CN115117625B - Method for generating phase-controllable OAM electromagnetic wave under phase-locked source random initial phase condition - Google Patents
Method for generating phase-controllable OAM electromagnetic wave under phase-locked source random initial phase condition Download PDFInfo
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Abstract
The invention discloses a method for generating phase-controllable OAM electromagnetic waves under the random initial phase condition of a phase-locked source; the method is based on a uniform circular antenna array technology, and the feed network comprises one path of intermediate frequency signal source, one path of local oscillation signal source and multiple paths of weighted signal sources. Calculating the output angular frequency of the intermediate frequency source and the local oscillation source according to the target transmitting frequency and the topological charge number; and calculating the output angular frequency of the weighted signal source according to the target beam direction so as to generate vortex electromagnetic waves with required frequency, topological charge number and beam direction. The feed network adopted by the invention only uses the delay line as the phase shifting unit, and the primary phase interference of each signal source is counteracted through the multiple frequency mixing structure in the feed network, so that the beam steering precision of the system and the purity of the OAM wave generated by the beam steering precision are ensured.
Description
Technical Field
The invention relates to the technical field of OAM electromagnetic waves, in particular to a method for generating phase-controllable OAM electromagnetic waves under the random initial phase condition of a phase-locked source.
Background
Research shows that electromagnetic waves have not only spin angular momentum but also orbital angular momentum. Some later studies have clearly indicated that electromagnetic waves carrying orbital angular momentum, called OAM electromagnetic waves, have a helical phase structure with a wavefront that rotates in space along the beam axis. The OAM electromagnetic waves of different OAM modes have different phase structures, and the integer modes are mutually orthogonal, which means that orbital angular momentum can provide rotational freedom for the electromagnetic field, and the novel multiplexing application is facilitated. Orbital angular momentum has been found in optical research, and OAM electromagnetic waves have been used in the fields of radar imaging, quantum state manipulation, and the like. In contrast to the tremendous role that OAM electromagnetic waves play in the optical arts, their research in the wireless communications arts is still continuing.
The most advanced OAM generating architecture can be mainly divided into four types, namely, a transmission spiral structure, a transmission grating structure, a spiral reflector structure, and an array antenna. As early as OAM electromagnetic waves were proposed, supporters described how to feed a uniform circular array to create orbital angular momentum in the radio frequency band. The uniform circular phased array has the advantages of simple processing, convenient operation and the like, and is a good OAM electromagnetic wave generator.
Systems for generating OAM electromagnetic waves based on uniform circular array antennas typically require high precision phase shifters with phase shifting ranges of 0-360 °. Since phase shifters are expensive, a modification is proposed herein to change the system architecture to save costs. In some schemes, delay lines are used instead of phase shifters to generate OAM electromagnetic waves with different topological charges, thereby simplifying the system. But if the beam-pointing control of the OAM is to be further implemented without changing the delay line length, a phase shifter is still required to complete the structure of the phased array.
Disclosure of Invention
The present invention provides a solution to the above-mentioned deficiencies of the prior art.
