A forward and backward scattering integrated microwave photonic radar system

Abstract

This invention discloses an integrated forward and backward scattering microwave photonic radar system, comprising: a light source module for generating an optical carrier signal; a signal generation module for generating a linear frequency modulated (LFM) signal based on the optical carrier signal and modulating the LFM signal onto the optical carrier to form an optical sideband signal; a photoelectric conversion module for converting the optical sideband signal into a microwave signal; a transmitting antenna for transmitting the microwave signal to illuminate a target within a detection area; and a receiving antenna for receiving microwave signals scattered back by the target, wherein the scattered signals include forward scattering signals and / or backscattering signals. This invention achieves highly coherent processing and fusion of forward and backscattering signals on the same optical platform using microwave photonics technology, thereby simultaneously obtaining high-sensitivity detection of targets with small radar cross-sections and accurate range resolution of targets.

Description

Technical Field

[0001] This invention relates to the field of radar technology, and specifically to an integrated forward and backward scattering microwave photonic radar system. Background Technology

[0002] As a core sensor in modern military detection, air traffic control, and meteorological observation, radar performance directly affects the system's sensing capabilities and security. Traditional radars mostly employ a monostatic design, where the transmitting and receiving antennas are co-located. This structure suffers a significant drop in detection effectiveness when facing targets with extremely small radar cross-sections (RCS), such as stealth aircraft, small drones, insects, or micro-meteorological particles. The fundamental reason is that the reflected signals from such targets are too weak and easily drowned out by environmental noise and clutter.

[0003] To enhance the detection capability of targets with small RCS (Radar Cross Section), bistatic radar was developed. Bistatic radar separates the transmitting and receiving stations, utilizing the scattering characteristics of targets under different geometric configurations to improve detection performance. Forward scattering (FSR) radar is a special and highly promising operating mode of bistatic radar. When the bistatic angle (i.e., the angle between the transmitting station, target, and receiving station) approaches 180°, the target enters the forward scattering region dominated by the optical Babienne complementarity principle, resulting in a significant increase in its RCS by several orders of magnitude—a phenomenon known as the "forward scattering peak." This gives FSR a natural "anti-stealth" capability against targets employing stealth designs and radar-absorbing materials, as the target's inherently low RCS characteristics are greatly weakened by the forward scattering mechanism.

[0004] However, traditional forward-scattering radar systems face several key technical challenges in practical deployment and application, limiting their performance and application scope: Time synchronization is challenging: Separate transmitting and receiving stations require extremely high-precision time synchronization for coherent signal processing. Traditional electronic synchronization methods (such as transmitting a reference clock via wired cable or microwave relay) introduce significant transmission losses and phase noise, especially in long-baseline deployments, where synchronization accuracy is difficult to guarantee, severely limiting the radar's range resolution and measurement accuracy.

[0005] Electronic bandwidth bottleneck: High-resolution radar requires the generation and processing of wide-bandwidth signals. However, traditional electronic devices are limited by the "electronic bottleneck," facing problems such as high loss, limited bandwidth, and sensitivity to electromagnetic interference when generating, transmitting, and processing high-frequency (such as millimeter waves) and wide-bandwidth signals. This directly limits the resolution capability of FSR systems.

[0006] Integration and Positioning Challenges: Pure FSR systems inherently face difficulties in target positioning, particularly in direct ranging. They typically rely on the "shadow" time of the target crossing the transmit-receive baseline for detection, making it difficult to directly and accurately measure target distance information through signal delay, unlike backscatter radar. Therefore, integrating FSR with a backscatter radar system possessing precise ranging capabilities is an effective way to improve its overall performance. However, the integrated design of heterogeneous systems based on traditional electronic technologies is complex and further amplifies the aforementioned synchronization and bandwidth issues.

[0007] Microwave photonics technology offers a new approach to solving the aforementioned problems. This technology processes microwave signals using optoelectronic devices, combining the advantages of both microwave and optical waves. It boasts outstanding features such as broadband processing capabilities, low transmission loss, lightweight design, and strong resistance to electromagnetic interference. It can efficiently generate and distribute high-frequency, wide-bandwidth radar signals, providing an ideal technical solution for addressing the high-precision time synchronization and bandwidth bottlenecks in FSR systems.

