阅读说明：本技术 基于径向波导的阵列天线孔径场设计及波束调控方法 (Array antenna aperture field design and beam regulation and control method based on radial waveguide ) 是由 杨钊 殷丹 文光俊 于 2020-05-21 设计创作，主要内容包括：本发明公开了一种基于径向波导的阵列天线孔径场设计及波束调控方法,阵列天线包括圆形且相互平行的径向波导顶层金属板和径向波导底层金属板,径向波导顶层金属板上设有多个均匀分布的环形天线阵列,每个天线的耦合探针位于径向波导顶层金属板上朝向径向波导底层金属板的一侧；径向波导底层金属板朝向径向波导顶层金属板的一侧设有馈电探针,馈电探针设置在径向波导底层金属板的中心位置。本发明可以通过适当调节波导内探针尺寸合成特定天线单元的激励幅度,同时通过调节探针和天线单元之间的传输线长度或者移相器,可以有效合成激励相位。可以根据特定的近场/远场波束计算得出天线单元激励系数,能够在射频频段生成近场或者远场特定波束。(The invention discloses an array antenna aperture field design and beam regulation and control method based on radial waveguide, wherein the array antenna comprises a circular and mutually parallel radial waveguide top metal plate and a radial waveguide bottom metal plate, a plurality of uniformly distributed annular antenna arrays are arranged on the radial waveguide top metal plate, and a coupling probe of each antenna is positioned on one side of the radial waveguide top metal plate, which faces the radial waveguide bottom metal plate; and a feed probe is arranged on one side of the radial waveguide bottom metal plate, which faces the radial waveguide top metal plate, and is arranged at the central position of the radial waveguide bottom metal plate. The invention can synthesize the excitation amplitude of a specific antenna unit by properly adjusting the size of the probe in the waveguide, and can effectively synthesize the excitation phase by adjusting the length of a transmission line or a phase shifter between the probe and the antenna unit. The antenna element excitation coefficients can be calculated from the specific near field/far field beams, enabling the generation of either near field or far field specific beams in the radio frequency band.)

1. The array antenna aperture field design method based on the radial waveguide is characterized by comprising a circular and mutually parallel radial waveguide top metal plate and a radial waveguide bottom metal plate, wherein a plurality of uniformly distributed annular antenna arrays are arranged on the radial waveguide top metal plate, and a coupling probe of each antenna is positioned on one side of the radial waveguide top metal plate, which faces the radial waveguide bottom metal plate; and a feed probe is arranged on one side of the radial waveguide bottom metal plate, which faces the radial waveguide top metal plate, and is arranged at the central position of the radial waveguide bottom metal plate.

2. The method for designing the aperture field of the radial waveguide-based array antenna according to claim 1, wherein an annular metal wall is arranged at the edge of the bottom metal plate of the radial waveguide in the direction towards the top metal plate of the radial waveguide.

3. The method for designing the aperture field of the radial waveguide-based array antenna according to claim 1, wherein a plurality of concentric circular antenna arrays are arranged on the top metal plate of the radial waveguide, and antennas in each circular antenna array are uniformly distributed;

the method for calculating the coupling factor of each coupling unit comprises the following steps: suppose that the kth ring contains N_kAn antenna and a power value coupled to each antenna element is p_rad,k；

The total power of all antenna elements coupled to the kth circle is P_rad,k＝N_k×p_rad,k(ii) a The total input power for the (k + 1) th ring is:

P_in,k+1＝P_in,k-P_rad,k＝P_in,k-N_kp_rad,k

P_in,kis the total input of all cells of the kth ringPower;

assuming total input power P_in,1All coupled to the antenna elements; coefficient p_rad,kTo a specific unit power value, byReplacing; q represents the total number of rings; the coupling factor of the kth coupling unit is calculated by:

the total coupling factor of the kth ring is through C_k＝N_kc_kIs calculated by the method of (1).

4. The radial waveguide-based array antenna aperture field design method of claim 1, wherein the coupling probe is made of a vertical printed patch element.

5. The method for regulating array antenna beams based on the radial waveguides as claimed in any one of claims 1 to 4, wherein under the condition that the feeding amplitude is kept unchanged, the feeding phase is modulated to obtain the focused beams with different focus positions, wherein the feeding phase modulation is realized through a phase shifter between the input end of the antenna unit and the output port of the feeding network.

