Subjects: Geosciences >> Space Physics submitted time 2017-03-10
Abstract：三极管倍频器是根据晶体三极管的非线性特性，得到输入信号的各次谐波，然 后通过带通滤波器选出所需要的频率，从而实现输入信号的倍频。文中详细阐述了三极 管倍频电路的设计，实现了对 10MHz 输入信号的四倍频，通过电路测试，结果证明输 出信号的相噪没有明显恶化，在 1MHz 带宽内相噪优于-80.87 dBc/Hz，在 100kHz 内杂 散抑制可达-79.54dBc/Hz，满足设计需求。
Peer Review Status:
Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2017-01-22
Abstract： This study use the wind data from the observation of China Langfang (39°N，117°E) meteor radar during the 1 April 2012 to 31 March 2013 to investigate the features of the mesospheric and lower thermospheric mean winds within 80-100 km altitude regions. The results show that the mean zonal winds and mean meridional winds both have obviously seasonal variations. During the winter, eastward winds prevail in the MLT ranges, which is strong in mesosphere and decrease versus increasing altitude. In the summer, westward winds dominate in mesosphere, and decrease along with increasing altitude, then turn to the strong eastward in lower thermosphere. The wind evolution in the spring and autumn are the transition characters between the summer and winter. The mean meridional winds are southward in summer and northward with sometimes reversal in winter, in general. The above main seasonal variations of mean winds are captured largely by the simulation of WACCM4 model and HWM93 model. WACCM overestimates the winds, but HWM93 underestimates the winds.
Peer Review Status:Awaiting Review
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