CN113328239B - Periodic impedance modulation surface for arbitrary pitching surface rectangular beam forming - Google Patents

Abstract

The invention discloses a periodic impedance modulation surface for arbitrary elevation plane rectangular beam forming, and belongs to the technical field of antennas and periodic impedance modulation surfaces. The periodic impedance modulation surface of the present invention applies the periodic impedance modulation surface to the rectangular beamforming. Compared with the existing technology of combining array synthesis and algorithm, it does not need to use multiple feed sources and complex feeding networks, only It is necessary to extend the inner core of the coaxial line to form a monopole for feeding, and the structure is simple and easy to implement. Another advantage of the present invention is that compared with the existing method to realize rectangular beam forming in the normal direction, it can realize rectangular beam forming in a direction with a certain inclination angle.

Description

A Periodic Impedance Modulation Surface for Rectangular Beamforming in Arbitrary Elevation Planes

technical field

The invention belongs to the technical field of antennas and periodic impedance modulation surfaces, and in particular relates to a periodic impedance modulation surface for arbitrary elevation plane rectangular beam forming.

Background technique

As the terminal of the wireless communication system, the antenna plays an extremely important role in mobile communication. The gain lobe of the electromagnetic wave emitted by the traditional base station antenna is generally spherical, and the lobe width is relatively wide. Rectangular beamforming techniques with a certain roll-off rate are required to eliminate or reduce the mutual interference of signals in the multi-beam multiplexing area.

The document "Flat-Top Footprint Pattern Synthesis Through the Design of Arbitrary Planar-Shaped Apertures" realizes rectangular beamforming through two techniques, one is to use the Rayleigh quotient to obtain a pattern array with a constant phase distribution; the other is to use the power-based The synthesis technique has no requirements on the phase of the array pattern. The paper "Synthesizing Uniform Amplitude Sparse Dipole Arrays WithShaped Patterns by Joint Optimization of Element Positions, Rotations and Phases" implements beamforming of arbitrary shapes by using a joint optimization algorithm to determine the position, rotation angle and phase excitation of each element.

However, the above-mentioned prior art combines the optimization algorithm to control the amplitude and phase of the array to realize beamforming, but generally uses multiple feed sources, thus requiring a complex feeding network, large size/volume and difficult to implement, and the prior art Only the normal rectangular beamforming is realized, and the rectangular beamforming cannot be realized on any elevation plane.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the above-mentioned defects of the prior art, and to provide a periodic impedance modulation surface for arbitrary elevation plane rectangular beamforming.

The technical problem proposed by the present invention is solved like this:

A periodic impedance modulation surface for arbitrary pitch plane rectangular beamforming, including a chamfered rectangular metal patch unit 1, a dielectric substrate 2, a metal ground plate 3 and a monopole feed 4; the chamfered rectangular metal patch unit 1 is located in the The upper surface of the dielectric substrate 2, the metal grounding plate 3 is located on the lower surface of the dielectric substrate 2; the overall shape of the periodic impedance modulation surface is a circle, which is divided into a uniformly distributed lattice, and the metal patch unit 1 is confined within the lattice ;

The monopole feed source 4 adopts a coaxial wire, the inner core of the coaxial wire passes through the metal ground plate 3 and the dielectric substrate 2 and extends into the space, and the outer conductor is connected to the metal ground plate 3; the monopole feed source 4 corresponds to The position of the upper surface of the dielectric substrate 2 is not provided with a chamfered rectangular metal patch unit 1;

The width a, height b and counterclockwise rotation angle θ along the longitudinal axis of the chamfered rectangular metal patch unit 1 are different at different positions. The specific determination method is as follows:

Step 1. Model the impedance element in electromagnetic simulation software, including a chamfered rectangular metal patch element 1 and a lattice of dielectric substrate and metal ground plate, and set periodic boundary conditions to chamfer the element metal patch The width a, height b and the counterclockwise rotation angle θ of slice 1 are used as variables to scan the parameters to obtain the corresponding relationship between the patch size and the tensor impedance distribution, and save it as a database for future use;

Step 2. Given the desired target field, calculate the impedance distribution of the final periodic impedance surface;

Step 2-1. Given the desired target field E _A :

表示半径方向单位极坐标，

和

分别表示单位极化向量方位角方向的幅度和相位，

表示方位角方向单位极坐标，j为虚数符号；where E ₀ represents the amplitude of the target field, kl(ρ) represents the phase factor of the target field, ρ is the radius value, e _ρ (ρ) and γ _ρ (ρ) represent the amplitude and phase of the unit polarization vector in the radial direction,

represents the unit polar coordinate in the radial direction,

and

represent the magnitude and phase of the unit polarization vector in the azimuth direction, respectively,

Indicates the unit polar coordinate in the azimuth direction, j is the imaginary number symbol;

和方位角方向的平均阻抗

的初始值，令当前迭代次数＝1；Step 2-2. Given the phase factor Ks(ρ) of the surface impedance, the modulation coefficient m, and the average impedance in the radial direction

and the average impedance in the azimuth direction

The initial value of , let the current number of iterations = 1;

Step 2-3. Inversely solve the propagation constant β _SW of the initial surface wave field according to the following formula:

Step 2-4. Calculate the impedance distribution X of the periodic impedance surface for the current iteration number:

为半径方向和方位角方向的耦合阻抗分量，

为方位角方向阻抗分量；m_ρ(ρ)为半径方向调制系数模值，φ_ρ(ρ)为半径方向调制系数相位，

为方位角方向调制系数模值，

为方位角方向调制系数相位；Among them, X _ρρ is the impedance component in the radial direction,

are the coupling impedance components in the radial and azimuth directions,

is the impedance component in the azimuth direction; m _ρ (ρ) is the modulo value of the modulation coefficient in the radial direction, φ _ρ (ρ) is the phase of the modulation coefficient in the radial direction,

is the modulo value of the modulation coefficient in the azimuth direction,

is the phase of the modulation coefficient in the azimuth direction;

Step 2-5. Make the updated

反解下式更新表面波场的传播常数β_SW：make the updated

Update the propagation constant β _SW of the surface wave field by inversely solving the following equation:

Update the phase factor Ks(ρ) of the surface impedance:

Among them, β _Δ (ρ) is the difference between the propagation constants of the surface wave field after the update and before the update;

Step 2-6. Update the modulation coefficient m:

The impedance distribution X of the periodic impedance surface is organized into the following form:

X=X ⁽⁰⁾ +X ⁽⁺¹⁾ +X ^(-1)

为第二类一阶贝塞尔函数；

和

分别为零阶和负一阶的接地介质阻抗；where j ₀ is the magnitude of the excitation field,

is a first-order Bessel function of the second kind;

and

zero-order and negative-first-order ground dielectric impedances, respectively;

和方位角方向的平均阻抗

计算最终的周期阻抗表面的阻抗分布X；否则，令当前迭代次数+1，返回执行步骤2-3；Step 2-6. Determine whether the cut-off condition is met. If yes, then update the phase factor Ks(ρ) of the surface impedance, the modulation coefficient m, and the average impedance in the radial direction.

and the average impedance in the azimuth direction

Calculate the impedance distribution X of the final periodic impedance surface; otherwise, set the current iteration number +1, and return to step 2-3;

The cut-off condition is that the current number of iterations reaches the set maximum number of iterations, or the difference between the updated modulation coefficient m and before the update is less than the set threshold;

Step 3. Match the impedance distribution of the final periodic impedance surface calculated in step 2 with the tensor impedance distribution in the database in step 1, and find the corresponding relationship between the patch size and the tensor impedance distribution in the database. The patch size of the impedance distribution on the final periodic impedance surface;

Step 4. Given the desired target field EA' again _:

表示再次给定的期望目标场的单位极化向量方位角方向的相位；where kl(ρ) represents the phase factor of the re-given desired target field, γ′ _ρ (ρ) represents the phase in the radial direction of the unit polarization vector of the re-given desired target field,

represents the phase in the azimuth direction of the unit polarization vector of the again given desired target field;

Repeat steps 2-3 to obtain the patch size corresponding to the impedance distribution of the periodic impedance surface calculated given the desired target field again; average the patch size of the impedance distribution of the final periodic impedance surface obtained twice value.

Further, the overall shape of the periodic impedance modulation surface is a circle, and the radius corresponds to 5 times the free space wavelength corresponding to the center frequency of 30 GHz. The periodic impedance modulation surface is divided into uniformly distributed lattices, and the side length of each lattice is the center. The frequency of 30GHz corresponds to 1/10 of the free space wavelength, and the metal patch unit 1 is confined within the lattice.

Further, the thickness of the dielectric substrate 2 is h=0.508 mm, the relative permittivity is 10.2, and the shape and radius of the metal ground plate 3 are consistent with the dielectric substrate 2 .

