It is of great scientific significance to construct a 3D dynamic structural color with a special color effect based on the microlens array.However,the problems of imperfect mechanisms and poor color quality need to be...It is of great scientific significance to construct a 3D dynamic structural color with a special color effect based on the microlens array.However,the problems of imperfect mechanisms and poor color quality need to be solved.A method of 3D structural color turning on periodic metasurfaces fabricated by the microlens array and self-assembly technology was proposed in this study.In the experiment,Polydimethylsiloxane(PDMS)flexible film was used as a substrate,and SiO2 microspheres were scraped into grooves of the PDMS film to form 3D photonic crystal structures.By adjusting the number of blade-coated times and microsphere concentrations,high-saturation structural color micropatterns were obtained.These films were then matched with microlens arrays to produce dynamic graphics with iridescent effects.The results showed that by blade-coated two times and SiO2 microsphere concentrations of 50%are the best conditions.This method demonstrates the potential for being widely applied in the anticounterfeiting printing and ultra-high-resolution display.展开更多
Tin-lead(Sn-Pb)mixed perovskites are extensively investigated in near-infrared(NIR)photodetectors(PDs)owing to their excellent photoelectric performance.However,achieving high-performance Sn-Pb mixed PDs remains chall...Tin-lead(Sn-Pb)mixed perovskites are extensively investigated in near-infrared(NIR)photodetectors(PDs)owing to their excellent photoelectric performance.However,achieving high-performance Sn-Pb mixed PDs remains challenging,primarily because of the rapid crystallization and the susceptibility of Sn^(2+) to oxidation.To ad⁃dress these issues,this study introduces the multifunctional molecules 2,3-difluorobenzenamine(DBM)to modulate the crystallization of Sn-Pb mixed perovskites and retard the oxidation of Sn^(2+),thereby significantly enhancing film quality.Compared with the pristine film,Sn-Pb mixed perovskite films modulated by DBM molecules exhibit a high⁃ly homogeneous morphology,reduced roughness and defect density.The self-powered NIR PDs fabricated with the improved films have a spectral response range from 300 nm to 1100 nm,a peak responsivity of 0.51 A·W^(-1),a spe⁃cific detectivity as high as 2.46×10^(11)Jones within the NIR region(780 nm to 1100 nm),a linear dynamic range ex⁃ceeding 152 dB,and ultrafast rise/fall time of 123/464 ns.Thanks to the outstanding performance of PDs,the fabri⁃cated 5×5 PDs array demonstrates superior imaging ability in the NIR region up to 980 nm.This work advances the development of Sn-Pb mixed perovskites for NIR detection and paves the way for their commercialization.展开更多
Optical field manipulation,an emerging frontier in photonics,demonstrates significant potential in biomedical microscopy,quantum state engineering,and micro-nano fabrication.To address the critical limitations of curr...Optical field manipulation,an emerging frontier in photonics,demonstrates significant potential in biomedical microscopy,quantum state engineering,and micro-nano fabrication.To address the critical limitations of current optical modulation technologies in achieving full-parameter precision control,we proposed a novel approach for dynamic azimuthal optical field modulation based on dual-spiral arrays.By designing spatially interleaved spiral structures with different initial radii while maintaining identical periodic parameters,we achieved continuous optical modulation spanning the full 0-2πrange in azimuthal field distribution.Through rigorous numerical simulations,we systematically established a quantitative correlation between the structural parameters and azimuthal optical field patterns,revealing,for the first time,a quasi-linear relationship between the radius difference and the resultant optical distribution.This theoretical framework advances our fundamental understanding of structured optical field manipulation as well as provides a new paradigm for programmable photonic device design,with distinct technical advantages in super-resolution imaging and optical tweezer systems.展开更多
Low-frequency signals have been proven valuable in the fields of target detection and geological exploration.Nevertheless,the practical implementation of these signals is hindered by large antenna diameters,limiting t...Low-frequency signals have been proven valuable in the fields of target detection and geological exploration.Nevertheless,the practical implementation of these signals is hindered by large antenna diameters,limiting their potential applications.Therefore,it is imperative to study the creation of lowfrequency signals using antennas with suitable dimensions.In contrast to conventional mechanical antenna techniques,our study generates low-frequency signals in the spatial domain utilizing the principle of the Doppler effect.We also defines the antenna array architecture,the timing sequency,and the radiating element signal waveform,and provides experimental prototypes including 8/64 antennas based on earlier research.In the conducted experiments,121 MHz,40 MHz,and 10 kHz composite signals are generated by 156 MHz radiating element signals.The composite signal spectrum matches the simulations,proving our low-frequency signal generating method works.This holds significant implications for research on generating low-frequency signals with small-sized antennas.展开更多
