The idea that radio waves could be used to transmit unique information
is not new. During World War II, German planes returning to base would
routinely roll slightly to change the radio signal sent to the ground.
In doing so, those men reading the radar screen would be able to
discern the German planes from the planes of the Allied Forces.
Additionally, the British developed a transmitter for their planes.
After receiving a signal from the ground, the transmitter would send a
signal identifying itself as a British plane.
The leap to individual identification came about in the late 1970s when
researchers at the Los Alamos National Laboratory developed two unique
systems of identification, one for nuclear materials and another for
cows. Trucks carrying nuclear materials were equipped with a
transponder. When the truck approached the gate of the facility, the
transponder sent data, including the identification of the truck, the
materials, and the identification of the driver, to the facility. Upon
checking this information, the truck was allowed to pass through the
gates. The second system, for cows, was needed to make sure that an
individual cow did not receive more hormones or medication than
necessary. To do this, a tiny transponder was injected under the skin
of the cow. When a reader passed over this transponder, it reflected
back a signal. The technology of radio waves to actively identify an
object such as truck carrying nuclear materials, or to passively
identify a medicated cow are the same technologies that are used in
RFID today. 1