CN114927883B - Method for generating arbitrary-order OAM waves by co-phase feeding of low-order OAM array elements in a ring array - Google Patents
Method for generating arbitrary-order OAM waves by co-phase feeding of low-order OAM array elements in a ring array Download PDFInfo
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- CN114927883B CN114927883B CN202210579239.3A CN202210579239A CN114927883B CN 114927883 B CN114927883 B CN 114927883B CN 202210579239 A CN202210579239 A CN 202210579239A CN 114927883 B CN114927883 B CN 114927883B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q21/00—Antenna arrays or systems
- H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
- H01Q21/061—Two dimensional planar arrays
- H01Q21/065—Patch antenna array
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q21/00—Antenna arrays or systems
- H01Q21/0006—Particular feeding systems
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q21/00—Antenna arrays or systems
- H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
- H01Q21/061—Two dimensional planar arrays
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
A method for generating random order OAM waves by low order OAM array element ring array in-phase feeding relates to the technical field of microwaves and antennas. N low-order OAM antenna radiating elements are used as array elements, array elements are uniformly distributed on a circular ring to form a uniform circular array, in-phase feeding is carried out on each array element of the uniform circular array, uniform spatial phase differences are formed at different positions of the array elements, and after the uniform spatial phase differences are synthesized with spiral phases of the array elements, the (+/-) (1-N) order vortex waves are generated. The array is easy, the feed network is simple, and OAM waves with different orders are generated by selecting the number of array elements. The complex feed network is omitted, the antenna volume is reduced, and the antenna design difficulty is reduced. The vortex wave with higher order can be generated, and the limit that the traditional OAM antenna array can only generate vortex waves with the order lower than N/2 is broken through. The array elements can be selected and replaced according to practical application. The vortex wave presents a phase singular point in the direction of the array axis, firstly presents a fixed first order OAM in a region close to the array axis, and then presents a (1-N) order vortex wave in the region.
Description
Technical Field
The invention relates to the technical field of microwaves and antennas, in particular to a method for generating an arbitrary-order OAM wave by in-phase feeding of a low-order OAM (Orbital Angular Momentum) array element annular array with simple feeding.
Background
In recent years, with the rapid development of wireless communication technology, the problem of the frequency band utilization rate has been highlighted. As the number of users increases and the frequency range for wireless communication is fixed, the problem of bandwidth allocation has become serious. Vortex wave communication is a promising approach to solve the bandwidth shortage with low frequency band utilization, and has led to extensive research. Vortex waves are electromagnetic waves containing orbital angular momentum and have a spiral phase distribution and an annular field strength distribution. The different modes of vortex waves are mutually orthogonal when propagating, and the orthogonal characteristic allows the vortex waves of different modes to be multiplexed together, thereby realizing spatial multiplexing based on orbital angular momentum. Vortex waves are considered to be a solution to achieve high-speed, high-capacity, high-band utilization communications due to their theoretically infinite number of modes available.
The generation and reception of vortex waves is one of the key technologies for vortex wave communication. Summarizing, the methods for generating vortex waves generally include the following:
(1) The spiral phase plate method is a method of generating a vortex wave by passing a normal plane wave through a spiral phase plate. The spiral phase plate may distort the wavefront of the plane wave, i.e. a vortex wave is generated. The spiral phase plate is a microwave dielectric substrate with the thickness changing in proportion to the azimuth angle. When plane waves are incident on the surface of the spiral phase plate, the thickness of the phase plate changes along with the change of azimuth angles, and the plane waves incident on each azimuth angle have wave path differences, and the wave path differences lead to the delay of the phase, so that the plane waves have corresponding spiral wave front structures after being transmitted out of the spiral phase plate.
(2) The working principle of the spiral reflecting surface antenna is similar to that of the spiral phase plate, but the non-uniformity of the reflecting surface is utilized to enable reflected waves to have different wave ranges in different directions, so that phase difference is generated.
(3) Uniform circular array-the use of a circular array is one of the classical methods of generating vortex waves. The main principle of the method is that array elements are arranged into equidistant circular arrays, signals with different phase differences are applied to the array elements, and vortex waves with continuous phase changes along azimuth angles can be obtained after superposition. A uniform circular array is one of the most common methods for generating vortex waves, and the method is simple and visual in design and easy to implement. The disadvantage is that in order to achieve continuous phase change, a complex feed network is often required to be introduced, resulting in a complex overall structure and limiting the miniaturization development of the antenna array.
