I'm a programmer, working on designing a project, but I have very little experience with sensors other than RFID and radar technology. After doing my fair share of research, I've found myself stumped, I can't figure out which type of sensor I'm looking for. I apologize if I'm using incorrect terminology, this is not my field of expertise.
About the project: I'm building a 1.5 foot x 1.5 foot grid system. A 324 square inch grid, if you will. I'd be looking to have an accuracy of location down to the inch, so I'm thinking I'd probably need 324 sensors spaced out evenly. The sensors will be encased in no more than a half inch of painted plastic, some under rubber, and/or some under artificial grass material laid out on a flat plain. The sensors would ideally be no more than a half-inch tall and a half-inch wide. I'd like the sensors to either detect a small electronic signal or a quarter sized piece of metal, for the lack of a better word, I will call this the target item. The target item will be passing right over the material holding the sensors or possibly a quarter-inch to half-inch above. The sensor in which the object is closest too would ideally be able to output the highest reading or some indication that the target item is closest to it than any other sensor. I'm also worried about interference of the sensors, say if a phone was sitting next to the grid system.
Any thoughts or help on the sensors and ideal target items for this would be greatly appreciated. Thank you.