In this paper, the reactive splitter network and meta-surface are proposed to radiate the wide-beam isolated element pattern and suppress mutual coupling (MC) of the low-profile phased array with the triangular lattic...In this paper, the reactive splitter network and meta-surface are proposed to radiate the wide-beam isolated element pattern and suppress mutual coupling (MC) of the low-profile phased array with the triangular lattice, respectively. Thus, broadband wide-angle impedance matching (WAIM) is imple-mented to promote two-dimensional (2D) wide scanning. For the isolated element, to radiate the wide-beam patterns approximat-ing to the cosine form, two identical slots backed on one sub-strate integrated cavity are excited by the feeding network con-sisting of a reactive splitter and two striplines connected with splitter output paths. For adjacent elements staggered with each other, with the metasurface superstrate, the even-mode cou-pling voltages on the reactive splitter are cancelled out, yielding reduced MC. With the suppression of MC and the compensa-tion of isolated element patterns, WAIM is realized to achieve 2D wide-angle beam steering up to ± 65° in E-plane, ± 45° in H-plane and ± 60° in D-plane from 4.9 GHz to 5.85 GHz.展开更多
For multi-channel synthetic aperture radar（SAR） systems, since the minimum antenna area constraint is eliminated,wide swath and high resolution SAR image can be achieved.However, the unavoidable array errors, consis...For multi-channel synthetic aperture radar（SAR） systems, since the minimum antenna area constraint is eliminated,wide swath and high resolution SAR image can be achieved.However, the unavoidable array errors, consisting of channel gainphase mismatch and position uncertainty, significantly degrade the performance of such systems. An iteration-free method is proposed to simultaneously estimate position and gain-phase errors.In our research, the steering vectors corresponding to a pair of Doppler bins within the same range bin are studied in terms of their rotational relationships. The method is based on the fact that the rotational matrix only depends on the position errors and the frequency spacing between the paired Doppler bins but is independent of gain-phase error. Upon combining the projection matrices corresponding to the paired Doppler bins, the position errors are directly obtained in terms of extracting the rotational matrix in a least squares framework. The proposed method, when used in conjunction with the self-calibration algorithm, performs stably as well as has less computational load, compared with the conventional methods. Simulations reveal that the proposed method behaves better than the conventional methods even when the signal-to-noise ratio（SNR） is low.展开更多
A new mulfitarget constant modulus array is proposed for CDMA systems based on least squares constant modulus algorithm. The new algorithm is called pre-despreading decision directed least squares constant modulus alg...A new mulfitarget constant modulus array is proposed for CDMA systems based on least squares constant modulus algorithm. The new algorithm is called pre-despreading decision directed least squares constant modulus algorithm （D-DDLSCMA）. In the new algorithm, the pre-despreading is first applied for multitarget arrays to remove some multiple access signals, then the despreaded signal is processed by the algorithm which united the constant modulus algorithm and decision directed method. Simulation results illustrate the good performance for the proposed algorithm.展开更多
Unmanned aerial vehicles(UAVs)may be subjected to unintentional radio frequency interference(RFI)or hostile jamming attack which will lead to fail to track global navigation satellite system(GNSS)signals.Therefore,the...Unmanned aerial vehicles(UAVs)may be subjected to unintentional radio frequency interference(RFI)or hostile jamming attack which will lead to fail to track global navigation satellite system(GNSS)signals.Therefore,the simultaneous realization of anti-jamming and high-precision carrier phase difference positioning becomes a dilemmatic problem.In this paper,a distortionless phase digital beamforming(DBF)algorithm with self-calibration antenna arrays is proposed,which enables to obtain distortionless carrier phase while suppressing jamming.Additionally,architecture of high precision Beidou receiver based on anti-jamming antenna arrays is proposed.Finally,the performance of the algorithm is evaluated,including antenna calibration accuracy,carrier phase distortionless accuracy,and carrier phase measurement accuracy without jamming.Meanwhile,the maximal jamming to signal ratio(JSR)and real time kinematic(RTK)positioning accuracy under wideband jamming are also investigated.The experimental results based on the real-life Beidou signals show that the proposed method has an excellent performance for precise relative positioning under jamming when compared with other anti-jamming methods.展开更多
A medium wave(MW)640×512(25μm)Mercury Cadmium Telluride(HgCdTe)polarimetric focal plane array(FPA)was demonstrated.The micro-polarizer array(MPA)has been carefully designed in terms of line grating structure opt...A medium wave(MW)640×512(25μm)Mercury Cadmium Telluride(HgCdTe)polarimetric focal plane array(FPA)was demonstrated.The micro-polarizer array(MPA)has been carefully designed in terms of line grating structure optimization and crosstalk suppression.A monolithic fabrication process with low damage was explored,which was verified to be compatible well with HgCdTe devices.After monolithic integration of MPA,NETD<9.5 mK was still maintained.Furthermore,to figure out the underlying mechanism that dominat⁃ed the extinction ratio(ER),specialized MPA layouts were designed,and the crosstalk was experimentally vali⁃dated as the major source that impacted ER.By expanding opaque regions at pixel edges to 4μm,crosstalk rates from adjacent pixels could be effectively reduced to approximately 2%,and promising ERs ranging from 17.32 to 27.41 were implemented.展开更多
