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This paper summarizes over 60 years of radar system development at MIT Lincoln Laboratory, from early research on satellite tracking and planetary radar to the present ability to perform the centimeter-resolution imaging of resident space objects and future plans to extend this capability to geosynchronous range. [ABSTRACT FROM AUTHOR]

There is growing demand for the high-fidelity characterization of satellites in Geosynchronous Earth Orbit (GEO) to support Space Domain Awareness (SDA). This is particularly true for newly launched satellites, where it is necessary for satellite providers to ascertain whether components have deployed properly. Conventional wideband radar systems are capable of imaging satellites provided that (i) they have sufficient power aperture and bandwidth, and (ii) they observe enough target aspect change to generate a resolved image. While wideband radars are used routinely for characterizing satellites in Low-Earth Orbit (LEO), powerful radars with sensitivity sufficient for large GEO ranges (36,000 km or greater) are lacking. Thus, researchers often rely on more widely available high-power narrowband tracking radars for GEO characterization. In this paper, we present a novel range-Doppler-time (RDT) tensor processing technique for GEO characterization with narrowband radar. This technique encapsulates the strengths of previously proposed methods for narrowband-radar characterization at GEO, providing a generalized approach that can be applied in a variety of settings. The technique generates fully resolved 2D images of rotating GEO satellites in low-bandwidth scenarios. In cases where aspect change is limited, the technique provides detailed Doppler information for enhanced satellite status monitoring. This work presents a comprehensive quantitative analysis of the technique that considers the impact of key parameters on characterization performance. Simulated radar data, and radar data collected in a compact range on a scaled satellite model, are used to evaluate the technique. [ABSTRACT FROM AUTHOR]

Wearable devices have several benefits for the fast-growing senior adult population. However, the adoption rate of these devices by seniors is low and our understanding of their attitudes and behaviors is limited. This study explored the psychological barriers that influenced seniors' attitudes and intentions to use wearable devices by conducting mixed-methods research. Forty four members of the senior population were interviewed prior to and subsequent to using wearable devices. Next, a quantitative study was conducted using an online survey with 321 valid responses to confirm the qualitative study's findings. The results showed that perceived complexity and uncertainty were the most significant barriers that negatively impacted seniors' attitudes about their decisions to use wearable devices. Surprisingly, the results showed that perceived disability positively impacted seniors' attitudes about using wearable devices. These results provide interesting implications for both theory and practice. • Psychological barriers to seniors using wearable devices are empirically examined. • This study uses a mixed-methods research. • Perceived complexity and uncertainty are the most critical barriers that negatively impact seniors' attitudes. • Perceived disability positively impacts seniors' attitudes about using wearable devices. [ABSTRACT FROM AUTHOR]

Reviews previous presentation of an approach to a four-way hybrid ring power divider design. Way to reduce a multiport matching problem to a one-port matching problem; Optimization of the star-ring geometry; Analysis of the matched and mismatched five-port ring geometry in terms of the couplings and phase differences between the adjacent ports.