Multi-band shared phased array transceiving system based on optical pulse and implementation method of multi-band shared phased array transceiving system

Abstract

According to the multi-band shared phased array transceiver system based on the optical pulse and the implementation method thereof, based on the microwave photon technology, the optical pulse is used for signal generation and up-down frequency conversion, and multi-band phase control is achieved by changing the delay of the optical pulse in the up-down frequency conversion process. Therefore, multi-band signal generation and beam forming receiving and transmitting can be completed by one set of equipment at the same time. According to the multi-band phased array radar system, the compactness of the multi-band phased array radar system and the coherence among multiple bands are improved, the power consumption, the size and the cost of the system are greatly reduced, and meanwhile the complexity of a multi-band signal fusion algorithm can be simplified.

Description

Technical Field

[0001] The present invention relates to microwave photon technology, in particular to a multi-band shared phased array transceiver technology based on optical pulses and a method for realizing the same. Background Art

[0002] With the continuous advancement of radar technology, multi-band radar has become an important research direction in the radar field. Multi-band radar can capture the unique electromagnetic scattering characteristics of targets in different frequency bands, provide richer and more comprehensive information for target identification, and significantly improve the identification accuracy and efficiency. In addition, by fusing multi-band received signals, multi-band radar can also effectively enhance the detection resolution, especially in complex environments. The detection capability of stealth targets is greatly improved, because existing stealth technology is often only effective in limited frequency bands. At the same time, compared with single-band radar, multi-band radar exhibits stronger anti-interference ability, ensuring stable and reliable detection in complex electromagnetic environments.

[0003] However, traditional electronic radar transmitters face many challenges in achieving multi-band operation. Each band usually requires an independent set of hardware support, which not only greatly increases the complexity and power consumption of the system, but also introduces signal inconsistency problems caused by vibration delays, phase differences and other factors between multiple sets of hardware, which require complex compensation algorithms to handle. In addition, limited by the inherent bandwidth of electronic systems, traditional radars find it difficult to generate and efficiently process high-frequency, large-bandwidth multi-band radar signals, limiting their further performance improvement.

[0004] To overcome the above difficulties, microwave photonic technology, with its significant advantages such as large instantaneous bandwidth, strong parallel signal processing capability, anti-electromagnetic interference and multi-dimensional multiplexing, provides a new way to build efficient and compact multi-band radar systems. Among them, the use of ultra-short optical pulse trains to achieve multi-band up-conversion and down-conversion of intermediate frequency signals has become one of the key technologies. [P. Ghelfi, et al., "Photonics for Radars Operating on Multiple Coherent Bands," in Journal of Lightwave Technology, vol. 34, no. 2, pp. 500-507, 2016.]. In addition, the generation of dual-band signals through polarization multiplexing technology and the removal of signal chirp combined with photon mixing technology have further broadened the boundaries of multi-band radar signal processing. [X.Wang,et al.,"Dual-Band Coherent Microwave Photonic Radar Using LinearFrequency Modulated Signals With Arbitrary Chirp Rates,"in IEEE Journal ofSelected Topics in Quantum Electronics,vol.29,no.6,pp.1-9,2023.]. However, existing research focuses on traditional mechanical scanning radars, which are difficult to directly apply to phased array radar systems, and lack an effective phase control mechanism for phased array multi-band beamforming. Phased array radar technology, with its high flexibility in electronically controlling the beam direction, strong anti-interference, high signal-to-noise ratio and fast scanning response, has become an important part of radar and communication systems since its birth, and is widely used in military reconnaissance, space exploration and radio astronomy. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art, and propose a multi-band shared phased array transceiver system based on optical pulses and its implementation method, using optical pulses as signal carriers, and controlling the delay of optical pulses in the process of up and down frequency conversion to achieve phase control of multi-band signals, thereby completing the generation, beamforming and transceiver of multi-band signals in one set of equipment. Not only does it greatly improve the compactness of the multi-band phased array radar system and the coherence between each band, it also significantly reduces the power consumption, volume and cost of the system, opening up a new direction for the development of radar technology.

