From their conclusion:
The helmets amplify frequency bands that coincide with those allocated to the US government between 1.2 Ghz and 1.4 Ghz. According to the FCC, These bands are supposedly reserved for ''radio location'' (ie, GPS), and other communications with satellites (see, for example, [3]). The 2.6 Ghz band coincides with mobile phone technology. Though not affiliated by government, these bands are at the hands of multinational corporations.
