I recently purchased a RFID Reader ID-20LA. My goal is to detect which of multiple animals is using a behavioral box to receive rewards. Each animal has a small RFID Glass Capsule embedded in their collar. Unfortunately despite having an advertised range of 180mm, I can read the RFID tag only within about 20mm of the reader, while I would need at least 100mm. I read the RFID tag with a Raspberry Pi but this could be changed. How could I extend the range of the RFID reader? Would using a 5V supply instead of the rPi 3.3V help? Could I use a 10cm coil? It looks like the ID-20LA does not allow an external antenna (if I read the datasheet correctly). Then would an ID-3LA better fit my use? I’ve also tried a RFID Button and had about the same range. Why is a 180mm range advertised if the actual range is so small?
So I tested with an arduino 5V supply and did get a ~1cm longer range, but only with the RFID button (SEN-09417) when it is perfectly parallel to the reader. There didn’t seem to be any difference with the glass capsule (SEN-09416). And overall that was still only about a 5cm range, so far short of the 18cm reported in the datasheet with an ID-Innovations clamshell card.
Having worked in RF for more than 35 years i see this type of issue all the time. The spec is for exactly aligned devices with very clean solidly regulated power supplied to the reader in a “RF quiet” environment. Is your power supply clean with lots of capacitance across the input to the device? to read the tag the reader has to send enough RF to power up the device so it can modulate the signal and affect RF field enough that the reader can sense its signal. RF signals obey the laws of physics and the range you get from any RF device depends on the capture area of the antenna’s and the alignment of the antenna’s involved. The smaller the antenna relative to the frequency involved the less efficient the antenna and the less signal it send / pick up. Also if the antenna’s are not aligned correctly the amount of signal received can be degraded significantly (typical reduction for cross polarized antennas is from 10 to 30 db that is a reduction of 10 to 1000 times and since cross polarization will affect both the receive path and the transmit path for RFID the loss doubles) Using RFID tags that are higher frequency might work better for this application Also circular polarized tags would likely work better but i don’t think you will find any that work at 125 KHZ due to the challenge of creating a circular antenna at that low of frequency. in summary 1. make sure you have a clean well filtered power supply. 2 make sure you have a clean RF environment (all computers, lighting, any other possible RF creating devices , etc are well shielded 3. consider a different reader with a better antenna. 4 consider a different frequency of RFID system.