The beneficial effects of the present invention are:

The periodic impedance modulation surface of the present invention applies the periodic impedance modulation surface to rectangular beamforming. Compared with the existing technology combining array synthesis and algorithm, it does not need to use multiple feed sources and complex feeding networks, and only It is necessary to extend the inner core of the coaxial line to form a monopole for feeding, and the structure is simple and easy to implement. Another advantage of the present invention is that compared with the existing method to realize rectangular beam forming in the normal direction, it can realize rectangular beam forming in a direction with a certain inclination angle.

Description of drawings

1 is a top view and a side view of the overall structure of the periodic impedance modulation surface of the present invention;

FIG. 2 is a detailed view of the portion near the center of the periodic impedance modulation surface of the present invention;

3 is a schematic structural diagram and a top view of a tensor impedance unit in an embodiment;

Fig. 4 is the Cartesian coordinate gain pattern of the XOZ plane of the periodic impedance modulation surface at 30GHz in the embodiment;

Fig. 5 is the polar coordinate gain pattern of the XOZ plane of the periodic impedance modulation surface at 30GHz in the embodiment;

Fig. 6 is the Cartesian coordinate gain pattern of the section of the periodic impedance modulation surface at the pitch angle of 37 degrees in the embodiment;

7 is a three-dimensional gain pattern of a periodic impedance modulating surface in an embodiment.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and embodiments.

This embodiment provides a periodic impedance modulation surface for arbitrary elevation plane rectangular beamforming, whose overall structure top view and side view are shown in FIG. 1 , and a detailed view near the center is shown in FIG. The chip unit 1, the dielectric substrate 2, the metal ground plate 3 and the monopole feed source 4; the cut-corner rectangular metal patch unit 1 is located on the upper surface of the dielectric substrate 2, and the metal ground plate 3 is located on the lower surface of the dielectric substrate 2;

The overall shape of the periodic impedance modulation surface is a circle, and the radius corresponds to 5 times the free space wavelength corresponding to the center frequency of 30GHz. The periodic impedance modulation surface is divided into uniformly distributed lattices, and the side length of each lattice is corresponding to the center frequency of 30GHz. 1/10 of the free space wavelength of the metal patch unit 1 is confined within the lattice. The thickness h of the dielectric substrate 2 is 0.508 mm, the relative dielectric constant is 10.2, and the shape and radius of the metal ground plate 3 are consistent with those of the dielectric substrate 2 .

The monopole feed source 4 adopts a coaxial wire, the inner core of the coaxial wire passes through the metal grounding plate 3 and the dielectric substrate 2 and extends into the space, and the outer conductor is connected to the metal grounding plate 3 . The chamfered rectangular metal patch unit 1 is not provided on the upper surface of the dielectric substrate 2 corresponding to the monopole feed 4; in this embodiment, the 5×5 chamfered rectangular metal patch unit 1 located in the center of the periodic impedance modulation surface is remove.

The width a, height b and counterclockwise rotation angle θ along the longitudinal axis of the chamfered rectangular metal patch unit 1 are different at different positions. The specific determination method is as follows:

Step 1. Model the impedance unit in the electromagnetic simulation software. The schematic diagram of the impedance unit is shown in Figure 3, including a chamfered rectangular metal patch unit 1 and a lattice dielectric substrate and metal grounding plate, and set Periodic boundary conditions, and take the width a, height b and counterclockwise rotation angle θ of the chamfered element metal patch 1 as variables to scan the parameters to obtain the corresponding relationship between the patch size and the tensor impedance distribution, and Save it as a database for backup;

Step 2. Given the desired target field, calculate the impedance distribution of the final periodic impedance surface;

Step 2-1. Given the desired target field E _A :

表示半径方向单位极坐标，

和

分别表示单位极化向量方位角方向的幅度和相位，

表示方位角方向单位极坐标，j为虚数符号；where E ₀ represents the amplitude of the target field, kl(ρ) represents the phase factor of the target field, ρ is the radius value, e _ρ (ρ) and γ _ρ (ρ) represent the amplitude and phase of the unit polarization vector in the radial direction,

represents the unit polar coordinate in the radial direction,

and

represent the magnitude and phase of the unit polarization vector in the azimuth direction, respectively,

Indicates the unit polar coordinate in the azimuth direction, j is the imaginary number symbol;

和方位角方向的平均阻抗

的初始值，令当前迭代次数＝1；Step 2-2. Given the phase factor Ks(ρ) of the surface impedance, the modulation coefficient m, and the average impedance in the radial direction

and the average impedance in the azimuth direction

The initial value of , let the current number of iterations = 1;

Step 2-3. Inversely solve the propagation constant β _SW of the initial surface wave field according to the following formula:

Step 2-4. Calculate the impedance distribution X of the periodic impedance surface for the current iteration number:

