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How Are RFID Tags Read?
Is this a simple or complex process?
It is definitely not simple. There is a great deal of complexity that occurs as invisible radio waves travel to and from an RFID tag, but let me try to give you a non-technical explanation.
There are essentially two types of radio frequency identification tags. One is called passive RFID because it has no power source. Its chip receives power by harvesting the energy emitted by a reader antenna and reflecting back a signal. Imagine two boats on an ocean on a dark night that want to communicate with each other but have no radio. One captain shines a bright light toward the other. When the captain of the boat without a light wants to communicate, he or she holds up a mirror to reflect back the light, or keeps the mirror down. In this way, the captain with the mirror could send Morse code to the other captain. Active tags, on the other hand, are more like cell phones. They have batteries or other sources of energy, and can broadcast their information, which is then received by reader antennas.
If you would like a more technical explanation of how tags and readers communicate, I provided one in response to a question posed earlier this year (see How Does an RFID Transponder Work?).
—Mark Roberti, Founder and Editor, RFID Journal
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