Noise is a common reason for decreased read range.  HDX and FDX can both be affected by noise although some types may only disturb one or the other.  Further information about noise can be found in this article.

Where does noise come from?

A prime factor that affects read range is the antenna design. If it is critical to get the maximum read range then more effort will need to find the nest design.  Try antennas with different numbers of turns (inductance), spacing between turns and different wire sizes to find the best combination.  Most antenna designs that can be tuned will read tags but with extra effort the range can sometimes be greatly increased.

The read range on our long range HDX readers can often be increased by using a higher supply voltage. The operating range is 7 to 24 volts but most antennas work fine with 12 volts from a lead acid battery. To try a higher voltage you can use a 6 volt battery in series with a 12 volt to get nominally 18 volts although it will measure closer to 20 volts. With a voltage increase the reader will run a little warmer but may or may not show an improvement depending on the antenna design. We usually suggest using higher voltages only on antennas over 25 meters wide. We do not recommend using two 12 volt batteries because the combination will produce over 26 volts which will fry the reader electronics.

Our HDX/FDX Dual Mode Reader should only be operated from 12-13 volts DC.  Increasing the voltage will not increase performance and may damage the reader electronics.