[0006] The technical solution of the present invention is as follows:

[0007] On the one hand, the present invention provides a multi-band shared phased array transceiver system based on optical pulses, which is characterized by comprising:

[0008] At the signal transmitting end: the first optical pulse generator generates a first optical pulse, which is divided into two paths after the delay is adjusted by the first delay line. One path modulates the baseband signal output by the digital-to-analog converter and phase-shifted by the first phase shifter onto the first optical pulse through the first modulator, and then inputs the baseband signal to the balanced photodetector after the baseband is up-converted to multiple frequency bands. The other path of the first optical pulse is input to the balanced photodetector after the power is adjusted by the attenuator. The signals of the two paths of the first optical pulses after differential detection by the balanced photodetector are amplified by the first amplifier and then transmitted by the antenna array.

[0009] At the signal receiving end: the second optical pulse generator generates a second optical pulse. After the delay is adjusted by the second delay line, the multi-band signal received by the antenna is modulated onto the second optical pulse by the second modulator. After down-conversion to baseband, the optical signal is converted into an electrical signal by the photodetector. After filtering by a low-pass filter and phase shifting by the second phase shifter, it is quantized into a digital signal by the analog-to-digital converter.

[0010] Preferably, the center frequency f and bandwidth B of the baseband signal generated by the digital-to-analog converter meet the following conditions:

[0011]

[0012] Among them, f s1 is the repetition rate of the first optical pulse generated by the first optical pulse generator, f s2 is the repetition rate of the second optical pulse generated by the second optical pulse generator, and

[0013] Furthermore, the signal transmitting end also includes a first phase shifter for adjusting the phase of the signal to achieve beamforming of the multi-band signal.

[0014] Preferably, both the first phase shifter and the second phase shifter are digital phase shifters.

[0015] Furthermore, it also includes a power divider and a combiner, wherein the power divider is used to distribute the output signal of the digital-to-analog converter to the first phase shifters of multiple array elements, and the combiner is used to combine the received signals of the multiple array elements and input them into the analog-to-digital converter.

[0016] Preferably, the first optical pulse generator and the second optical pulse generator are both actively mode-locked lasers, passively mode-locked lasers, or optical frequency combs generated based on external modulation.

[0017] Preferably, the first modulator and the second modulator are both Mach-Zehnder intensity modulators, lithium niobate electro-optic modulators, polymer electro-optic modulators, silicon-based integrated electro-optic modulators, acousto-optic modulators or spatial light modulators.

[0018] Preferably, the first delay line and the second delay line are both electric delay lines, micro-ring delay lines or delay lines based on high-order dispersion optical fibers.

[0019] On the other hand, the present invention also provides a multi-band implementation method using the above-mentioned multi-band shared phased array transceiver system based on optical pulses, which is characterized in that it includes the following steps:

[0020] ① The first optical pulse generator generates a first optical pulse at the signal transmitting end, and the second optical pulse generator generates a second optical pulse at the signal receiving end;

[0021] ② At the signal transmitting end, the baseband signal output by the digital-to-analog converter is phase-shifted by the first phase shifter and then modulated onto the optical pulse by the first modulator to achieve baseband up-conversion to multiple frequency bands; at the same time, the other optical pulse is power-adjusted by the attenuator, differentially detected with the output of the first modulator, and amplified and transmitted by the antenna array;

[0022] ③ At the signal receiving end, the multi-band signal received by the antenna is amplified and modulated onto the second optical pulse by the second modulator to achieve down-conversion to baseband; the optical signal is converted into an electrical signal by the photodetector, filtered by a low-pass filter and phase-shifted by the second phase shifter, and then quantized into a digital signal by the analog-to-digital converter;

[0023] ④ By adjusting the first delay line, the second delay line, the first phase shifter and the second phase shifter, the phase control of the multi-band signal during the transmission and reception process is achieved to ensure the coherence of the multi-band signal and the accuracy of beamforming.

