They wanted you to just toss some devices arbitrarily on the mat and have it "just work". The one you discuss requires alignment, like all others -- for a reason! There's a reason the watch has a magnetic alignment setup.
I thought you might be able to use a 2D array of small loops but a little bit of modeling shows that to be a pretty dumb idea.
I thought you might be able to use a 2D array of small loops but a little bit of modeling shows that to be a pretty dumb idea.