Technical Field

The invention belongs to the technical field of wireless communication, and particularly relates to an array antenna aperture field design and beam regulation and control method based on radial waveguides.

Background

Due to the characteristics of low profile and low loss, the antenna array based on the radial waveguide structure is widely applied to satellite communication systems, and is suitable for design work with higher working frequency bands (such as 5G and millimeter wave frequency bands) and higher requirements on gain and efficiency.

The traditional radial waveguide consists of two parallel metal circular plates and a feed source positioned at the circle center of a bottom plate. When the distance between the two parallel metal circular plates is less than half wavelength, a TEM radial mode can be excited in the waveguide, and cylindrical waves transmitted along the radial direction can be generated.

The most common antennas based on radial waveguide structures are the radial line slot array antennas (RLSA) (Ando, Makoto, et al. "A radial line slot antenna for 12GHz satellite TV reception." E transmission on antennas and propagation 33.12(1985): 1347-. However, since the slot elements can only couple a small amount of energy, the array antenna requires a large number of slot elements to achieve low return loss and high efficiency, which results in a time-consuming optimization process for the size and position of the slot elements. In addition, since the position of each slot element cannot be known in advance, the method of the present invention, which presupposes the positions of the antenna elements and calculates the amplitude/phase distribution of each element, is not suitable for the design work of such a slot array antenna, and optimizes the radiation pattern of the slot array antenna according to the continuous aperture distribution, which greatly limits the range of use of such a design method.

Other radial waveguide based array antenna structures may effectively address the above-mentioned problems. For example, in the context of "Carver, k.r." a cavity-fed centralized ring phased array of resonators for use in radiostronomy ", dis.ph.d., University of Ohio, 1967", the energy coupling process is accomplished by using a vertical probe (connected to a low-profile helical antenna element) inside the radial waveguide. Wherein a specific excitation phase is achieved by spinning each antenna element and a specific coupling factor is achieved by adjusting the probe length inside the waveguide. In addition, "antenna and Propagation antenna symposium1991digest. IEEE, 1991" using other antenna element structures (such as microstrip patch Antennas) has been successfully designed. However, for this type of array antenna, the position of the probe inside the waveguide and its mutual coupling effect have a great influence on the excitation phase, and in addition, the phase synthesis process is also complicated.

"IEEE polarized radial alignment antenna with internal linear coupling patches", "IEEE transaction Antennas and Propagation 59.8(2011):3049 and 3052", proposes a different coupling mechanism, and energy coupling is performed through a horizontal patch coupling unit located inside a waveguide, so that the antenna assembly process can be simplified, and better radiation performance can be achieved, and finally a concentric ring array antenna is designed, so that uniform excitation amplitude distribution is achieved, but the distance between adjacent rings is 3/4 λ (so that the reflection wave influence of the coupling unit between the rings can be effectively reduced), which limits the use range of the radial waveguide. In addition, the dielectric thickness of the horizontal patch coupling unit is proportional to the magnitude of the coupling factor, so for the case of a large coupling factor, the dielectric thickness of the horizontal patch coupling unit needs to be increased, which increases the return loss in the radial waveguide.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method which can synthesize the excitation amplitude of a specific antenna unit by properly adjusting the size of a probe in a waveguide and can effectively synthesize the excitation phase by adjusting the length of a transmission line between the probe and the antenna unit or a phase shifter. In addition, the excitation coefficient of the antenna unit can be calculated according to the specific near field/far field wave beam, and the array antenna aperture field design and wave beam regulation method based on the radial waveguide can generate the near field or far field specific wave beam in a radio frequency band.

The purpose of the invention is realized by the following technical scheme: the array antenna aperture field design method based on the radial waveguide comprises a circular radial waveguide top metal plate and a radial waveguide bottom metal plate which are parallel to each other, wherein a plurality of uniformly distributed annular antenna arrays are arranged on the radial waveguide top metal plate, and a coupling probe of each antenna is positioned on one side of the radial waveguide top metal plate, which faces to the radial waveguide bottom metal plate; and a feed probe is arranged on one side of the radial waveguide bottom metal plate, which faces the radial waveguide top metal plate, and is arranged at the central position of the radial waveguide bottom metal plate.

Furthermore, an annular metal wall is arranged at the edge of the bottom metal plate of the radial waveguide in the direction towards the top metal plate of the radial waveguide.

