A low-profile tri-polarized meter-wave array antenna

Abstract

The present invention proposes a tri-polarized meter-wave antenna unit, which is composed of five dielectric layers and six metal layers; wherein the six metal layers are, from top to bottom, respectively a top square parasitic patch surrounded by a metal decoupling square ring, a middle square radiating patch, a bottom circular patch loaded with an annular metal short-circuit column, a ground plane 1, a feeding strip line, and a ground plane 2. Among them, the lower layer is a circular patch antenna loaded with an annular metal column, which provides a vertically polarized horizontal omnidirectional radiation pattern similar to a monopole. In the design of the upper horizontal polarization radiator structure, in order to achieve the characteristics of horizontal polarization, a side-fed square microstrip patch antenna structure is adopted. Its structure is simple, easy to implement, and can generate two polarization orthogonal radiation patterns in the zenith direction. 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.

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] To meet the demands of higher capacity, faster transmission rates, and longer transmission distances, traditional antennas and antenna arrays are facing a series of new changes and challenges. To improve antenna performance, modern antennas are replacing traditional mechanical scanning with faster and more precise electronic scanning. Polarized antennas also leverage the polarization information of polarized antennas to further enhance antenna performance. Andrews et al., reporting in Nature, demonstrated that polarization can be used to generate six uncorrelated channels in a multipath wireless propagation environment, significantly improving the transmission rate and capacity of wireless communication systems. Phased array antennas, with their high gain, fast scanning speed, and high scanning accuracy, are widely used in various wireless systems, such as military radar, electronic countermeasures, satellite communications, mobile communications, broadcasting, and weather detection.

[0003] Research has shown that when the scanning angle deviates by 60° from the antenna normal, a dual-polarized antenna unit will experience a gain fluctuation of up to 6dB. Simultaneously, the synthetic polarization purity decreases at a faster rate, and the 3dB axial ratio width is reduced to one-third of that when scanning in the normal direction. Compared to dual-polarized antennas, tri-polarized antennas offer a higher degree of freedom due to the additional polarization dimension. Tri-polarized antennas can achieve both polarization diversity and spatial diversity, attracting considerable attention and finding widespread application in wireless communications, radar filtering, and other fields in recent years. Tri-polarized antenna units add a Z-polarization component, orthogonal to the two existing polarization directions (X and Y), to the dual-polarized antenna unit.

[0004] Current fully polarized antennas mostly utilize dipoles and slots, resulting in a generally narrow bandwidth and difficulty expanding it. Furthermore, for co-located antennas, the close spacing or shared grounding of their elements results in suboptimal isolation between antenna ports and poor cross-polarization isolation. Furthermore, the three polarization elements of most fully polarized antennas are not completely conformal, making it difficult to reduce the overall height or volume of the antenna. Summary of the Invention

[0005] In response to the problems 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 tri-polarized meter-wave antenna unit, which is composed of five dielectric layers and six metal layers;

[0007] Among them, the six metal layers are, in order, the top square parasitic patch surrounded by a metal decoupling 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;

[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 similar to monopole radiation;

[0010] The square radiating patch in the middle is excited by the coaxial probe edge feeding of the square microstrip patch antenna TM 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] According to a second aspect of the present invention, an antenna array is provided, 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. By loading a metal short-circuit column on the bottom circular patch, the height of the antenna is successfully reduced, the overall volume of the antenna is reduced, the low-profile isolation requirement of the antenna is met, and the bandwidth of the antenna is increased by using a double-layer microstrip antenna. 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 following briefly introduces the drawings required for describing the embodiments or the prior art.

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

[0018] Figure 3 This is a schematic diagram of the structure of the various parts of the tri-polarized meter-wave antenna unit proposed in the present invention;

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

[0020] Figure 5 is the port isolation S of the upper low-profile dual-polarization 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 This is 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 clearer, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0025] The overall structural diagram of the tri-polarized meter-wave antenna unit provided by the present invention is as follows: Figure 1 As shown in the figure, the tri-polarized meter-wave antenna unit consists of five dielectric layers and six metal layers. The six metal layers include: a top square parasitic patch surrounded by a metal decoupling ring, a middle square radiating patch, a bottom circular patch loaded with an annular metal shorting post, ground plane 1, a feed stripline, and ground plane 2. The side lengths of the top square parasitic patch and the middle square radiating patch are l1 and l2, respectively. Both square patches are miniaturized and cross-polarization is reduced by chopping corners. The radius of the bottom circular patch loaded with the annular shorting post is r3. Tri-polarized radiation waves are generated by exciting the middle square radiating patch and the bottom circular patch. The loading of the top square parasitic patch introduces capacitance, further improving the bandwidth of the horizontal dual-polarization antenna. Chopping corners on the square patch can miniaturize the antenna structure and improve cross-polarization levels, which has irreplaceable advantages for improving the beam scanning performance of subsequent arrays. The top metal decoupling ring is loaded with metal short-circuit posts to connect the metal decoupling ring and the ground plane 1. This has little effect on the performance of the antenna and can effectively reduce the coupling and surface wave propagation between the elements after the array is formed, thereby achieving a wide-beam active element pattern with stable gain. The bottom circular patch is equipped 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, introducing dual resonance points to widen the antenna bandwidth. For example, four symmetrically distributed metal short-circuit posts are loaded, connecting the ground plane 1 and the circular patch respectively, with a distance S2 from the center of the circle and rotationally symmetric about the center, to stimulate the TM of the circular patch antenna. 02 The square radiating patch in the middle excites the TM of the square microstrip patch antenna through the coaxial probe edge feeding. 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 three-dimensional exploded structure diagram of the tri-polarized meter-wave antenna unit is shown in FIG. 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 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 stripline in the six metal layers is as follows: Figure 3 As shown in the four sub-figures (a), (b), (c), and (d).