[0008] Currently, most research on forward-scattering radar systems is based on traditional electronic technology, and it faces core challenges such as low synchronization accuracy, limited system bandwidth, and difficulties in heterogeneous integration. These are precisely the technical problems that this invention aims to solve. Therefore, there is an urgent need in the field for an integrated radar system that can comprehensively leverage the high detection sensitivity of forward-scattering radar against low RCS targets, the accurate ranging and high resolution advantages of backscattering radar, and effectively overcome the inherent defects of traditional electronic systems. Summary of the Invention

[0009] In order to overcome the shortcomings of the prior art, the present invention aims to provide an integrated forward and backward scattering microwave photonic radar system, which realizes highly coherent processing and fusion of forward and backward scattering signals on the same optical platform through microwave photonic technology, thereby simultaneously obtaining the ability to detect targets with high sensitivity to small radar cross-section and accurately resolve the range of the targets.

[0010] A forward and backward scattering integrated microwave photonic radar system, comprising: The light source module is used to generate optical carrier signals; A signal generation module is used to generate a linear frequency modulated signal based on the optical carrier signal, and modulate the linear frequency modulated signal onto the optical carrier to form an optical sideband signal; A photoelectric conversion module is used to convert the optical sideband signal into a microwave signal; A transmitting antenna is used to transmit the microwave signal to illuminate the target within the detection area; A receiving antenna is used to receive microwave signals scattered back by a target, wherein the microwave signals scattered back by the target are scattered signals, and the scattered signals include forward scattered signals and / or backscattered signals; The optical mixing module is used to perform optical mixing processing on the received scattered signal and the reference optical signal to obtain an optical beat frequency signal containing target information; The information processing module is used to process the optical beat frequency signal and extract the target distance information.

[0011] Furthermore, the light source module includes a fixed-wavelength laser for generating a single-frequency optical carrier signal with a fixed wavelength.

[0012] Furthermore, the signal generation module includes: An external microwave signal source is used to generate a linear frequency modulated electrical signal; An electric amplifier is used to amplify the linear frequency modulated electrical signal; An electro-optic modulator is used to modulate an amplified linear frequency modulated electrical signal onto the optical carrier to generate an optical sideband signal.

[0013] Furthermore, the photoelectric conversion module includes a photodetector for beat frequency detection of the optical sideband signal and converting it into a microwave signal.

[0014] Furthermore, the optical mixing module includes: An optical coupler is used to provide one optical carrier signal as a reference optical signal. An electro-optic modulator is used to modulate a received scattered signal onto another optical signal; An optical mixer is used to mix the reference optical signal with an optical signal carrying a scattered signal.

[0015] Furthermore, it also includes a polarization controller module for changing the polarization state of the optical carrier signal to optimize modulation efficiency.

[0016] Furthermore, it also includes an optical coupler module, which is a 1-to-3 optical coupler used to split the optical sideband signal into three paths. The first path is connected to the photoelectric conversion module, the second path is used as a reference signal output for forward scattering mixing, and the third path is used as a reference signal output for backscattering mixing.

[0017] Furthermore, the information processing module includes: An optical amplifier is used to optically amplify the optical beat frequency signal; Optical filters are used to filter amplified optical signals. A photodetector is used to convert filtered optical signals into electrical signals. A low-pass filter is used to filter the converted electrical signal; The spectrum analysis unit is used to perform spectrum analysis on the filtered electrical signal to extract target distance information.

[0018] Furthermore, the receiving antenna includes a first receiving antenna and a second receiving antenna, which are respectively used to receive forward-scattered signals and backscattered signals.

[0019] Furthermore, the spectrum analysis unit is a spectrum analyzer.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention achieves effective integration of forward and backscattering modes, comprehensively enhancing detection capabilities. This invention creatively integrates forward and backscattering detection modes within the same microwave photonic architecture. The backscattering mode is primarily used for precise target localization, ranging, and high-resolution imaging, exhibiting strong detection capabilities against conventional targets. The forward scattering mode, by receiving the forward-scattered signal from the target, significantly enhances the detection capabilities against low radar cross-section (RCS) targets, especially stealth targets, primarily used for target detection, tracking, and velocity measurement, but its independent ranging capability is relatively weak. The integrated design of this system allows the forward scattering mode to effectively compensate for the shortcomings of traditional backscattering radar in detecting low RCS stealth targets, while simultaneously addressing the inherent difficulty in ranging with pure forward scattering radar. By fusing data from both modes, the system can acquire richer and more comprehensive target information, thereby significantly improving the robustness of target identification and tracking in complex environments.

