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Circular Polarization vs Linear Polarization for RFID Applications



What are the advantages and disadvantages of circular and linear polarization for RFID applications? Which one is better?


EM waves usually travel in two main modes i.e Linearly Polarized (Vertical or Horizontal) or Circularly Polarized (RHCP or LHCP). When EM waves propagate in a single plane either horizontal or vertical, it is called as linear propagation. And when EM waves propagate in a manner where the amplitude of the waves are constant but they rotate with time, it is called circular polarization.

Antenna polarization is very important when it comes to RFID. The reader sends out EM waves via an RFID antenna to the RFID Tag. Each polarization has advantages and disadvantages which can be seen in the table below.

Linear Polarization Circulator Polarization
Longer Read Range Shorter Read Range
Tags and the Reader need to be on the same plane and have a similar height Tags and the Reader can be on different planes at different heights
The reader needs to know the orientation of the tag The reader does not need to know the orientation of the tag. Better for applications where you cannot predict tag orientation.