I think Cormac was interested in the technology behind the blurb. At the kind of frequencies that the unit is monitoring antennas are usually huge (wavelengths in hundreds or thousands of metres) and small antennas (in wavelength terms) often have unusual radiation/reception patterns which would make it difficult to work out where the signal came from.
Like nikoshepherd, I wonder if ferrite antennas are used, but if there are only two then directivity would be tricky. Ferrites tend to have two strong nulls and two strong peaks in opposite directions. So if you had two ferrites at right angles you might get a good signal off one and almost none off the other. This would only give you (for example) a North or South direction with no way of knowing which it was.
I suspect that there’s something more than just ferrite antennas in the ‘block’. Mine gets warm to the touch which suggests there’s something significant going on inside it (active antennas of some sort?) A couple of ferrite antennas with attached receivers wouldn’t generate that much heat.