The Detection and Location of Buried Metallic and Plastic Targets

A quasi-optical grid array low noise amplifier (LNA) operating over a bandwidth of several GHz centered at 94GHz is proposed. The GaAs resonant tunneling diode (RTD), a two-terminal device, is selected as the active semiconductor element. Because a two-terminal device will be used, a reflection amplifier mode of operation, as opposed to the transmission amplifier mode, will be employed. The LNA grid array will be constructed of a tiled pattern of several hundred MMIC devices each containing hundreds of unit cell RTD reflection amplifiers. The reflecting quasi-optic grid LNA is intended for application on passive millimeter wave imaging cameras where it would overcome the effects of losses in the camera optics to reduce the effective system noise temperature. On Phase I, single-device RTD's will be designed an fabricated. They will be tested for DC characteristics and for RF negative resistance and reactance. The unit cell reflection amplifier element will be designed around this RTD element, then the baseline design for the MMIC will be produced on Phase II, the unit cell amplifier will be fabricated and tested, then the MIMICs will be produced, and the full grid array constructed. Development of techniques for suppression of oscillations will be an important task on the project. The LNA grid amplifier which we will develop would have for its primary application the millimeter wave focal plane array passive imaging system. These systems have a great potential demand in civilian and government applications for contraband detection.