[0021] 2. This invention utilizes microwave photonics technology to overcome the bottlenecks of traditional electronic systems and achieve high performance. This invention transfers the core generation, distribution, and processing of radar signals to the optical domain, fully leveraging the unique advantages of photonics technology: It solves the high-precision synchronization problem by distributing signals based on a unified optical carrier and low-loss optical fiber, providing a highly coherent reference for distributed transceiver units, fundamentally overcoming the problems of high loss and poor synchronization accuracy in long-distance transmission of traditional electronic synchronization methods; it overcomes bandwidth and resolution limitations. Photonics technology has a naturally large bandwidth, enabling convenient generation and processing of ultra-wideband radar signals. The larger signal bandwidth directly translates to higher range resolution, thereby achieving more refined target detection and imaging, breaking through the electronic bottlenecks of traditional electronic devices; and it enhances system reliability and deployment flexibility. Optical signals have strong immunity to electromagnetic interference, ensuring operational stability in complex electromagnetic environments. The low transmission loss characteristics of optical fibers make the system particularly suitable for large-aperture, long-distance deployment, greatly expanding its application range.

[0022] 3. This invention constructs a high-performance, highly practical advanced radar system platform. Through the aforementioned technological innovations, this invention ultimately provides an integrated radar system that combines high sensitivity (for weak / stealth targets), high accuracy (ranging and resolution), high stability, and strong environmental adaptability. This system has significant application value in military anti-stealth, low-altitude security surveillance, civil aviation control, and meteorological monitoring, effectively improving the overall performance and practicality of radar technology. Attached Figure Description

[0023] Figure 1 This is a block diagram of the integrated forward and backward scattering microwave photonic radar system in an embodiment of the present invention; Figure 2 This is a schematic diagram of the integrated forward and backward scattering microwave photonic radar system in an embodiment of the present invention. Figure 3 This is a schematic diagram of a system device according to one specific embodiment of the present invention; Figure 4 This is a schematic diagram of the spectrum of the optical sideband signal generated in an embodiment of the present invention; Figure 5 This is a schematic diagram of the spectrum of the microwave signal obtained after photoelectric conversion in an embodiment of the present invention; Figure 6 The above are comparison diagrams of detection results in backscattering mode in the embodiments of the present invention; where (a) is a schematic diagram of free space detection spectrum and (b) is a schematic diagram of detection spectrum after placing a small RCS target; Figure 7 The above are comparison diagrams of detection results in forward scattering mode in the embodiments of the present invention; where (a) is a schematic diagram of the free space detection spectrum and (b) is a schematic diagram of the detection spectrum after placing a small RCS target. Figure 8 This is a schematic diagram of the detection spectrum obtained by detecting a target in the detection area under the forward scattering mode in an embodiment of the present invention. Figure 9 This is a schematic diagram of the detection spectrum obtained by detecting two targets in the detection area under the backscattering mode in an embodiment of the present invention.

[0024] Reference numerals: 1. Signal generation module; 2. First photoelectric conversion module; 3. First transmitting antenna; 4. First receiving antenna; 5. First optical mixing module; 6. Third photoelectric conversion module; 7. Second transmitting antenna; 8. Second optical mixing module; 9. Second photoelectric conversion module; 10. First information processing module; 11. Second information processing module; 12. Light source module; 13. First polarization controller module; 14. First electro-optic modulator module; 15. First arbitrary waveform generator; 16. First DC bias source; 17. First optical amplifier; 18. First optical filter; 9. Optical coupler module; 20. First photodetector; 21. First electrical amplifier; 22. First low-pass filter; 23. Second polarization controller module; 24. First phase modulator; 25. Second electrical amplifier; 26. Second optical amplifier; 27. Second optical filter; 28. Second photodetector; 29. ​​Third polarization controller module; 30. Second phase modulator; 31. Third electrical amplifier; 32. Third optical amplifier; 33. Third optical filter; 34. Third photodetector; 35. First signal spectrum analyzer; 36. Second signal spectrum analyzer. Detailed Implementation

[0025] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0026] like Figure 1 As shown, an embodiment of the present invention provides an integrated forward and backward scattering microwave photonic radar system, comprising: The light source module 12 is used to generate optical carrier signals.

