Low-profile tri-polarization meter-wave array antenna

Abstract

The invention provides a tri-polarization meter-wave antenna unit which is composed of five dielectric layers and six metal layers. Wherein the six metal layers comprise a top-layer square parasitic patch surrounded by a metal decoupling square ring, a middle square radiation patch, a bottom-layer circular patch loaded by an annular metal short circuit column, a ground plane 1, a feed strip line and a ground plane 2 in sequence from top to bottom. Wherein the lower layer is a circular patch antenna loaded with an annular metal column, and provides a monopole-like vertical polarization horizontal omnidirectional radiation pattern. In the structural design of the upper-layer horizontal polarization radiator, in order to realize the characteristic of horizontal polarization, an edge-fed square microstrip patch antenna structure is adopted, and the antenna is simple in structure, easy to realize and capable of generating two polarized orthogonal directional diagrams in the zenith direction. Meanwhile, a capacitive parasitic patch and a dielectric layer are loaded above the square microstrip patch antenna, so that the Q value can be further reduced, and double resonance points are introduced, so that the bandwidth of the antenna is further expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of antennas for wireless communications, and in particular to a three-polarized meter-wave array antenna. Background Art

[0002] In order to adapt to the communication needs of higher capacity, faster transmission rate and longer transmission distance, traditional antennas and antenna arrays are facing a series of new changes and challenges. In order to improve antenna performance, modern antennas use faster and more accurate electronic scanning to replace traditional mechanical scanning; at the same time, they make full use of the polarization information of polarized antennas to further improve antenna performance. In Nature magazine, Andrews et al. pointed out that the use of polarization can obtain six unrelated channels in a multipath wireless propagation environment, thereby greatly improving the transmission rate and system capacity of wireless communication systems. Phased array antennas are widely used in various wireless systems due to their excellent characteristics such as high gain, fast scanning speed and high scanning accuracy, such as military radar, electronic countermeasures, satellite communications, mobile communications, broadcasting, meteorological detection, etc.

[0003] Research shows that when the scanning angle deviates from the antenna normal direction by 60°, the dual-polarized antenna unit will have a maximum gain fluctuation of 6dB, and the synthetic polarization purity will decrease faster, and the 3dB axial ratio width will be reduced to 1 / 3 of that when scanning in the normal direction. Compared with the dual-polarized antenna, the tri-polarized antenna has a higher degree of freedom because it has an additional polarization direction. The tri-polarized antenna can achieve polarization diversity and spatial diversity at the same time, so it has attracted much attention and has been widely used in wireless communications, radar filtering and other fields in recent years. The tri-polarized antenna unit adds a Z-polarization component that is orthogonal to the original two polarization directions (X polarization and Y polarization) on the basis of the dual-polarized antenna unit.

[0004] Currently, most fully polarized antennas use antennas in the form of oscillators and slots, which makes the bandwidth generally narrow and difficult to expand. At the same time, for co-located antennas, since their units are closely spaced or share the same ground, the isolation between antenna ports is not ideal and the cross-polarization isolation is poor. In addition, the three polarization units of most fully polarized antennas cannot be completely conformal, so it is difficult to reduce the height or volume of the entire antenna. Summary of the invention

[0005] In view of the problem that the bandwidth of meter-wave antennas is difficult to expand and the size is large, the present invention provides a low-profile three-polarization meter-wave array antenna to solve the above problems.

[0006] In a first aspect, the present invention provides a three-polarized meter-wave antenna unit, which is composed of five dielectric layers and six metal layers;

[0007] Among them, the six metal layers are respectively the top square parasitic patch surrounded by the metal decoupling square ring, the middle square radiation patch, the bottom circular patch loaded by the ring-shaped metal short-circuit column, the ground plane 1, the feeding strip line and the ground plane 2;

[0008] The top square parasitic patch and the middle square radiating patch are miniaturized and have reduced cross polarization by cutting corners;

[0009] The bottom circular patch is loaded with N metal short-circuit posts, which are connected to the ground plane 1 and the circular patch respectively to stimulate the TM of the circular patch antenna. 02 mode, thus producing a horizontal omnidirectional pattern of monopole-like radiation;

[0010] The square radiating patch in the middle is excited by the coaxial probe edge feeding of the square microstrip patch antenna. 01 mode, thereby generating radiation in the zenith direction and achieving beam coverage in the zenith direction;

[0011] The feeding stripline includes three striplines, which are respectively connected to the bottom circular patch and the middle square radiation patch through three metal probes.

[0012] A second aspect of the present invention provides an antenna array, comprising a plurality of the above-mentioned three-polarized meter-wave antenna units.