为半径方向和方位角方向的耦合阻抗分量，

为方位角方向阻抗分量；m_ρ(ρ)为半径方向调制系数模值，φ_ρ(ρ)为半径方向调制系数相位，

为方位角方向调制系数模值，

为方位角方向调制系数相位；Among them, X _ρρ is the impedance component in the radial direction,

are the coupling impedance components in the radial and azimuth directions,

is the impedance component in the azimuth direction; m _ρ (ρ) is the modulo value of the modulation coefficient in the radial direction, φ _ρ (ρ) is the phase of the modulation coefficient in the radial direction,

is the modulo value of the modulation coefficient in the azimuth direction,

is the phase of the modulation coefficient in the azimuth direction;

Step 2-5. Make the updated

反解下式更新表面波场的传播常数β_SW：make the updated

Update the propagation constant β _SW of the surface wave field by inversely solving the following equation:

Update the phase factor Ks(ρ) of the surface impedance:

Among them, β _V (ρ) is the difference between the propagation constants of the surface wave field after the update and before the update;

Step 2-6. Update the modulation coefficient m:

The impedance distribution X of the periodic impedance surface is organized into the following form:

X=X ⁽⁰⁾ +X ⁽⁺¹⁾ +X ^(-1)

为第二类一阶贝塞尔函数；

和

分别为零阶和负一阶的接地介质阻抗。where j ₀ is the magnitude of the excitation field,

is a first-order Bessel function of the second kind;

and

Ground dielectric impedance of zero order and negative first order, respectively.

和方位角方向的平均阻抗

计算最终的周期阻抗表面的阻抗分布X；否则，令当前迭代次数+1，返回执行步骤2-3。Step 2-6. Determine whether the cut-off condition is met. If yes, then update the phase factor Ks(ρ) of the surface impedance, the modulation coefficient m, and the average impedance in the radial direction.

and the average impedance in the azimuth direction

Calculate the impedance distribution X of the final periodic impedance surface; otherwise, set the current iteration number +1, and return to step 2-3.

The cut-off condition is that the current number of iterations reaches the set maximum number of iterations, or the difference between the updated modulation coefficient m and before the update is less than the set threshold.

Step 3. Match the impedance distribution of the final periodic impedance surface calculated in step 2 with the tensor impedance distribution in the database in step 1, and find the corresponding relationship between the patch size and the tensor impedance distribution in the database. The patch size of the impedance distribution on the final periodic impedance surface.

Step 4. Given the desired target field EA' again _:

表示再次给定的期望目标场的单位极化向量方位角方向的相位；where kl(ρ) represents the phase factor of the re-given desired target field, γ′ _ρ (ρ) represents the phase in the radial direction of the unit polarization vector of the re-given desired target field,

represents the phase in the azimuth direction of the unit polarization vector of the again given desired target field;

Repeat steps 2-3 to obtain the patch size corresponding to the impedance distribution of the periodic impedance surface calculated given the desired target field again; average the patch size of the impedance distribution of the final periodic impedance surface obtained twice value.

Figures 4 and 6 are the rectangular and polar patterns of the azimuth angle of the section gain changing with the pitch angle, respectively. It can be seen from the figure that the 3dB beam width is 25 degrees, that is, the pitch angle is 26° to 51°, and the maximum gain is 15.8dB; Fig. 5 is a Cartesian coordinate pattern of the section gain changing with the azimuth angle when the pitch angle is 37 degrees. It can be seen from the figure that the pattern in this section is distributed in a pen shape, and the 3dB beam width is 13 degrees. Figure 7 is a three-dimensional gain pattern of a periodic impedance modulating surface. The results show that this scheme realizes two-dimensional rectangular beamforming with a certain pitch angle.

Claims (3)

1. A periodic impedance modulation surface for arbitrary elevation plane rectangular beamforming, characterized in that it comprises a corner-cut rectangular metal patch unit (1), a dielectric substrate (2), a metal ground plate (3) and a monopole feeder. The source (4); the chamfered rectangular metal patch unit (1) is located on the upper surface of the dielectric substrate (2), and the metal ground plate (3) is located on the lower surface of the dielectric substrate (2); the overall shape of the periodic impedance modulation surface is a circle The shape is divided into a uniformly distributed lattice, and the chamfered rectangular metal patch unit (1) is confined within the lattice; The monopole feed source (4) adopts a coaxial wire, the inner core of the coaxial wire passes through the metal grounding plate (3) and the dielectric substrate (2) and extends into the space, and the outer conductor is connected to the metal grounding plate (3); The position of the upper surface of the dielectric substrate (2) corresponding to the monopole feed source (4) is not provided with a chamfered rectangular metal patch unit (1); The width a, height b and counterclockwise rotation angle θ along the vertical axis of the chamfered rectangular metal patch unit (1) at different positions are different, and the specific determination method is as follows: Step 1. Model the impedance element in electromagnetic simulation software, including a chamfered rectangular metal patch element (1) and a lattice of dielectric substrate and metal ground plate, and set periodic boundary conditions to chamfer the element The width a, height b and counterclockwise rotation angle θ along the vertical axis of the metal patch (1) are used as variables to perform parameter scanning to obtain the corresponding relationship between the patch size and the tensor impedance distribution, and save it as a database for future use; Step 2. Given the desired target field, calculate the impedance distribution of the final periodic impedance surface; Step 2-1. Given the desired target field E _A :

