Independent controllable multi-beam forming method and system based on time modulation array

Abstract

The invention discloses an independent controllable multi-beam forming method and system based on a time modulation array. The method comprises the following steps of: distributing corresponding time modulation sidebands for required multiple beams; determining the inter-unit time delay of each time modulation sideband according to the multi-beam direction; optimizing the initial phase of each time modulation sideband, and designing the waveform of the time modulation sideband; superposing and normalizing the time modulation sideband waveforms in a time domain to form a time modulation theoretical waveform of each antenna unit; and designing a discretized time modulation theoretical waveform based on a time modulation hardware circuit, and determining an FPGA control program of the time modulation array. According to the method, the time modulation sideband waveform is independently designed, and the time domain superposition waveform is generated by hardware, so that multi-beam forming with independent and controllable beam pointing is realized, and the method has an important practical value.

Description

Technical Field

[0001] The present invention belongs to the field of microwave technology and antenna engineering technology, and in particular to an independently controllable multi-beam forming method and system based on a time modulation array. Background Art

[0002] Multi-beam antennas enable a single antenna to simultaneously receive multiple signals, and are therefore extremely valuable in fields such as communications and radar. Among these implementations, time-modulated array antennas, based on their mechanism, can generate a large number of harmonics and produce multiple beams with sidebands of varying orientations without the need for additional hardware. This adds "time" as a fourth design dimension to traditional three-dimensional antenna design, periodically modulating the antenna's state to influence its radiation characteristics and generate a large number of sidebands and their corresponding beams. To meet the requirements for multi-beams with varying orientations, different phase differences are required between each element, which in a time-modulated array is manifested as time differences between the time-modulated waveforms.

[0003] Currently, multi-beam time-modulated arrays can only adjust the beam pointing of all sidebands simultaneously. This is because the traditional method for adjusting beam pointing involves setting a uniform delay after generating the waveform for each time-modulated array element, resulting in the same phase difference. This design method has limited degrees of freedom and is not conducive to practical application. Summary of the Invention

[0004] The object of the present invention is to address the problems existing in the above-mentioned prior art and to provide an independently controllable multi-beamforming method based on a time modulation array.

[0005] The technical solution for achieving the purpose of the present invention is as follows: on the one hand, an independently controllable multi-beam forming method based on a time modulation array is provided, which realizes independent control of multiple beams by separately adjusting the different delays of each sideband of the time modulation waveform.

[0006] Furthermore, the method comprises the following steps:

[0007] Allocate corresponding time modulation sidebands for the required multiple beams;

[0008] Determine the inter-element delay of each time-modulated sideband based on the multi-beam pointing direction;

[0009] Optimize the initial phase of each time-modulated sideband and design the waveform of the time-modulated sideband;

[0010] The time modulation sideband waveforms are superimposed in the time domain and normalized to form the theoretical time modulation waveform of each antenna element;

[0011] The theoretical waveform of time modulation is discretized based on the time modulation hardware circuit design, and the FPGA control program of the time modulation array is determined.

[0012] Furthermore, the method is based on a time modulation array comprising: an antenna array consisting of N antenna units, N orthogonal time modulators based on multi-level step waveforms, an FPGA control circuit and a 1-N power divider, where N is a natural number.

[0013] Furthermore, the orthogonal time modulator based on a multi-level step waveform includes a first port, a second port, a synchronization channel and a quadrature channel; the first port is respectively connected to the synchronization channel and the quadrature channel and then connected to the second port; the orthogonal time modulator is controlled by a signal generated by an FPGA control circuit to generate a step-shaped time modulation signal; the synchronization channel includes a first digitally controlled attenuator and a first 0 / 180° phase shifter arranged in sequence along the direction from the first port to the second port; the quadrature channel includes a second digitally controlled attenuator, a second 0 / 180° phase shifter and a 90° phase shifter arranged in sequence along the direction from the first port to the second port.

