| 摘要 |
<p>PROBLEM TO BE SOLVED: To observe a high frequency observation noise signal with simple constitution and good sensitivity by synthesizing an observation signal and a reference signal by a high frequency hybrid circuit, and separating and detecting them by an intermediate frequency hybrid circuit again after they are amplified and frequency-converted. SOLUTION: A high frequency hybrid circuit 11 being 0-90 degree hybrid superposes an observation noise signal from an antenna 1 and a reference signal from reference noise resistance 2 and outputs a 90 degree-phase different signal. These signals are amplified by a low noise amplifier 4, frequency conversion is performed by a signal from a local oscillator 6 by a frequency converter 5, a band is limited by BPF 7, amplified up to signal strength capable of being detected by an intermediate amplifier 8, and input to an intermediate frequency hybrid circuit 12. The circuit 12 detects a separated observation noise signal and a reference noise signal by a diode 9, which are input to a differential amplifier 10, and a differential signal of both the signal whose mutual difference is always constant is output. At this time, since measurement of the observation noise signal is performed within the whole measuring time, resolution is high.</p> |
