NRD guide pulse radar front-end for level sensor applications at 60 GHz

An NRD guide pulse radar front-end was fabricated for level sensor applications at 60GHz. Main emphasis was placed on circuit configuration. 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. A maximum sensing distance was found to be 120 m, while that was estimated to be 42 m in the typical pulse radar without an amplifier, and thus the high performance of the proposed radar was confirmed.