In order to achieve the aim of the invention, the invention adopts the following technical scheme:
a method for generating a controllable OAM electromagnetic wave under a phase-locked source random initial phase condition, comprising the steps of:
an OAM electromagnetic wave mixing feed network comprising one intermediate frequency signal source, one local oscillation signal source and multiple weighted signal sources is constructed;
The feed network comprises a local oscillation signal source, an M local oscillation signal splitter, an intermediate frequency signal source, an M intermediate frequency signal splitter, an M weighting signal source, M two weighting signal splitters, M local oscillation signal heterodyne mixers, M local oscillation signal filters, M intermediate frequency signal heterodyne mixers, M intermediate frequency signal filters, M delay lines, M radio frequency signal heterodyne mixers and M radio frequency signal filters;
one path of intermediate frequency signal source sends out M paths of intermediate frequency signals through M paths of intermediate frequency signal splitters, one path of weighted signals which are respectively split with the corresponding weighted signal source in the M paths of weighted signal sources through two paths of weighted signal splitters are mixed through the corresponding intermediate frequency signal heterodyne mixer, and the mixed intermediate frequency signals are filtered through the corresponding intermediate frequency signal filters;
One local oscillation signal source sends out M local oscillation signals through M local oscillation signal splitters, the local oscillation signals are respectively mixed with the other weighted signals which are respectively split by the corresponding weighted signal sources in the M weighted signal sources through two weighted signal splitters through the corresponding local oscillation signal heterodyne mixers, and the mixed local oscillation signals are filtered through the corresponding local oscillation signal filters and then are subjected to phase regulation through delay lines with fixed lengths;
mixing the intermediate frequency signals after filtering and the local oscillation signals after phase regulation of the paths through corresponding radio frequency signal heterodyne mixers, filtering the radio frequency signals after mixing through corresponding radio frequency signal filters respectively, and sending the radio frequency signals into each antenna unit in the uniform circular antenna array;
Calculating the output angular frequency of the intermediate frequency signal source and the local oscillation signal source according to the load number of the target OAM topology and the beam pointing angle; calculating the output angular frequency of the weighted signal source according to the target emission frequency;
and (3) accessing the OAM electromagnetic wave mixing feed network into a uniform circular antenna array, and adjusting the output frequencies of each local oscillation signal source, intermediate frequency signal source and weighting signal source according to the calculated output angular frequency to generate the OAM electromagnetic wave with target transmitting frequency, topological charge number and beam direction.
Optionally, calculating output angular frequencies of an intermediate frequency signal source and a local oscillation signal source in the feed network according to the target OAM topology charge number and the beam pointing angle; and then according to the target emission frequency, calculating the output angular frequency of the weighted signal source, which comprises the following steps:
According to the target OAM topology charge number and the beam pointing angle, determining a phase excitation vector required by each antenna unit of the uniform circular antenna array;
determining the phase offset required by each antenna unit of the uniform circular antenna array according to the phase excitation vector required by each antenna unit of the uniform circular antenna array;
according to the phase shift generated by the delay line with fixed length and the phase shift required by each antenna unit of the uniform circular antenna array, determining the output angular frequency of an intermediate frequency signal source and a local oscillation signal source, mixing the two signals, and filtering to obtain the input signal angular frequency applied to the delay line corresponding to each antenna unit of the uniform circular antenna array;
and determining the output angular frequency of the intermediate frequency source according to the target emission frequency.
Optionally, the phase excitation vector required by each antenna element of the uniform circular antenna array is specifically:
where S is the phase offset required by the antenna element, l is the number of OAM topology charges required to be generated, For the phase difference of adjacent antenna units with the topological charge number of 1, k is the wave number of the radio frequency signals, a is the array radius of the uniform circular array, θ is the beam pitch angle, γ is the beam azimuth angle, M is the antenna unit serial number of the uniform circular array, and M is the number of the antenna units of the uniform circular array.
Optionally, the phase offset required by each antenna element of the uniform circular antenna array is specifically:
Wherein, For the phase offset required by the mth antenna unit, l is the number of OAM topology charges, M is the number of antenna units of the uniform circular array, k is the wave number of the radio frequency signal, a is the array radius of the uniform circular array, θ is the beam pitch angle, and γ is the beam azimuth angle.
Optionally, the phase shift generated by the fixed length delay line is specifically:
Wherein, For the phase shift produced by the delay line ω is the angular frequency of the signal passing through the delay line, l' is the length of the delay line, ε is the dielectric constant of the delay line, μ is the permeability of the delay line.
Optionally, the input signal angular frequency applied to the delay line corresponding to each antenna element of the uniform circular antenna array is specifically:
Wherein omega m is the input signal angular frequency applied to the delay line corresponding to each antenna unit of the uniform circular antenna array, omega 'is the set signal angular frequency, l is the number of OAM topology charges required to be generated, omega' l is the local oscillator source signal frequency, For weighting the signal frequencies of the signal sources.