[0014] Furthermore, the time modulation waveform of each time modulation sideband is expressed as: where a m is the complex weighted value on the mth sideband, f p is the time modulation frequency, and t represents time.

[0015] Furthermore, when the beam pointing direction of the m-th sideband is θm, the delay t between different units is mn Set to:

[0016] t mn =(n-1)βdsinθ m

[0017] Where β represents the free-space beam and d is the element spacing.

[0018] Furthermore, the time modulation waveform of each time modulation sideband has an initial phase, which is expressed as Optimize the initial phase by using the bee swarm optimization algorithm Get a more efficient time modulation waveform; where U(t) represents the time modulation waveform at time t, f p is the time modulation frequency.

[0019] Furthermore, the multi-beam time modulation signal formed by superimposing the time modulation sideband waveforms in the time domain and normalizing them is expressed as: where a m,n is the complex weighted value of the m-th sideband component of the n-th unit, f p is the time modulation frequency.

[0020] On the other hand, an independently controllable multi-beam forming system based on a time modulation array is provided, wherein the system realizes independent control of multiple beams by separately adjusting the different time delays of each sideband of the time modulation waveform.

[0021] Furthermore, the system includes:

[0022] The first module is used to allocate corresponding time modulation sidebands to the required multi-beams;

[0023] The second module is used to determine the inter-unit delay of each time-modulated sideband according to the multi-beam pointing;

[0024] The third module is used to optimize the initial phase of each time modulation sideband and design the waveform of the time modulation sideband;

[0025] The fourth module is used to superimpose the time modulation sideband waveforms in the time domain and normalize them to form the time modulation theoretical waveform of each antenna unit;

[0026] The fifth module is used to design the discretized time modulation theoretical waveform based on the time modulation hardware circuit and determine the FPGA control program of the time modulation array.

[0027] Compared with the prior art, the present invention has the following significant advantages:

[0028] (1) The independently controllable multi-beam technology proposed in the present invention adds different time delays when designing the waveform to generate different phase differences, so that the beam corresponding to each sideband can be independently controlled, which has a high degree of freedom and application value.

[0029] (2) By changing the time delay between different sideband units separately, the independent control of multiple beams can be achieved. It is easy to operate, has strong applicability, and has important practical value.

[0030] The present invention is further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 FIG. 1 is a schematic diagram of a multi-beam time-modulated phased array structure based on the present invention in one embodiment.

[0032] Figure 2 FIG. 1 is a schematic diagram of the hardware structure of a multi-beam time modulator based on the present invention in one embodiment.

[0033] Figure 3 FIG. 1 is a schematic diagram of a time modulation waveform and its components in each sideband and the relationship between the beam pattern on which the present invention is based in one embodiment.

[0034] Figure 4Schematic diagram of a one-unit stepped time modulation signal for orthogonal and synchronized two channels generated based on a multi-beam time modulation array in one embodiment.

[0035] Figure 5 FIG. 1 is a schematic diagram of a two-unit stepped time modulation signal for orthogonal and synchronized two channels generated based on a multi-beam time modulation array in one embodiment.

[0036] Figure 6 FIG. 1 is a schematic diagram of an 8-unit stepped time modulation signal for orthogonal and synchronous two-channel generation based on a multi-beam time modulation array in one embodiment.

[0037] Figure 7 FIG. 4 is a flow chart of an independently controllable multi-beam technology based on a multi-beam time modulation array in one embodiment.

[0038] Figure 8 FIG. 4 is a measured spectrum diagram based on a multi-beam time modulation array in one embodiment.

[0039] Figure 9 1 is a measured normalized pattern of independently controllable multi-beams based on a multi-beam time modulation array in one embodiment. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0041] It should be noted that if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0042] In one embodiment, the present invention provides an independently controllable multi-beam forming method based on a time modulation array, wherein the method achieves independent control of multiple beams by separately adjusting the different delays of each sideband of the time modulation waveform.

[0043] Furthermore, in one embodiment, in combination Figure 1The multi-beam time modulation array on which the present invention is based includes an antenna array 1 consisting of N antenna units, N time modulators 2, an FPGA control circuit 3, and a 1-N power divider 4, where N is a natural number.

[0044] Preferably, in some embodiments, Figure 2 The time modulator 2 includes a first port 5, a second port 6, a synchronization channel 7, and a quadrature channel 8; the first port 5 is connected to the synchronization channel 7 and the quadrature channel 8, respectively, and then to the second port 6. The quadrature time modulator 2 is controlled by a signal generated by the FPGA control circuit to generate a step-shaped time modulation signal. The synchronization channel 7 includes a first digitally controlled attenuator 9 and a first 0 / 180° phase shifter 10, which are arranged in sequence from the first port to the second port. The quadrature channel 8 includes a second digitally controlled attenuator 11, a second 0 / 180° phase shifter 12, and a 90° phase shifter 13, which are arranged in sequence from the first port to the second port.

[0045] Combine Figure 3 The present invention is based on the relationship between the time-modulated waveform and its components in each sideband and the beam pattern. The time delay between the waveform units of each sideband of the time-modulated waveform is different. The waveform of antenna unit 1 is formed after time delays Δt1, Δt2 and Δt3 to form the waveform of antenna unit 2. The waveform of antenna unit 2 is formed after time delays Δt1, Δt2 and Δt3 to form the waveform of antenna unit 3. Similarly, the waveforms of 8 antenna units are formed. The waveforms of each sideband are superimposed in the time domain to form the time-modulated waveform of each antenna unit, and then superimposed in the spatial domain to form simultaneous multi-beams.

[0046] Combine Figure 4 、 Figure 5 and Figure 6 The multi-beam time modulation signal is formed by combining the step signals generated by the in-phase channel and the quadrature channel respectively controlled by the FPGA circuit. The step-shaped time modulation signal has S steps, an attenuation value of K, and a waveform period of T. p The stepped modulation wave.

[0047] Furthermore, in one embodiment, in combination Figure 7 , the method comprises the following steps:

[0048] S1, allocates the corresponding time modulation sidebands for the required multi-beams.

[0049] The multi-beam time-modulated signal can be expressed as The value of m is determined based on the required sideband.

[0050] S2, determine the inter-unit delay t of each time-modulated sideband according to the multi-beam pointing mn .

[0051] Time modulation array antennas can generate a large number of harmonics, which can be used to generate sideband multi-beams with different directions. To meet the requirements of multi-beams with different directions, the time modulator antenna units need to have different phase differences, which in the time modulation array are manifested as different time delays t between the time modulation waveforms. mn .

[0052] When the beam direction of the mth sideband is θ m When the delay between different units is t mn Can be set to t mn =(n-1)βdsinθ m .

[0053] S3, optimizes the initial phase of different sidebands based on the bee colony algorithm A time-modulated signal with higher efficiency is obtained.

[0054] S4, superimpose the time modulation sideband waveforms in the time domain and normalize them to form the theoretical time modulation waveform of each antenna element, which is expressed as:

[0055] S5, based on the time modulation hardware circuit design, discretize the time modulation theoretical waveform and determine the FPGA control program of the time modulation array.

[0056] In one embodiment, an independently controllable multi-beam forming system based on a time modulation array is provided. The system achieves independent controllability of multiple beams by separately adjusting the different delays of each sideband of the time modulation waveform.

[0057] Furthermore, in one embodiment, the system includes:

[0058] The first module is used to allocate corresponding time modulation sidebands to the required multi-beams;

[0059] The second module is used to determine the inter-unit delay of each time-modulated sideband according to the multi-beam pointing;

[0060] The third module is used to optimize the initial phase of each time modulation sideband and design the waveform of the time modulation sideband;

[0061] The fourth module is used to superimpose the time modulation sideband waveforms in the time domain and normalize them to form the time modulation theoretical waveform of each antenna unit;

[0062] The fifth module is used to design the discretized time modulation theoretical waveform based on the time modulation hardware circuit and determine the FPGA control program of the time modulation array.

