Method, system, storage medium and electronic device for estimating modal purity of vortex electromagnetic waves based on main lobe ripple measurement

Abstract

This article discloses a method, system, storage medium and electronic device for estimating the modal purity of vortex electromagnetic waves based on main lobe ripple measurement, including the following steps: measuring the electric field amplitude and phase of the vortex electromagnetic wave in free space; finding the center of the vortex electromagnetic wave beam through phase distribution; successively determining the main lobe position of the vortex electromagnetic wave with the beam center as the center of the circle; calculating the average amplitude and the maximum and minimum amplitude differences along the circumference of the main lobe and calculating the relative main lobe ripple; finally, calculating the modal purity of the vortex electromagnetic wave; through the present invention, the modal purity of the generated vortex electromagnetic wave can be accurately calculated, which is beneficial to the subsequent collection and processing of the received data and can effectively reduce the impact of modal aliasing on the waste of collected information.

Description

Technical Field

[0001] The present application relates to the field of signal processing technology, and in particular to a method, system, computer-readable storage medium, and electronic device for estimating the modal purity of vortex electromagnetic waves based on main lobe ripple measurement. Background Art

[0002] Because vortex electromagnetic waves carry orbital angular momentum, they exhibit a new degree of freedom beyond the traditional degrees of freedom of intensity, phase, frequency, and polarization. Theoretically, they can generate infinite modes at any frequency. These modes are mutually orthogonal and propagate independently, forming an infinite-dimensional Hilbert space. Like the time and frequency domains, this space can theoretically modulate more information. However, in practice, the number of array elements that can be used is limited. According to the duality property of the Fourier transform, l is equivalent to the "frequency" of the array element index n. If the UCA array factor is considered the result of the continuous Fourier transform of a spatial function, then the UCA array factor is the result of the discrete Fourier transform of the spatial function after uniform periodic sampling. According to Fourier transform theory, uniform periodic sampling leads to a periodic extension of the spectrum, with the period being the inverse of the sampling interval. Therefore, the uniformly distributed circular array is equivalent to uniform sampling of the spatial azimuth angle, which will lead to the periodic extension of the OAM spectrum in the OAM domain with a period of N. The periodic extension of the OAM spectrum produces OAM harmonics, which also means that pure vortex electromagnetic waves cannot be generated. As a result, other harmonics will be included in the generated electromagnetic waves, which will affect their application.

[0003] In summary, in order to reduce the impact of modal aliasing of vortex electromagnetic waves on their applications and prevent the inability to effectively receive and process the received electromagnetic waves, resulting in information waste, it is necessary to obtain the proportion of the fundamental wave and harmonics of the generated vortex electromagnetic waves in advance and calculate the modal purity of the generated vortex electromagnetic waves. Summary of the Invention

[0004] The purpose of this application is to provide a method, system, storage medium and electronic device for estimating the modal purity of vortex electromagnetic waves based on main lobe ripple measurement, so as to solve or alleviate the problems existing in the above-mentioned prior art.

[0005] In order to achieve the above objectives, this application provides the following technical solutions:

[0006] The present application provides a method for estimating the modal purity of a vortex electromagnetic wave based on main lobe ripple measurement, comprising: step S101, measuring the electric field amplitude and phase of the vortex electromagnetic wave in free space; step S102, finding the center of the vortex electromagnetic wave beam through phase distribution; step S103, successively determining the main lobe position of the vortex electromagnetic wave with the beam center as the center of the circle; step S104, calculating the average amplitude and the maximum and minimum amplitude differences along the circumference of the main lobe and calculating the relative main lobe ripple; step S105, calculating the modal purity of the vortex electromagnetic wave based on the relative main lobe ripple obtained in step S104.

[0007] Preferably, in step S101, the electric field amplitude and phase of the vortex electromagnetic wave in free space are measured.

[0008] Preferably, in step S102, based on the electric field phase in free space measured in step S101, the electric field is decomposed into a spatial phase and a pure vortex phase, which is described by the following formula:

[0009]

[0010] Where r is the distance from the source point to the field point, l is the OAM modulus, is the azimuth of the field point with respect to the source point. The first term in the above equation is the spatial phase, and the second term is the pure vortex phase. Assuming that the phase section takes the beam center as the origin, a polar coordinate system is established, and the distance between the source and the phase section is R0, then any point on the section is The distance from the source can be expressed as

[0011]

[0012] It can be seen from the above formula that when ρ remains unchanged, r remains unchanged, so the spatial phase will not change either. On concentric circles with the same polar diameter, the electric field phase is the same, that is, the equal phase lines are concentric circles with the beam center as the center.

