I am writing this post to inquire the bright minds on this forum about an RFID design project. I am taking a senior design class where our project idea is an RFID Inventory System. We are aware that these systems exist, however our idea differs in the sense that our reader will emit a constant field and when the tagged items are brought in range of that field, the system will register it. So rather than bringing the reader to the item and individually scanning it, our idea brings the items all at once to the reader. This brings up some questions, the most pressing being which range to use, 13.56MHz or the UHF range (800-960 MHz). We are leaning towards the 13.56MHz range for purely cost reasons, however our research seems to indicate that achieving our 1-2m range would be difficult. This explains our other option of the UHF which gives us increased range at a price.
Also, given our $600 budget, we are hoping to build our own reader, similar to the famous (infamous?) Arduino example here (http://playground.arduino.cc/Main/DIYRFIDReader). We would change the values to fit our required range, which leads to our second question about the antenna? None of our research was able to show a relation between the antennas design and its reading range. Is it possible to design an antenna in the 13.56 MHz range that can read a 13.56 MHz passive RFID tag up to 2m away? If we had to design the antenna in the UHF range, how could we ensure it would not read farther than 2m?
I have read many of the forum posts on here about RFID, and have seen the bright minds that respond to them. I am eager to learn and hear what you have to say, and I anxiously await your responses. Thank you!