[0063] The specific definition of the independently controllable multi-beamforming system based on a time modulation array can be found in the definition of the independently controllable multi-beamforming method based on a time modulation array above, and will not be repeated here. The various modules in the above-mentioned independently controllable multi-beamforming system based on a time modulation array can be implemented in whole or in part through software, hardware, or a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in hardware form, or can be stored in the memory of the computer device in software form, so that the processor can call and execute the corresponding operations of the above-mentioned modules.

[0064] In one embodiment, a computer device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the independently controllable multi-beamforming method based on a time modulation array when executing the computer program.

[0065] For the specific definition of each step, please refer to the above definition of the independently controllable multi-beamforming method based on the time modulation array, which will not be repeated here.

[0066] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the independent controllable multi-beamforming method based on the time modulation array is implemented.

[0067] For the specific definition of each step, please refer to the above definition of the independently controllable multi-beamforming method based on the time modulation array, which will not be repeated here.

[0068] As a specific example, the present invention is further verified and explained in one of the embodiments.

[0069] The time modulation array based on the independently controllable multi-beam technology of the present invention is composed of N time modulators and N connected antenna units, an FPGA control circuit, and a 1-N power divider.

[0070] In this embodiment, the scale of the entire time modulation antenna array composed of N antenna units can be any required one-dimensional or two-dimensional array. For example, in this embodiment, a one-dimensional 8-unit antenna array is used and is connected to 8 single-sideband time modulators accordingly. This embodiment of the present invention does not limit this.

[0071] The measured hardware circuit of this embodiment operates at 2 GHz, and the frequency of the multi-level staircase time modulation signal it generates is 100 kHz.

[0072] For example, the embodiment of the present invention adopts an 8-level staircase time modulation waveform. According to the amplitude distribution of an actual digitally controlled attenuator, the attenuation value of each step of the multi-level staircase time modulation signal of the synchronous channel and the quadrature channel of all time modulators is -2dB.

[0073] For example, the embodiment of the present invention uses {m=+1,+2,+3} as the multi-beam sideband, that is, the time modulation array is used to generate three beams corresponding to the +1, +2, and +3 sidebands, where the +1 beam points to -20°, the +2 beam points to 10°, and the +3 beam points to 40°. According to the basic design principles of time modulation, the final time modulation waveform U n (t) can be set to:

[0074]

[0075] where t 1n , t 2n , t 3n is the delay between the three sideband units. are the initial phases of the three sidebands, which are optimized using the bee swarm optimization algorithm.

[0076] Through optimization, the parameters of the time modulation waveform are finally obtained as follows:

[0077] t 1n =-0.171, t 2n =0.0436, t 3n =0.1153.

[0078]

[0079] Finally, based on the duration of each step of the multi-step time modulation signal of the eight single-sideband time modulators, the control program of the FPGA circuit is determined to realize a multi-beam time modulation array with beam pointing angles of -20°, 10°, and 40°, respectively.

[0080] See also Figure 8 , which are the measured and simulated spectrum diagrams of the independently controllable multi-beam technology based on the time modulation array according to an embodiment of the present invention. The measured sideband level is -34.98dB.

[0081] See also Figure 9 , which is the measured and simulated normalized radiation pattern of the independently controllable multi-beam technology based on the time modulation array in an embodiment of the present invention. The measured sidelobe level is -19.87dB.

[0082] In summary, the present invention realizes multi-beam forming with independently controllable beam pointing by independently designing time-modulated sideband waveforms and generating their time-domain superposition waveforms through hardware, which has important practical value.

