Steel and other materials can block RFID signals and "detune" RFID antennas, preventing them from using the frequency they are supposed to use, according to Stevens. RuBee signals can go through steel, water and other materials because they use very long wavelengths with "near-field" communication, he said.

RuBee uses frequencies in the kilohertz range, far below those typically used for radio communications, where it's easier to use magnetic than radio signals, Stevens said. The wavelengths used in a typical RuBee network are about 1.5 miles (2.4 kilometers) long, while the wireless links between tags and base stations typically span less than 50 feet. With less than one wavelength between the elements of the network, the signals can penetrate materials more easily.

Another advantage of low frequencies and long wavelengths is low power consumption, according to Visible Assets. RuBee tags have been proven in the field to last several years on one coin-sized lithium battery, the company said.

Visible Networks, founded in 2002 and based in Chatham, New Hampshire, makes its own RuBee chips and licenses the technology to other vendors. Epson Seiko makes RuBee tags, and gunmaker Sig Sauer builds tags into guns for use with tracking systems. Visible's chips range in price from a few dollars to more than US$100, depending on how specialized they are, Stevens said. The company has demonstrated RuBee with steel and water in a YouTube .

The company licenses RuBee technology on a fair, reasonable and non-discriminatory basis, as required for IEEE standards, Stevens said. He expects the completion of the standard to expand the RuBee market. Most countries afford a wide latitude for use of the bands where RuBee operates, he said.