[0024] Furthermore, the center frequency f and bandwidth B of the baseband signal generated by the digital-to-analog converter meet the following conditions:

[0025]

[0026] Among them, f s1 is the repetition rate of the first optical pulse generated by the first optical pulse generator, f s2 is the repetition rate of the second optical pulse generated by the second optical pulse generator, and

[0027] Furthermore, the step ④ adjusts the delay Δt1 of the first delay line and the phase shift of the first phase shifter satisfy

[0028] The following conditions:

[0029]

[0030] Alternatively, adjust the delay Δt2 of the second delay line and the phase shift of the second phase shifter The following conditions must be met:

[0031]

[0032] Both can realize multi-band phase shift and multi-band beamforming, and complete multi-band signal generation and transmission; among them, is the transit time difference between the transmitting array elements, is the transit time difference between the receiving array elements, and is the pulse period of the optical pulse at the transmitting end and the optical pulse at the receiving end.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] 1) The present invention realizes the shared transmission and reception of multiple frequency band signals through optical pulse technology, improves the utilization rate of spectrum resources, and is particularly suitable for application scenarios that require simultaneous processing of multiple frequency band signals, such as radar communication integrated systems. By using optical pulses as carriers and combining high-speed optoelectronic conversion technology, efficient processing of broadband signals is achieved, supporting signal bandwidths of up to tens of GHz, and improving data transmission rates and system response speeds. Optical pulses are used to generate, convert, and phase shift multi-band signals in a single link, ensuring phase coherence between multiple bands, so that the multi-band fusion process does not require complex algorithms for phase compensation, reducing the complexity of the algorithm in the processing.

[0035] 2) A balanced photodetector is used for differential detection, which effectively eliminates the common-mode noise and frequency components of the optical pulse, improves the signal purity and signal-to-noise ratio, and uses a digital phase shifter for precise phase adjustment to ensure the accuracy of beamforming.

[0036] 3) The multi-band shared phased array transceiver technology and its implementation method proposed in the present invention can simultaneously transmit and receive multi-band radar signals, obtain more information about the target, greatly improve the detection resolution and improve the anti-interference ability. Multiple bands share the same transceiver system, which greatly reduces the redundancy and cost of the system, improves the compactness of the system, and reduces the weight and volume of the multi-band phased array system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is an overall architecture diagram of an embodiment of a multi-band shared phased array transceiver system based on optical pulses of the present invention;

[0038] Figure 2 Schematic diagram of simultaneously generating multi-band emission signals for a first optical pulse.

[0039] Figure 3 A schematic diagram of using a balanced photodetector to perform differential balanced detection to remove the first optical pulse frequency component and increase the energy of a multi-band signal.

[0040] Figure 4 Schematic diagram of the second optical pulse simultaneously down-converting the multi-band signal to baseband. DETAILED DESCRIPTION

[0041] A specific embodiment of the present invention is given below in conjunction with the accompanying drawings. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and process, but the protection scope of the present invention is not limited to the following embodiment.

[0042] See also Figure 1 , Figure 1 This is an overall architecture diagram of an embodiment of a multi-band shared phased array transceiver system based on optical pulses of the present invention. As can be seen from the figure, a multi-band shared phased array transceiver system based on optical pulses includes a first optical pulse generator, a second optical pulse generator, a first modulator, a second modulator, a first coupler, a second coupler, a first delay line, a second delay line, an attenuator, a balanced photodetector, a photodetector, a low-pass filter, a first phase shifter, a second phase shifter, a combiner, a power divider, an analog-to-digital converter, a digital-to-analog converter, a first amplifier, and a second amplifier.

[0043] At the signal generation and transmission end: the first optical pulse generator is an actively mode-locked laser, and its output end is connected to the first coupler to provide the first optical pulse for multiple phased array elements; the output end of the first coupler is connected to the input end of the first delay line; the first delay line is an electric delay line, and its output end is divided into an upper and lower path through the coupler, the upper path is connected to the optical input end of the first modulator 1, and the lower path is connected to the attenuator input end.

[0044] The output end of the digital-to-analog converter is connected to the input end of the power divider, and the output end of the power divider is connected to the input end of the first phase shifter of multiple array elements; its output end is connected to the RF input end of the first modulator. The optical output end of the first modulator and the output end of the attenuator are respectively connected to the same-direction input end and the reverse input end of the balanced photodetector; its output is connected to the input end of the first amplifier, and the output end of the first amplifier is connected to the antenna array element of the transmitting array antenna. In this embodiment, the first phase shifter is a digital phase shifter, the first modulator is a Mach-Zehnder intensity modulator, the balanced photodetector is a large-bandwidth balanced photodetector, and the first amplifier is a power amplifier.

