Radio over Fiber is an integration of microwave and optical fiber technologies having numerous benefits. RoF technology can give a scope of advantages including the capacity for backing multiple radio services and sta...Radio over Fiber is an integration of microwave and optical fiber technologies having numerous benefits. RoF technology can give a scope of advantages including the capacity for backing multiple radio services and standards. In coming future, there is need of integrated wireless service with high speed satellite broadband and multifunctional indoor/outdoor antennas. Radio over fiber is one of the most favorite candidates to meet all these requirements of future multifunctional integrated wireless communication. Due to planer profile, small size and low cost patch antennas are most favorite to use for multi- frequency applications. In this paper, we present system level design for future multifunctional radio over fiber network. Under FTTH (Fiber To The Home) technology, it will be possible to use multi-frequency applications on single fiber medium. Firstly, we designed S band circular patch antenna (2.5 GHz) and Ka band (29 GHz) horn antenna. Circular patch antenna performance is estimated with different substrate height. After getting S parameters and far-field results, we did modeling of Radio over Fiber system over (10 Km) with same parameters from antenna results.展开更多
电源网络S参数与芯片电源模型(Chip Power Module,CPM)级联可实现电源时域噪声仿真,完成电源完整性设计签核。当下部分仿真工具在AC阻抗优化过程中导出的S参数存在低频段无法覆盖的问题,影响时域纹波仿真精度,如果重新对S参数进行提取,...电源网络S参数与芯片电源模型(Chip Power Module,CPM)级联可实现电源时域噪声仿真,完成电源完整性设计签核。当下部分仿真工具在AC阻抗优化过程中导出的S参数存在低频段无法覆盖的问题,影响时域纹波仿真精度,如果重新对S参数进行提取,又会增加仿真时间降低仿真效率。针对AC阻抗优化过程中导出的S参数无法覆盖低频段的问题,提出了一种电源网络S参数低频段拓展方法,结合电压调节模块(Voltage Regulator Module,VRM)的R-L模型,推导出低频段的S参数可以借用抽取的S参数中最低频点处的S参数实现低频段S参数的拓展。仿真和实验结果表明,通过对低频段S参数进行拓展,电源时域纹波噪声仿真的精度提升31%。同时,低频段的S参数直接借用已抽取的S参数中低频点的数值无须重复提取,在8 GB内存的配置下,仿真时间节约14%左右,提高了仿真效率。展开更多
As the infrared technology continues to advance, there is a growing demand for multispectral detectors for advanced IR systems with better target discrimination and identification. Both HgCdTe detectors and quantum we...As the infrared technology continues to advance, there is a growing demand for multispectral detectors for advanced IR systems with better target discrimination and identification. Both HgCdTe detectors and quantum well GaAs/AlGaAs photodetectors offer wavelength flexibility from medium wavelength to very long wavelength and multicolor capability in these regions. The main challenges facing all multicolor devices are more complicated device structtures, thicker and multilayer material growth, and more difficult device fabrication, especially when the array size gets larger and pixel size gets smaller. In the paper recent progress in development of two color HgCdTe photodiodes and quantum well infrared photodetectors is presented. More attention is devoted to HgCdTe detectors. The two color detector arrays are based upon an n P N (the capital letters mean the materials with larger bandgap energy) HgCdTe triple layer heterojunction design. Vertically stacking the two p n junctions permits incorporation of both detectros into a single pixel. Both sequential mode and simultaneous mode detectors are fabricated. The mode of detection is determined by the fabrication process of the multilayer materials. Also the performances of stacked multicolor QWIPs detectors are presented. For multicolor arrays, QWIP’s narrow band spectrum is an advantage, resulting in low spectral crosstalk. The major challenge for QWIP is developing broadband or multicolor optical coupling structures that permit efficient absorption of all required spectral bands.展开更多
This letter reports the development of a 50MW S-band klystron in the Institute of Electronics, Chinese Academy of Sciences (IECAS). It adopted a structure of six-cavity and single output window. Under conditions of an...This letter reports the development of a 50MW S-band klystron in the Institute of Electronics, Chinese Academy of Sciences (IECAS). It adopted a structure of six-cavity and single output window. Under conditions of an RF (Radio Frequency) pulse width of 4μs, a beam voltage of 305.9kV and a beam current of 368A, the peak output power has achieved 51.4MW with an efficiency of 45.6% and a gain of 54dB.展开更多
In this paper, modified two-dimensional peri- odic lattice materials with local resonance phononic band gaps are designed and investigated. The design concept is to introduce some auxiliary structures into conventiona...In this paper, modified two-dimensional peri- odic lattice materials with local resonance phononic band gaps are designed and investigated. The design concept is to introduce some auxiliary structures into conventional pe- riodic lattice materials. Elastic wave propagation in this kind of modified two-dimensional lattice materials is studied us- ing a combination of Bloch＇s theorem with finite element method. The calculated frequency band structures of illus- trative modified square lattice materials reveal the existence of frequency band gaps in the low frequency region due to the introduction of the auxiliary structures. The mechanism underlying the occurrence of these frequency band gaps is thoroughly discussed and natural resonances of the auxiliary structures are validated to be the origin. The effect of geo- metric parameters of the auxiliary structures on the width of the local resonance phononic band gaps is explored. Finally, a conceptual broadband vibration-insulating structure based on the modified lattice materials is designed and its capabil- ity is demonstrated. The present work is anticipated to be useful in designing structures which can insulate mechanical vibrations within desired frequency ranges.展开更多
In this paper,we present the general design methods and parameter measurements of a 1-k W solidstate radio frequency(RF) power amplifier at 2856 MHz,for the soft X-ray free electron laser facility.Three-stage amplific...In this paper,we present the general design methods and parameter measurements of a 1-k W solidstate radio frequency(RF) power amplifier at 2856 MHz,for the soft X-ray free electron laser facility.Three-stage amplification with a 4-way combination is used.An RF switch module is integrated with the solid-state RF power amplifier to convert the continuous wave(CW) signal into pulse signal,with adjustable pulse width.The power gain is measured at 57.7 d B at 60 d Bm output.The RF phase noise,which is measured by the low-level RF system,is\0.015 degree(RMS),while the pulse frontier jitter is\5 ns.展开更多
This letter introduces the design ideas, simulation and test results of an S-band klystron with bandwidth of 11%, which was developed by the Institute of Electronics, Chinese Academy of Sciences (IECAS). On the peak p...This letter introduces the design ideas, simulation and test results of an S-band klystron with bandwidth of 11%, which was developed by the Institute of Electronics, Chinese Academy of Sciences (IECAS). On the peak power level of 800 kW, the efficiency of klystron is more than 30%; the gain is more than 41 dB; the equal-driving relative instantaneous bandwidth is over 11%; the average power is larger than 8 kW, and the power fluctuation within bandwidth is less than 1.5 dB.展开更多
为了解决微波无线输能系统中微波源的小型化和高效率需求,提出了一种高效谐波调谐功率振荡器的设计方法,振荡器由晶体管、谐波控制网络、反馈网络和负载网络组成。首先,通过调谐晶体管谐波阻抗以减少漏极电压与电流波形的重叠,从而提高...为了解决微波无线输能系统中微波源的小型化和高效率需求,提出了一种高效谐波调谐功率振荡器的设计方法,振荡器由晶体管、谐波控制网络、反馈网络和负载网络组成。首先,通过调谐晶体管谐波阻抗以减少漏极电压与电流波形的重叠,从而提高其效率;其次,反馈网络与负载网络使用仿真获得的数据合成,两者可独立设计,避免了反馈回路对振荡器输出效率的影响。使用Cree CGH40010F GaN HEMT设计并制作了一款工作在S波段的高效功率振荡器,测试结果表明振荡器在2.445 GHz下成功实现了41.7 dBm的输出功率和79.9%的直流到射频(direct current to radio frequency,DC-RF)转化效率,在偏移载波1 MHz处,相位噪声低至-136 dBc/Hz。该功率振荡器性能优越,在微波无线能量传输系统中具有良好的应用前景。展开更多
文摘Radio over Fiber is an integration of microwave and optical fiber technologies having numerous benefits. RoF technology can give a scope of advantages including the capacity for backing multiple radio services and standards. In coming future, there is need of integrated wireless service with high speed satellite broadband and multifunctional indoor/outdoor antennas. Radio over fiber is one of the most favorite candidates to meet all these requirements of future multifunctional integrated wireless communication. Due to planer profile, small size and low cost patch antennas are most favorite to use for multi- frequency applications. In this paper, we present system level design for future multifunctional radio over fiber network. Under FTTH (Fiber To The Home) technology, it will be possible to use multi-frequency applications on single fiber medium. Firstly, we designed S band circular patch antenna (2.5 GHz) and Ka band (29 GHz) horn antenna. Circular patch antenna performance is estimated with different substrate height. After getting S parameters and far-field results, we did modeling of Radio over Fiber system over (10 Km) with same parameters from antenna results.
