CN106450709B - Four-unit interconnected symmetrical oscillator circular antenna array for electric small-distance direction finding - Google Patents
Four-unit interconnected symmetrical oscillator circular antenna array for electric small-distance direction finding Download PDFInfo
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/36—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/50—Structural association of antennas with earthing switches, lead-in devices or lightning protectors
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- H—ELECTRICITY
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Abstract
A four-unit interconnection symmetry oscillator circular antenna array for electric small-distance direction finding relates to an array antenna. The antenna comprises 4 symmetrical dipole structure antennas and 2 antenna connecting section structures; the 4 symmetrical dipole structure antennas are uniformly distributed in a circular array mode, wherein the upper and lower parts of the 4 symmetrical dipoles are directly connected by using an antenna connecting section structure, the electric small distance means that the distance between adjacent units is far smaller than the working wavelength, the radiation unit comprises 4 symmetrical dipole structures made of 4 materials and having the same size, the symmetrical dipole structures are placed in parallel on the same reference plane and are uniformly distributed at equal angular intervals in the circular array mode; the antenna connecting section structure is characterized in that the upper half parts of 4 symmetrical dipole structures are directly connected by using the antenna connecting section structure, the lower half parts of the 4 symmetrical dipole structures are directly connected by using the same antenna connecting section structure, and the antenna connecting section structure is a connecting structure formed by connecting four sections of cylindrical structures according to a regular quadrangle; the antenna connecting section structure and the symmetrical oscillator are made of metal materials with the same diameter.
Description
Technical Field
The present invention relates to array antennas, and more particularly, to an electrical small-pitch array antenna design for super-resolution Arrival angle (DOA) estimation.
background
The spatial spectrum estimation is used to solve the problem of spatial energy distribution of the received signals, so as to determine the number of signals or the direction of the incoming wave of the signals ([1] Wangyonglian, Dingqiang, Lirongfeng.Adaptation processing [ M ]. Beijing: Qinghua university Press, 2009; [2] Wangyonglian, Chenghui, Pengning, Wan Geng. The problem of interest in incoming wave direction estimation is finding the position of the radiation source in space. In general, the estimation of the incoming wave direction mainly includes two aspects: (1) determining the number of radiation sources in space; (2) the spatial position of each radiation source is determined. With the development of direction-finding technology, many methods have been developed to address different problems. Direction finding techniques can be divided into active direction finding techniques and passive direction finding techniques from the perspective of active and passive reconnaissance (or antenna type). A direction finding method of acquiring a distance and an orientation of a target by transmitting an electromagnetic wave and by receiving a scattering signal of the target is called an active direction finding technology. Since the active direction-finding system has an active radiation device, the spatial position of the active direction-finding system is exposed, and the active direction-finding system can be easily detected and positioned by other devices, which is fatal to military application. Passive direction finding technology is becoming more and more popular due to its high degree of privacy and has been widely developed. The passive direction finding technology for measuring the arrival angle of an incoming wave of an electromagnetic wave by using a two-unit or multi-unit array antenna has important applications in various aspects (4).
An electrically small pitch array refers to an array system where the array pitch is much smaller than the wavelength (typically 0.1 wavelength or less). The array can reduce the size of the conventional array to 1/10, and can greatly reduce the size of the array. However, a pair of contradictions arises between miniaturization and direction finding accuracy. The smaller the array size, the lower the gain of the array and the lower the signal-to-noise ratio. The cell pitch becomes small and the phase difference between the cells changes relatively slowly. And strong electromagnetic coupling (5) among array elements, namely, C.electric small, super-directive and super-conductive antenna [ M ]. John Wiley & Sons,2006), influences the actual performance of the array antenna, so that the traditional electric small-spacing array cannot meet the high-precision direction-finding requirement under the condition of only depending on an improved algorithm. The low gain and the small phase difference are technical bottlenecks which limit the direction-finding development and application of the electrically small antenna. Therefore, it is of great practical significance to develop high-precision electrical small-pitch arrays based on new mechanisms.
