A lot of my RFID Toys readers often email me or post on the forum telling me about problems they are having using glass tags with certain readers. Mostly the issue is not being able to get good range, etc. When it comes to RFID tags, especially glass ampoule tags, size matters.
There are several types of passive RFID reader antennas, but in the small OEM style reader market you mostly encounter flat plane antennas. These are either circular or square in shape, but basically flattened down into a 2D plane. These types of flat antennas work very well with the majority of tags out there because most tag antennas are also flat planes. Things like access key cards, key chain fobs, etc… are all examples of tags that use flat plane antennas. These tags work great with flat plane readers if you present the tag’s flat plane antenna parallel to the reader’s flat plane antenna. However, range is significantly reduced if you present the tag’s flat plane antenna in a perpendicular orientation to the reader’s flat plane antenna.
Other readers use a cylindrical coil antenna, and these antenna work great for reading glass tags who’s antennas are also cylindrical coils. But again, most of the cheap readers you can buy out there for projects and such use a flat plane antenna… so does that affect the ability to read a glass tag? The answer depends on how large the glass tag is. With new DIYers getting glass tags implanted every day to use with their own home brew projects, it could be a significant issue if you went through the trouble of getting a glass tag implanted only to find out it can’t work with your project simply because of this antenna/range issue.
This video was shot in response to a reader’s query. He was having problems getting a 2mm by 12mm glass tag to read. I thought this video would do a good job showing the performance difference between a flat access key card, a 3mm by 13mm glass tag, and a 2mm by 12mm glass tag.