RFID questions

[roborg]

Hi,

I would like to have a RFID reader periodically read all the RFID tags (attached to some items)
in a room (say of size 50ftx50ft) to see which items are in the room and which are not. How do I go about doing this ? Would passive RFID tags work here ? I read that their range is only few feet but the good thing is they don't need battery or any other power source. If passive RFID tag is not the right one, which one is ? On the RFID reader side, I am thinking of a device with a micro controller that activates the reader periodically to probe for all the tags (not sure if there is such a broadcast signal in RFID) at once and reads the response signals one by one. Is this possible ? or does the reader probe for each RFID tag one by one ? I am also wondering whether solar powered tags/readers exist.

Thanks,
RO.