Standard market products should not limit your potential to create a solution. Learn how to easily test RFID antenna to optimize battery-free sensors to your needs.

One size does not fit all

You have already been looking for battery-free sensor tags or RFID tags with embedded sensors and you have seen the products being offered are quite big. You recon manufacturers have to embed sensors – often times being big components such as a relay – and even take wires out for the sensing probes to be connected to user defined locations/parts, but you still think you would like to have a smaller device.

You may also be thinking that read ranges with RFID sensor tags are shorter than you require. While typical RFID tags can be read up to 10 meters away, sensor tags seem to be read at over 2 meters but you would like them to communicate a little bit further.

Well, you should consider proper evaluation of the products and your application. Device size and read range are directly proportional: the bigger the size of the RFID antennas, the longer the communication ranges.

Whenever possible, if market standard products do not fit your requirements you should consider a savvy and easy way of testing with RFID antennas. Keeping the products as they are, there are ways to play with antenna properties and take your conclusions as to how feasible would be to have a device of your required size and communication range.

SMA connector for testing with antennas

Pyros temperature sensor with thermistor and SMA connector

Pyros temperature sensor with thermistor and SMA connector

As an example, take the SMA connector version of Farsens tags. While the electronics are kept in a small PCB, you can test with commercial 50 Ohm antennas and check the results. Antenna characteristics – mainly gain and radiation pattern – can easily be tested and, aside of the commercial antenna size, you can assess what the gain and radiation pattern for integrated RFID antenna would be.

You can also be looking for a longer communication range but not really limited by size. In this case you can select a big patch antenna, such as the ones generally used for readers, and increase the read range a lot.

Example of testing results

The picture below shows the read range of different antenna types used with battery-free sensor tags with SMA connector from Farsens.

RFID antenna tests with commercial SMA antennas

RFID antenna tests with commercial SMA antennas

As you can see, there are multiple antenna types that could be used as well as just tested to end up designing your own integrated antenna.

The idea here is that you don’t need to reduce your options to the market available packages and sizes. Your application is unique and for that reason, you can think out of the box and come up with new designs that cover your needs.

Feel free to contact us should you have any question or ideas around optimizing a sensor tag for your application.