; At the same time, establish the circuit parameters and structural parameters The functional relationship f s : ; Step 5. Set the structural parameters As optimization parameters, the gradient descent algorithm is used to call the full antenna equivalent circuit model for simulation optimization until the S parameters output by the full antenna equivalent circuit model meet the design indicators, and the corresponding structural parameters are used as the optimal structural parameters of the tightly coupled dipole antenna.

2. The method for optimizing parameters of a tightly coupled dipole antenna based on an equivalent circuit model according to claim 1, wherein: In step 1, the structural parameters of the matching layer are specifically: ,in, represents the width of the rectangular matching patch, represents the gap between adjacent rectangular matching patches, represents the length of the rectangular matching patch; The equivalent circuit model of the matching layer is composed of a transmission line T1, with the two ends of the transmission line T1 serving as the output and input ends of the equivalent circuit model respectively. The specific circuit parameters are: ,in, and They represent the relative permittivity and magnetic permeability of the transmission line T1, L fss1 Represents the electrical length of transmission line T1.

3. The method for optimizing parameters of a tightly coupled dipole antenna based on an equivalent circuit model according to claim 2, wherein: In step 1, the functional relationship f s1 Expressed as: ， ， ， ， ， in, 、 represents the S parameter obtained by full-wave simulation of the matching layer, k0 represents the wave number in vacuum, and k c is the electrostatic force constant.

4. The method for optimizing parameters of a tightly coupled dipole antenna based on an equivalent circuit model according to claim 1, wherein: In step 2, the structural parameters of the radiator are specifically: , where h, W d 、W s 、L cp 、S f They represent the distance between the radiator and the floor, the width of the radiator, the length of the radiator, the length of the rectangular coupling patch, and the width of the central gap of the radiator; The equivalent circuit model of the radiator consists of a lumped capacitor C p , lumped capacitance C1, lumped inductance L p , lumped inductor L1 and short-circuited transmission line T2, wherein the left end of the lumped inductor L1 serves as the input end of the equivalent circuit model, and the right end of the lumped inductor L1 is connected in series with the lumped inductor L p With the lumped capacitance C p , lumped capacitance C p The right end of is used as the output end of the equivalent circuit model, and the lumped capacitor C1 is connected in parallel with the lumped inductor L1 and the lumped inductor L p The common end of the equivalent circuit model is connected in parallel with the short-circuited transmission line T2. The specific circuit parameters are: , where L p , L1 is the inductance value, C p , C1 are capacitance values, Z0 and H represent the characteristic impedance and electrical length of the short-circuited transmission line T2.

5. The method for optimizing parameters of a tightly coupled dipole antenna based on an equivalent circuit model according to claim 4, characterized in that: In step 2, the functional relationship f s2 Expressed as: ， ， ， ， ， Where μ0 represents the magnetic permeability in vacuum, ε0 represents the dielectric constant in vacuum, c represents the speed of light in vacuum, ε1 represents the relative dielectric constant of the dielectric substrate, k0 is the wave number in vacuum, and k c is the electrostatic force constant, t s Indicates the thickness of the dielectric substrate.

6. The method for optimizing parameters of a tightly coupled dipole antenna based on an equivalent circuit model according to claim 1, wherein: In step 3, the structural parameters of the feeder are as follows: , where W op , s represent the conductor width of the open-circuit coplanar waveguide transmission line and the gap between the conductor and the ground, W sc 、S sc Respectively represent the conductor width of the short-circuited coplanar stripline and the distance between the two conductors; W st 、W et Indicates the starting width and the ending width of the gradient microstrip line; The equivalent circuit model of the feeder consists of an open transmission line T3, a tapered width transmission line T4, a short-circuited transmission line T5, and an ideal transformer. The left ends of the tapered width transmission line T4 and the open transmission line T3 serve as the input ends of the equivalent circuit model, and the right ends of the tapered width transmission line T4 and the open transmission line T3 are connected to the two ends of the primary of the ideal transformer respectively; the two ends of the secondary of the ideal transformer serve as the output ends of the equivalent circuit model, and the short-circuited transmission line T5 is connected in parallel to the output end of the equivalent circuit model. The circuit parameters are as follows: , where Z st , Z et They represent the characteristic impedances of the starting and ending points of the tapered width transmission line T4, Z oc represents the characteristic impedance of the open transmission line T3, Z sc N represents the characteristic impedance of the short-circuited transmission line T5. t Represents the transformation ratio of an ideal transformer.

7. The method for optimizing parameters of a tightly coupled dipole antenna based on an equivalent circuit model according to claim 6, wherein: In step 3, the functional relationship f s3 Expressed as: ， ， ， ， ， ， ， Where ε1 represents the relative dielectric constant of the dielectric substrate, t s represents the thickness of the dielectric substrate, t c represents the thickness of the metal layer; K(·) represents the elliptic integral of the first kind, and tanh(·) represents the hyperbolic tangent function.

8. The method for optimizing parameters of a tightly coupled dipole antenna based on an equivalent circuit model according to claim 1, wherein: In step 4, the functional relationship f s Expressed as: .

9. The method for optimizing parameters of a tightly coupled dipole antenna based on an equivalent circuit model according to claim 1, wherein: In step 5, the circuit simulation software is used to build the full antenna equivalent circuit model, and the S output by the full antenna equivalent circuit model is 11 The parameters are expressed as: ， Among them, g s represents the transfer function of the full antenna equivalent circuit model; Use gradient descent algorithm to adjust the structural parameters , until the full antenna equivalent circuit model outputs S 11 The parameters meet the design indicators, and the corresponding structural parameters of the output are the optimal structural parameters of the tightly coupled dipole antenna.

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