Furthermore, a plurality of concentric annular antenna arrays are arranged on the top metal plate of the radial waveguide, and antennas in each annular antenna array are uniformly distributed;

the method for calculating the coupling factor of each coupling unit comprises the following steps: suppose that the kth ring contains N_kAn antenna and a power value coupled to each antenna element is p_rad,k；

The total power of all antenna elements coupled to the kth circle is P_rad,k＝N_k×p_rad,k(ii) a The total input power for the (k + 1) th ring is:

P_in,k+1＝P_in,k-P_rad,k＝P_in,k-N_kp_rad,k

P_in,kthe total input power of all units of the kth ring;

assuming total input power P_in，1All coupled to the antenna elements; coefficient p_rad，kTo a specific unit power value, byReplacing; q represents the total number of rings; the coupling factor of the kth coupling unit is calculated by:

the total coupling factor of the kth ring is through C_k＝N_kc_kIs calculated by the method of (1).

Further, the coupling probe is made of a vertical printed patch unit.

The invention also provides a radial waveguide-based array antenna beam regulation and control method, which is characterized in that under the condition that the feed amplitude is kept unchanged, the feed phase is modulated to obtain the focused beams with different focus positions, wherein the feed phase modulation is realized through a phase shifter between the input end of the antenna unit and the output port of the feed network.

The invention has the beneficial effects that: the feed network of the invention is formed on the basis of a radial waveguide structure, the feed probe is positioned at the circle center of the waveguide bottom plate, and a plurality of metal probes distributed according to concentric rings are connected with the antenna unit through the waveguide top plate. The invention can synthesize the excitation amplitude of a specific antenna unit by properly adjusting the size of the probe in the waveguide, and can effectively synthesize the excitation phase by adjusting the length of a transmission line or a phase shifter between the probe and the antenna unit. In addition, the antenna element excitation coefficient can be calculated according to the specific near field/far field beam, and the near field or far field specific beam can be generated in a radio frequency band.

Drawings

Fig. 1 is a schematic structural diagram of a radial waveguide-based array antenna according to the present invention;

FIG. 2 is a schematic diagram of a cascaded power divider according to the present invention;

FIG. 3 is a schematic structural diagram of a vertical printed patch coupling unit according to the present invention;

FIG. 4 is a side view, top view and schematic of a layered structure of a uniform circular array antenna based on a radial waveguide structure;

fig. 5(a) is a schematic diagram of an antenna structure, and (b) and (c) are schematic diagrams of a microstrip transmission line, a coupling probe unit and a double-layer circular patch antenna unit structure.

FIG. 6 is a schematic diagram of an equivalent model and a side view of a coupling unit;

fig. 7(a) is a graph showing normalized electric field energy density changes with propagation distance when the focal position is zf 1.5m,2m, and 2.5m, respectively, (b) is a distribution diagram showing normalized transverse electric field energy density at z 1.5m when the focal position is 1.5m, (c) is a distribution diagram showing normalized transverse electric field energy density at z 2m when the focal position is 2m, and (d) is a distribution diagram showing normalized transverse electric field energy density at z 2.5m when the focal position is 2.5 m.

Detailed Description

The technical scheme of the invention is further explained by combining the attached drawings.

As shown in fig. 1, the method for designing an aperture field of an array antenna based on a radial waveguide includes a circular and mutually parallel radial waveguide top metal plate and a radial waveguide bottom metal plate, wherein a plurality of uniformly distributed loop antenna arrays are disposed on the radial waveguide top metal plate, and a coupling probe of each antenna is located on one side of the radial waveguide top metal plate facing the radial waveguide bottom metal plate; a feed probe is arranged on one side of the radial waveguide bottom metal plate facing the radial waveguide top metal plate (the height of the feed probe is h)_pAs a feed source), the feed probe is arranged at the central position of the bottom metal plate of the radial waveguide. When the waveguide height is less than a half wavelength (corresponding to the operating frequency), a low-loss TEM mode can be excited, thereby generating electromagnetic waves propagating radially outward within the waveguide. In addition, since the radial waveguide has a circularly symmetric characteristic, the design work of the uniform circular array antenna can be greatly simplified.

Furthermore, an annular metal wall is arranged on the edge of the bottom metal plate of the radial waveguide in the direction towards the top metal plate of the radial waveguide, and the height of the annular metal wall is h.

Furthermore, a plurality of concentric annular antenna arrays are arranged on the top metal plate of the radial waveguide, and antennas in each annular antenna array are uniformly distributed; the radial waveguide structure can be used as a cascade power divider, and the coupling probe unit is used as a coupling unit of the array antenna based on the radial waveguide; the coupling element determines the amount of energy fed into the antenna element and the amount of energy transmitted in the waveguide.