Optionally, the output angular frequency of the intermediate frequency signal source is determined in the following manner:
ωIF＝ωRF-ω′l
Wherein ω IF is the output angular frequency of the intermediate frequency signal source, ω RF is the target transmission frequency, and ω' l is the local oscillator source signal frequency.
The invention has the following beneficial effects:
(1) Under the condition of ensuring high phase control precision and range, only a delay line is used as a phase shifting unit, so that an expensive phase shifter is saved for the system.
(2) The accuracy of which depends on the tuning accuracy of the phase-locked loop used by the system, typically much higher than the phase shifter, by adjusting the frequency and thus controlling the phase shift parameters. The system is therefore theoretically capable of achieving higher accuracy in beam steering angle adjustment than a uniform circular array based on phase shifters. Meanwhile, the system with higher precision can also generate OAM electromagnetic waves with higher modal purity.
(3) The system omits complex circuit devices, is only composed of simple components and is convenient to replace and adjust. The initial phase random structure ensures that the system is not affected by phase noise to a certain extent, and meanwhile, the phase interference which cannot be processed by the initial phase random structure can be compensated by correcting the frequency matrix, so that the robustness of the system is improved.
Drawings
Fig. 1 is a flow chart of a method for generating a controllable OAM electromagnetic wave under a phase-locked source random initial phase condition according to an embodiment of the present invention;
Fig. 2 is a schematic diagram of a system structure for generating a controllable OAM electromagnetic wave without a phase shifter according to an embodiment of the present invention;
Fig. 3 is a beam pointing analysis chart and an amplitude chart when the topology lotus l=1 and the deflection angle v= (20 ° ) in the embodiment of the present invention;
fig. 4 is a beam pointing analysis chart and an amplitude chart when the topology lotus l=2 and the deflection angle v= (45 ° ) in the embodiment of the present invention;
Fig. 5 is a three-dimensional phase diagram when the topology charge l=1 and the deflection angle v= (15 ° ) in the embodiment of the present invention;
Fig. 6 is a front view phase diagram when the topology charge l=1 and the deflection angle v= (15 ° ) in the embodiment of the present invention;
Fig. 7 is a three-dimensional phase diagram when the topology charge l=2 and the deflection angle v= (30 ° ) in the embodiment of the present invention;
Fig. 8 is a front view phase diagram when the topology charge l=2 and the deflection angle v= (30 ° ) in the embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention is provided to facilitate understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and all the inventions which make use of the inventive concept are protected by the spirit and scope of the present invention as defined and defined in the appended claims to those skilled in the art.
As shown in fig. 1, an embodiment of the present invention provides a method for generating a controllable OAM electromagnetic wave under a phase-locked source random initial phase condition, including steps S1 to S3 as follows:
S1, constructing an OAM electromagnetic wave mixing feed network comprising one intermediate frequency signal source, one local oscillation signal source and multiple weighted signal sources;
The feed network comprises a local oscillation signal source, an M local oscillation signal splitter, an intermediate frequency signal source, an M intermediate frequency signal splitter, an M weighting signal source, M two weighting signal splitters, M local oscillation signal heterodyne mixers, M local oscillation signal filters, M intermediate frequency signal heterodyne mixers, M intermediate frequency signal filters, M delay lines, M radio frequency signal heterodyne mixers and M radio frequency signal filters;
one path of intermediate frequency signal source sends out M paths of intermediate frequency signals through M paths of intermediate frequency signal splitters, one path of weighted signals which are respectively split with the corresponding weighted signal source in the M paths of weighted signal sources through two paths of weighted signal splitters are mixed through the corresponding intermediate frequency signal heterodyne mixer, and the mixed intermediate frequency signals are filtered through the corresponding intermediate frequency signal filters;
One local oscillation signal source sends out M local oscillation signals through M local oscillation signal splitters, the local oscillation signals are respectively mixed with the other weighted signals which are respectively split by the corresponding weighted signal sources in the M weighted signal sources through two weighted signal splitters through the corresponding local oscillation signal heterodyne mixers, and the mixed local oscillation signals are filtered through the corresponding local oscillation signal filters and then are subjected to phase regulation through delay lines with fixed lengths;