Disclosure of Invention
The invention aims to solve the problems in the prior art, provides a method for generating random order OAM waves by feeding low order OAM array elements in-phase feeding, and is a method for generating random order vortex waves, which has a simple structure and is easy to realize. The method utilizes the superposition principle of vortex wave array element generation and antenna array generation.
The method comprises the specific steps of using N low-order OAM antenna radiating elements as array elements, uniformly distributing the array elements on a circular ring to form a uniform circular ring array, carrying out in-phase feeding on each array element of the uniform circular ring array, forming uniform spatial phase differences at different positions of the array elements, and generating the (1-N) order vortex waves after synthesizing with spiral phases of the array elements.
The array elements are uniformly distributed on the circular ring, the array arrangement is easy, the in-phase feeding is carried out on each array element, the feeding network is simple, and OAM waves with different orders can be generated by selecting the number of the array elements.
The low-order OAM antenna radiating element can be in a regular polygon, a round shape, a ring shape and the like, can be in a patch structure on a dielectric substrate with a grounding surface or a patch or wire structure without a grounding surface, and is a low-order mode of the OAM radiating element, and is the simplest single antenna element capable of realizing a 1-order OAM mode. The antenna comprises a ring, a certain number of low-order OAM antenna radiating elements which are uniformly distributed on the ring in a rotationally symmetrical way, and a feed structure for carrying out in-phase feed on the OAM radiating elements on the ring with the same radius.
The N low-order OAM antenna radiating elements are uniformly distributed on the same ring at equal intervals at 360/N degrees of central angle. Meanwhile, the influence of the feeding position and the array element circumference llambda is considered, and a (360 multiplied by l)/N-degree space phase difference is introduced between adjacent array elements.
The in-phase feeding is carried out on each array element of the uniform circular array, the center of the circular array is taken as an initial feeding point, the circular array is connected with each array element through a feeder line, the in-phase feeding is carried out on each array element, and the feeder line can be various transmission lines such as a microstrip line, a coplanar waveguide, a parallel double line and the like.
The vortex wave radiated by the circular array is a phase singular point in the direction of a circular array rotating shaft, namely an array shaft, the small area of the inner layer close to the circular array shaft is a vortex wave with the fixed order of first order, and the outer layer is a (1-N) order vortex wave with the order completely determined by the number of array elements.
The invention uses the same-phase feeding mode for the uniform circular array elements, omits a complex feeding network in the traditional OAM method for generating the antenna array, greatly reduces the volume of the antenna and reduces the design difficulty of the antenna. In addition, by the mode, higher-order vortex waves can be generated, and the limitation that the traditional OAM antenna array can only generate vortex waves lower than N/2-order vortex waves is broken through. And moreover, the array elements of the OAM in-phase feed uniform circular array can be replaced according to practical application, and the OAM antenna array meeting corresponding requirements is designed.
Drawings
FIG. 1 is a block diagram of an embodiment of the present invention.
Fig. 2 is a schematic front view of an antenna according to an embodiment of the invention.
Fig. 3 is a schematic back view of an antenna according to an embodiment of the invention.
Fig. 4 is a schematic view of an intermediate layer ground plane according to an embodiment of the invention.
Fig. 5 is a schematic diagram of a back feed line conductor bar layout according to an embodiment of the present invention.
Fig. 6 is a schematic diagram of a front radiating array element according to an embodiment of the present invention.
FIG. 7 is a graph showing the reflection coefficient of the feed end according to an embodiment of the present invention.
Fig. 8 is a phase profile of the vortex wave generated by the antenna at 4.6 GHz.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
The embodiment of the invention uses N low-order OAM antenna radiating elements as array elements, uniformly distributes the array elements on a circular ring to form a uniform circular ring antenna array, carries out in-phase feeding on each array element of the uniform circular ring antenna array, forms uniform spatial phase difference at different positions of the array elements, and generates a (1-N) order vortex wave after being synthesized with the spiral phase of the array elements.
The array elements are uniformly distributed on the circular ring, the array arrangement is easy, the in-phase feeding is carried out on each array element, the feeding network is simple, and OAM waves with different orders can be generated by selecting the number of the array elements.