The direction of ground-based interference reaching the satellite is generally very close to the spot beam of the satel-lite.The traditional array anti-jamming method may cause signifi-cant loss to the uplink signal w...The direction of ground-based interference reaching the satellite is generally very close to the spot beam of the satel-lite.The traditional array anti-jamming method may cause signifi-cant loss to the uplink signal while suppressing the interference.In this paper,an aperiodic multistage array is used,and a sub-array aperiodic distribution optimization scheme based on paral-lel differential evolution is proposed,which effectively improves the beam resolution and suppresses the grating lobe.On this basis,a two-stage signal processing method is used to sup-press interference.Finally,the comprehensive performance of the proposed scheme is evaluated and verified.展开更多
The microwave wireless power transmission technologies for space solar power station are a crucial field in the international space sector,where various countries are competing in its development.This paper surveys th...The microwave wireless power transmission technologies for space solar power station are a crucial field in the international space sector,where various countries are competing in its development.This paper surveys the research experiments and development efforts related to space solar power stations and microwave wireless power transmission technologies worldwide.The objective is to assess the progress and current state of this technological foundation,determine the necessary focus for developing high-power microwave wireless power transmission technology,and provide clarity on the direction of future technology development in these areas.Finally,a distributed space solar power station plan that is immediately feasible is proposed.展开更多
Microstrip transmission lines connecting to the millimeter wave radar chip and antenna significantly affect the radiation efficiency and bandwidth of the antenna.Here,a wideband non-uniform wavy microstrip line for co...Microstrip transmission lines connecting to the millimeter wave radar chip and antenna significantly affect the radiation efficiency and bandwidth of the antenna.Here,a wideband non-uniform wavy microstrip line for complex impedance in automotive radar frequency range is proposed.Unlike the gradient transmission line,the wavy structure is composed of periodically semi-circular segments.By adjusting the radius of the semi-circular,the surface current is varied and concentrated on the semi-circular segments,allowing a wider tunability range of the resonant frequency.The results reveal that the bandwidth of the loaded wavy transmission line antenna improves to 9.37 GHz,which is 5.81 GHz wider than that of the loaded gradient line.The gain and the half power beam width of the loaded antenna are about 14.69 dB and 9.58°,respectively.The proposed non-uniform microstrip line scheme may open up a route for realizing wideband millimeter-wave automotive radar applications.展开更多
The Ocean 4A scatterometer, expected to be launched in 2024, is poised to be the world’s first spaceborne microwave scatterometer utilizing a digital beamforming system. To ensure high-precision measurements and perf...The Ocean 4A scatterometer, expected to be launched in 2024, is poised to be the world’s first spaceborne microwave scatterometer utilizing a digital beamforming system. To ensure high-precision measurements and performance sta-bility across diverse environments, stringent requirements are placed on the dynamic range of its receiving system. This paper provides a detailed exposition of a field-programmable gate array (FPGA)-based automatic gain control (AGC) design for the spaceborne scatterometer. Implemented on an FPGA, the algo-rithm harnesses its parallel processing capabilities and high-speed performance to monitor the received echo signals in real time. Employing an adaptive AGC algorithm, the system gene-rates gain control codes applicable to the intermediate fre-quency variable attenuator, enabling rapid and stable adjust-ment of signal amplitudes from the intermediate frequency amplifier to an optimal range. By adopting a purely digital pro-cessing approach, experimental results demonstrate that the AGC algorithm exhibits several advantages, including fast con-vergence, strong flexibility, high precision, and outstanding sta-bility. This innovative design lays a solid foundation for the high-precision measurements of the Ocean 4A scatterometer, with potential implications for the future of spaceborne microwave scatterometers.展开更多
文摘It is of great scientific significance to construct a 3D dynamic structural color with a special color effect based on the microlens array.However,the problems of imperfect mechanisms and poor color quality need to be solved.A method of 3D structural color turning on periodic metasurfaces fabricated by the microlens array and self-assembly technology was proposed in this study.In the experiment,Polydimethylsiloxane(PDMS)flexible film was used as a substrate,and SiO2 microspheres were scraped into grooves of the PDMS film to form 3D photonic crystal structures.By adjusting the number of blade-coated times and microsphere concentrations,high-saturation structural color micropatterns were obtained.These films were then matched with microlens arrays to produce dynamic graphics with iridescent effects.The results showed that by blade-coated two times and SiO2 microsphere concentrations of 50%are the best conditions.This method demonstrates the potential for being widely applied in the anticounterfeiting printing and ultra-high-resolution display.