[0013] Take any three adjacent equal phase lines, the radii of the three equal phase lines are recorded as ρ1, ρ2, ρ3, and the spacing between the equal phase lines is Δρ1, Δρ2, and their winding phase value is set to φ0. In the actual scenario, R0>>ρ1, ρ2, ρ3, so the above formula can be simplified to

[0014]

[0015] So, for ρ2, we have

[0016]

[0017] From the definition of equal phase lines, we know that the change of kr caused by adjacent equal phase lines in the polar direction is 2π, so for ρ1 and ρ3 respectively

[0018]

[0019] According to the above formula, we can get

[0020]

[0021] It can be seen from the above formula that the spatial phase distribution of vortex electromagnetic waves can be used to estimate the radii of any three equal phase lines by measuring the distance between them, thereby determining the center of the circle on the equal phase line observation interface.

[0022] Preferably, in step S103, based on the center position of the circle measured in step S102 and the electric field amplitude of the free-space vortex electromagnetic wave measured in step S101, the circumference is expanded outward with the center of the beam as the center, and the circumference with the largest average electric field amplitude is found, which is the main lobe position of the vortex electromagnetic wave.

[0023] Preferably, in step S104, according to the main lobe position found in step S103, the average amplitude is calculated along the circumference of the main lobe and the maximum and minimum amplitudes are recorded, and then the difference between the maximum amplitude and the minimum amplitude is calculated and recorded as the main lobe ripple value. Then the relative main lobe ripple is defined as the ratio of the main lobe ripple value to the oscillation center amplitude, and the symbol is used. express

[0024]

[0025] Where N is the number of array elements, J l (·) is the Bessel function of the first kind, 2N|J l-N (kasinθ)| is the oscillation amplitude range, |J l (kasinθ)| is the amplitude of the oscillation center.

[0026] Preferably, in step S105, the ratio of the -1st harmonic to the fundamental wave is defined as the first harmonic ratio.

[0027]

[0028] It can be seen that HFR is related to the relative main lobe ripple. Only twice the difference

[0029]

[0030] At the same time, modal purity is defined as

[0031]

[0032] Where m represents the m-th order harmonic.

[0033] According to the experiment, it can be concluded that the main harmonic component of the vortex electromagnetic wave generated by the uniform circular ring array is the -1 harmonic. Therefore, the relationship between the modal purity and the first harmonic ratio can be obtained as follows:

[0034]

[0035] pass With p l,N It can be seen that the modal purity of the generated vortex electromagnetic wave can be directly calculated by measuring the relative main lobe ripple.

[0036] An embodiment of the present application also provides a vortex electromagnetic wave modal purity estimation system based on main lobe ripple measurement, including: a vortex electromagnetic wave measurement unit, configured to receive vortex electromagnetic waves in free space and measure the amplitude and phase of the electric field; a center determination unit, configured to determine the center position of the vortex electromagnetic wave beam according to the phase of the received vortex electromagnetic wave; a main lobe calculation unit, configured to find the main lobe position of the vortex electromagnetic wave with the beam center as the center of the circle; a relative main lobe ripple calculation unit, configured to calculate the relative main lobe ripple of the collected vortex electromagnetic wave; and a modal purity calculation unit, configured to calculate the modal purity of the collected vortex electromagnetic wave.

[0037] An embodiment of the present application also provides a computer-readable storage medium having a computer program stored thereon, wherein the program is any of the above-described methods for estimating the modal purity of vortex electromagnetic waves based on main lobe ripple measurement.

[0038] An embodiment of the present application also provides an electronic device, comprising: a memory, a processor, and a program stored in the memory and executable on the processor, wherein when the processor executes the program, it implements any of the above-described methods for estimating the modal purity of vortex electromagnetic waves based on main lobe ripple measurement.

[0039] Beneficial effects:

[0040] In the vortex electromagnetic wave modal purity estimation method based on main lobe ripple measurement provided by the present application, first, the electric field amplitude and phase of the vortex electromagnetic wave in free space are measured; the center of the vortex electromagnetic wave beam is found through the phase distribution; then, with the beam center as the center of the circle, the main lobe position of the vortex electromagnetic wave is determined one by one; along the circumference of the main lobe, the average amplitude and the maximum and minimum amplitude differences are calculated and the relative main lobe ripple is calculated; finally, the modal purity of the vortex electromagnetic wave is calculated based on the relative main lobe ripple. Through the present invention, the modal purity of the generated vortex electromagnetic wave can be accurately calculated, which is conducive to the subsequent collection and processing of the received data and can effectively reduce the impact of modal aliasing on the information waste caused by the collected information. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The drawings and descriptions that constitute part of this application are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. Among them:

[0042] Figure 1 A schematic flow chart of a single-track synthetic aperture radar interference source location method provided according to some embodiments of the present application;

[0043] Figure 2 is a phase line diagram of a spatial phase cross section according to the present application;

[0044] Figure 3 The modal purity of the present application varies with the array element.

[0045] Figure 4 This is a diagram of the unit configuration according to the present application. DETAILED DESCRIPTION

[0046] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments. Each example is provided by way of explanation of the present application and does not limit the present application. In fact, it will be clear to those skilled in the art that modifications and variations can be made in the present application without departing from the scope or spirit of the present application. For example, a feature shown or described as part of one embodiment can be used in another embodiment to produce yet another embodiment. Therefore, it is expected that the present application includes such modifications and variations within the scope of the appended claims and their equivalents.

[0047] Exemplary Methods

[0048] like Figure 1 As shown, the method for estimating the modal purity of vortex electromagnetic waves based on main lobe ripple measurement includes:

[0049] Step S101: measuring the electric field amplitude and phase of the vortex electromagnetic wave in free space.

[0050] Step S102: finding the center of the vortex electromagnetic wave beam through phase distribution;

[0051] Specifically, according to the electric field phase in free space measured in step S101, the electric field is decomposed into a spatial phase and a pure vortex phase, which can be described by the following formula:

[0052]

[0053] Where r is the distance from the source point to the field point, l is the OAM modulus, is the azimuth of the field point with respect to the source point. The first term in the above equation is the spatial phase, and the second term is the pure vortex phase. Assuming that the phase section takes the beam center as the origin, a polar coordinate system is established, and the distance between the source and the phase section is R0, then any point on the section is The distance from the source can be expressed as

[0054]

[0055] It can be seen from the above formula that when ρ remains unchanged, r remains unchanged, so the spatial phase will not change either. On concentric circles with the same polar diameter, the electric field phase is the same, that is, the equal phase lines are concentric circles with the beam center as the center.

[0056] like Figure 2 As shown, take any three adjacent equal phase lines, the radii of the three equal phase lines are recorded as ρ1, ρ2, ρ3, and the spacing between the equal phase lines is Δρ1, Δρ2, and their winding phase value is set to φ0. In the actual scenario, R0>>ρ1, ρ2, ρ3, so the above formula can be simplified to

[0057]

[0058] So, for ρ2, we have

[0059]

[0060] From the definition of equal phase lines, we know that the change of kr caused by adjacent equal phase lines in the polar direction is 2π, so for ρ1 and ρ3 respectively

[0061]

[0062] According to the above formula, we can get

[0063]

[0064] It can be seen from the above formula that the spatial phase distribution of vortex electromagnetic waves can be used to estimate the radii of any three equal phase lines by measuring the distance between them, thereby determining the center of the circle on the equal phase line observation interface.

[0065] Step S103: taking the beam center as the center of the circle, successively determining the main lobe position of the vortex electromagnetic wave;

[0066] Specifically, based on the center position measured in step S102 and the electric field amplitude of the free-space vortex electromagnetic wave measured in step S101, the circumference is expanded outward with the beam center as the center, and the circumference with the largest average electric field amplitude is found, which is the main lobe position of the vortex electromagnetic wave.

[0067] Step S104: Calculate the average amplitude and the difference between the maximum and minimum amplitudes along the circumference of the main lobe and calculate the relative main lobe ripple;

[0068] Specifically, according to the main lobe position found in step S103, the average amplitude is calculated along the circumference of the main lobe and the maximum and minimum amplitudes are recorded. Then, the difference between the maximum amplitude and the minimum amplitude is calculated and recorded as the main lobe ripple value. Then, the relative main lobe ripple is defined as the ratio of the main lobe ripple value to the oscillation center amplitude, and the symbol is used. express

[0069]

[0070] Where N is the number of array elements, J l (·) is the Bessel function of the first kind, 2N|J l-N (kasinθ)| is the oscillation amplitude range, |J l (kasinθ)| is the amplitude of the oscillation center.

