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131.
利用正交小波包变换的高信号时频分辨特性引入小波包能量特征提取法,用于五类典型大地目标的特征提取和距离可分性测度计算。结果显示,小波包能量特征提取法提取的五类典型大地目标特征具有更好的可分性。将小波包能量特征提取法与径向基函数网络相结合,提出了一种大地目标辨识算法。仿真实验表明,对于分解层次m=5,信噪比SNR≥0dB,五类典型大地目标能完全辨识。表明该大地目标辨识方法在一定条件下是可行的,具有强的抗噪声干扰能力。 相似文献
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A virtual loop model was built by the transmission analysis with virtual ground method to assist the negative-resistance oscillator design, providing more perspectives on output power and phase-noise optimization. In this work, the virtual loop described the original circuit successfully and the optimizations were effective. A 10 GHz high-efficiency low phase-noise oscillator utilizing an InGaP/GaAs HBT was achieved. The 10.028 GHz oscillator delivered an output power of over 15 dBm with a phase-noise of lower than -107 dBc/Hz at 100 kHz offset. The efficiency of DC to RF transformation was 35%. The results led to a good oscillator figure of merit of-188 dBc/Hz.The measurement results agreed well with those of the simulations. 相似文献
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Using a hybrid MoM-UTD formulation, this paper investigates the effects of ground-plane dimensions on the radiation fields of a slot antenna. It is shown that the radiated field strength of a slot cut in a finite ground plane is generally higher than that of a similar slot in a ground plane of infinite extent. Indeed, computational results reveal that the E-plane radiated field strength of a slot is about 3 dB higher when the ratio of the ground plane width to slot length is an even integer; and 1 dB higher when the ratio is an odd integer. In the case of the H-plane, the field strengths radiated by a slot in both infinite and finite sized ground planes are virtually identical, suggesting, therefore, that in this case, the contribution of the edge diffraction is insignificant. Results also indicate that a ground plane thickness of less than 20 mm has negligible effects on the radiation fields, as the strength of coupled fields, which is a manifestation of the effect of the finite thickness of the ground plane, is very small. As a validation, patterns computed compare favourably with experimental data available in the literature. 相似文献
138.
Ultra-wideband (UWB) is a radio technology that enables low-power-level, short-range, and wide-bandwidth communication, and it has been widely applied in personal area networks, precision geolocation, medical, surveillance, and vehicular radar systems. Since Federal Communications Commission released the unlicensed use of the UWB range (3.1–10.6 GHz), a significant attention has been paid to the development of UWB devices, particularly UWB bandpass filters. In this paper, we propose a novel UWB bandpass filter based on circular patch resonator that is grounded by via and perturbed by slits and defected ground structures. The resonator’s behaviour is analysed in detail and it is shown that its specific configuration allows a flexible control of the three lowest resonant modes, which are used to form UWB passband. To demonstrate the potential of the resonator, a UWB filter has been designed, fabricated, and measured. The filter is characterized by the insertion loss lower than 1 dB and return loss higher than 17 dB within the passband, as well as by very small group delay variation of only 0.07 ns. Also, the filter exhibits suppression higher than 19 dB up to 30 GHz, and very small overall dimensions of only 0.31λg × 0.31λg, and thus it outperforms other published UWB filters. 相似文献
139.
周期性缺陷接地结构的BP神经网络模型 总被引:2,自引:1,他引:2
缺陷接地结构 (DGS)是由光子带隙结构 (PBG)发展而来的 ,它是在微波电路的接地金属平面上人为地蚀刻出“缺陷”,改变接地电流的分布 ,从而改变传输线的频率特性。周期性缺陷接地结构 (PDGS)是一种在微波电路的接地金属平面上人为地蚀刻出周期性的“缺陷”结构 ,能够使某些频段的电磁波无法从中通过 ,存在明显的阻带特性。文中采用人工神经网络对周期性缺陷接地结构进行建模 ,将其结构尺寸和频率作为输入样本 ,传输系数参数作为输出样本 ,采用贝叶斯正则化算法对神经网络进行训练。神经网络训练完成后 ,在学习范围内将其结构尺寸和频率输入到神经网络模型 ,从输出端立即得到准确的传输系数。 相似文献
140.
高速数字电路设计的电磁干扰控制技术 总被引:2,自引:0,他引:2
分析了电磁干扰的特点,阐述了抑制电磁干扰的几种有效的方法,探讨了高速数字电路在噪声抑制方面的设计原则,对于设计高速数字电路具有一定的指导作用。 相似文献