| Summary: | 碩士 === 國立交通大學 === 電信工程研究所 === 101 === This thesis presents a new type of mechanical steering amplitude detector, operating at 2.4 GHz. The system, which can determine the direction of DUT (device under test), is automatically controlled by computer program. Using the configuration of modern mono-pulse radar system, this work uses two Yagi-Uda antennas as receiving antennas. Sum and difference patterns are obtained after rotating the receiving antennas and the signal processing by rat-race ring. It is proved mathematically and confirmed numerically that the difference between two channels will have a maximum while the boresight of receiving antenna is in alignment with DUT, which enables the system to determine the direction. Distinct from conventional configuration utilizing two independent channels for sum and difference, this research exploiting a microwave switch to combine sum channel and difference channel in different time division, and thus the inaccuracy of circuitry fabrication in two channels can be avoided. Moreover, this method can decrease the usage of microwave components such as LNA (low noise amplifier) and BPF (bandpass filter), lowering cost, and reducing power consumption. In addition, this system employs NI LabVIEW DAQ to integrate RF electronic system and mechanical scanning device, which control the pulse width modulation, RF switching, signal processing, and data display. Finally, the experiment confirms that the proposed system can calculate the direction angle of incoming wave accurately. The average measurement deviation is about 1.34 degree.
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