Fig. 2 shows a schematic diagram of a cascaded power divider, where the coupling factor calculation method of each coupling unit is as follows: suppose that the kth ring contains N_kAn antenna and a power value coupled to each antenna element is p_rad,k；

The total power of all antenna elements coupled to the kth circle is P_rad,k＝N_k×p_rad,k(ii) a The (k + 1) th ringThe total input power of (c) is:

P_in,k+1＝P_in,k-P_rad,k＝P_in,k-N_kp_rad,k

P_in,kthe total input power of all units of the kth ring;

assuming total input power P_in,1All coupled to the antenna elements; coefficient p_rad,kTo a specific unit power value, byReplacing; q represents the total number of rings; the coupling factor of the kth coupling unit is calculated by:

the total coupling factor of the kth ring is through C_k＝N_kc_kIs calculated by the method of (1).

Further, the coupling probe is made using a vertical printed patch unit, as shown in fig. 3.

In the present embodiment, a uniform circular array antenna having 6 concentric circular rings is provided in advance (the number of elements included in each circular ring is 8, 16, 32, 32, 32, and 64 in this order from inside to outside), and the radial distances between the circular rings are λ, λ, λ,3/4 λ,3/4 λ, and 3/4 λ (λ is 51.7mm, corresponding to the free space wavelength at an operating frequency of 5.8 GHz) in this order from inside to outside, as shown in fig. 4. Table one is to calculate the corresponding coupling factor according to two amplitude distribution situations (i.e. the uniform amplitude distribution and the chebyshev amplitude distribution) of the uniform circular array antenna. It can be seen that the amplitude distribution has a large influence on the coupling factor, and the coupling factor corresponding to the chebyshev amplitude distribution is significantly greater than the coupling factor corresponding to the uniform amplitude distribution. Some coupling elements cannot synthesize a large coupling factor due to structural limitations and are therefore not suitable for a particular amplitude distribution. As shown in FIG. 3, the vertically printed coupling probe can achieve coupling factor values corresponding to Chebyshev amplitude distribution and uniform amplitude distribution through optimization, and obtain a return loss of-12.3 dB. Therefore, the coupling probe structure can synthesize a target coupling factor value, has little influence on the field distribution in the waveguide, and is suitable for the design work of an array with Chebyshev amplitude distribution.

Table corresponding coupling factor values for different excitation amplitude distributions

Number of circles k	1	2	3	4	5	6
							Is uniformly distributed	0.0432	0.0912	0.2016	0.2496	0.3328	1
Chebyshev distribution	0.0464	0.3152	0.4992	0.3616	0.3328	1

As can be seen from Table I, the total coupling factor values corresponding to the outermost rings are all 1. This is because it is assumed in this embodiment that the total input energy of the outermost one of the rings is all coupled to the uniform circular array antenna and is all radiated. In the invention, the corresponding coupling unit of the outermost ring is similar to a radial waveguide-microstrip line converter, and the function can be realized by changing the length of the coupling probe and the distance between the coupling probe and the annular metal wall.

Because a uniform circular array antenna based on a radial waveguide structure can synthesize different excitation amplitude distributions, a near-field or far-field radiation pattern can be generated. In the invention, the designed uniform circular array antenna can synthesize the adjustable focusing beam working in the Fresnel region, and fig. 4 shows a structural schematic diagram of the array antenna.

In this embodiment, the distance between the units and the distance between adjacent circular rings are preset to satisfy the nyquist sampling rate, and the coupling influence between the units is reduced, thereby synthesizing the target beam pattern. It should be noted that due to the presence of the phase shifting elements (microstrip transmission lines or phase shifters), the antenna elements on the top layer need to be spaced apart from the corresponding coupling elements. Based on this, as shown in fig. 4, the antenna unit is arranged to translate a distance x relative to the coupling unit in the present invention_f＝15mm。

In this embodiment, the excitation amplitude and phase distribution of each antenna element and the corresponding coupling factor value are shown in table two. For focused beam synthesis, the excitation phase profile plays a decisive role, and the excitation amplitude profile is mainly used to reduce the side lobe level. The structure can keep the excitation amplitude distribution (such as Chebyshev distribution, the focal point distance zf) unchanged, but the excitation phase distribution is synthesized by a phase shifter positioned at a uniform antenna array layer (the table II shows the corresponding excitation phase distribution when the focal point distances are respectively 1.5m,2m and 2.5 m; the structure can also synthesize other excitation phase distributions, and the focal point position is deviated from the broadside direction).

