Could a mix of items with two stock-keeping units, tagged with RFID transponders, be read at this rate?
If you were to affix tags to two different types of paper towel and then attempt to read 140 pieces, you should easily be able to do so, since paper towels are RF-friendly. If you were to put tags on 140 cases of two kinds of beer stacked on a pallet, however, you would be very unlikely to be able to read the tags on the cases located in the center of the pallet, as the energy from the reader antenna would never reach the tags at the center.
So one determinant of whether the 140 tags could be read is the material of the items being tagged and read. Another question is how the items are stacked. One hundred and forty items spread out would be much easier to read than that number of items stacked closely together. Sometimes, an RF-unfriendly material is stacked up in a way that energy cannot reach the tags in order to power them up and enable them to respond.
—Mark Roberti, Founder and Editor, RFID Journal
Can an RFID Tag Be Put Into a Microwave Oven? »