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在接收UHF电视频道节目时,特别是在本地强电视信号地区接收外区的弱电视信号节目时,采用UHF窄带滤波器来提高接收系统的抗干扰性是行之有效的方法。另外,在不同方向接收多个UHF频道电视节目时,采用窄带混合器具有混合衰减小、各信号间隔离优良的特性。本文提出一种由双调谐回路组成的,采用半集中参数方法的窄带滤波器与混合器的制作方法。用这种方法制成的UHF窄带滤波器和混合器具有带内幅频特性均匀、插入损耗小、带外衰减大的优点,适宜在CATV及电视接收技术中使用。
When receiving UHF television channel programs, especially when receiving weak television signals from outside areas in local strong TV signal areas, it is an effective way to use UHF narrow band filters to improve the noise immunity of the receiving system. In addition, when receiving multiple UHF channel television programs in different directions, the narrow band mixer has the advantages of small mixing attenuation and good signal isolation. In this paper, we propose a method of making a narrow-band filter and mixer using a semi-tuned loop and a semi-focused parameter method. The UHF narrowband filters and mixers made in this way have the advantages of uniform in-band amplitude frequency characteristics, small insertion loss and large out-of-band attenuation, which are suitable for CATV and television receiving technologies.