mixing the intermediate frequency signals after filtering and the local oscillation signals after phase regulation of the paths through corresponding radio frequency signal heterodyne mixers, filtering the radio frequency signals after mixing through corresponding radio frequency signal filters respectively, and sending the radio frequency signals into each antenna unit in the uniform circular antenna array;
s2, calculating the output angular frequency of the intermediate frequency signal source and the local oscillation signal source according to the load number of the target OAM topology and the beam pointing angle; calculating the output angular frequency of the weighted signal source according to the target emission frequency;
S3, the OAM electromagnetic wave mixed feed network is connected into the uniform circular antenna array, and the output frequencies of the local oscillation signal sources, the intermediate frequency signal sources and the weighted signal sources are adjusted according to the calculated output angular frequency, so that the OAM electromagnetic wave with the target transmitting frequency, the topological charge number and the beam pointing direction is generated.
The invention adopts a delay line as a phase shift element to realize an OAM electromagnetic wave generating system with beam control. The system is based on a uniform circular array and phased array technique, producing an input frequency matrix corresponding to each target situation.
According to the phased array principle of generating OAM electromagnetic waves, if a plurality of different signal sources exist in channels of each antenna unit, the system can successfully achieve the expected effect, and if the initial phases of the signal sources are consistent, the difference is kept until each path of signals of the antenna array are finally input, and finally the phase control structure of the OAM electromagnetic wave generating system is destroyed. However, the system of adding an M-path phase-locked loop to the constant-temperature crystal oscillator cannot ensure that the primary phases are consistent after decimal frequency modulation, and is different from the instantaneous phase, the primary phases have no practical meaning and an accurate and effective measuring method, and are difficult to realize in reality. Therefore, the invention considers the random initial phase problem of the actual phase-locked source, further improves the scheme, counteracts the interference of the initial phase by skillfully setting a circuit structure and adopting a continuous mixing and filtering mode, and filters the influence of the inconsistent initial phase on the phase control system. The scheme provided by the invention can completely get rid of the phase shifter and realize the free adjustment of the emission frequency/topological charge number/beam steering angle. The adjustment accuracy depends on the tuning accuracy of the phase-locked source, which is much higher than the phase shifter.
In an optional embodiment of the invention, the output angular frequencies of an intermediate frequency signal source and a local oscillation signal source in a feed network are calculated according to the target OAM topology charge number and the beam pointing angle; calculating the output angular frequency of the weighted signal source according to the target emission frequency specifically comprises:
According to the target OAM topology charge number and the beam pointing angle, determining a phase excitation vector required by each antenna unit of the uniform circular antenna array;
determining the phase offset required by each antenna unit of the uniform circular antenna array according to the phase excitation vector required by each antenna unit of the uniform circular antenna array;
according to the phase shift generated by the delay line with fixed length and the phase shift required by each antenna unit of the uniform circular antenna array, determining the output angular frequency of an intermediate frequency signal source and a local oscillation signal source, mixing the two signals, and filtering to obtain the input signal angular frequency applied to the delay line corresponding to each antenna unit of the uniform circular antenna array;
and determining the output angular frequency of the intermediate frequency source according to the target emission frequency.
Specifically, when the system for generating the controllable OAM electromagnetic wave without the phase shifter is constructed to generate the OAM electromagnetic wave with the topology lotus of l and the beam pointing angle of (theta, gamma), the phase excitation vector required by each antenna unit of the uniform circular array is determined specifically as follows:
Wherein S is the phase offset required by the antenna unit, l is the number of OAM topology charges required to be generated, k is the wave number of the radio frequency signal, a is the array radius of the uniform circular array, θ is the beam pitch angle, γ is the beam azimuth angle, M is the number of the antenna units of the uniform circular array, and M is the number of the antenna units of the uniform circular array.