Table two excitation amplitude and phase distribution corresponding to the generation of focused beams by the uniform circular array antenna in this embodiment using chebyshev distribution, and corresponding coupling factor values

As shown in fig. 4 and 5, a conventional double-layer circular patch antenna (the circular bottom patch antenna layer is located on the same layer as the phase-shifting microstrip transmission line, and robers RO4350B with a thickness h 1-0.508 mm is used as a dielectric material, and the circular parasitic patch antenna layer uses FR4 with a thickness h 2-0.4 mm as a dielectric material) is used as a uniform circular array antenna radiation unit.

And the antenna impedance Zant is set to 50 Ω. In addition, simulation optimization was performed using Ansys HFSS software (optimization results: ra 1-7.6 mm, ra 2-9.25 mm, and hair-2.85 mm).

As shown in fig. 4, based on the whole array antenna, the cases (the phase shifter is composed of equivalent circuits) when the focal positions are 1.5m,2m and 2.5m respectively are simulated, and the return loss values are less than-20 dB at 5.8GHz in all three cases. Furthermore, in fig. 7, a normalized electric field energy density (x ═ y ═ 0) curve along the z axis of the propagation direction is given, and a two-dimensional normalized electric field energy density distribution graph at the xy plane at z ═ zf is also plotted, and it can be seen that the propagation distance corresponding to the maximum normalized energy density value increases simultaneously with the focal point distance (the focal point distance does not coincide with the distance corresponding to the maximum normalized electric field energy density, which is due to the scattering characteristics of the electromagnetic wave).

In order to simplify the design process, the design work of the coupling elements is performed using an equivalent model as in fig. 6. The coupling factor values given in table two can be obtained by optimizing the coupling unit in fig. 6. It is known through simulation that the coupling factor becomes large (corresponding to the coupling units of the 2 nd to 5 th circular rings), the corresponding return loss increases, which greatly affects the excitation amplitude and phase synthesis accuracy, and increases the return loss of the input port of the antenna array. Based on this, the metal cylinder structures shown in fig. 5(a) are symmetrically placed in front of the coupling unit positions corresponding to the 2 nd to 5 th circular rings, and the metal cylinders are symmetrically arranged on two sides of each coupling probe and used for reducing the return loss of a single circular ring, further reducing the return loss in the radial waveguide, and further reducing the return loss of the input port. After the metal cylinder structure is added, firstly, an equivalent model is used for simulation optimization, and then a radial waveguide model is used for verifying and simulating a corresponding single circular ring structure after a target result is achieved (as the distance between the metal cylinder and the coupling unit is smaller in the equivalent model, the verification simulation result and the equivalent model simulation result have slight difference but are within an acceptable range).

As described above, by introducing phase shifters at the radial waveguide output ports, the target excitation phases can be synthesized and the corresponding antenna elements (e.g., Analog Devices AD HMC1133LP5E GaAs MMIC 6-bit digital phase shifter, operating at 4.8-6.2GHz) connected. For a particular focal distance, the target excitation phase may be synthesized by compensating the radial waveguide output phase using a microstrip transmission line. In this embodiment, the excitation phase of the unit corresponding to the last ring is set as the reference phase, and the microstrip transmission lines corresponding to other rings adopt the target excitation phase in the structural synthesis table two shown in fig. 4.

The invention also provides an array antenna beam regulation and control method based on the radial waveguide, which realizes the phase excitation distribution of the antenna unit through a phase shifter between the feed point of the antenna unit and the output port of the feed network, and controls the beam pattern by changing the excitation phase distribution: namely, under the condition that the feeding amplitude is kept unchanged, the feeding phase is modulated to obtain focused beams with different focus positions, wherein the feeding phase modulation is realized by a phase shifter between the input end of the antenna unit and the output port of the feeding network.

It will be appreciated by those of ordinary skill in the art that the embodiments described herein are intended to assist the reader in understanding the principles of the invention and are to be construed as being without limitation to such specifically recited embodiments and examples. Those skilled in the art can make various other specific changes and combinations based on the teachings of the present invention without departing from the spirit of the invention, and these changes and combinations are within the scope of the invention.