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这种衰减校准装置是一种步进频率式的单通道并联中频替代系统。可以在1—18GHz 的频率范围内测量高达110dB 的衰减量。其精度可以达到固定频率系统的精度。由于采用两只数控频率锁定的振荡器作为信号源和本地振荡器,一只30MHz 精密的数字替代标准,以及适当带宽的闭环替代方法,因而就减少了测量时间,并简化了操作使用,在插入点,入射功率和源阻抗是由一只精密宽带功分器和一只热变电阻作微波检测元件的稳幅环路来确立的。而负载阻抗则是用一只失配很小的掩蔽衰减器来确立。测量程序可由人工控制或由一台处理数据的程控计算器控制。当淹没在噪声中的信号得以再现并且伺服环路处于平衡状态时,中频替代过程就告结束。
This attenuation calibration device is a step-frequency single-channel parallel IF alternative system. Up to 110dB of attenuation can be measured in the 1-18GHz frequency range. Its accuracy can reach the precision of the fixed frequency system. The use of two NC frequency locked oscillators as a source and local oscillator, a 30 MHz precision digital replacement standard, and a closed-loop alternative to the proper bandwidth reduce the measurement time and ease of operation, The point, the incident power and the source impedance are established by a precision broadband power divider and a thermal resistor for the stable loop of the microwave sensing element. The load impedance is to use a masking attenuator with a small mismatch to establish. Measurement programs can be controlled manually or by a programmed calculator that processes the data. When the signal submerged in noise is reproduced and the servo loop is in balance, the IF replacement process ends.