The low-order OAM antenna radiating element used as an array element can take a regular polygon, a round shape, a ring shape and the like, the low-order OAM antenna radiating element can be in a patch structure on a dielectric substrate with a grounding surface or a patch or wire structure without the grounding surface, and a low-order mode of the OAM radiating element is selected, and the simplest is a single antenna element capable of realizing a 1-order OAM mode. The antenna comprises a ring, a certain number of low-order OAM antenna radiating elements which are uniformly distributed on the ring in a rotationally symmetrical way, and a feed structure for carrying out in-phase feed on the OAM radiating elements on the ring with the same radius.
The array elements are uniformly distributed in a circular ring antenna array, N array elements are uniformly distributed on the circular ring at equal intervals at 360/N degrees of central angles, and meanwhile, the influence of feeding positions and the circumferences llambda of the array elements is considered, so that (360 multiplied by l)/N-degree spatial phase differences are introduced between adjacent array elements.
The feeding network of each array element uniformly distributed on the circular ring antenna array takes the center of the circular ring as a starting end feeding point and is connected with each array element through a transmission line to realize in-phase feeding, the actual structure of the transmission line is determined by a specific array element antenna, for example, the array element is a microstrip antenna structure, and the transmission line can adopt a microstrip line.
The vortex wave pattern of the in-phase feed uniform circular ring antenna array based on the low-order OAM array elements is shown as + -1-order vortex waves in a smaller area close to the center of an array shaft after the array element vortex waves and the circular array vortex waves are overlapped, and the + -1-N-order vortex waves only determined by the number of the array elements are generated in the peripheral area of the vortex wave pattern.
A specific example is given below, in which the number of array elements n=8 is used to generate a-7 th order vortex wave.
Referring to fig. 1-3, the patch antenna structure array comprises an upper dielectric plate 1, a lower dielectric plate 2, a metal grounding surface 3, microstrip feeder conductor strips 4, circular patches 5, reactance circular arc sections 6 and through holes 7, wherein the upper dielectric plate 1 is tightly attached to the lower dielectric plate 2, the metal grounding surface 3 is clamped between the upper dielectric plate 1 and the lower dielectric plate 2, the lower bottom surface of the lower dielectric plate 2 is used as the microstrip feeder conductor strips 4, the upper surface of the upper dielectric plate 1 is provided with the metal patches consisting of the circular patches 5 and the reactance circular arc sections 6, and the through holes 7 are connected with the microstrip feeder conductor strips 4 and the metal patches. The conductor center 8 of the lower surface of the lower dielectric substrate 2 is the connection position of the feed port. The upper dielectric plate 1 and the lower dielectric plate 2 are both made of FR4 high-frequency dielectric substrates with relative dielectric constants epsilon r =2.2 and thickness of 0.8 mm.
Referring to fig. 4, the ground plane is generally square and has a feed port at its conductor center 8. The areas of the upper dielectric plate 1 and the lower dielectric plate 2 are consistent with the ground plane, and the side length W 0 is preferably 30 mm- 0 mm-55 mm.
Referring to fig. 5, the microstrip feeder conductor strip 4 at the bottom layer is distributed by rectangular spokes with equal width and equal length and uniform angle interval from the center of square outwards, and totally 8 microstrip feeder conductor strips are used for in-phase feeding of 8 array element patches. The length l 0 and the width w 1 of the feeder conductor strip can be selected from 35mm less than or equal to l 0≤60mm、1mm≤w1 mm less than or equal to 5mm.
Referring to fig. 6,8 antenna array element patches are circular patches 5 loaded by a reactance arc section 6, and the circle centers of the circular patches are uniformly distributed on a circular ring with a radius of l 0. The radius of the circular patch 5 is r 0, the radius of the loaded reactance arc section 6 is r 1, and the central angle of the loaded reactance arc section isThe parameters can be selected from r 0≤25mm、15mm≤r1 mm or less and 30mm or less,The circular patch 5 is connected with the microstrip line conductor strip 4 through the via hole 7 on one side of the cut line. The reactance arc section 6 is arranged outside the circular ring and is in a shape of a radius which is directed to the through hole of the circular patch 5The included angle is formed by the two ends of the connecting rod,
Fig. 7 shows the result of the S11 parameter at the feed port of the antenna array according to the embodiment, and shows that the operating band range of the antenna array is 4.59-4.61 GHz, and the S11 of the antenna array is less than-15 dB near 4.6 GHz.
Fig. 8 shows the phase distribution of the antenna array of the embodiment at the 4.6GHz frequency point, and the observation area is a square with a side length of 600mm, which is 100mm from the antenna surface. As can be clearly seen from fig. 8, the central region near the antenna array axis is a1 st order vortex wave, and the peripheral region is a-7 th order vortex wave.
