Are Bistatic or Monostatic Readers More Effective?

By RFID Journal

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Ask The ExpertsAre Bistatic or Monostatic Readers More Effective?
RFID Journal Staff asked 11 years ago
Which is better: An RFID interrogator with four bistatic antennas, or one with eight monostatic antennas?

—Name withheld

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Bistatic antenna systems generally deliver better performance in passive ultrahigh-frequency (UHF) RFID systems, because they have separate, dedicated antennas to send and receive signals, while a monostatic system utilizes the same antenna to both transmit and receive. Monostatic readers emit a lot of energy to power up a tag, then must stop and start again in order to receive a weak signal back from the interrogator. Their sensitivity and dynamic range are generally not as good as those of a bistatic system.

The main reason for choosing a monostatic system over a bistatic system is cost. It is cheaper to use one antenna to send and receive than two. However, if your choice is between an eight-port monostatic reader, which has eight separate antennas, and a four-port bistatic reader, which also requires eight antennas, the expense is likely to be the same. So under most conditions, I would choose a four-port bistatic system over an eight-port monostatic system.

Of course, if the eight-port monostatic antenna can cover two dock doors or portals, and the four-port bistatic antenna can cover only one portal, then it might be more cost-effective to use the monostatic antenna system.

—Mark Roberti, Editor, RFID Journal

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