基金Supported by National Key Research and Development Program of China(2022YFA1404201)National Natural Science Foundation of China(62205187,U23A20380,U22A2091,62222509,62127817,62075120)+3 种基金Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China(IRT_17R70)Fundamental Research Program of Shanxi Province(202103021223032,202303021222031)Project Funded by China Postdoctoral Science Foundation(2022M722006)Fund for Shanxi“1331 Project”Key Subjects Construction。
文摘Tin-lead(Sn-Pb)mixed perovskites are extensively investigated in near-infrared(NIR)photodetectors(PDs)owing to their excellent photoelectric performance.However,achieving high-performance Sn-Pb mixed PDs remains challenging,primarily because of the rapid crystallization and the susceptibility of Sn^(2+) to oxidation.To ad⁃dress these issues,this study introduces the multifunctional molecules 2,3-difluorobenzenamine(DBM)to modulate the crystallization of Sn-Pb mixed perovskites and retard the oxidation of Sn^(2+),thereby significantly enhancing film quality.Compared with the pristine film,Sn-Pb mixed perovskite films modulated by DBM molecules exhibit a high⁃ly homogeneous morphology,reduced roughness and defect density.The self-powered NIR PDs fabricated with the improved films have a spectral response range from 300 nm to 1100 nm,a peak responsivity of 0.51 A·W^(-1),a spe⁃cific detectivity as high as 2.46×10^(11)Jones within the NIR region(780 nm to 1100 nm),a linear dynamic range ex⁃ceeding 152 dB,and ultrafast rise/fall time of 123/464 ns.Thanks to the outstanding performance of PDs,the fabri⁃cated 5×5 PDs array demonstrates superior imaging ability in the NIR region up to 980 nm.This work advances the development of Sn-Pb mixed perovskites for NIR detection and paves the way for their commercialization.
文摘Optical field manipulation,an emerging frontier in photonics,demonstrates significant potential in biomedical microscopy,quantum state engineering,and micro-nano fabrication.To address the critical limitations of current optical modulation technologies in achieving full-parameter precision control,we proposed a novel approach for dynamic azimuthal optical field modulation based on dual-spiral arrays.By designing spatially interleaved spiral structures with different initial radii while maintaining identical periodic parameters,we achieved continuous optical modulation spanning the full 0-2πrange in azimuthal field distribution.Through rigorous numerical simulations,we systematically established a quantitative correlation between the structural parameters and azimuthal optical field patterns,revealing,for the first time,a quasi-linear relationship between the radius difference and the resultant optical distribution.This theoretical framework advances our fundamental understanding of structured optical field manipulation as well as provides a new paradigm for programmable photonic device design,with distinct technical advantages in super-resolution imaging and optical tweezer systems.
