Re: Denim blockers?
>They've got flat arms and heads?
Yes, in relation to the frequencies of RF used. From the MIT paper:
The challenge in using RF to capture a human figure is that not all body parts reflect the signal back to the sensors. Specifically, at frequency ranges that traverse walls, human limb curves act as ideal reflectors; hence, they may deflect the signal away from the sensors rather than back to them. (This is because RF signals that traverse walls have a wavelength of multiple centimeters, which is larger than the surface roughness of human body parts, causing each part to act as a perfect reflector [Beckmann and Spizzichino 1987].)
So, it is the geometry of the body, not the presence of blood vessels etc that this system works on.