Range Finding by Using NRD Guide Pulse Radar Front-End at 60 GHz

An NRD guide pulse radar front-end was fabricated for level sensor applications at 60 GHz. Main emphases were placed on circuit configuration and digital signal processing of multi-reflection for short range detection. Typically, an oscillation power is divided by a junction circuit and is introduced into two parts. One is for transmitter, and the other is for LO wave to construct hetero-dyne detection in receiver and the frequency of the former is up-converted so as to be different from the frequency of the LO wave, and thus, an amplifier is installed in the transmitting side due to low power of the up-converted millimeter-wave. In this paper, we proposed a new circuit configuration, which consists of a Gunn oscillator with two output ports to eliminate a junction circuit, a direct pulse-modulator to obtain a high level transmitting power without an expensive millimeter-wave amplifier, and a filter-based down-converter with an up-converter as a local oscillator. Multi-reflection between the radar front-end and target was removed by introducing an FPGA-based digital signal processing including high-speed counting, memorizing, and averaging. Good range finding was performed because the error was less than 1 % for the distance from 2 m to 40 m