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91.
Active cancellation stealth is a smart signal blanking method, that it has become an important developing direction on modern stealth technology. In order to further explore the active cancellation stealth technology, we are considering the detection and cancellation of receiving/transmitting antenna pattern is different. Put forward active cancellation system simulation structure diagram based on MATLAB/SIMULINK, where the phased array radar system as the modelling object, and established the active cancellation stealth system mathematical model based on digital radio frequency memory (DRFM) and the radar signal processing system of the coherent video simulation model, based on linear frequency modulation and radar coherent pulse signal simulation, verified the rationality and validity of the design, as the active cancellation stealth engineering technology laid the foundation. 相似文献
92.
The purpose of this study is to summarize the application rule of half-wave signal magneto-optical modulation in azimuth measurement, and obtain the limit on modulation signal when establishing the azimuth measurement model. After analysis on the azimuth measurement system principle, the model of modulated signal are present according to Malous law, the application feasibility of the four half-wave signal magneto-optical modulation in azimuth measurement are discussed respectively, the azimuth measurement models based on mixed signal are present, and the reason why the AC signal cannot be used to establish the azimuth measurement model is analyzed. 相似文献
93.
We proposed an electro-optic modulator with two-bus one-ring (TBOR) structure to improve the extinction ratio and reduce insert loss. It has a dual output compared with one-bus one-ring structure. In addition, double-layer graphene makes it possible for the modulation in the visible to mid-infrared wavelength range. It shows that this new electro-optic modulator can present two switching states well with low insertion loss, high absorption and high extinction ratio. At , when the switching states are based on the chemical potential, and , the insertion losses of both output ports are less than 2 dB, the absorption of the output port coupled via a micro-ring reaches 45 dB and the extinction ratio reaches 14 dB. When the refractive index of the dielectric material is 4.2, the applied voltage will be less than 1.2 V, thus can be used in low-voltage CMOS technology. 相似文献
94.
近年来,电磁计算成像的理论和技术得到了广泛的研究和发展,其中基于随机场照射的微波成像引起了诸多关注.与传统成像方法的连续波照射不同,基于随机场照射的成像方法以随机照射的方式获取多组非相关的目标散射测量值,经过反演计算就能提取散射目标体的轮廓和形状等信息.基于阵列天线理论,本文理论分析并实验验证了一种最优的二维微波成像系统,能够使用最少的天线单元实现随机照射,通过最少的测量次数完成矩阵求逆并得到重建图像.该系统主要有以下两个创新点:完全随机照射的获取和成像系统最优参数的选取.与基于超材料的成像系统相比,本文通过对1 bit相位调制器随机相位调制的方式获取随机场照射,使得每个天线单元都处于工作状态,因此整个系统的能量效率更高.此外,所述单频成像系统还具有频谱效率高、结构简单、成本低等优点,在安检、室内定位等不同场景中具有潜在的应用价值. 相似文献
95.
Yoshiteru Amemiya Tomohiro Tokunaga Yuichiro Tanushi Shin Yokoyama 《Optical Review》2009,16(3):247-251
Electric-field drive optical modulators using a Si ring resonator were fabricated on silicon-on-insulator (SOI) wafers. The
fabricated resonators consisted of Si waveguides with width and thickness of 1.0 and 0.3 μm, respectively. In order to induce
the linear electro-optic (EO) effect in the Si core layer, the strain was applied by covering the layer with Si3N4 film (0.26 μm thick) deposited by low pressure chemical vapor deposition (LPCVD) at 750 °C. The vertical electric-field was
applied to the Si waveguide through the top and bottom cladding layers, and the optical output from the drop port at the resonance
wavelength was measured. At a wavelength of 1501.6 nm, the optical modulation of 33% was obtained at 200V (electric-field
at the silicon surface ∼3 × 105 V/cm, nearly the breakdown field). The resonance wavelength was shifted toward the short wavelength side by applying both
positive and negative voltages, this shift was explained by carrier concentration modulation. The linear EO effect in the
Si core layer was not observed, presumably because the strain in the Si core layer was too small. 相似文献
96.
97.
Electric field modulation spectroscopy using scanning tunneling microscopy (STM-EFMS) measurements were performed for a Si(1 1 1) surface with epitaxially-grown β-FeSi2 islands. STM-EFMS spectra acquired around the indirect energy gap of Si reproduced the photon energy peak position observed in conventional macroscopic EFMS experiments. However, a considerable discrepancy was found in the energy position of the accompanying spectral dip. We examined two possibilities for the cause of this discrepancy. The first interpretation is that the STM-‘EFMS’ spectra may simply reflect the local density of states based on essentially the same principle as that of tunneling spectroscopy. However, this interpretation is ruled out by the facts that almost identical STM-EFMS spectra are obtained also out of the regime of tunneling. The second interpretation is a spectral distortion due to a large electric field steadily built in the sample surface, which is supported experimentally by a spectral shift of the dip energy that is induced by altering the tip-induced band bending. 相似文献
98.
In situ calibration of a Michelson type, speckle-shearing interferometer: Wobbling mirror effect 总被引:1,自引:0,他引:1
In situ calibration of piezoelectric transducers in a phase stepping, Michelson type, speckle-shearing interferometer can be affected by mirror wobbling introduced by the transducers. When this happens, a modulation of the curves employed for calibration can be readily detected in imaging systems with large apertures. A calibration method that takes into account the modulation of these curves is, therefore, essential to insure the required regularity of the phase steps. A computer model of speckle-shearing interferometry is used to deal with piezoelectric non-linearities and mirror wobbling in the interferometer, and to show how the calibration curves are affected when both phenomena are present. Computer simulated and experimental results validate the calibration technique advanced here. 相似文献
99.
100.