[0083] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only illustrative of the principles of the present invention. Without departing from the spirit and scope of the present invention, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. An independently controllable multi-beamforming method based on a time modulation array, characterized in that: The method realizes independent control of multiple beams by respectively adjusting the different time delays of each sideband of the time modulation waveform.

2. The independently controllable multi-beamforming method based on a time modulation array according to claim 1, characterized in that: The method comprises the following steps: Allocate corresponding time modulation sidebands for the required multiple beams; Determine the inter-element delay of each time-modulated sideband based on the multi-beam pointing direction; Optimize the initial phase of each time-modulated sideband and design the waveform of the time-modulated sideband; The time modulation sideband waveforms are superimposed in the time domain and normalized to form the theoretical time modulation waveform of each antenna element; The theoretical waveform of time modulation is discretized based on the time modulation hardware circuit design, and the FPGA control program of the time modulation array is determined.

3. The independently controllable multi-beamforming method based on a time modulation array according to claim 1, characterized in that: The method is based on a time modulation array comprising: an antenna array consisting of N antenna units, N orthogonal time modulators based on multi-level staircase waveforms, an FPGA control circuit and a 1-N power divider, where N is a natural number.

4. The independently controllable multi-beamforming method based on a time modulation array according to claim 3, characterized in that: The orthogonal time modulator based on a multi-level step waveform includes a first port, a second port, a synchronization channel and a quadrature channel; the first port is connected to the synchronization channel and the quadrature channel respectively and then to the second port; the orthogonal time modulator is controlled by a signal generated by an FPGA control circuit to generate a step-shaped time modulation signal; the synchronization channel includes a first digitally controlled attenuator and a first 0 / 180° phase shifter arranged in sequence along the direction from the first port to the second port; the quadrature channel includes a second digitally controlled attenuator, a second 0 / 180° phase shifter and a 90° phase shifter arranged in sequence along the direction from the first port to the second port.

5. The independently controllable multi-beamforming method based on a time modulation array according to claim 2, characterized in that: The time modulation waveform of each time modulation sideband is expressed as: where a m is the complex weighted value on the mth sideband, f p is the time modulation frequency, and t represents time.

6. The independently controllable multi-beamforming method based on a time modulation array according to claim 2, characterized in that: When the beam direction of the mth sideband is θ m When the delay between different units is t mn Set to: t mn =(n-1)βdsinθ m Where β represents the free-space beam and d is the element spacing.

7. The independently controllable multi-beamforming method based on a time modulation array according to claim 2, characterized in that: The time-modulated waveform of each time-modulated sideband has an initial phase, expressed as Optimize the initial phase by using the bee swarm optimization algorithm Obtain a more efficient time modulation waveform; Where U(t) represents the time modulation waveform at time t, f p is the time modulation frequency.

8. The independently controllable multi-beamforming method based on a time modulation array according to claim 2, characterized in that: The multi-beam time modulation signal formed by superimposing the time modulation sideband waveforms in the time domain and normalizing them is expressed as: where a m,n is the complex weighted value of the m-th sideband component of the n-th unit, f p is the time modulation frequency.

9. An independently controllable multi-beamforming system based on a time modulation array according to the method of any one of claims 1 to 8, characterized in that: The system realizes independent control of multiple beams by separately adjusting the different time delays of each sideband of the time modulation waveform.

10. The independently controllable multi-beamforming system based on a time modulation array according to claim 9, characterized in that: The system comprises: The first module is used to allocate corresponding time modulation sidebands for the required multi-beams; The second module is used to determine the inter-unit delay of each time-modulated sideband according to the multi-beam pointing; The third module is used to optimize the initial phase of each time modulation sideband and design the waveform of the time modulation sideband; The fourth module is used to superimpose the time modulation sideband waveforms in the time domain and normalize them to form the time modulation theoretical waveform of each antenna unit; The fifth module is used to design the discretized time modulation theoretical waveform based on the time modulation hardware circuit and determine the FPGA control program of the time modulation array.

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