[0045] In this embodiment, the first optical pulse generator generates a repetition frequency of f s1 , with a period of T s1The first optical pulse of the downlink is used to adjust the delay of the first optical pulse, and the first delay line is used to adjust the delay of the first optical pulse, which is divided into two paths through the coupler. The baseband signal output by the digital-to-analog converter is phase-shifted by the first phase shifter. The uplink first modulator modulates the phase-shifted signal onto the first optical pulse, and the first optical pulse up-converts the baseband signal to multiple frequency bands. The attenuator is used to adjust the power of the downlink first optical pulse, and the balanced photodetector is used to realize the photoelectric conversion and differential detection of the uplink and downlink. The signal output by the balanced photodetector is amplified by the amplifier and radiated by the antenna array.

[0046] At the receiving end, the second optical pulse generator is an active mode-locked laser, and its output end is connected to a coupler to provide a second optical pulse for multiple phased array elements; the output of the coupler is connected to the input end of the second delay line; the second delay line is an electric delay line, and its output end is connected to the optical input end of the second modulator; the RF input end of the second modulator is connected to the output end of the second amplifier; the input end of the second amplifier is connected to the antenna array element of the receiving antenna array; the optical output end of the second modulator is connected to the input end of the photodetector; the output end of the photodetector is connected to the input end of the low-pass filter; the output end of the low-pass filter is connected to the input end of the second phase shifter; the output end of the second phase shifter is connected to the input end of the combiner; the combiner combines the outputs of the second phase shifters of multiple array elements into one path, and the output end of the combiner is connected to the input end of the analog-to-digital converter. In this embodiment, the second modulator is a Mach-Zehnder intensity modulator, the second amplifier is a power amplifier, and the second phase shifter is a digital phase shifter.

[0047] In this embodiment, the second optical pulse generator generates a repetition frequency of f s2 , with a period of T s2 The second optical pulse is used to adjust the delay of the second optical pulse. The second amplifier amplifies the multi-band signal received by the antenna, and the second modulator modulates the amplified multi-band signal onto the second optical pulse, which down-converts the received multi-band signal to baseband. The photodetector converts the optical signal into an electrical signal, which is quantized into a digital signal by the analog-to-digital converter after filtering by a low-pass filter and phase shifting by a phase shifter.

[0048] The working principle of the multi-band shared phased array transceiver system of the present invention is as follows:

[0049] The first optical pulse generator generates a first optical pulse 1u1(t), which is transmitted to the first modulator after being delayed by the first delay line. The digital-to-analog converter generates a center frequency of The baseband signal s0(t) with bandwidth B and duration T0 is phase shifted by the first phase shifter. After that, the first modulator modulates the signal onto the first optical pulse of the added path and converts the baseband frequency to multiple frequency bands. The above process can be expressed as:

[0050]

[0051] Where p1(t,Δt1) is the output of the first modulator, Δt1 is the delay of the first optical pulse adjusted by the first delay line, T M is the transfer function of the first modulator, and α is related to the modulation depth.

[0052] The uplink optical output is converted into an electrical signal by a balanced photodetector. The output electrical signal is affected by the bandwidth of the balanced photodetector. Figure 2 shown.

[0053] The power of the first optical pulse in the drop channel is adjusted to half of the previous power after adjustable attenuation. After photoelectric conversion, it is differentially subtracted from the electrical signal in the drop channel to eliminate the frequency component and common mode noise of the first optical pulse and generate a pure multi-band signal. After ignoring the signal amplitude coefficient, the process is expressed as:

[0054]

[0055] k0 is a coefficient determined by the transmission channel bandwidth, which represents the number of frequency bands of the output signal. Figure 3 shown.

[0056] When the transmitter performs beamforming on a multi-band signal, assuming the beam angle θ1, the transit time difference between array elements t d1 =ndsinθ1 / c; the frequency of the multi-band signal is The required phase shift for the multi-band signal is Right now

[0057]

[0058] Since the phase change is periodic when the phase is shifted, there is no need to move the absolute phase value. It is only necessary to adjust the phase so that 2πf s1 Δt1=2πf s1 t d1 -2π[f s1 t d1 ], That is, adjust the first delay line and the first phase shifter so that It is possible to achieve correct multi-band phase shift, realize multi-band beamforming, and complete multi-band signal generation and transmission.

