Detection of trapped survivors using 270/400 MHz dual-frequency IR-UWB radar based on time division multiplexing

Being capable of detecting vital signs of human beings, impulse radio ultra wideband (IR-UWB) radar can be applied to search and rescue (SAR) operation in post-disaster scenarios to detect trapped survivors under collapsed buildings. In the application, IR-UWB radar systems with a low center frequency are commonly used to guarantee good penetrability. These systems transmit pulses with nanosecond width. So they have relatively low range resolution, which in turn impacts their performance of detecting the vital signs. To cope with the problem, a dual-frequency IR-UWB radar system is developed. The system combines two IR-UWB radars with different center frequencies, namely 400 MHz and 270 MHz, and utilizes time division multiplexing, composite antenna array and novel signal processing techniques to ensure its compatibility and performance. Experimental results are also presented to show the system's advantages over single-frequency IR-UWB radar systems.