[0013] The third aspect of the present invention provides a control system for an antenna array, which is used to control the feeding of each tri-polarized meter-wave antenna unit in the antenna array, characterized in that three TR components are provided for each tri-polarized meter-wave antenna unit, which are respectively connected to the three strip lines of the tri-polarized meter-wave antenna unit, and are aggregated to the feeding port via an equal-amplitude and in-phase feeding network, corresponding to one RF signal.

[0014] The present invention forms a tri-polarized antenna by superimposing a patch dual-polarized antenna on a vibrator antenna, and loads a metal short-circuit column on the bottom circular patch, thereby successfully reducing the height of the antenna, reducing the overall volume of the antenna, meeting the antenna's low-profile isolation requirement, and using a double-layer microstrip antenna to increase the antenna's bandwidth. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0016] Figure 1 This is a schematic diagram of the overall structure of the three-polarized meter-wave antenna unit proposed in the present invention;

[0017] Figure 2 This is a schematic diagram of the three-dimensional explosion structure of the triple-polarized meter-wave antenna unit proposed by the present invention;

[0018] Figure 3 This is a schematic diagram of the structure of each part of the three-polarized meter-wave antenna unit proposed by the present invention;

[0019] Figure 4 is the port isolation S of the upper low-profile dual-polarized microstrip patch antenna 11 ;

[0020] Figure 5 is the port isolation S of the upper low-profile dual-polarized microstrip patch antenna 21 ;

[0021] Figure 6 The port isolation S of the bottom circular patch antenna loaded with an annular metal short-circuit column 11 ;

[0022] Figure 7 The tri-polarized meter-wave antenna array model proposed in the present invention;

[0023] Figure 8 This is a schematic diagram of the antenna array control system proposed in the present invention. DETAILED DESCRIPTION

[0024] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0025] The overall structural diagram of the three-polarized meter-wave antenna unit provided by the present invention is as follows: Figure 1 As shown. The tri-polarized meter-wave antenna unit includes five dielectric layers and six metal layers. The six metal layers include: a top square parasitic patch surrounded by a metal decoupling square ring, a middle square radiation patch, a bottom circular patch loaded by an annular metal short-circuit column, a ground plane 1, a feed strip line and a ground plane 2. Among them, the side lengths of the top square parasitic patch and the middle square radiation patch are l1 and l2 respectively. Both square patches are miniaturized and cross-polarization is reduced by cutting corners. The radius of the bottom circular patch loaded by the annular short-circuit column is r3. Tri-polarized radiation waves are generated by exciting the middle square radiation patch and the bottom circular patch. The loading of the top square parasitic patch introduces capacitance, which further improves the bandwidth of the horizontal dual-polarization antenna. By cutting corners on the square patch, the antenna structure can be miniaturized and the cross-polarization level can be improved, which has an irreplaceable advantage in improving the beam scanning performance of the subsequent array. The metal decoupling ring on the top layer is loaded with metal short-circuit posts to connect the metal decoupling ring and the ground plane 1, which has little effect on the performance of the antenna and can effectively reduce the coupling and surface wave propagation between the units after the array is formed, thereby achieving a wide-beam active unit radiation pattern with stable gain. The bottom circular patch is provided with several metal short-circuit posts, which are placed in a ring shape on the TM 02 The zero point position of the mode electric field. 02 The resonant frequency of the mode changes under the condition of TM01 The resonant frequency of the mode. By adjusting the number of short-circuit posts and the size of the circular patch, the resonant frequencies of the two modes can be brought close to each other to introduce dual resonance points to widen the antenna bandwidth. For example, four symmetrically distributed metal short-circuit posts are loaded, connected to the ground plane 1 and the circular patch respectively, with a distance of S2 from the center of the circle and rotationally symmetric about the center, to excite the TM of the circular patch antenna. 02 mode, thus producing a horizontal omnidirectional pattern of monopole-like radiation. The middle square radiating patch excites the TM of the square microstrip patch antenna through the coaxial probe edge feed. 01 mode, thereby generating radiation in the zenith direction and achieving beam coverage in the zenith direction.

[0026] In order to further illustrate the three-dimensional structure of the tri-polarized meter-wave antenna unit, combined with Figure 2 The schematic diagram of the three-dimensional exploded structure of the tri-polarized meter-wave antenna unit shown in the figure, the thicknesses of dielectric layers 1 to 5 are h1, h2, h3, h4, and h5 respectively; the side length of the dielectric layer is λ m , which is half of the wavelength of the center frequency. The specific structure of the top square parasitic patch, the middle square radiation patch, the bottom circular patch and the feeding strip line in the six metal layers is as follows: Figure 3 As shown in the four sub-figures (a), (b), (c) and (d).

