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近年来,由于国际卫星通讯、远程雷达,射电天文学,深空间探测和遥测技术的极速发展,在微波范围内,对于高灵敏度接收机的要求异常强烈。例如,在卫星通讯中,卫星一般处在几百公里到40000公里的高空,由于本身运载能力的限制,只有几百毫瓦到几十瓦的发射功率,因此发射到地面的信号十分微弱,仅在-70dBm～-140dBm之间。要可靠地接收这些来自外层空间的信号,必须要保证足够高的G/T(天线增益与
In recent years, due to the rapid development of international satellite communications, long-range radar, radio astronomy, deep space exploration and telemetry, the requirements for high-sensitivity receivers are extremely high in the microwave range. For example, in satellite communications, satellites are generally in the high altitude of several hundred kilometers to 40,000 kilometers. Because of their limited carrying capacity, only a few hundred milliwatts to tens of watts of transmitted power, so the signal launched to the ground is very weak, only Between-70dBm ~ -140dBm. To reliably receive these signals from outer space, it is necessary to ensure a sufficiently high G / T (antenna gain and