The array elements in the antenna array of the embodiment are rotationally arranged in the opposite direction, so that vortex waves of-1 order and 7 order can be displayed in the corresponding observation area.
The array element structure in the antenna array of the embodiment is not limited to this, and regular polygon, circular or annular patches of vortex waves can be generated, and the vortex wave characteristics in the embodiment can be realized.
The invention provides a method for generating an OAM wave of any order based on low-order OAM (Orbital Angular Momentum) array element uniform circular array in-phase feeding. The method utilizes the space phase difference between the array elements to generate vortex waves and the in-phase feeding array elements to generate vortex waves to generate high-order vortex waves through superposition synthesis. The low-order or even simple first-order OAM single antenna radiating element is adopted as a uniform circular array element, and in-phase feeding is carried out on each array element. When the array element number is N, it can generate the + - (1-N) order vortex wave. The complex feed structure can be omitted because of in-phase feed of each array element, the high-order OAM mode is easy to realize because the vortex wave order is only determined by the number of the array elements, and the selection of the array elements and the replacement of different array elements are convenient because the array elements adopt low-order OAM antenna elements. The vortex wave generated by the OAM antenna array presents a phase singular point in the array axis direction, firstly presents a fixed first-order OAM in a region close to the array axis, and then presents a (1-N) order vortex wave in the region.
The embodiment of the present invention is an implementation manner, but the implementation manner of the present invention is not limited by the embodiment, and any other changes, modifications, substitutions, combinations and simplifications that do not depart from the spirit and principle of the present invention should be equivalent to the modification, substitutions and combinations, and are included in the protection scope of the present invention. The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the foregoing embodiments, which have been described in the foregoing description merely illustrates the principles of the invention, and that various changes and modifications may be made therein without departing from the spirit and scope of the invention, which is defined in the appended claims.
Claims (6)
1. The method for generating random order OAM waves by the in-phase feeding of the low order OAM array is characterized by comprising the specific steps of using N low order OAM antenna radiating elements as array elements, uniformly distributing the array elements on a circular ring to form a uniform circular array, and carrying out in-phase feeding on each array element of the uniform circular array;
The low-order OAM antenna radiating element adopts a regular polygon, a round or annular structure, and adopts a patch structure on a dielectric substrate with a grounding surface or a patch or wire structure without a grounding surface.
2. The method for generating an arbitrary-order OAM wave by in-phase feeding of a ring array of low-order OAM elements as recited in claim 1, wherein OAM waves of different orders are generated by selecting a number of elements.
3. The method for generating an arbitrary-order OAM wave by in-phase feeding of a ring array of low-order OAM elements as recited in claim 1, wherein said N low-order OAM antenna radiating elements are uniformly spaced apart on the same ring at a central angle of 360/N degrees.
4. The method for generating random order OAM wave by in-phase feeding of a ring array of low order OAM elements as recited in claim 1, wherein said in-phase feeding of each element of the uniform ring array is performed by in-phase feeding of each element by connecting the ring center with each element through a feeder line and taking the ring center as an initial feeding point.
5. The method for generating an arbitrary order OAM wave by in-phase feeding of a ring array of low order OAM elements as recited in claim 4, wherein said feeding line is selected from a microstrip line, a coplanar waveguide, or a parallel twin line transmission line.
6. The method for generating random order OAM waves by in-phase feeding of the low order OAM array element annular array according to claim 1, wherein the vortex waves radiated by the annular array are phase singular points in the direction of an annular array rotating shaft, namely an array shaft, the small area of the inner layer close to the annular array shaft is a vortex wave with the fixed order, and the outer layer is a (1-N) order vortex wave with the order completely determined by the number of array elements.
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| CN107645068A (en) * | 2017-09-15 | 2018-01-30 | 中南大学 | A kind of circular array design method for rotating circular polarisation array element and producing OAM wave beams |
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| CN105071034A (en) * | 2015-08-27 | 2015-11-18 | 宁夏大学 | Multi-modal orbital angular momentum (OAM) vortex electromagnetic wave microstrip array antenna |
| CN206471491U (en) * | 2016-10-31 | 2017-09-05 | 宁夏大学 | A kind of multi-modal OAM electromagnetism vortex ripple array antenna of twin nuclei |
| CN112736474B (en) * | 2020-12-25 | 2022-04-01 | 厦门大学 | Single-port high-order OAM radiator based on discrete periodic element SSPP modes |
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