[0071] Step S105: Calculate the modal purity of the vortex electromagnetic wave according to the relative main lobe ripple obtained in step S104;

[0072] Specifically, the ratio of -1 harmonic to fundamental wave is defined as the first harmonic ratio.

[0073]

[0074] It can be seen that HFR is related to the relative main lobe ripple. Only twice the difference

[0075]

[0076] At the same time, modal purity is defined as

[0077]

[0078] Where m represents the m-th order harmonic.

[0079] Depend on Figure 3 As described above, (a) is M = 10, a = λ. (b) is M = 1, a = λ; it can be seen that the main harmonic component of the vortex electromagnetic wave generated by the uniform circular ring array is the -1 harmonic. Therefore, the relationship between modal purity and the first harmonic ratio can be obtained as follows:

[0080]

[0081] pass With p l,N It can be seen that the modal purity of the generated vortex electromagnetic wave can be directly calculated by measuring the relative main lobe ripple.

[0082] Through the present invention, the modal purity of the generated vortex electromagnetic wave can be accurately calculated, which is beneficial to the subsequent collection and processing of the received data and can effectively reduce the impact of modal aliasing on the waste of collected information.

[0083] Exemplary Systems

[0084] Figure 4 The embodiment of the present application also provides a vortex electromagnetic wave modal purity estimation system based on main lobe ripple measurement, including: a vortex electromagnetic wave measurement unit, configured to receive vortex electromagnetic waves in free space and measure the amplitude and phase of the electric field; a center determination unit, configured to determine the center position of the vortex electromagnetic wave beam according to the phase of the received vortex electromagnetic wave; a main lobe calculation unit, configured to find the main lobe position of the vortex electromagnetic wave with the beam center as the center of the circle; a relative main lobe ripple calculation unit, configured to calculate the relative main lobe ripple of the collected vortex electromagnetic wave; and a modal purity calculation unit, configured to calculate the modal purity of the collected vortex electromagnetic wave.

[0085] The vortex electromagnetic wave modal purity estimation system based on main lobe ripple measurement provided in the embodiment of the present application can implement any of the above-mentioned vortex electromagnetic wave modal purity estimation method steps and processes based on main lobe ripple measurement, and achieve the same technical effect, which will not be repeated here one by one.

[0086] Exemplary devices

[0087] The present application provides an electronic device, including a storage medium and a processor, the processor being suitable for executing various programs; and a memory being used to store multiple programs; characterized in that when the memory executes the program on the processor, it implements the method for estimating the modal purity of vortex electromagnetic waves based on main lobe ripple measurement as described in any one of claims 1-5.

[0088] Since the method for estimating the modal purity of vortex electromagnetic waves based on main lobe ripple measurement has been introduced in detail in the specific implementation method example, it will not be described in detail here.

[0089] The processor includes a central processing unit (CPU), a network processor (NP), etc., and may also be a digital signal processor, an application-specific integrated circuit, an off-the-shelf programmable gate array or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component. The methods, steps, and logic block diagrams disclosed in the embodiments of this application can be implemented or executed. A general-purpose processor may be a microprocessor or any conventional processor.

[0090] The processor can be specifically configured as follows: the input system inputs the electric field amplitude and phase of the vortex electromagnetic wave measured in free space; according to the phase of the received vortex electromagnetic wave, the center position of the vortex electromagnetic wave beam is determined; the main lobe position of the vortex electromagnetic wave is found with the beam center as the center of the circle; the relative main lobe ripple of the collected vortex electromagnetic wave is calculated; and the modal purity of the collected vortex electromagnetic wave is calculated.

[0091] It should be pointed out that, according to the needs of implementation, the various components / steps described in the embodiments of the present application can be split into more components / steps, or two or more components / steps or partial operations of components / steps can be combined into new components / steps to achieve the purpose of the embodiments of the present application.

[0092] The above-mentioned method according to the embodiment of the present application can be implemented in hardware, firmware, or as software or computer code that can be stored in a recording medium (such as a CD ROM, RAM, floppy disk, hard disk or magneto-optical disk), or as computer code originally stored in a remote recording medium or a non-temporary machine storage medium downloaded via a network and stored in a local recording medium, so that the method described herein can be stored in such software processing on a recording medium using a general-purpose computer, a dedicated processor or programmable or dedicated hardware (such as an ASIC or FPGA). It can be understood that a computer, a processor, a microprocessor controller or programmable hardware includes a storage component (e.g., RAM, ROM, flash memory, etc.) that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor or hardware, the single-track synthetic aperture radar interference source location method described herein is implemented. In addition, when a general-purpose computer accesses the code for implementing the method shown herein, the execution of the code converts the general-purpose computer into a dedicated computer for executing the method shown herein.