[0027] The patch center feed of the bottom circular patch antenna can excite TM 02 The antenna's radiation pattern is similar to a monopole, achieving horizontal omnidirectional radiation characteristics. In order to make the mode work in a small patch size, a set of conductive vias is introduced into the antenna, thereby reducing the operating frequency of the mode.

[0028] For the feed layer structure, the three strip lines are connected to the bottom circular patch and the middle square radiation patch respectively through metal probes. The bottom circular patch is fed through the third metal probe 333 in the center to obtain a horizontal omnidirectional radiation pattern of vertical polarization, and the middle square radiation patch excites horizontal dual polarization through the first metal probe 331 and the second metal probe 332, thereby obtaining a horizontal dual polarization zenith radiation pattern. In order to prevent the metal probe from contacting the metal ground plane 1 and the bottom circular patch and affecting the radiation, two holes 334 with a radius of dh1 are etched on the bottom circular patch so that the second metal probe 332 and the first metal probe 331 can pass through, and three holes with a diameter of dh2 are etched on the ground plane 1 so that the three metal probes can pass through. The outer conductor of the coaxial N connector is welded on the ground plane 2, and the inner conductor probe is welded on the three strip lines on the feed network layer.

[0029] The two lower feeding network dielectric layers are made of domestic F4BM dielectric with a dielectric constant of 3 and a loss tangent of 0.0013, with thicknesses of h4 and h5 respectively. The upper three radiation dielectric layers are made of Taconic TYL-5 dielectric with a dielectric constant of 2.2 and a loss tangent of 0.0009, with thicknesses of h1, h2 and h3 respectively.

[0030] The above-mentioned three-polarized microwave antenna unit structure has a circular patch antenna loaded with a ring-shaped metal column on the lower layer, which provides a monopole-like radiation pattern. In the design of the upper horizontal polarization radiator structure, in order to achieve broadband and horizontally polarized characteristics, an edge-fed square microstrip patch antenna structure is adopted, which can produce broadband impedance matching characteristics and a zenith radiation pattern. Its structure is simple and easy to implement. At the same time, loading a capacitive parasitic patch and a dielectric layer above the square microstrip patch antenna can further reduce the Q value, and introduce a dual resonance point to further expand the antenna bandwidth.

[0031] Through simulation, the S parameters of the upper low-profile dual-polarized microstrip patch antenna are as follows: Figure 5 As shown. For this antenna, the electrical performance of the X-port and the Y-port are basically the same, so only the simulation results of the X-polarized port are shown. It can be seen that the loading of the parasitic patch causes the antenna to have two resonant points within the frequency band. The impedance bandwidth satisfied by the antenna is about 12.4%. Within the frequency band, the isolation between the X-polarized port and the Y-polarized port is greater than 20dB.

[0032] The matching of the vertically polarized circular patch antenna is as follows: Figure 6 As shown, it can be seen that the antenna resonance point is near the center frequency and the -10dB impedance bandwidth is 3.9%.

[0033] The present invention also provides an antenna array composed of the above-mentioned three-polarized meter-wave antenna units, and the antenna array is a uniform planar two-dimensional array, such as Figure 7 As shown, each antenna unit in the array adopts the above-mentioned three-polarization meter-wave antenna unit.

[0034] The comparison between the common microstrip antenna unit and the tri-polarized microwave antenna unit proposed in the present invention as array elements can illustrate the superiority of the fully polarized antenna array in performance. The data shows that its gain is significantly improved compared with the traditional microstrip antenna array. The specific improvement indicators are shown in Table 1.

[0035] Table 1 Main polarization gain improvement index of tri-polarized microwave array antenna

[0036]

[0037] Traditional microstrip antenna arrays often have obvious grating lobe effects at large scanning angles, while fully polarized arrays have stronger grating lobe suppression capabilities. The improvement data of grating lobe suppression performance at various scanning angles is shown in Table 2.

[0038] Table 2 Grating lobe suppression improvement index of tri-polarized meter-wave array antenna

[0039]

[0040] Each of the three-polarized meter-wave antenna units of the present invention is provided with three metal probes, corresponding to the excitation of different polarization directions, thereby realizing the beam synthesis of the antenna array.

