| 摘要 |
The proposed switching heterodyne radiometer contains a microwave antenna, a directional coupler, a balanced mixer, a low-frequency oscillator, a microwave heterodyne, a power divider, a balanced modulator, a controlled attenuator, and an intermediate-frequency signal amplifier that is connected in series with a square-law detector with a low-pass filter, a selective low-frequency signal amplifier, a synchronous detector with a low-pass filter, and a recording unit. Additionally, for the purpose to increase accuracy in measuring microwave noise signals being received, the radiometer contains an automatic switch, a reentrant waveguide loading element, a reflector, a phase detector, an intermediate-frequency oscillator, an additional controlled attenuator, and a low-pass filter. The output of the low-frequency oscillator is connected to the control input of the synchronous detector. The output of the heterodyne is connected to the first input of the balanced mixer, via the first branch of the power divider, and the input of the balanced modulator via the second input of the power divider. The output of the balanced modulator is connected to the input of the directional coupler. The input of the heterodyne is connected to the output of the phase detector via the low-pass filter. The first input of the phase detector is connected to the output of the intermediate-frequency oscillator, and the second input is connected to the input of the intermediate-frequency signal amplifier. The inputs of the attenuators are connected to the output of the intermediate-frequency oscillator, and the outputs are connected to the corresponding control inputs of the balanced modulator. The first input of the switch is connected to the output of the antenna, and the second input is connected to the output of the reflector via the reentrant waveguide loading element . The output of the switch is connected to the second input of the balanced mixer via the directional coupler. The control input of the switch is connected to the output of the low-frequency oscillator.
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