KNU Students Design High-Accuracy AM-FM Radar With Active Reflector Using NI AWR Software
Founded in 1946, Kyungpook National University (KNU) is a national university in South Korea. The Department of Electronic Engineering provides professional engineers focused on advanced research and development in the 21st century and to contribute to industrial competitiveness and national economics. The objective of the EE program is to prepare students for successful careers in a dynamic industry and to meet the needs of an industrial sector for working professionals. The department furthers educational and research capabilities through enhanced cooperation with regional industries and strategic specialization to meet the technological demands of a knowledge-based society.
The Design Challenge
The student design team at KNU set out to design a practical ranging system with millimeter-accuracy using AM-FM radar combined with active reflectors. The AM-FM radar used narrower bandwidth as compared with other methods and the frequency translating active reflector was used to significantly reduce the phase detection ambiguity in AM radars related to interference or multipath signal reception.
The design team chose NI AWR Design Environment, specifically Microwave Office circuit design software, for this unique, high-accuracy AM-FM radar. The system consisted of two parts. One part was the base module (BM) AM-FM radar and the other was the tag module (TM) active reflector. An amplitude-modulated and frequency-modulated 10.5 GHz signal was transmitted through the TX antenna of the BM and received by the RX antenna of the TM at the target location. The TM converted the center frequency of the received signal from 10.5 GHz to 8.5 GHz with the help of a 19 GHz STALO and retransmitted the filtered and amplified signal using the TX of the TM. Finally, the BM received the 8.5 GHz AM-FM signal and demodulated it into the phase-delayed signal, which was produced by the envelope detector, and also into the beat signal with the help of the frequency mixer. The combination of the phase difference and the beat frequency enabled the calculation of the absolute distance of the target with high accuracy.
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