Performance Evaluation of Millimeter-Wave Wearable Antennas for Electronic Travel Aid

The aim of this article is to identify and evaluate the main limitations of several wearable antennas when applied to different collision avoidance situations to help visually impaired people. The analysis is conducted at a medium distance (1–2 m, which is in the order of hundreds of wavelengths) for obstacle detection, as well as in the short distance (10–30 cm, which is in the order of tens of wavelengths) when advanced imaging techniques, based on synthetic aperture radar (SAR) exploiting natural movement, are applied to generate an image of the surrounding. For this purpose, different measurements are accomplished with stepped-frequency and frequency-modulated devices, and subsequent error metrics are defined and applied, highlighting their main limitations for those test scenarios.