The use of High-Frequency MicroWaves (HFMW) for high-resolution imagery has gained interest over the last
years. Very promising in-depth applications can be foreseen for composite non-metal, non-polarized materials,
widely used in the aeronautic and aerospace industries. Most of these materials present a high transparency
in the HFMW range and, therefore, defects, delaminations or occlusions within the material can be located.
This property can be exploited by applying 3-D HFMW imaging where conventional focused imaging systems
are typically used but a different approach such as Synthetic Aperture (SA) radar can be addressed.
This paper will present an end-to-end 3-D imagery system for short-range, non-destructive testing based on a
frequency-modulated continuous-wave HFMWsensor operating at 100 GHz, implying no health concerns to the
human body as well as relatively low cost and limited power requirements. The sensor scans the material while
moving sequentially in every elevation plane following a 2-D grid and uses a significantly wide beam antenna
for data acquisition, in contrast to focused systems. Collected data must be coherently combined using a
SA algorithm to form focused images. Range-independent, synthetically improved cross-range resolutions are
remarkable added values of SA processing. Such algorithms can be found in the literature and operate in the
time or frequency domains, being the former computationally impractical and the latter the best option for
in-depth 3-D imaging. A balanced trade-off between performance and image focusing quality is investigated
for several SA algorithms.