Feasibility Study on Optically Transparent Cylindrical Dielectric Resonator Antennas Integrated in an Enclosed Light Bulb Using Doppler Based Radar for Human Presence Detection
M. Truong (TU Delft - Electrical Engineering, Mathematics and Computer Science)
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Abstract
This thesis will focus on an 24 GHz indoor human presence detection radar with an optically transparent dielectric resonator antenna (DRA) applied in an enclosed light source. The DRA was studied extensively by simulations and measurements and demonstrated to suffer from blind spots for radar implementation because of the light bulb housing. To apply a DRA for the presence detection, one should do measurements on the radiation patterns of the DRA to match the DRA to its housing environment. A Frequency Modulated Continuous Wave (FMCW) radar was studied because of its possibility to detect almost static and moving humans.
Simple waveforms such as the ramp and triangular waveform are used to obtain a beat frequency for presence detection. To linearize and remove the temperature and chip sample dependence of the BGT24MTR11 radar transceiver, a phase locked loop (PLL) was used based on the ADF4159 chip. The PLL was designed to have a loop bandwidth above 200 kHz and phase margin above 70 degrees, to reduce the frequency overshoot and have a relative fast lock. The system was tested and generated sweeps successfully for slow ramps, but failed on operating in the proper sweep bandwidth for ramps faster than 10 ms. The limitation on sweep time, lower transmit power and lossy circuitry were factors which made the radar system not suitable for human motion detection.