[0027] Signal generation module 1 is used to generate a linear frequency modulated signal based on the optical carrier signal, and modulate the linear frequency modulated signal onto the optical carrier to form an optical sideband signal.

[0028] The photoelectric conversion module is used to convert the optical sideband signal into a microwave signal. In this embodiment, three photoelectric conversion modules are provided: a first photoelectric conversion module 2, a second photoelectric conversion module 9, and a third photoelectric conversion module 6.

[0029] A transmitting antenna is used to transmit the microwave signal to illuminate the target within the detection area. In this embodiment, two transmitting antennas are provided, namely a first transmitting antenna 3 and a second transmitting antenna 7.

[0030] A receiving antenna is used to receive microwave signals scattered back by a target, wherein the microwave signals scattered back by the target are scattered signals, and the scattered signals include forward scattered signals and / or backscattered signals.

[0031] An optical mixing module is used to perform optical mixing processing on the received scattered signal and the reference optical signal to obtain an optical beat frequency signal containing target information. In this embodiment, two optical mixing modules are provided: a first optical mixing module 5 and a second optical mixing module 8.

[0032] The information processing module is used to process the optical beat frequency signal and extract the target distance information. In this embodiment, there are two information processing modules: a first information processing module 10 and a second information processing module 11.

[0033] The first information processing module 10 is used to process the optical beat frequency signal of the light carrying the backscattering radar detection signal and extract the backscattering information of the target.

[0034] The second information processing module 11 is used to process the optical beat frequency signal of the light carrying the forward radar detection signal and extract the forward scattering information of the target.

[0035] Furthermore, the light source module 12 includes a fixed-wavelength laser for generating a single-frequency optical carrier signal with a fixed wavelength.

[0036] Furthermore, the signal generation module 1 includes: an external microwave signal source for generating a linear frequency modulated (LFM) electrical signal; an electrical amplifier for amplifying the LFM electrical signal; and an electro-optic modulator for modulating the amplified LFM electrical signal onto the optical carrier to generate an optical sideband signal.

[0037] Furthermore, the photoelectric conversion module includes a photodetector for beat frequency detection of the optical sideband signal and converting it into a microwave signal.

[0038] Furthermore, the optical mixing module includes: an optical coupler for providing one optical carrier signal as a reference optical signal; an electro-optic modulator for modulating the received scattered signal onto another optical signal; and an optical mixer for mixing the reference optical signal with the optical signal carrying the scattered signal.

[0039] Furthermore, it also includes a polarization controller module for changing the polarization state of the optical carrier signal to optimize modulation efficiency. In this embodiment, three polarization controller modules are provided: a first polarization controller module 13, a second polarization controller module 23, and a third polarization controller module 29.

[0040] Furthermore, it also includes an optical coupler module 19, which is a 1-to-3 optical coupler used to divide the optical sideband signal into three paths. The first path is connected to the photoelectric conversion module, the second path is used as a reference signal output for forward scattering mixing, and the third path is used as a reference signal output for backscattering mixing.

[0041] Furthermore, the information processing module 10 and information processing module 11 include: an optical amplifier for optically amplifying the optical beat frequency signal; an optical filter for filtering the amplified optical signal; a photodetector for converting the filtered optical signal into an electrical signal; a low-pass filter for filtering the converted electrical signal; and a spectrum analysis unit for performing spectrum analysis on the filtered electrical signal to extract target distance information.

[0042] Furthermore, the receiving antenna includes a first receiving antenna 4 and a second receiving antenna 7, which are respectively used to receive forward-scattered signals and back-scattered signals.

[0043] Furthermore, the spectrum analysis unit is a spectrum analyzer. In this embodiment, two spectrum analyzers are provided, namely a first spectrum analyzer 35 and a second spectrum analyzer 36.

[0044] The integrated forward and backward scattering microwave photonic radar system of this invention will be further described in detail below: like Figure 2 As shown, the integrated forward and backward scattering microwave photonic radar system of this invention includes: a light source module 12, a signal generation module 1, a photoelectric converter module, an optical mixer module, a photoelectric conversion module, a signal processing module, a transmitting antenna, and a receiving antenna.