[0027] The center feed of the bottom circular patch antenna can stimulate TM 02 The antenna's radiation pattern is similar to a monopole, achieving horizontal omnidirectional radiation. To enable the mode to operate 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 striplines 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 with vertical polarization, and the middle square radiation patch is stimulated by the first metal probe 331 and the second metal probe 332 to obtain a horizontal dual-polarization zenith radiation pattern. In order to prevent the metal probes 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 to allow the second metal probe 332 and the first metal probe 331 to pass through, and three holes with a diameter of dh2 are etched on the ground plane 1 to allow the three metal probes to pass through. The outer conductor of the coaxial N connector is welded to the ground plane 2, and the inner conductor probe is welded to the three striplines on the feed network layer.

[0029] The two lower feed network dielectric layers are made of domestically produced F4BM dielectric with a dielectric constant of 3 and a loss tangent of 0.0013, with thicknesses of h4 and h5, respectively. The three upper 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 tri-polarized meter-wave antenna unit structure described above features a circular patch antenna loaded with a ring-shaped metal post at the bottom, providing a monopole-like radiation pattern. To achieve broadband and horizontally polarized characteristics, the upper horizontally polarized radiator structure uses an edge-fed square microstrip patch antenna. This achieves both broadband impedance matching and a zenith-direction radiation pattern. Its structure is simple and easy to implement. Furthermore, adding a capacitive parasitic patch and a dielectric layer above the square microstrip patch antenna further reduces the Q factor and introduces dual resonance points, further extending 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 in the figure, the electrical performance of the X- and Y-ports of this antenna is essentially identical, so only the simulation results for the X-polarized port are shown. It can be seen that the parasitic patch loading creates two resonant points within the antenna's frequency band. The antenna achieves an impedance bandwidth of approximately 12.4%. The isolation between the X- and Y-polarized ports is greater than 20 dB across the frequency band.

[0032] The matched vertically polarized circular patch antenna is as follows Figure 6 As shown in the figure, 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, which is a uniform planar two-dimensional array. Figure 7 As shown, each antenna unit in the array adopts the above-mentioned three-polarized meter-wave antenna unit.

[0034] Comparing conventional microstrip antenna elements with the proposed tri-polarized meter-wave antenna element demonstrates the superior performance of the fully polarized antenna array. Data shows a significant gain improvement compared to conventional microstrip antenna arrays. Specific improvement metrics are shown in Table 1.

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

[0036]

[0037] Traditional microstrip antenna arrays often exhibit a more obvious grating lobe effect at large scanning angles. The fully polarized array has a stronger grating lobe suppression capability. The improved 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 beam synthesis of the antenna array.

[0041] To this end, the present invention also 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.

[0042] The overall antenna array control system is as follows Figure 8 As shown in the figure, TR is used to control the amplitude and phase information of a multi-polarization element antenna, enabling the antenna to transmit a multi-polarization beam in a specified direction and expanding the polarization information acquired during reception. After passing through the TR, the three ports of the element antenna are fed together through a uniform amplitude and phase feed network to the feed port, allowing the multi-polarization antenna to respond 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 achieve the characteristic pointing pattern of each multi-polarization unit. The method adopted is: by regulating the amplitude and phase of the different polarization ports, the radiation gain can be increased or decreased at a specified position in space, thereby achieving 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 a precise reference, but also the coupling relationship between the array elements must be considered due to the complexity of the array units. This coupling relationship, as a necessary factor, can be determined by means of simulation or test inversion, and comprehensively considered in the mapping between the physical composition of the array and the beam characteristics, so that it is incorporated into the digital beamforming strategy, 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 within the scope of protection of the present invention.

Claims

1. A tri-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 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 TM 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 tri-polarized meter-wave antenna unit according to claim 1, wherein: The top 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 tri-polarized meter-wave antenna unit according to claim 1, wherein: The side length of the dielectric layer is λ m , which is half the wavelength of the center frequency.

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

5. The tri-polarized meter-wave antenna unit according to claim 1, wherein: The bottom circular patch is loaded with four metal short-circuit posts and is rotationally symmetrical about the center of the circle.

6. The tri-polarized meter-wave antenna unit according to claim 1, wherein: Two holes of the 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 of the 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 tri-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 according to claim 7, 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 the equal-amplitude and in-phase feeding network, corresponding to one RF signal.

9. The antenna array control system according to claim 8, wherein: The three TR components can regulate the amplitude and phase of different polarization ports to achieve a specific directional pattern.

10. The antenna array control system according to claim 9, wherein: Use simulation or test inversion to determine the coupling relationship between array elements and then adjust each RF signal.

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