Chinese patent 201610350399.5 discloses a dual-ring antenna, which uses an amplitude method to measure direction, and uses a first antenna ring body and a second antenna ring body in two mutually perpendicular directions to simultaneously receive signals for calculation to accurately judge the direction of an electromagnetic wave emission source, thereby effectively improving the resolution of an incident wave direction angle and further effectively improving the measurement accuracy; and because of the vertical and coaxial nested connection of the double-ring structure, the volume is relatively small ([6] land Dejian, Yundi double-ring antenna [ P ]. Beijing: CN105870631A, 2016-08-17).
Chinese patent 201410080935.5 discloses a passive direction-finding antenna array of a phase interferometer and a phase interferometer ([7] aristoloc, moshaohui, yaoshao, jones, quebracho, zhao, passive direction-finding antenna array of a phase interferometer and a phase interferometer [ P ]. guangdong: CN103887613A, 2014-06-25).
Chinese patent 201410347386.3 discloses a novel portable five-antenna element direction-finding circular array ([8] guo square, tan deuxin. novel portable five-antenna element direction-finding circular array [ P ] sichuan: CN104167613A,2014-11-26), which aims to provide a five-antenna element direction-finding circular array that has small volume and light weight, can be quickly disassembled and assembled, and can simultaneously meet the requirements of various direction-finding systems such as an interferometer, a correlation interferometer, spatial spectrum estimation and the like.
The direction-finding antenna structures of the above three patents are not suitable for the space-limited platform or the low frequency band, although the factors of miniaturization, simple structure, etc. are considered.
Disclosure of Invention
The invention aims to solve the problems of the electric small-distance array, and provides a four-unit interconnected symmetrical oscillator circular-ring antenna array which is used for electric small-distance direction measurement, can be used for enhancing the electromagnetic coupling among electric small-distance symmetrical oscillator array antennas, improving the sensitivity of antenna response to the arrival angle of incoming waves, improving the measurement precision of the arrival angle of the incoming waves, is suitable for a space-limited platform or the incoming wave direction measurement of low-frequency signals, and has important significance for the miniaturization, the simplification of the structure and the easy operation of direction-finding equipment.
The invention comprises 4 symmetrical dipole structure antennas and 2 antenna connecting section structures;
The 4 symmetrical dipole structure antennas are uniformly distributed in a circular array mode, wherein the upper and lower parts of the 4 symmetrical dipoles are directly connected by using an antenna connecting section structure, the electric small distance means that the distance between adjacent units is far smaller than the working wavelength, the radiation unit comprises 4 symmetrical dipole structures made of 4 materials and having the same size, the symmetrical dipole structures are placed in parallel on the same reference plane and are uniformly distributed at equal angular intervals in the circular array mode; the antenna connecting section structure is characterized in that the upper half parts of 4 symmetrical dipole structures are directly connected by using the antenna connecting section structure, the lower half parts of the 4 symmetrical dipole structures are directly connected by using the same antenna connecting section structure, and the antenna connecting section structure is a connecting structure formed by connecting four sections of cylindrical structures according to a regular quadrangle; the antenna connecting section structure and the symmetrical oscillator are made of metal materials with the same diameter.
The antenna connecting section structure is respectively positioned at the metal tail ends of the upper part and the lower part of the 4 symmetrical oscillators, which are closest to the middle parts of the symmetrical oscillators, and is vertical to the symmetrical oscillator main body to form an upper integral part and a lower integral part, so that a new antenna structure unit is formed to strengthen the electromagnetic coupling between the symmetrical oscillators.
The excitation position of the invention is the same as the excitation position of the traditional symmetrical oscillator and is between the upper arm and the lower arm of the oscillator antenna. The amplitude and phase directional diagrams of the single unit of the four-unit symmetrical oscillator circular array are greatly changed along with the structural spacing distance of the upper antenna connecting section and the lower antenna connecting section of the symmetrical oscillator, the change of the amplitude and the change of the phase are gradually and slowly changed along with the change of an observation angle along with the increase of the structural spacing distance of the upper antenna connecting section and the lower antenna connecting section of the symmetrical oscillator, full-wave electromagnetic simulation based on an active unit is required to be applied to scan parameters to search for the structural spacing distance of the upper antenna connecting section and the lower antenna connecting section of the optimum symmetrical oscillator, the electromagnetic coupling between the antenna units is strongest, and energy is mainly electromagnetically coupled to other unit directions.
