There is a lot of technology that we use today that we don’t quite know how old it actually is. With the recent passing of Fernando Corbató, who is credited with inventing the computer password America learned that this was over 60 years old. That’s pretty old. We know that computers saw true development during World War 2 and that was not the only technology that the necessities of wartime developed. Another piece of technology that we use everyday saw its development during World War 2 and we may not realize it. That was RFID technology.


Radio Frequency Identification or RFID is something that can be found commonly in today’s world. It can be found in our vehicles to track them like with trains and airplanes or in the transponders found in our cars so we can pay tolls electronically. Anything can be tracked, from goods and merchandise to animals to people. They can be found in our payment options like credit cards or cards used on mass transit systems all over the country through contactless payment. RFID can be used to help with sporting events or to even control access to specific areas with by just touching the card to a reader.

This past decade has seen RFID technology explode as it becomes incorporated into more industries. This explosion was a result of an increase in the power of this technology as well as a decrease in costs. International standards were also developed for the technology which has also made global acceptance easier. Chances are you have something that uses RFID technology either on your person or in your car. Did you know that the technology dates back to World War 2?

War Necessitated RFID Technology

In 1935 Scottish physicist Sir Robert Alexander Watson-Watt developed a new technology that could identify the approach of planes from miles away. Despite what Neville Chamberlain said, war was on the horizon. This new technology was groundbreaking technology and would play a major role in helping the Royal Air Force stave off the Luftwaffe during the Battle of Britain and the subsequent Blitz. We know it as radar.

Radar worked fine when only German planes were coming but the Royal Air Force did begin to conduct offensive sorties into France and even into Germany. So, when the blips came onto the radar screen after a mission, how could the defenses on the ground know that the incoming aircraft were their own or were a German attack? That lack of knowledge could have devastating results.

RFID Could!

Determining the identity of those coming to your gates has been a problem that has faced leaders for centuries and moving into the air only made the problem harder. The blip of a Messerschmitt 109 looked the same as a Spitfire on early radar and so does the blip of a Lancaster bomber and a German Henkel He 177. German pilots, using their own primitive radar device, found that if they rolled their plane as they returned to base it changed the radar signal and alerted radar crews on the ground that the incoming planes were friendly.

Watson-Watt developed a better system. He placed a transmitter on each plane and when a radar signal was sent it would activate and send a return signal that would identify the aircraft as friendly. This was the first true IFF (Identify Friend or Foe) system and the first usage of RFID technology. 


Watson-Watt had actually been working on this problem since at least 1935, when he filed his first patents for new IFF technology. He was not alone. Researchers at a radar installation developed a simple reflector system that would resonate at a certain frequency which would be picked up by the radar. This solution proved to be unreliable as it required the aircraft to be at certain locations and fly in certain directions to work.

Those same researchers set out to take the next step and their next innovation was a regenerative receiver, which would amplify a radio signal and send it into a circuit which would resonate at a certain frequency. This was developed in 1939, just before the war began. It would then be sent back which would cause feedback which would be picked up by the radar. 

They were on to something with this, which they called IFF Mark I but there were two major drawbacks as the pilot had to control the feedback since a certain frequency was required and the aircraft might only be visible to some radar stations but not all in their operational area since each used its own frequency. To overcome this the pilots were given cards that listed the frequencies of all radar stations but many pilots did not change their frequencies as they moved about and some became lost and didn’t realize where they were.

Trying Again

The Royal Air Force and British Army were testing their own systems as radar installations were beginning to be deployed just before wartime. The Mark II was much more complicated allowing for switching among bands and being able to sweep through frequency ranges within those bands. No more manual tuning was required. One thousand of these sets were ordered in October 1939 from Manchester-based Ferranti (who also were pioneers in developing early commercial computers) and the first 100 were in place a month later but the rest were slow in coming. 

While not fully implemented yet the Mark II got its trial by fire in 1940 during the Battle of Britain. There were limitations as the limited number of sets in place were facing out over the English Channel, which allowed for early warning when a Luftwaffe raid was on its way but did little once those planes crossed onto land. While the 15 minutes of early warning were extremely valuable as it gave time to scramble RAF planes manual spotters were still required once the planes went off of radar to determine their target.

The Mark II still had its drawbacks as it was hard to differentiate British aircraft and enemy aircraft when they were in close proximity to each other. Upon learning this the Germans quickly adapted their tactics and worked to fit their bombers into formations of British aircraft returning home at night, meaning they could then strike with near impunity. The transponder was also installed on Spitfire aircraft following the Battle of Britain and due to the two antennas that were installed on the tail pilots noticed a decrease in top speeds and less mobility as the transponder set weighed 40 pounds. By that point the Luftwaffe did not have the same power and was devoting its resources to fighting the Soviet Union so the problem was not as glaring as it could have been.

Mark III

Mark II radar was used through 1942 but development on the next generation continued. English engineer Freddie Williams suggested that all radar operations move to one frequency therefore simplifying operations in what should have been an obvious suggestion. With the United States in the war production of this new equipment was moved to the relative safety of the United States and the Mark III and became the primary IFF system for the remainder of the war. The next generation was not introduced until late in the war and saw limited use in the Pacific Theater before the surrender of the Axis powers.

So, if you use any form of contactless payment, if you use an EZ-Pass transponder, if you stay at a hotel that uses RFID keycards or if you use anything with RFID technology remember that it helped to save the free world and defeat facism. That technology and those who developed it are true heroes.

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