Therefore, according to the phase excitation vector required by each antenna unit of the uniform circular array, the phase offset required by each antenna unit of the uniform circular array can be determined specifically as follows:
Wherein, For the phase offset required by the mth antenna unit, l is the number of OAM topology charges, M is the number of antenna units of the uniform circular array, k is the wave number of the radio frequency signal, a is the array radius of the uniform circular array, θ is the beam pitch angle, and γ is the beam azimuth angle.
To determine the phase shift produced by a delay line of fixed length, the phase shift constant of the delay line is first determined by:
Where ε is the dielectric constant of the delay line and μ is the magnetic permeability of the delay line.
Let the delay line length be l' and correspond to the phase shift generatedThe method comprises the following steps:
In order to obtain the OAM electromagnetic wave, the phase offset required for the mth antenna element is:
and the length of the delay line corresponding to the mth antenna unit is set as follows:
Wherein omega m is the input signal angular frequency of the delay line corresponding to the mth antenna unit, namely the output signal angular frequency of the local oscillation signal and the weighted signal after heterodyne mixing and filtering.
Let l=1, Ω M＝(ω1,ω2,...,ωM)T＝(ω′,ω′,...,ω′)T, and substituting the above formula to obtain
Wherein ω' is the angular frequency of the signal that M phase-locked loops should regulate when the topology lotus is 1 and beam pointing regulation is not added.
Thus, the length of the delay line corresponding to each antenna unit can be determined according to the relation between the phase shift generated by the delay line with fixed length and the phase shift required by each antenna unit of the uniform circular array.
Furthermore, according to the length of the delay line corresponding to each antenna unit, the input signal angular frequency of the delay line corresponding to the mth antenna unit is determined as follows:
Assuming that the target beam pointing angle of the OAM electromagnetic wave is (θ 1,γ1), let (θ 1,γ1)＝ν1, The angular frequency expression can be derived from the above equation:
the above is that when the OAM mode of the target waveform is l and the beam pointing angle is (θ 1,γ1)＝ν1, the input frequency corresponding to each delay line is given that the output frequency of the local oscillator signal source is ω' l, the weighted signal source should be Mixing the two signals, and filtering to obtain the input signal applied to the delay line corresponding to each antenna unit of the uniform circular array, wherein the angular frequency of the input signal is omega m.
If the target emission frequency is omega RF, determining that the output angular frequency of one path of intermediate frequency source is omega IF＝ωRF -omega' l.
The process of generating OAM electromagnetic waves with target transmitting frequency, topological charge number and beam direction by connecting the OAM electromagnetic wave frequency mixing feed network to the uniform circular antenna array and adjusting the output frequencies of each local oscillator signal source, intermediate frequency signal source and weighting signal source according to the calculated output angular frequency is analyzed.
Let the intermediate frequency signal be:
Let the local oscillator signal be:
let m weighted signals be:
Wherein, Random phases of 0-360 degrees, omega C (m) is/>V 0＝(θ0,γ0), is a preset beam pointing angle.
After mixing and filtering with m paths of weighted signals, the intermediate frequency signals and the local oscillation signals become respectively:
According to the calculated input signal angular frequency applied by the delay line corresponding to the antenna unit, if ω LO =lω', ω LO+ωC (m) is the desired delay line input angular frequency, and each local oscillation signal passes through the delay line and is obtained:
after that, the process is carried out, I.e. the desired phase relationship. Mixing and filtering the M paths of local oscillation signals with intermediate frequency to obtain final signals:
Wherein the method comprises the steps of And/>Independent of array element sequence number m, except/>Besides, signals input into each path of antenna units have no other phase difference relation, and the structures of OAM electromagnetic waves and beam pointing control remain intact.
The following describes the simulation analysis of the solution of the present invention in connection with specific examples.
When the radio frequency is selected as X band (10 GHz), the array radius is lambda/2, and when beam deflection is not added and the OAM mode is 1, the local oscillation signal source frequency f=500 MHz, and the length of each delay line is confirmed by omega' =2pi f. Based on this, the system is tested.
In the simulation of the present invention, the beam pointing angle is uniformly defined as the direction of the lowest value of the amplitude of the zero depth region. Let v= (20 ° ), and when topological lotus l=1, drawing beam pointing analysis graph and amplitude graph as shown in fig. 3, in azimuth section, amplitude value reaches low valley when pitch angle variable value is 20 degrees, that is, represents beam pitch angle deflection 20 degrees, meanwhile, the right lower corner of the graph gives complete amplitude graph, and it can be seen that zero deep region originally pointed to be (0 ° ) points to (20 °). Fig. 4 shows the case when the topology is l=2, v= (45 ° ).
After the angle is deflected, the phase diagram of the OAM electromagnetic wave generated by the system is shown in fig. 5-8, fig. 5 and fig. 6 show the case of l=1, v= (15 ° ), fig. 7 and fig. 8 show the case of l=2, v= (30 ° ), fig. 5 and fig. 7 are perspective views, and fig. 5 and fig. 8 are front views.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The principles and embodiments of the present invention have been described in detail with reference to specific examples, which are provided to facilitate understanding of the method and core ideas of the present invention; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present invention, the present description should not be construed as limiting the present invention in view of the above.
Those of ordinary skill in the art will recognize that the embodiments described herein are for the purpose of aiding the reader in understanding the principles of the present invention and should be understood that the scope of the invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other specific modifications and combinations from the teachings of the present disclosure without departing from the spirit thereof, and such modifications and combinations remain within the scope of the present disclosure.
Claims (7)
1. A method for generating a phase-controllable OAM electromagnetic wave under a phase-locked source random initial phase condition, comprising the steps of:
an OAM electromagnetic wave mixing feed network comprising one intermediate frequency signal source, one local oscillation signal source and multiple weighted signal sources is constructed;
The feed network comprises a local oscillation signal source, an M local oscillation signal splitter, an intermediate frequency signal source, an M intermediate frequency signal splitter, an M weighting signal source, M two weighting signal splitters, M local oscillation signal heterodyne mixers, M local oscillation signal filters, M intermediate frequency signal heterodyne mixers, M intermediate frequency signal filters, M delay lines, M radio frequency signal heterodyne mixers and M radio frequency signal filters;
one path of intermediate frequency signal source sends out M paths of intermediate frequency signals through M paths of intermediate frequency signal splitters, one path of weighted signals which are respectively split with the corresponding weighted signal source in the M paths of weighted signal sources through two paths of weighted signal splitters are mixed through the corresponding intermediate frequency signal heterodyne mixer, and the mixed intermediate frequency signals are filtered through the corresponding intermediate frequency signal filters;
One local oscillation signal source sends out M local oscillation signals through M local oscillation signal splitters, the local oscillation signals are respectively mixed with the other weighted signals which are respectively split by the corresponding weighted signal sources in the M weighted signal sources through two weighted signal splitters through the corresponding local oscillation signal heterodyne mixers, and the mixed local oscillation signals are filtered through the corresponding local oscillation signal filters and then are subjected to phase regulation through delay lines with fixed lengths;
mixing the intermediate frequency signals after filtering and the local oscillation signals after phase regulation of the paths through corresponding radio frequency signal heterodyne mixers, filtering the radio frequency signals after mixing through corresponding radio frequency signal filters respectively, and sending the radio frequency signals into each antenna unit in the uniform circular antenna array;
Calculating the output angular frequency of the intermediate frequency signal source and the local oscillation signal source according to the load number of the target OAM topology and the beam pointing angle; calculating the output angular frequency of the weighted signal source according to the target emission frequency;
and (3) accessing the OAM electromagnetic wave mixing feed network into a uniform circular antenna array, and adjusting the output frequencies of each local oscillation signal source, intermediate frequency signal source and weighting signal source according to the calculated output angular frequency to generate the OAM electromagnetic wave with target transmitting frequency, topological charge number and beam direction.