[0045] like Figure 3 As shown, specifically, the core component of the light source module 12 is a first fixed-wavelength laser.

[0046] The signal generation module 1 includes a first polarization controller (which is the core device of the first polarization controller module 13), a first arbitrary waveform generator 15, a first DC bias source 16, and a first electro-optic modulator (which is the core device of the first electro-optic modulator module 14).

[0047] The first photoelectric conversion module 2 includes a first optical amplifier 17, a first optical filter 18, a first optical coupler (which is the core device of the optical coupler module 19), a first photodetector 20, a first electrical amplifier 21, and a first low-pass filter 22.

[0048] The transmitting antenna includes a first transmitting antenna 3 and a second transmitting antenna 7. The first receiving antenna 4 and the second receiving antenna 7 are used to receive signals respectively.

[0049] The first optical mixing module 5 includes a second polarization controller (which is the core device of the second polarization controller module 23), a first phase modulator 24, a second electrical amplifier 25, a second optical amplifier 26, a second optical filter 27, and a second photodetector 28. The circuitry associated with the second photodetector 28 constitutes the second photoelectric conversion module 9.

[0050] The second optical mixing module 8 includes a third polarization controller (which is the core device of the third polarization controller module 29), a second phase modulator 30, a third electrical amplifier 31, a third optical amplifier 32, a third optical filter 33, and a third photodetector 34. The circuitry associated with the third photodetector 34 constitutes the third photoelectric conversion module 6.

[0051] The core of the information processing module is the first spectrum analyzer 35 and the second spectrum analyzer 36.

[0052] The signal generation process of the integrated forward and backward scattering microwave photonic radar system according to an embodiment of the present invention is as follows: The first fixed-wavelength laser generates a fixed-wavelength optical carrier, which can be expressed as: in This represents the amplitude of the light. The optical signal's polarization state is changed by the first polarization controller and then input to the first electro-optic modulator.

[0053] The microwave signal generated by the first arbitrary waveform generator 15 can be described as follows: in The amplitude of the reference signal; The center frequency; is the chirp rate. Among them... The linear frequency modulation signal is controlled to operate the first electro-optic modulator at its minimum bias point, thus achieving carrier-suppressed double-sideband modulation. The frequencies of the positive and negative first-order sidebands are as follows: and Its light field expression can be stated as: Since DC bias introduces a phase shift, the optical field can be described as follows: in The phase shift introduced by DC bias; Represents the 0th order Bessel function. Represents the first-order Bessel function; Let be the modulation coefficient, where , For the reference signal amplitude, This is the half-wave voltage in MZM.

[0054] The output photocurrent can then be expressed as: The spectrum of the signal light generated in this embodiment is as follows: Figure 4 As shown.

[0055] The optical signal passes through the first optical amplifier 17 and the first optical filter 18 before entering the first optical coupler. The optical signal is split into three paths. The first path of the split signal passes through the first photodetector 20, which converts the optical signal into an electrical signal. The resulting signal is then amplified by the first electrical amplifier 21. The amplified electrical signal passes through the first low-pass filter 22 to obtain a second-harmonic signal.

[0056] The spectrum of the electrical signal generated in this embodiment is as follows: Figure 5 As shown.

[0057] The second path of the optical coupler splits the light and passes through the second polarization controller 23, then enters the first phase modulator 24. The first receiving antenna 4 receives backscatter radar information. This signal is amplified by the second electrical amplifier 25 and then enters the first phase modulator 24. After modulation, the optical signal carries the backscatter reception information and passes through the second optical amplifier 26 to amplify the optical signal. The amplified optical signal passes through the second optical filter 27 and enters the second photodetector 28 to convert the optical signal into an electrical signal. The signal is then analyzed by the signal spectrum analyzer 35.

[0058] like Figure 6 As shown, in this embodiment, a target with a small RCS is placed within the test detection area of ​​the forward scattering radar and the backscattering radar. Figure 6 (a) is the detection spectrum in free space of the backscatter radar. Figure 6 (b) is the target detection spectrum of a small RCS placed within the backscatter radar detection area.