The gain of the directly-connected symmetrical oscillator array is obviously enhanced relative to the non-directly-connected condition, the actual gain of the antenna unit is obviously improved, the directivity is stronger, and the gain changes more violently under different observation angles, namely, the sensitivity of the unit gain and the phase difference to the arrival angle of the incoming wave of the target signal is improved. In the variation range of the whole azimuth angle, the symmetry of the electrically small-spacing four-unit direct-connection symmetrical dipole circular array antenna can cause the Clar CRB estimated in the direction of arrival angle of incoming wave to be far lower than the condition of non-direct connection, namely the direction-finding precision is obviously improved.
The invention has the advantages and positive effects that: the topological structure antenna array, namely the interconnection structure among the units, can increase the electromagnetic coupling among the units, and improve the change between the amplitude and the phase difference of a directional pattern among the units, thereby improving the sensitivity of an antenna array element to the incoming wave direction of a target signal and improving the direction-finding precision.
Drawings
Fig. 1 is a schematic front view of an embodiment of the present invention.
Fig. 2 is a schematic top view of the embodiment of the invention.
fig. 3 is a comparison of the S11 parameters for the example at a distance of up and down separation of the dipoles and at a dipole diameter of 0.1 lambda.
Fig. 4 is a comparison of the amplitudes of the antenna elements 1 with dipoles spaced apart up and down and a dipole diameter of 0.1 lambda according to an embodiment of the invention.
Fig. 5 is a phase pattern comparison of the antenna unit 1 when the dipoles are spaced apart from each other up and down and the diameter of the dipole is 0.1 λ according to the embodiment of the present invention.
FIG. 6 is a comparison of S-parameters of the co-parametric antenna array considering the non-direct coupling of electromagnetic coupling when the diameter of the transducer is 0.1 λ in accordance with the embodiment of the present invention.
Fig. 7 is a directional diagram of the antenna unit 1 according to the embodiment of the present invention when the diameter of the element is 0.1 λ.
FIG. 8 shows the phase difference change at a transducer diameter of 0.1 λ in the example of the present invention
Fig. 9 is a comparison graph of mean square error of DOA of the present invention, when the diameter of the oscillator is 0.1 λ, the SNR is 15dB, the sampling frequency is triple working frequency, that is, fs is 3f0, and the snapshot number K is 300, compared with that of the same-parameter antenna array which is not directly connected by considering electromagnetic coupling, and which performs the sub-monte carlo simulation.
Fig. 10 is a schematic perspective view of an embodiment of the present invention.
Detailed Description
The invention provides an electric small-distance symmetrical dipole array antenna structure based on dipole interconnection, and in order to make the purposes, technical schemes and advantages of the invention more clear, the invention is further described in detail below by combining with the attached drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The method comprises the following concrete steps:
1) Take a 0.1 lambda diameter four-unit electric small-spacing symmetrical dipole array antenna as an example
2) The parameters are set as that the unit antenna is in an xOy plane, as shown in FIG. 1, four dipole structure antennas with the same material and size: the antenna units 1, 2, 3 and 4 are arranged on a ring with the origin as the center, the operating frequency of 1GHz and the corresponding diameter of 0.1 times the wavelength, that is, Φ ARRAY is 0.1 λ is 30mm, and the oscillator radius R is 0.05 λ is 1.5 mm; the lengths of the four oscillators are optimized by a half-wave symmetrical oscillator basic model to obtain L which is 69 mm; the port of each unit is loaded with an impedance of 73.2 Ω, corresponding to a load.
