Radar Based Material Characterization at 145 GHz Utilizing an Ellipsoidal Reflector

Quasioptical Fresnel-based lens antenna with frequency-steerable focal length for millimeter wave radars

“…This is, for example, utilized in reflector antennas with the transmitter or the receiver in the focal spot [3,4]. Focusing is also applied in material characterization to selectively illuminate specific parts of a sample, as illustrated in [5] and [6]. Additionally, shaping electromagnetic beams finds applications in medical therapy for hyperthermia cancer treatment [7] and to enhance the range resolution of a radar system [8].…”

“…Redirecting or shaping of electromagnetic beams relies on passive components such as lenses and mirrors. Shaping through mirrors is either done by a curved mirror, as shown in [5] and [6] or by utilizing reflect arrays, which consist of arrays of microstrip patches [9], making reflect arrays thinner than curved mirrors.…”

Considering Nonsurface Scattering in Physical Optics Approximations

“…Within the field of non-destructive testing, e.g., electromagnetic waves are used to inspect radomes [1]- [5] regarding their electric properties to ensure their quality for aeronautical and automotive applications. Furthermore, the characterization of materials with free-space setups [6]- [10] is important for mobile material characterization applications which might be useful in emergency situations. An important application is the monitoring of infrastructure and building conditions [11]- [16] for the early detection of possibly disastrous cracks that are buried inside the structure and therefore are not visible.…”