[0059] The third path of the optical coupler splits the light and passes through the third polarization controller 29, then enters the second phase modulator 30. The second receiving antenna 7 receives backscatter radar information. This signal is amplified by the third electrical amplifier 31 and then enters the second phase modulator 30. After modulation, the optical signal carries forward scattering reception information and passes through the third optical amplifier 32 to amplify the optical signal. The amplified optical signal passes through the third optical filter 33 and enters the third photodetector 34 to convert the optical signal into an electrical signal. The signal is then analyzed by the signal spectrum analyzer 36.

[0060] like Figure 7 As shown, Figure 7 (a) is the detection spectrum of the forward-scattering radar in free space. Figure 7(b) shows the detection spectrum of a small RCS target placed within the detection area of ​​the forward scatter radar. The peak difference between the two figures is 9.58 dB, indicating that the forward scatter radar has a good detection capability for small RCS targets.

[0061] like Figure 8 As shown, this is the detection spectrum after placing a detection object in the forward scatter radar detection area. The enlarged image shows the spectral information at the peak, and two peaks can be observed.

[0062] like Figure 9 As shown, the detection spectrum is the spectrum after placing two detection objects in the backscatter radar detection area. The magnified image shows the spectral information at the peak, and two peaks can be observed.

[0063] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A forward and backward scattering integrated microwave photonic radar system, characterized in that, include: The light source module is used to generate optical carrier signals; A signal generation module is used to generate a linear frequency modulated signal based on the optical carrier signal, and modulate the linear frequency modulated signal onto the optical carrier to form an optical sideband signal; A photoelectric conversion module is used to convert the optical sideband signal into a microwave signal; A transmitting antenna is used to transmit the microwave signal to illuminate the target within the detection area; A receiving antenna is used to receive microwave signals scattered back by a target, wherein the microwave signals scattered back by the target are scattered signals, and the scattered signals include forward scattered signals and / or backscattered signals; The optical mixing module is used to perform optical mixing processing on the received scattered signal and the reference optical signal to obtain an optical beat frequency signal containing target information; The optical mixing module includes: an optical coupler for providing one optical carrier signal as a reference optical signal; an electro-optic modulator for modulating the received scattered signal onto another optical signal; and an optical mixer for mixing the reference optical signal with the optical signal carrying the scattered signal. An optical coupler module, wherein the optical coupler module is a 1-to-3 optical coupler, is used to split the optical sideband signal into three paths, the first path is connected to the photoelectric conversion module, the second path is used as a reference signal output for forward scattering mixing, and the third path is used as a reference signal output for backscattering mixing. The information processing module is used to process the optical beat frequency signal and extract the target distance information.

2. The integrated backscattering and forward scattering microwave photonic radar system according to claim 1, characterized in that, The light source module includes a fixed-wavelength laser for generating a single-frequency optical carrier signal with a fixed wavelength.

3. The integrated forward and backward scattering microwave photonic radar system according to claim 1, characterized in that, The signal generation module includes: An external microwave signal source is used to generate a linear frequency modulated electrical signal; An electric amplifier is used to amplify the linear frequency modulated electrical signal; An electro-optic modulator is used to modulate an amplified linear frequency modulated electrical signal onto the optical carrier to generate an optical sideband signal.

4. The integrated forward and backward scattering microwave photonic radar system according to claim 1, characterized in that, The photoelectric conversion module includes a photodetector for beat frequency detection of the optical sideband signal and converting it into a microwave signal.

5. The integrated forward and backward scattering microwave photonic radar system according to claim 1, characterized in that, It also includes a polarization controller module for changing the polarization state of the optical carrier signal to optimize modulation efficiency.

6. The integrated forward and backward scattering microwave photonic radar system according to claim 1, characterized in that, The information processing module includes: An optical amplifier is used to optically amplify the optical beat frequency signal; Optical filters are used to filter amplified optical signals. A photodetector is used to convert filtered optical signals into electrical signals. A low-pass filter is used to filter the converted electrical signal; The spectrum analysis unit is used to perform spectrum analysis on the filtered electrical signal to extract target distance information.

7. The integrated forward and backward scattering microwave photonic radar system according to claim 1, characterized in that, The receiving antenna includes a first receiving antenna and a second receiving antenna, which are respectively used to receive forward-scattered signals and back-scattered signals.

8. The integrated backscattering and forward scattering microwave photonic radar system according to claim 6, characterized in that, The spectrum analysis unit is a spectrum analyzer.

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