3) The antenna connecting section structure is characterized in that the upper half parts of four symmetrical dipole structures are directly connected by using the antenna connecting section structure, the lower half parts of the four symmetrical dipole structures are directly connected by using the same antenna connecting section structure, and the antenna connecting section structures are arranged according to a regular quadrangle; the antenna connecting section structure and the symmetrical oscillator are made of metal materials with the same diameter. Front, top and perspective views of schematic diagrams of element-interconnected dipole array antennas are shown in figures 1, 2 and 10.
4) In a certain parameter range, scanning parameters to search for the optimal distance rho h between the antenna connecting section structure and the feeding point by applying electromagnetic simulation based on the active unit, wherein the interval distance between the upper antenna connecting section structure and the lower antenna connecting section structure of the dipole is twice of the distance between the antenna connecting section structure and the feeding point, namely 2 x rho h. The variation of the parameter of the four-element dipole circular array S11 with the distance between the antenna connection section structure and the feeding point according to the rho h of the distance between the antenna connection section structure and the feeding point is obtained, as shown in fig. 3, and the diameter of the four-element dipole circular array S11 is 0.1 lambda. It can be found that, as with the linear array, the larger the distance between the connection segment structure of the dipole antenna and the feeding point is, the more the port resonance characteristic of the antenna unit shifts to the high frequency, and the worse the resonance characteristic is. The overall decrease in the S11 parameter was more pronounced throughout the observed frequency range. As shown in fig. 4 and 5, the amplitude and phase patterns of the four-element dipole circular array antenna unit 1 with the diameter of 0.1 λ respectively vary with the distance ρ h between the dipole antenna connection section structure and the feeding point, and it can be seen that the amplitude and phase vary greatly with the distance ρ h between the dipole antenna connection section structure and the feeding point, but the variation trends of the amplitude and phase are consistent, and the amplitude and phase change more and more slowly as the distance ρ h between the dipole antenna connection section structure and the feeding point increases. The maximum radiation direction of the antenna unit 1 is that strong electromagnetic coupling between the antenna units is verified, and energy is mainly electromagnetically coupled to other unit directions. From the above, it can be known that the distance between the optimal dipole antenna connection section structure and the feeding point is ρ h ═ 3mm, that is, the distance between the antenna connection section structures of the upper and lower parts of the symmetric array is 2 × ρ h ═ 6 mm.
5) Compared with the traditional non-direct-connection four-unit symmetrical oscillator, a comparison graph of S parameters of a direct-connection four-unit symmetrical oscillator circular array considering electromagnetic coupling and a same-parameter antenna array considering electromagnetic coupling and not direct connection can be obtained as shown in FIG. 6. Considering the symmetry of the array, only the interaction between antenna elements 1, 2 and 3 will be discussed here. As shown in fig. 6, at an operating frequency of 1GHz, the S31 of the elements of the antenna is less than-10 dB, and the impedance matching characteristics of the array elements are better than for the case of non-straight connections. Whereas S21 is approximately-8 dB and S31 is less than-15 dB, indicating that there is some electromagnetic coupling of energy between adjacent antenna ports, but not significant electromagnetic coupling of energy between non-adjacent cells.
6) Compared with the conventional non-direct-connection four-element dipoles, the actual gain of the four-element electrically small-pitch direct-connection dipole array antenna unit 1 shown in fig. 7 can be obtained. It can be known that the gain of the directly connected dipole array is obviously enhanced compared with the non-directly connected situation, the actual gain of the antenna unit is improved by about 5dB, the directivity is stronger, and the gain is more severely changed.
7) Compared with the traditional non-direct-connection four-unit symmetrical oscillator, the four-unit electric small-pitch direct-connection symmetrical oscillator array antenna phase difference change shown in the figure 8 can be obtained. Where Φ 21 denotes a phase difference between the element antenna element 1 and the antenna element 2, and Φ 31 denotes a phase difference between the element antenna element 1 and the antenna element 3. The phase difference variation range between the unit antenna element 1 and the antenna element 2 is 90 ° in the case of the non-direct electromagnetic coupling, and 140 ° in the case of the direct electromagnetic coupling. The phase difference variation range between the unit antenna element 1 and the antenna element 3 is 124 ° in the case of the non-direct electromagnetic coupling, and 150 ° in the case of the direct electromagnetic coupling. The phase difference between the antenna array elements is larger in the direct connection electromagnetic coupling than that in the non-direct connection condition, and the sensitivity of the whole antenna array to the incoming wave direction of the target signal is improved.
