摘要
分别对前后两级均有镜频抑制、仅前级或仅后级有镜频抑制以及两级均无镜频抑制4种情况下二次变频系统的噪声系数进行了研究,从噪声系数定义出发给出4种情况下系统噪声系数计算公式;特别指出,在一般情况下,仅单级有镜频抑制的情况将导致系统的噪声系数增大约3d B,两级均无镜频抑制的情况将导致系统的噪声系数增大约6d B。同时给出一个Ka频段二次变频组件研制实例,实测结果与理论分析结果一致。
The noise figures of the two-stages frequency conversion system which both stages are with or without image rejection, as well as either stage has image rejection are studied respectively in this paper. The formula for calculating the system noise figure is given for each situation based on the definition of noise figure. In particular,the system with only one- stage image rejection will lead to the noise figure about 3dB deterioration, and the case which has no image rejection will re- sult in the deterioration of noise figure approximately 6dB. A Ka band dual conversion type receiver is developed for valida- tion. The measured noise figure is consistent well with the theoretical analysis.
出处
《空间电子技术》
2015年第5期63-66,共4页
Space Electronic Technology
关键词
二次变频系统
噪声系数
镜频抑制
Two-stages frequency conversion system
Noise figure
Image rejection
