To answer this question, the difference boils down to the relationship between an antenna's gain and beamwidth. The reality is as long as you don’t need these to cover a distance over 3 meters or so, both will work. However, the gain (the ability of the antenna to travel a further distance) is inversely proportional to the antenna’s beamwidth (the size of the coverage area).
- The 5x5 S9025P antenna won’t transmit as far into the distance (maybe only 3 meters) but has a wide beamwidth (which could cause unwanted tag reads)
- The 10x10 S9028PC antenna will transmit further into the distance (maybe 5+ meters) but has a more narrow beamwidth (which could prevent unwanted tag reads)
In addition, consider that the 5x5 has VERY limited mounting options. The only bracket sold for the S9025P antenna is part# ALLPMTE-002. It is plastic, not heavy duty, and has limited range of motion.
The 10x10 is typically mounted with the heavy duty HDMNT-100MM bracket, which most installers prefer.
If you are still confused, we understand! Here is a visual representation: