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针对多台高功率微波源组阵进行功率合成时相位离散分布的问题,基于数理统计方法对合成阵元相位误差呈正态分布情况下阵列合成效率进行了理论分析,提出了相位误差有界分布下其概率密度函数的表达式,修正了相位分布标准差较大时微波功率合成效率的理论计算公式。为验证修正后的理论公式正确性,使用数值模拟方法计算了合成阵列天线阵元激励信号相位误差呈正态分布下的空间功率合成效率,计算结果表明,数值模拟结果与理论分析给出的计算结果吻合得较好,修正后空间功率合成效率公式的预估精度得到有效提高。 相似文献
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在对空气-地面分层媒质中微波传播与反射理论分析的基础上,研究了地面反射对测点处不同垂直高度电场分布的影响,推导得到了电场分布随垂直高度变化曲线的振荡周期理论计算公式,针对高功率微波源总功率测量,提出了一种双天线阵列抑制地面反射影响的高功率微波辐射场测量方法,通过数值计算、低功率连续波实验、大功率短脉冲实验等进一步验证了理论公式的正确性,以及双天线阵列抑制地面反射影响方法的可行性。结果表明,与单接收天线相比,双天线阵列法可将地面反射影响由原有的4dB降低至0.6dB以下,从而有效减小了高功率微波辐射场的测量不确定度,为高功率微波源总功率准确测量奠定了基础。 相似文献
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阐述了提高微光成像系统低照度探测极限的本质是需保证成像系统对光信号足够的积累时间,从理论上指出降低CCD温度实现低照度探测的局限性和实现技术的复杂性后,提出在光阴极与光电子接收器(屏靶)之间耦合一个磁镜装置(即微通道电子瓶板结构)作为一种新的光电子接收器,即可有效保证图像信号的积分时间,提高成像系统的探测信噪比,达到拓展微光成像系统低照度探测极限的目的。论证了磁镜场的物理机理,并用计算机模拟显示出了预期的结果。该方案在常温下能实现当前微光成像系统低温探测灵敏度极限10-11lx的目标。 相似文献
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Anomalous propagation conditions of electromagnetic wave observed over Bosten Lake,China in July and August, 2014 下载免费PDF全文
Atmospheric duct is a common phenomenon over large bodies of water, and it can significantly affect the performance of many radio systems. In this paper, a two-month(in July and August, 2014) sounding experiment in ducting conditions over Bosten Lake was carried out at a littoral station(41.89°N, 87.22°E) with high resolution GPS radiosondes, and atmospheric ducts were observed for the first time in this area. During the two months, surface and surface-based ducts occurred frequently over the Lake. Strong diurnal variations in ducting characteristics were noticed in clear days. Ducting occurrence was found at its lowest in the early morning and at its highest(nearly 100%) in the afternoon. Duct strength was found increasing from early morning to forenoon, and reaching its maximum in the afternoon. But contrarily, duct altitude experienced a decrease in a clear day. Then the meteorological reasons for the variations were discussed in detail, turbulent bursting was a possible reason for the duct formation in the early morning and the prevailing lake-breeze front was the main reason in the afternoon. The propagation of electromagnetic wave in a ducting environment was also investigated. A raytracing framework based on Runge–Kutta method was proposed to assess the performance of radio systems, and the precise critical angle and grazing angle derived from the ray-tracing equations were provided. Finally, numerical investigations on the radar performance in the observed ducting environments have been carried out with high accuracy, which demonstrated that atmospheric ducts had made great impacts on the performance of radio systems. The range/height errors for radar measurement induced by refraction have also been presented, too, which shows that the height errors were very large for trapped rays when the total range was long enough. 相似文献
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This paper presents the results of research on microwave breakdown in air, it includes the experimental study and the theoretical analysis. The experimental study has been done in a waveguide with a frequency of 9.37GHz, the peak power up to 200kW, pulse width from 0.3 to 2.0μs. The repetition rate of microwave source is from single pulse to 970 pulse per second. The process of the breakdown of repetition pulse has also been recorded for a burst of ten pulses. A theoretical model for breakdown threshold is presented also. The theoretical are in good agreement with the experimental ones. 相似文献
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通过对半导体材料中载流子迁移率的特性分析,在原HPM探测器的基础上,提出了探测器中半导体传感器的新设计,使探测器的检测灵敏度提高一个量级;同时研制成功S波段HPM探测器。在传感器的加工方面采用了新的工艺,并对电源进行了改进,使之功能完善、使用简单、具有实用性。其电源偏压在40V时,X波段的探测器在60kW时输出检测脉冲信号幅度高达9V,S波段的探测器在600kW时输出检测脉冲信号幅度高达10V,可适用于10~500ns脉宽的HPM功率测量。 相似文献