[0093] Those skilled in the art will appreciate that the units and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the embodiments of this application.

[0094] It should be noted that the various embodiments in this specification are described in a progressive manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences from the other embodiments. In particular, the device and system embodiments are described briefly because they are generally similar to the method embodiments. For relevant parts, refer to the description of the method embodiments.

[0095] The device and system embodiments described above are merely illustrative. Units not described as separate may or may not be physically separate, and units not described as units may or may not be physical units, i.e., they may be located in one place or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiments. Persons of ordinary skill in the art will be able to understand and implement the present embodiments without inventive effort.

[0096] The foregoing description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are readily apparent to those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for estimating modal purity of vortex electromagnetic waves based on main lobe ripple measurement, characterized in that: include: Step S101, measuring the electric field amplitude and phase of the vortex electromagnetic wave in free space; Step S102, finding the center of the vortex electromagnetic wave beam through the phase distribution measured in the previous step; the step S102 specifically includes the following steps: according to the electric field phase in the free space measured in step S101, decomposing the electric field into the spatial phase and the pure vortex phase, which is described by the following formula Where r is the distance from the source point to the field point, l is the OAM modulus, is the azimuth of the field point with respect to the source point, k is the wave number of the signal; exp(-jkr) is the spatial phase, is a pure vortex phase; assuming that the phase section takes the beam center as the origin, establish a polar coordinate system, and set the distance between the source and the phase section as R0, then any point on the section The distance from the source can be expressed as Where ρ is the distance from the center of the circle to any point in the field. As can be seen from the above formula, when ρ remains unchanged, r remains unchanged, so the spatial phase will not change. On concentric circles with the same polar diameter, the electric field phase is the same, that is, the equal phase line is the concentric circle with the beam center as the center. Take any three adjacent equal phase lines, the radii of the three equal phase lines are recorded as ρ1, ρ2, ρ3, and the spacing between the equal phase lines is Δρ1, Δρ2, and their winding phase value is set to φ0; in actual scenarios, R0>>ρ1, ρ2, ρ3, so the above formula can be simplified to So, for ρ2, we have From the definition of equal phase lines, we know that the change of kr caused by adjacent equal phase lines in the polar direction is 2π, so for ρ1 and ρ3 respectively, Where n∈Z, λ is the wavelength, according to the above formula we can get From the above formula, we can know that the spatial phase distribution of vortex electromagnetic waves can be used to estimate the radius of any three equal phase lines by measuring the distance between them, thereby determining the center of the circle on the equal phase line observation interface; Step S103, taking the beam center as the center of the circle, successively determining the main lobe position of the vortex electromagnetic wave; Step S104, along the circumference of the main lobe, calculate the average amplitude and the difference between the maximum and minimum amplitudes and calculate the relative main lobe ripple; the step S104 specifically includes the following steps: according to the main lobe position found in step S103, calculate the average amplitude along the circumference of the main lobe and record the maximum and minimum amplitudes, then calculate the difference between the maximum amplitude and the minimum amplitude, and record it as the main lobe ripple value; then define the relative main lobe ripple as the ratio of the main lobe ripple value to the oscillation center amplitude as the relative main lobe ripple, and use the symbol express Where N is the number of array elements, a is the radius of the antenna array that generates vortex electromagnetic waves, and J l (·) is the first-kind Bessel function of order l, 2N|J l-N (kasinθ)| is the oscillation amplitude range, |J l (kasinθ)| is the amplitude of the oscillation center; Step S105, calculating the modal purity of the vortex electromagnetic wave according to the relative main lobe ripple obtained in step S104; said step S105 specifically includes the following steps: defining the ratio of the -1st harmonic to the fundamental wave as the first harmonic ratio to measure the vortex mode purity; it can be seen that: At the same time, modal purity is defined as Where m represents the m-th order harmonic; According to the experiment, it can be concluded that the main harmonic component of the vortex electromagnetic wave generated by the uniform circular ring array is the -1 harmonic; therefore, the relationship between the modal purity and the first harmonic ratio can be obtained as follows: pass With p l,N It can be seen that the modal purity of the generated vortex electromagnetic wave can be directly calculated by measuring the relative main lobe ripple.

