It is essential to understand the limits and challenges associated with any technology that you implement. Luckily, in the case of RFID systems, there are no significant challenges that one may face. Even after years of implementation, RFID systems work just as fine. However, with Electromagnetic waves, there are always some precautions required so that the system can work flawlessly. This article focuses on RFID Tag Shadowing and how one can mitigate it.
What is RFID Tag Shadowing?
Environmental conditions and interference are often a problem when it comes to radio waves. However, another unique challenge for RFID is RFID Tag Shadowing which can affect the accuracy of RFID read rate in the system. Tag Shadowing is often a problem associated with the physical setup of RFID systems, and therefore, it can be mitigated effectively to make RFID systems robust.
As the name might suggest, RFID Tag Shadowing is a phenomenon that takes place when one RFID tag shadows another RFID tag. Here, shadowing a tag represents interference of another tag between the shadowed tag and RFID reader. It generally takes place when a tag overshadows another tag by physically covering it in near proximity. This overshadowing blocks RF energy from reaching the shadow card. As the card does not get enough RF energy, it is not read within the RFID system.
Applications where RFID Tag Shadowing can take place:
RFID Tag Shadowing occurs in environments and applications where many RFID tags are placed in a stack. Here is a list of several applications where tags are placed together closely and may cause Tag Shadowing:
- Retail inventory tracking & management
- Using RFID to track files and documents
- Pallet inventory management in warehouses
- Managing books into libraries
- Clothes stacked in a fashion store
Ways to mitigate RFID Tag Shadowing
RFID Tag Shadowing can be mitigated through various techniques:
- Rearranging Readers & tags in a different orientation:
This is the simplest method where just changing the placement of tags and readers ensures that all the tags are exposed to readers without shadowing. The key here is to either increase the distance between tags or have tags on different places or angles so to eliminating chances for shadowing. - Using movements of items or readers to expose every tag:
This one is also a simple method where the movement of the reader through every side of the cart can be used to scan all the RFID tags without fail. Also, the tags can be passed through fixed readers at a position and can read tags through different angles. - Staggered tag placement to avoid alignment and shadowing:
Imagine placing RFID tags on files in a staggered manner. A reader can read every tag even though the tags would be close as none of them are placed in the exact alignment. Therefore all the tags can be read without any misses due to shadowing.
Conclusion
Tag Shadowing is a simple phenomenon and can be easily mitigated through a proper physical setup. The ease of mitigation here once again proves the robustness of RFID-based technical architecture in all of its applications.