[0059] The process at the signal receiving end can be expressed by the following formula:

[0060] The second optical pulse generator generates a second optical pulse. In order to ensure that no aliasing occurs during the signal transmission and reception process, the bandwidth B of the baseband signal and the repetition frequency f of the first optical pulse generator are s1 and the repetition rate f of the second optical pulse generators2 The relationship between The number of received frequency bands is That is, the multi-band signal supported by the transceiver system in

[0061]

[0062] After the multi-band signal received by the antenna is amplified by the amplifier, the second modulator modulates the signal onto the second optical pulse on the uplink, and the second optical pulse down-converts the multi-band signal to baseband. The second delay line adjusts the delay of the second optical pulse to Δt2. This process can be expressed as:

[0063]

[0064] After the photoelectric conversion, it is low-pass filtered and only the bandwidth is retained. The signal in the range is phase-shifted by the phase shifter, and the signal finally input to the analog-to-digital converter is expressed as:

[0065]

[0066] The above process is as follows Figure 4 shown.

[0067] When the receiving end performs beamforming reception on multi-band signals, assuming that the beam angle is θ2, the transit time difference between array elements is t d2 =ndsinθ2 / c, then the phase shift required for the multi-band signal is but

[0068]

[0069] Similarly, when performing phase shift, it is not necessary to move the absolute phase value, but only to move it within the interval [-π,π]. The above phase shift effect is applicable to both wide-band and narrow-band signals. Therefore, it is only necessary to adjust the second delay line and the second phase shifter so that Multi-band beamforming can be achieved to complete signal reception.

[0070] The method for implementing the above-mentioned multi-band shared phased array transceiver system based on optical pulses comprises the following steps:

[0071] 1) The first optical pulse generator generates a repetition frequency of f s1 The first light pulse, in this embodiment, is s1 The value is 11 GHz. The second optical pulse generator generates a repetition frequency of f s2 The second light pulse, in this embodiment, is s2 The value is 5GHz.

[0072] 2) The digital-to-analog converter generates the center frequency bandwidth In this embodiment, B = 0.5 GHz. After passing through the first phase shifter, the first modulator modulates the first optical pulse.

[0073] 3) Adjust the attenuator so that the optical power output by the attenuator is half of the optical power output by the first modulator.

[0074] 4) The bandwidth of the balanced photodetector in this embodiment is 20 GHz. The output of the first modulator and the output of the attenuator are photoelectrically converted by the balanced photodetector, and differential balanced detection is performed, and multi-band broadband signals of 2.5-3 GHz, 8-8.5 GHz, 13.5-14 GHz, and 19-19.5 GHz are output simultaneously.

[0075] 5) Adjust the first delay line and the first phase shifter so that Realize multi-band beamforming and complete signal generation and transmission.

[0076] 6) The broadband multi-band echo signals of 2.5-3 GHz, 8-8.5 GHz, 13.5-14 GHz, and 19-19.5 GHz are received by the antenna, amplified by the amplifier, and modulated onto the second optical pulse by the modulator.

[0077] 7) The second optical pulse down-converts the multi-band signal to 2-2.5 GHz, 1.5-2 GHz, 1-1.5 GHz, and 0.5-1 GHz. After photoelectric conversion by the photodetector, it is filtered by a 0-2.5 GHz low-pass filter.

[0078] 8) Adjust the second delay line and the second phase shifter so that

[0079] Implement multi-band beamforming.

[0080] 9) The output of the low-pass filter is combined by a combiner and then converted into digital form to complete multi-band signal reception.

[0081] In the above process, the baseband signal is up-converted and down-converted by optical pulses, and the phase adjustment of the multi-band signal is completed by adjusting the delay line and the phase shifter to realize multi-band beamforming.

[0082] Experiments have shown that the present invention can use the above-mentioned set of equipment (single link) to realize the generation, frequency conversion, phase shifting and digitization of multi-band signals, and simultaneously complete the coherent transmission and reception of multi-band signals. The above is only a preferred example of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made on the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A multi-band shared phased array transceiver system based on optical pulses, characterized in that: include: At the signal transmitting end: the first optical pulse generator generates a first optical pulse, which is divided into two paths after the delay is adjusted by the first delay line. One path modulates the baseband signal output by the digital-to-analog converter and phase-shifted by the first phase shifter onto the first optical pulse through the first modulator, and then inputs the baseband signal to the balanced photodetector after the baseband is up-converted to multiple frequency bands. The other path of the first optical pulse is input to the balanced photodetector after the power is adjusted by the attenuator. The signals of the two paths of the first optical pulses after differential detection by the balanced photodetector are amplified by the first amplifier and then transmitted by the antenna array. At the signal receiving end: the second optical pulse generator generates a second optical pulse. After the delay is adjusted by the second delay line, the multi-band signal received by the antenna is modulated onto the second optical pulse by the second modulator. After down-conversion to baseband, the optical signal is converted into an electrical signal by the photodetector. After filtering by a low-pass filter and phase shifting by the second phase shifter, it is quantized into a digital signal by the analog-to-digital converter.