文摘As the infrared technology continues to advance, there is a growing demand for multispectral detectors for advanced IR systems with better target discrimination and identification. Both HgCdTe detectors and quantum well GaAs/AlGaAs photodetectors offer wavelength flexibility from medium wavelength to very long wavelength and multicolor capability in these regions. The main challenges facing all multicolor devices are more complicated device structtures, thicker and multilayer material growth, and more difficult device fabrication, especially when the array size gets larger and pixel size gets smaller. In the paper recent progress in development of two color HgCdTe photodiodes and quantum well infrared photodetectors is presented. More attention is devoted to HgCdTe detectors. The two color detector arrays are based upon an n P N (the capital letters mean the materials with larger bandgap energy) HgCdTe triple layer heterojunction design. Vertically stacking the two p n junctions permits incorporation of both detectros into a single pixel. Both sequential mode and simultaneous mode detectors are fabricated. The mode of detection is determined by the fabrication process of the multilayer materials. Also the performances of stacked multicolor QWIPs detectors are presented. For multicolor arrays, QWIP’s narrow band spectrum is an advantage, resulting in low spectral crosstalk. The major challenge for QWIP is developing broadband or multicolor optical coupling structures that permit efficient absorption of all required spectral bands.
文摘This letter reports the development of a 50MW S-band klystron in the Institute of Electronics, Chinese Academy of Sciences (IECAS). It adopted a structure of six-cavity and single output window. Under conditions of an RF (Radio Frequency) pulse width of 4μs, a beam voltage of 305.9kV and a beam current of 368A, the peak output power has achieved 51.4MW with an efficiency of 45.6% and a gain of 54dB.
基金supported by the National Natural Science Foundation of China (90916007)
文摘In this paper, modified two-dimensional peri- odic lattice materials with local resonance phononic band gaps are designed and investigated. The design concept is to introduce some auxiliary structures into conventional pe- riodic lattice materials. Elastic wave propagation in this kind of modified two-dimensional lattice materials is studied us- ing a combination of Bloch＇s theorem with finite element method. The calculated frequency band structures of illus- trative modified square lattice materials reveal the existence of frequency band gaps in the low frequency region due to the introduction of the auxiliary structures. The mechanism underlying the occurrence of these frequency band gaps is thoroughly discussed and natural resonances of the auxiliary structures are validated to be the origin. The effect of geo- metric parameters of the auxiliary structures on the width of the local resonance phononic band gaps is explored. Finally, a conceptual broadband vibration-insulating structure based on the modified lattice materials is designed and its capabil- ity is demonstrated. The present work is anticipated to be useful in designing structures which can insulate mechanical vibrations within desired frequency ranges.
文摘In this paper,we present the general design methods and parameter measurements of a 1-k W solidstate radio frequency(RF) power amplifier at 2856 MHz,for the soft X-ray free electron laser facility.Three-stage amplification with a 4-way combination is used.An RF switch module is integrated with the solid-state RF power amplifier to convert the continuous wave(CW) signal into pulse signal,with adjustable pulse width.The power gain is measured at 57.7 d B at 60 d Bm output.The RF phase noise,which is measured by the low-level RF system,is\0.015 degree(RMS),while the pulse frontier jitter is\5 ns.
文摘This letter introduces the design ideas, simulation and test results of an S-band klystron with bandwidth of 11%, which was developed by the Institute of Electronics, Chinese Academy of Sciences (IECAS). On the peak power level of 800 kW, the efficiency of klystron is more than 30%; the gain is more than 41 dB; the equal-driving relative instantaneous bandwidth is over 11%; the average power is larger than 8 kW, and the power fluctuation within bandwidth is less than 1.5 dB.
文摘为了解决微波无线输能系统中微波源的小型化和高效率需求,提出了一种高效谐波调谐功率振荡器的设计方法,振荡器由晶体管、谐波控制网络、反馈网络和负载网络组成。首先,通过调谐晶体管谐波阻抗以减少漏极电压与电流波形的重叠,从而提高其效率;其次,反馈网络与负载网络使用仿真获得的数据合成,两者可独立设计,避免了反馈回路对振荡器输出效率的影响。使用Cree CGH40010F GaN HEMT设计并制作了一款工作在S波段的高效功率振荡器,测试结果表明振荡器在2.445 GHz下成功实现了41.7 dBm的输出功率和79.9%的直流到射频(direct current to radio frequency,DC-RF)转化效率,在偏移载波1 MHz处,相位噪声低至-136 dBc/Hz。该功率振荡器性能优越,在微波无线能量传输系统中具有良好的应用前景。
