Microw(h)att?! Ultralow-Power Six-Port Radar

Journal
IEEE microwave magazine  
Volume
19
Issue
1
Start Page
91
End Page
98
Citation
IEEE Microwave Magazine 1 (19): 91-98 (2018)
Publisher DOI
10.1109/MMM.2017.2759640
An ultralow-power, 24-GHz six-port radar was designed during the annual student design competition (SDC) at IEEE Microwave Theory and Techniques Society (MTT-S) 2017 International Microwave Symposium (IMS) in Honolulu, Hawaii. The operation principle of the system presented involves a single-tone Doppler radar operating at a frequency of 24 GHz, with an interferometric evaluation using a six-port structure. A voltage-controlled oscillator (VCO) generates the sinusoidal RF signal, which serves as both a reference and transmit (Tx) signal, using a reference coupler and a 90 degree hybrid as the Tx/receive (Rx) isolator. This transmitted signal is reflected by the target and finally received by the antenna. To further reduce the system’s energy consumption, short pulses of the Tx signal are used rather than a continuous signal. The generated RF output signal is fed to a reciprocal radar coupler, which separates the Tx and Rx paths and so allows the use of a single antenna.