2. The multi-band shared phased array transceiver system based on optical pulses according to claim 1, characterized in that: The signal transmitting end also includes a first phase shifter for adjusting the phase of the signal to achieve beamforming of the multi-band signal.

3. The multi-band shared phased array transceiver system based on optical pulses according to claim 2, characterized in that: The first phase shifter and the second phase shifter are both digital phase shifters.

4. The multi-band shared phased array transceiver system based on optical pulses according to claim 2, characterized in that: It also includes a power divider and a combiner, wherein the power divider is used to distribute the output signal of the digital-to-analog converter to the first phase shifters of multiple array elements, and the combiner is used to combine the received signals of the multiple array elements and input them into the analog-to-digital converter.

5. The multi-band shared phased array transceiver system based on optical pulses according to claim 1, characterized in that: The first optical pulse generator and the second optical pulse generator are both actively mode-locked lasers, passively mode-locked lasers or optical frequency combs generated based on external modulation method.

6. The multi-band shared phased array transceiver system based on optical pulses according to claim 1, characterized in that: The first modulator and the second modulator are both Mach-Zehnder intensity modulators, lithium niobate electro-optic modulators, polymer electro-optic modulators, silicon-based integrated electro-optic modulators, acousto-optic modulators or spatial light modulators.

7. The multi-band shared phased array transceiver system based on optical pulses according to claim 1, characterized in that: The first delay line and the second delay line are both electric delay lines, micro-ring delay lines or delay lines based on high-order dispersion optical fibers.

8. A method for realizing multi-band using the multi-band shared phased array transceiver system based on optical pulses according to any one of claims 1 to 7, characterized in that: The following steps are involved: ① The first optical pulse generator generates a first optical pulse at the signal transmitting end, and the second optical pulse generator generates a second optical pulse at the signal receiving end; ② At the signal transmitting end, the baseband signal output by the digital-to-analog converter is phase-shifted by the first phase shifter and then modulated onto the optical pulse by the first modulator to achieve baseband up-conversion to multiple frequency bands; at the same time, the other optical pulse is power-adjusted by the attenuator, differentially detected with the output of the first modulator, and amplified and transmitted by the antenna array; ③ At the signal receiving end, the multi-band signal received by the antenna is amplified and modulated onto the second optical pulse through the second modulator to achieve down-conversion to baseband; The optical signal is converted into an electrical signal by a photodetector, filtered by a low-pass filter and phase-shifted by a second phase shifter, and then quantized into a digital signal by an analog-to-digital converter; ④ By adjusting the first delay line, the second delay line, the first phase shifter and the second phase shifter, the phase control of the multi-band signal during the transmission and reception process is achieved to ensure the coherence of the multi-band signal and the accuracy of beamforming.

9. The multi-band implementation method according to claim 8, characterized in that: The center frequency f and bandwidth B of the baseband signal generated by the digital-to-analog converter meet the following conditions: Among them, f s1 is the repetition rate of the first optical pulse generated by the first optical pulse generator, f s2 is the repetition rate of the second optical pulse generated by the second optical pulse generator, and 10. The multi-band implementation method according to claim 8, characterized in that: The step ④ adjusts the delay Δt1 of the first delay line and the phase shift of the first phase shifter The following conditions must be met: Alternatively, adjust the delay Δt2 of the second delay line and the phase shift of the second phase shifter The following conditions must be met: Both can realize multi-band phase shift and multi-band beamforming, and complete multi-band signal generation and transmission; among them, is the transit time difference between the transmitting array elements, is the transit time difference between the receiving array elements, and is the pulse period of the optical pulse at the transmitting end and the optical pulse at the receiving end.

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