8) Compared with the conventional non-direct-connection four-element dipole, the mean square error of the estimation of the arrival angle and direction of the incoming wave by using a Multiple Signal Classification algorithm (MUSIC) and the clamer-meror boundary which is the estimation of the arrival angle and direction of the incoming wave with the four-element electric small distance as shown in fig. 9 can be obtained. It can be known that, in the variation range of the whole azimuth angle, the mean square error of the CRB of the four-element direct-connection dipole circular array with the diameter of 0.1 λ and the incoming wave arrival angle direction estimation by using the MUSIC algorithm is far lower than that of the non-direct-connection situation, which is caused by the symmetry of the antenna of the four-element dipole array with the electric small distance. Under the condition of non-direct electromagnetic coupling, the direction finding precision of the array is 0.38 degrees. And the direction-finding precision of the direct-connection electromagnetic coupling four-unit circular array is 0.25 degrees in the whole observation angle range, which shows that the direction-finding precision of the antenna array is improved.
Claims (1)
1. The four-unit interconnected symmetrical dipole circular antenna array for electrical small-distance direction finding is characterized by comprising 4 symmetrical dipole structure antennas and 2 antenna connecting section structures;
the 4 symmetrical dipole structure antennas are uniformly distributed in a circular array mode, wherein the upper and lower parts of the 4 symmetrical dipoles are directly connected by using an antenna connecting section structure, the electric small distance means that the distance between adjacent units is far smaller than the working wavelength, the radiation unit comprises 4 symmetrical dipole structures made of 4 materials and having the same size, the symmetrical dipole structures are placed in parallel on the same reference plane and are uniformly distributed at equal angular intervals in the circular array mode; the antenna connecting section structure is characterized in that the upper half parts of 4 symmetrical dipole structures are directly connected by using the antenna connecting section structure, the lower half parts of the 4 symmetrical dipole structures are directly connected by using the same antenna connecting section structure, and the antenna connecting section structure is a connecting structure formed by connecting four sections of cylindrical structures according to a regular quadrangle; the antenna connecting section structure and the symmetrical vibrators are made of metal materials with the same diameter;
The antenna connecting section structure is respectively positioned at the metal tail ends of the upper part and the lower part of the 4 symmetrical oscillators, which are closest to the middle parts of the symmetrical oscillators, and is vertical to the symmetrical oscillator main body to form an upper integral part and a lower integral part, so that a new antenna structure unit is formed to strengthen the electromagnetic coupling between the symmetrical oscillators.
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| CN201611200989.6A CN106450709B (en) | 2016-12-22 | 2016-12-22 | Four-unit interconnected symmetrical oscillator circular antenna array for electric small-distance direction finding |
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| CN201611200989.6A CN106450709B (en) | 2016-12-22 | 2016-12-22 | Four-unit interconnected symmetrical oscillator circular antenna array for electric small-distance direction finding |
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| CN106450709B true CN106450709B (en) | 2019-12-06 |
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| CN112380657A (en) * | 2020-12-01 | 2021-02-19 | 厦门大学 | Directional diagram synthesis method and device of circular ring array antenna |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2581444A (en) * | 1949-09-28 | 1952-01-08 | Standard Telephones Cables Ltd | Direction finder |
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| US8866691B2 (en) * | 2007-04-20 | 2014-10-21 | Skycross, Inc. | Multimode antenna structure |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2581444A (en) * | 1949-09-28 | 1952-01-08 | Standard Telephones Cables Ltd | Direction finder |
Non-Patent Citations (1)
| Title |
|---|
| 《Investigation of wideband Coaxial-Fed Circular dipole Array antenna in a Borehole》;Satoshi Ebihara et-al;《2011 6th International Workshop on Advanced Ground Penetrating Radar (IWAGPR)》;20010729;第1-5页 * |
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