基金Science and Technology Project of Aerospace Information Research Institute,Chinese Academy of Sciences(Y910340Z2F)Science and Technology Project of BBEF(E3E2010201)。
文摘Low-frequency signals have been proven valuable in the fields of target detection and geological exploration.Nevertheless,the practical implementation of these signals is hindered by large antenna diameters,limiting their potential applications.Therefore,it is imperative to study the creation of lowfrequency signals using antennas with suitable dimensions.In contrast to conventional mechanical antenna techniques,our study generates low-frequency signals in the spatial domain utilizing the principle of the Doppler effect.We also defines the antenna array architecture,the timing sequency,and the radiating element signal waveform,and provides experimental prototypes including 8/64 antennas based on earlier research.In the conducted experiments,121 MHz,40 MHz,and 10 kHz composite signals are generated by 156 MHz radiating element signals.The composite signal spectrum matches the simulations,proving our low-frequency signal generating method works.This holds significant implications for research on generating low-frequency signals with small-sized antennas.
基金supported by Sichuan Science and Technology Programs(2022NSFSC0547,2022ZYD0109)the 2020 Open Foundation of Key Laboratory of Cognitive Radio and Information Processing,Ministry of Education(Guilin University of Electronic Technology)(CRKL200201).
文摘In this paper, the reactive splitter network and meta-surface are proposed to radiate the wide-beam isolated element pattern and suppress mutual coupling (MC) of the low-profile phased array with the triangular lattice, respectively. Thus, broadband wide-angle impedance matching (WAIM) is imple-mented to promote two-dimensional (2D) wide scanning. For the isolated element, to radiate the wide-beam patterns approximat-ing to the cosine form, two identical slots backed on one sub-strate integrated cavity are excited by the feeding network con-sisting of a reactive splitter and two striplines connected with splitter output paths. For adjacent elements staggered with each other, with the metasurface superstrate, the even-mode cou-pling voltages on the reactive splitter are cancelled out, yielding reduced MC. With the suppression of MC and the compensa-tion of isolated element patterns, WAIM is realized to achieve 2D wide-angle beam steering up to ± 65° in E-plane, ± 45° in H-plane and ± 60° in D-plane from 4.9 GHz to 5.85 GHz.
基金supported by the Natural Science Basic Research Plan in Shaanxi Province of China(2015JM6278)the China Postdoctoral Science Foundation(2015M582586)the China Academy of Space Technology Innovation Fund
文摘For multi-channel synthetic aperture radar（SAR） systems, since the minimum antenna area constraint is eliminated,wide swath and high resolution SAR image can be achieved.However, the unavoidable array errors, consisting of channel gainphase mismatch and position uncertainty, significantly degrade the performance of such systems. An iteration-free method is proposed to simultaneously estimate position and gain-phase errors.In our research, the steering vectors corresponding to a pair of Doppler bins within the same range bin are studied in terms of their rotational relationships. The method is based on the fact that the rotational matrix only depends on the position errors and the frequency spacing between the paired Doppler bins but is independent of gain-phase error. Upon combining the projection matrices corresponding to the paired Doppler bins, the position errors are directly obtained in terms of extracting the rotational matrix in a least squares framework. The proposed method, when used in conjunction with the self-calibration algorithm, performs stably as well as has less computational load, compared with the conventional methods. Simulations reveal that the proposed method behaves better than the conventional methods even when the signal-to-noise ratio（SNR） is low.
文摘A new mulfitarget constant modulus array is proposed for CDMA systems based on least squares constant modulus algorithm. The new algorithm is called pre-despreading decision directed least squares constant modulus algorithm （D-DDLSCMA）. In the new algorithm, the pre-despreading is first applied for multitarget arrays to remove some multiple access signals, then the despreaded signal is processed by the algorithm which united the constant modulus algorithm and decision directed method. Simulation results illustrate the good performance for the proposed algorithm.
基金supported by the Key Research and Development Program of Science&Technology Department of Sichuan Province(2021YFG0155)the Technical Innovation Fund of Southwest China Institute of Electronic Technology(H21004.2).
文摘Unmanned aerial vehicles(UAVs)may be subjected to unintentional radio frequency interference(RFI)or hostile jamming attack which will lead to fail to track global navigation satellite system(GNSS)signals.Therefore,the simultaneous realization of anti-jamming and high-precision carrier phase difference positioning becomes a dilemmatic problem.In this paper,a distortionless phase digital beamforming(DBF)algorithm with self-calibration antenna arrays is proposed,which enables to obtain distortionless carrier phase while suppressing jamming.Additionally,architecture of high precision Beidou receiver based on anti-jamming antenna arrays is proposed.Finally,the performance of the algorithm is evaluated,including antenna calibration accuracy,carrier phase distortionless accuracy,and carrier phase measurement accuracy without jamming.Meanwhile,the maximal jamming to signal ratio(JSR)and real time kinematic(RTK)positioning accuracy under wideband jamming are also investigated.The experimental results based on the real-life Beidou signals show that the proposed method has an excellent performance for precise relative positioning under jamming when compared with other anti-jamming methods.