2. The method for estimating modal purity of vortex electromagnetic waves based on main lobe ripple measurement according to claim 1, characterized in that: The step S103 specifically includes the following steps: based on the center position of the circle measured in step S102 and the electric field amplitude of the free space vortex electromagnetic wave measured in step S101, with the beam center as the center of the circle; the circumference is expanded outward in sequence to find the circumference with the largest average electric field amplitude, which is the main lobe position of the vortex electromagnetic wave.

3. A device for estimating modal purity of vortex electromagnetic waves based on main lobe ripple measurement, characterized in that: include: a vortex electromagnetic wave measuring unit configured to receive the vortex electromagnetic wave in free space and measure the amplitude and phase of the electric field; The center determination unit is configured to determine the center position of the vortex electromagnetic wave beam according to the phase of the received vortex electromagnetic wave; specifically, the steps are as follows: according to the measured electric field phase in free space, the electric field is decomposed into a spatial phase and a pure vortex phase, which is described by the following formula Where r is the distance from the source point to the field point, l is the OAM modulus, is the azimuth of the field point with respect to the source point, k is the wave number of the signal; exp(-jkr) is the spatial phase, is a pure vortex phase; assuming that the phase section takes the beam center as the origin, establish a polar coordinate system, and set the distance between the source and the phase section as R0, then any point on the section The distance from the source can be expressed as Where ρ is the distance from the center of the circle to any point in the field. As can be seen from the above formula, when ρ remains unchanged, r remains unchanged, so the spatial phase will not change. On concentric circles with the same polar diameter, the electric field phase is the same, that is, the equal phase line is the concentric circle with the beam center as the center. Take any three adjacent equal phase lines, the radii of the three equal phase lines are recorded as ρ1, ρ2, ρ3, and the spacing between the equal phase lines is Δρ1, Δρ2, and their winding phase value is set to φ0; in actual scenarios, R0>>ρ1, ρ2, ρ3, so the above formula can be simplified to So, for ρ2, we have From the definition of equal phase lines, we know that the change of kr caused by adjacent equal phase lines in the polar direction is 2π, so for ρ1 and ρ3 respectively Where n∈Z, λ is the wavelength, according to the above formula we can get From the above formula, we can know that the spatial phase distribution of vortex electromagnetic waves can be used to estimate the radius of any three equal phase lines by measuring the distance between them, thereby determining the center of the circle on the equal phase line observation interface; a main lobe calculation unit configured to find the main lobe position of the vortex electromagnetic wave with the beam center as the center of the circle; a relative main lobe ripple calculation unit, configured to calculate the relative main lobe ripple of the collected vortex electromagnetic wave; The modal purity calculation unit is configured to calculate the modal purity of the collected vortex electromagnetic wave, specifically including the following steps: according to the main lobe position found, the average amplitude is calculated along the circumference of the main lobe and the maximum and minimum amplitudes are recorded, and then the difference between the maximum amplitude and the minimum amplitude is calculated, which is recorded as the main lobe ripple value; then the relative main lobe ripple is defined as the ratio of the main lobe ripple value to the oscillation center amplitude as the relative main lobe ripple, and the symbol is used. express Where N is the number of array elements, a is the radius of the antenna array that generates vortex electromagnetic waves, and J l (·) is the first-kind Bessel function of order l, 2N|J l-N (kasinθ)| is the oscillation amplitude range, |J l (kasinθ)| is the amplitude of the oscillation center; Definition - The ratio of the first harmonic to the fundamental wave is the first harmonic ratio to measure the vortex mode purity; it can be seen that: At the same time, modal purity is defined as Where m represents the m-th order harmonic; According to the experiment, it can be concluded that the main harmonic component of the vortex electromagnetic wave generated by the uniform circular ring array is the -1 harmonic; therefore, the relationship between the modal purity and the first harmonic ratio can be obtained as follows: pass With p l,N It can be seen that the modal purity of the generated vortex electromagnetic wave can be directly calculated by measuring the relative main lobe ripple.

4. A storage medium storing a plurality of programs, characterized in that: The program application is loaded and executed by a processor to implement the method for estimating the modal purity of vortex electromagnetic waves based on main lobe ripple measurement as described in any one of claims 1-2.

5. An electronic device comprising a storage medium and a processor; the processor being adapted to execute various programs; and a memory being adapted to store a plurality of programs; characterized in that: When the memory executes the program on the processor, the method for estimating the modal purity of vortex electromagnetic waves based on main lobe ripple measurement as described in any one of claims 1-2 is implemented.

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