Im looking to design a syystem that detects (location and identification) multiple rfid tags on a table top. Im quite new to rfid design and, i was hoping someone might point me in the right direction.

What i know so far:

  • RFID readers are quite expensive and it would be naive to have multiple rfid readers to detect multiple points on table

  • Since all RFID tags have a coil that is responsible for emitting power to the tags Then why not get a massive coil inside the table that powers all the tags and one reader that sequentially reads each response.

Im quite new to this field and any documentation that would further my understanding of "multiple tags one reader" RFID system would be greatly appreciated



The term that you are looking for is Anti collision.

"In the context of RFID, anti-collision refers to different ways to keep radio waves from one device from interfering with radio waves from another device. RFID readers may make use of anti-collision algorithms to enable a single reader to read more than one tag in the reader's field". This is taken from here

Generally 900 MHz is the preferred choice when it comes to high read rate. The 13.66 MHz ISO 14443A/B, and 15693 standards include anti-collision in their specifications. But the manufacturer decides whether to implement anti-collision or not.

  • 2
    \$\begingroup\$ If you want high read rate and multiple tags you go with 900 MHz RFID. Several hundred tag reads per second at 20m range is normally enough for most people. \$\endgroup\$ – Andrew Mar 13 '17 at 9:15
  • \$\begingroup\$ Thanks alot, i found the information quite useful, ive read the document and i believe i now understand the theoretical aspect of tag collision. but i'm still a bit confused on the process required for one reader to energize multiple tags. Is it the same process that an rfid reader energizes one tag (by sending a radio wave), that multiple tags are also energized, but with the reader in this case generating a radio wave so more tags can be interrogated?. \$\endgroup\$ – Ahmed Mar 13 '17 at 14:58
  • \$\begingroup\$ A better way to word my misunderstanding is : are the transmitting antenna in a multi tag system the same as the receiving antenna? and if so how would you multiplex a signal that goes in both directions?. \$\endgroup\$ – Ahmed Mar 13 '17 at 15:21
  • \$\begingroup\$ There are two types of tags classified by how they are excited. They are Active & Passive. The concepts are same for a single chip and multi chip scenarios \$\endgroup\$ – mic Mar 14 '17 at 4:55

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