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RF Technologies & IOT

What is RFID?

4 Nov , 2016  

Since 1974 the barcode has been the most widely used UPC scanner in the world. Although barcodes are great, they can only be read from a very close range, and only unique to the specific type and brand of a product. With RFID chips, each product can have a unique ID and be read without being in line of sight of the reader which allows the chip to be embedded into a tracked object.  There are many different questions about topics like healthimplants, security, how they work and of course what they are, today I will answer all of those questions.

Brief History

RFID or Radio Frequency IDentification chips have been around since 1973, but the technology of using power by waves from an outside source to retransmit information was in 1945 when Léon Theremin invented an espionage tool for the Soviet Union. In 1973 Mario Cardullo’s “toll device” was the first pantented device to closely relate to the RFID we know today. Just like RFID today, it also was powered by the interrogating signal and even had 16-bit memory. Now that you know a little about where it all started, let’s get into how it works.


To understand how RFID communication works, first we have to explain RFID tags and readers.

RFID tags have two parts: an IC ( integrated circuit ) for storing and processing information, and an antenna for retreiving and transmitting data.

RFID readers are classified as one of three different types: PRAT ( Passive Reader Active Tag ), ARPT ( Active Reader Passive Tag ) or ARAT ( Active Reader Active Tag ). PRAT readers only receive signals from active tags ( battery operated, transmit only ). ARPT readers transmit interrogator signals and also receives authentication from passive tags, while ARAT readers use active tags awoken with an interrogator signal from the active reader.

In most cases, an RFID reader device sends a signal via radio signals to the RFID tag and the data is received through the tags’ antenna. Then, the tag uses the power obtained from those radio signals to take what data it has in its’ memory and send it back to the reader. In cases like this one where the tag has no power source except the radio signal it receives, the range is lower because of the lack of power. If the tag is powered then it can transmit the data back to the reader much farther.


The diagram above shows passive, semi-passive and active RFID tags. As you can see, the passive tag must have power from the reader to send back the information. The semi-passive tag has its’ own power but still waits to be initialized by the transmitter. Lastly, the active tag has its’ own power source, and it can send a signal whenever it wants to the transmitter without being prompted for data.

What Is It For?

RFID is a very useful technology because of the minimum amount of power needed for the tag. With most RFID technologies requiring almost no power for the tag to work, it is very self-efficient and long-lasting. Here is a list of just some of the popular uses for RFID technology:

  • Access management
  • Tracking of goods
  • Tracking of persons and animals
  • Toll collection and contactless payment
  • Machine readable travel documents
  • Tracking sports memorabilia to verify authenticity
  • Airport baggage tracking logistics
  • Timing sporting events


While there are many benefits to implementing RFID chips in every way possible, there are many concerns about the safety of the technology, mainly security. If you search for RFID you are sure to find a lot of articles focusing on the scary security disadvantages than any of the great advantages out there. Take for example, RFID chips embedded into your skin. If everybody had RFID tags in their skin, and all products in stores were uniquely tagged with an RFID chip, we could in theory walk in with nothing, and walk out with a full cart without taking out a credit card, or even stopping at a register. Sounds pretty awesome right? For some this is a great idea, but for others this poses a huge security risk.


There are already many methods for making sure your information is not leaked by someone attempting to track your RFID tag or any other kind of unauthorized reading. One way is challenge-response authentication ( CRA ) which uses software to ask for a cryptographically coded response from the tag. Other ways use what is called “shielding” which only works with some RFID frequencies, and uses thick metal cases, ( like the one shown above for wallets ), around the RFID tags to protect them from the long range readings.


In many ways, RFID can be used in the medical field as a great way to identify patients quicker in emergency situations. Finding out previous illnesses or allergies when a patient has nobody there to speak for them can be life changing and all done by an RFID tag. Although this implementation seems like a great solution, sometimes the radio wave signals could get in the way of the medical devices already implanted into a patient, and therefore RFID tags are not used yet.

Since the technology around RFID tags and readers continues evolving, engineers in the medical device field must be more aware of the potential for interference with pacemakers, implantable cardioverter defibrillators ( ICDs ), and other electronic medical devices.


RFID could be your next credit card, passport, insurance card and many more. Some things about RFID are yet to be “ironed” out for security and healthcare purposes, but in the near future this technology could be much more common. If you look around today you can already find RFID being used in inventory tracking, logistics, attendee tracking, kiosks, libraries and many more.


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Firmware Engineer at MikroElektronika from Oregon with a passion for learning and programming.