where E ₀ represents the amplitude of the target field, kl(ρ) represents the phase factor of the target field, ρ is the radius value, e _ρ (ρ) and γ _ρ (ρ) represent the amplitude and phase of the unit polarization vector in the radial direction,

represents the unit polar coordinate in the radial direction,

and

represent the magnitude and phase of the unit polarization vector in the azimuth direction, respectively,

Indicates the unit polar coordinate in the azimuth direction, and j is the imaginary number symbol; Step 2-2. Given the phase factor Ks(ρ) of the surface impedance, the modulation coefficient m, and the average impedance in the radial direction

and the average impedance in the azimuth direction

The initial value of , let the current number of iterations = 1; Step 2-3. Inversely solve the propagation constant β _SW of the initial surface wave field according to the following formula:

Step 2-4. Calculate the impedance distribution X of the periodic impedance surface for the current iteration number:

Among them, X _ρρ is the impedance component in the radial direction,

are the coupling impedance components in the radial and azimuth directions,

is the impedance component in the azimuth direction; m _ρ (ρ) is the modulo value of the modulation coefficient in the radial direction, f _ρ (ρ) is the phase of the modulation coefficient in the radial direction,

is the modulo value of the modulation coefficient in the azimuth direction,

is the phase of the modulation coefficient in the azimuth direction; Step 2-5. Make the updated

make the updated

Update the propagation constant β _SW of the surface wave field by inversely solving the following equation:

Update the phase factor Ks(ρ) of the surface impedance:

Among them, β _Δ (ρ) is the difference between the propagation constants of the surface wave field after the update and before the update; Step 2-6. Update the modulation coefficient m:

The impedance distribution X of the periodic impedance surface is organized into the following form: X=X ⁽⁰⁾ +X ⁽⁺¹⁾ +X ^(-1)

where j ₀ is the amplitude of the excitation field,

is a first-order Bessel function of the second kind;

and

Ground dielectric impedance of zero-order and negative first-order, respectively; Step 2-6. Determine whether the cut-off condition is met. If yes, then update the phase factor Ks(ρ) of the surface impedance, the modulation coefficient m, and the average impedance in the radial direction.

and the average impedance in the azimuth direction

Calculate the impedance distribution X of the final periodic impedance surface; otherwise, set the current iteration number +1, and return to step 2-3; Step 3. Match the impedance distribution of the final periodic impedance surface calculated in step 2 with the tensor impedance distribution in the database in step 1, and find the corresponding relationship between the patch size and the tensor impedance distribution in the database. The patch size of the impedance distribution on the final periodic impedance surface; Step 4. Again given the desired target field _EA ':

Among them, kl'(ρ) represents the phase factor of the re-given desired target field, γ' _ρ (ρ) represents the phase in the radial direction of the unit polarization vector of the re-given desired target field,

represents the phase in the azimuth direction of the unit polarization vector of the again given desired target field; Repeat steps 2-3 to obtain the patch size corresponding to the impedance distribution of the periodic impedance surface calculated given the desired target field again; average the patch size of the impedance distribution of the final periodic impedance surface obtained twice value. 2. The periodic impedance modulation surface of any pitch plane rectangular beamforming according to claim 1, wherein the radius of the periodic impedance modulation surface corresponds to 5 times the free space wavelength corresponding to the center frequency of 30 GHz, and the The side length is 1/10 of the free space wavelength corresponding to the center frequency of 30 GHz, and the metal patch unit (1) is confined within the lattice. 3. The periodic impedance modulation surface for arbitrary pitch plane rectangular beamforming according to claim 1, characterized in that, the thickness of the dielectric substrate (2) is h=0.508mm, the relative permittivity is 10.2, and the metal ground plate (3) ) in shape and radius consistent with the dielectric substrate (2).

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