基金Supported by the self-funded project of Kunming Institute of Physics。
文摘A medium wave(MW)640×512(25μm)Mercury Cadmium Telluride(HgCdTe)polarimetric focal plane array(FPA)was demonstrated.The micro-polarizer array(MPA)has been carefully designed in terms of line grating structure optimization and crosstalk suppression.A monolithic fabrication process with low damage was explored,which was verified to be compatible well with HgCdTe devices.After monolithic integration of MPA,NETD<9.5 mK was still maintained.Furthermore,to figure out the underlying mechanism that dominat⁃ed the extinction ratio(ER),specialized MPA layouts were designed,and the crosstalk was experimentally vali⁃dated as the major source that impacted ER.By expanding opaque regions at pixel edges to 4μm,crosstalk rates from adjacent pixels could be effectively reduced to approximately 2%,and promising ERs ranging from 17.32 to 27.41 were implemented.
基金supported by the National Key Research and Development Program of China(2022YFB3904402).
文摘The direction of ground-based interference reaching the satellite is generally very close to the spot beam of the satel-lite.The traditional array anti-jamming method may cause signifi-cant loss to the uplink signal while suppressing the interference.In this paper,an aperiodic multistage array is used,and a sub-array aperiodic distribution optimization scheme based on paral-lel differential evolution is proposed,which effectively improves the beam resolution and suppresses the grating lobe.On this basis,a two-stage signal processing method is used to sup-press interference.Finally,the comprehensive performance of the proposed scheme is evaluated and verified.
基金Entrusted Fund of National Institute of Information and Communications Technology(NICT),Japan(JPJ012368C02401)。
文摘The microwave wireless power transmission technologies for space solar power station are a crucial field in the international space sector,where various countries are competing in its development.This paper surveys the research experiments and development efforts related to space solar power stations and microwave wireless power transmission technologies worldwide.The objective is to assess the progress and current state of this technological foundation,determine the necessary focus for developing high-power microwave wireless power transmission technology,and provide clarity on the direction of future technology development in these areas.Finally,a distributed space solar power station plan that is immediately feasible is proposed.
基金Supported by the National Natural Science Foundation of China( 61974104)。
文摘Microstrip transmission lines connecting to the millimeter wave radar chip and antenna significantly affect the radiation efficiency and bandwidth of the antenna.Here,a wideband non-uniform wavy microstrip line for complex impedance in automotive radar frequency range is proposed.Unlike the gradient transmission line,the wavy structure is composed of periodically semi-circular segments.By adjusting the radius of the semi-circular,the surface current is varied and concentrated on the semi-circular segments,allowing a wider tunability range of the resonant frequency.The results reveal that the bandwidth of the loaded wavy transmission line antenna improves to 9.37 GHz,which is 5.81 GHz wider than that of the loaded gradient line.The gain and the half power beam width of the loaded antenna are about 14.69 dB and 9.58°,respectively.The proposed non-uniform microstrip line scheme may open up a route for realizing wideband millimeter-wave automotive radar applications.
文摘The Ocean 4A scatterometer, expected to be launched in 2024, is poised to be the world’s first spaceborne microwave scatterometer utilizing a digital beamforming system. To ensure high-precision measurements and performance sta-bility across diverse environments, stringent requirements are placed on the dynamic range of its receiving system. This paper provides a detailed exposition of a field-programmable gate array (FPGA)-based automatic gain control (AGC) design for the spaceborne scatterometer. Implemented on an FPGA, the algo-rithm harnesses its parallel processing capabilities and high-speed performance to monitor the received echo signals in real time. Employing an adaptive AGC algorithm, the system gene-rates gain control codes applicable to the intermediate fre-quency variable attenuator, enabling rapid and stable adjust-ment of signal amplitudes from the intermediate frequency amplifier to an optimal range. By adopting a purely digital pro-cessing approach, experimental results demonstrate that the AGC algorithm exhibits several advantages, including fast con-vergence, strong flexibility, high precision, and outstanding sta-bility. This innovative design lays a solid foundation for the high-precision measurements of the Ocean 4A scatterometer, with potential implications for the future of spaceborne microwave scatterometers.