[0041] To this end, the present invention also provides a control system of an antenna array, which is used to control the feeding of each tri-polarized meter-wave antenna unit in the antenna array, and is characterized in that three TR components are provided for each tri-polarized meter-wave antenna unit, which are respectively connected to the three strip lines of the tri-polarized meter-wave antenna unit, and are aggregated to the feeding port via an equal-amplitude and in-phase feeding network, corresponding to one RF signal.

[0042] The overall antenna array control system is as follows: Figure 8 As shown. TR is used to control the amplitude and phase information of the multi-polarization unit antenna, so that the multi-polarization antenna can transmit a multi-polarization beam in a specified direction and expand the polarization information obtained in the receiving state. After passing through TR, the three ports in the unit antenna are aggregated to the feeding port through the equal-amplitude and in-phase feeding network, so that the multi-polarization antenna corresponds to one RF signal. The specific antenna pattern is controlled by the TR component.

[0043] The beamforming described in the present invention includes two parts. One is the digital control of the unit multi-polarization channel to realize the characteristic pointing pattern of each multi-polarization unit. The method adopted is: the amplitude and phase of different polarization ports are adjusted to increase or attenuate the radiation gain at a specified position in space, thereby realizing a specific pointing pattern; the other is the digital control of the array factor of a large-scale array. Combining the traditional phased array antenna beam control method with the amplitude and phase control of the multi-polarization antenna can achieve a larger beam coverage range. In addition, in this control, not only the traditional array synthesis theory is used as an accurate reference, but also the coupling relationship between the array elements must be considered due to the complexity of the array unit. As a necessary factor, this coupling relationship can be determined by means of simulation or test inversion, and comprehensively considered and included in the mapping of the physical composition of the array and the beam characteristics, so that it is incorporated into the strategy of digital beamforming, and then each RF signal is adjusted.

[0044] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A three-polarized meter-wave antenna unit, consisting of five dielectric layers and six metal layers; in, The six metal layers are, in order, the top square parasitic patch surrounded by a metal decoupling square ring, the middle square radiation patch, the bottom circular patch loaded by a ring-shaped metal short-circuit column, the ground plane 1, the feed stripline, and the ground plane 2; The top square parasitic patch and the middle square radiating patch are miniaturized and have reduced cross polarization by cutting corners; The bottom circular patch is loaded with N metal short-circuit posts, which are connected to the ground plane 1 and the circular patch respectively to stimulate the TM of the circular patch antenna. 02 mode, thereby achieving a low-profile monopole-like horizontal omnidirectional pattern; The square radiating patch in the middle is excited by the coaxial probe edge feeding of the square microstrip patch antenna. 01 mode, thereby generating dual-polarized radiation in the zenith direction and achieving beam coverage in the zenith direction; The feeding stripline includes three striplines, which are respectively connected to the bottom circular patch and the middle square radiation patch through three metal probes.

2. The three-polarized meter-wave antenna unit according to claim 1, characterized in that: The top-level square parasitic patch is provided with a metal decoupling ring, and the metal short-circuit column connects the metal decoupling ring and the ground plane 1 .

3. The three-polarized meter-wave antenna unit according to claim 1, characterized in that: The side length of the dielectric layer is λ m , which is half the wavelength of the center frequency.

4. The three-polarized meter-wave antenna unit according to claim 1, characterized in that: The N metal short-circuit pillars are arranged in a ring shape on the TM 02 The zero position of the mode electric field.

5. The three-polarized meter-wave antenna unit according to claim 7, characterized in that: The bottom circular patch is loaded with four metal short-circuit posts and is rotationally symmetrical about the center of the circle.

6. The three-polarized meter-wave antenna unit according to claim 1, characterized in that: Two holes with a first diameter are etched on the bottom circular patch so that the second metal probe and the first metal probe can pass through, and three holes with a second diameter are etched on the ground plane 1 so that the three metal probes can pass through.

7. An antenna array, characterized in that: It comprises a plurality of triple-polarized meter-wave antenna units as described in any one of claims 1 to 6.

8. A control system for an antenna array, used to control the feeding of each tri-polarized meter-wave antenna unit in the antenna array as claimed in claim 8, characterized in that: Three TR components are set for each tri-polarized meter-wave antenna unit, which are respectively connected to the three strip lines of the tri-polarized meter-wave antenna unit and aggregated to the feeding port through an equal-amplitude and in-phase feeding network, corresponding to one RF signal.

9. The control system of the antenna array according to claim 9, characterized in that: The three TR components can adjust the amplitude and phase of different polarization ports to achieve a specific directional pattern.

10. The control system of the antenna array according to claim 9, characterized in that: The coupling relationship between array elements is determined by simulation or test inversion, and each RF signal is adjusted accordingly.

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