2. The method for generating controllable OAM electromagnetic waves under a random initial phase condition of a phase lock source as recited in claim 1, wherein said calculating output angular frequencies of an intermediate frequency signal source and a local oscillator signal source according to a target OAM topology payload number and a beam pointing angle; and then according to the target emission frequency, calculating the output angular frequency of the weighted signal source, which comprises the following steps:
According to the target OAM topology charge number and the beam pointing angle, determining a phase excitation vector required by each antenna unit of the uniform circular antenna array;
determining the phase offset required by each antenna unit of the uniform circular antenna array according to the phase excitation vector required by each antenna unit of the uniform circular antenna array;
according to the phase shift generated by the delay line with fixed length and the phase shift required by each antenna unit of the uniform circular antenna array, determining the output angular frequency of an intermediate frequency signal source and a local oscillation signal source, mixing the two signals, and filtering to obtain the input signal angular frequency applied to the delay line corresponding to each antenna unit of the uniform circular antenna array;
And determining the output angular frequency of the intermediate frequency signal source according to the target emission frequency.
3. The method for generating controllable OAM electromagnetic waves under random initial phase conditions of a phase lock source as recited in claim 2, wherein said phase excitation vector required for each antenna element of said uniform circular antenna array is specifically:
where S is the phase offset required by the antenna element, l is the number of OAM topology charges required to be generated, For the phase difference of adjacent antenna units with the topological charge number of 1, k is the wave number of the radio frequency signals, a is the array radius of the uniform circular array, θ is the beam pitch angle, γ is the beam azimuth angle, M is the antenna unit serial number of the uniform circular array, and M is the number of the antenna units of the uniform circular array.
4. The method for generating controllable OAM electromagnetic waves under a random initial phase condition of a phase lock source as recited in claim 2, wherein said phase offset required for each antenna element of said uniform circular antenna array is specifically:
Wherein, For the phase offset required by the mth antenna unit, l is the number of OAM topology charges, M is the number of antenna units of the uniform circular array, k is the wave number of the radio frequency signal, a is the array radius of the uniform circular array, θ is the beam pitch angle, and γ is the beam azimuth angle.
5. The method for generating a controllable OAM electromagnetic wave under a random initial phase condition of a phase lock source as recited in claim 2, wherein said phase shift generated by said fixed length delay line is specifically:
Wherein, For the phase shift produced by the delay line ω is the angular frequency of the signal passing through the delay line, l' is the length of the delay line, ε is the dielectric constant of the delay line, μ is the permeability of the delay line.
6. The method for generating controllable OAM electromagnetic waves under a random initial phase condition of a phase lock source as recited in claim 2, wherein said input signal angular frequency applied to the delay line corresponding to each antenna element of the uniform circular antenna array is specifically:
ωm＝ω′l+ψν1(m)
wherein ω m is the input signal angular frequency applied to the delay line corresponding to each antenna unit of the uniform circular antenna array, ω 'is the set signal angular frequency, l is the number of load of the OAM topology to be generated, ω' l is the local oscillator source signal frequency, and ψ ν1 (m) is the signal frequency of the weighted signal source.
7. The method for generating a controllable OAM electromagnetic wave under a random initial phase condition of a phase lock source as recited in claim 2, wherein said output angular frequency of said intermediate frequency signal source is determined by:
ωIF＝ωRF-ω′l
Wherein ω IF is the output angular frequency of the intermediate frequency signal source, ω RF is the target transmission frequency, and ω' l is the local oscillator source signal frequency.
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| "一种旋转圆极化阵元产生OAM 波束的圆形阵设计方法";董健等;《电子元件与材料》;20181231;全文 * |
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