Pulse-echo radar for short range sensing

In the past decade, advances in solid-state electronics have led to the development of pulse-echo radar that utilizes the transmission of very narrow EM pulses on the order of a few 100 ps in duration. These pulses, coupled with equally fast range gate delay circuitry and high speed samplers, allow “time of flight” sensing to be utilized for distances from 0 to 1 meter. This technology is a subset of a class of radar referred to as Ultra-Wideband radar that includes other modulation techniques such as FMCW and stepped frequency. These radar units operate at bandwidths on the order of 25% to 100% of their center frequency. In this paper, we present the principle of operation and design and testing of a prototype unit that utilizes the properties of short helical antennas. The test results obtained for its use in short range motion and proximity sensing are discussed