Is there any way to make them work as a single antenna?
Yes. Passive RFID readers typically support from one to eight antennas, and you can use multiplexors to add more. Antennas do not all blast energy at the same time and then try to read tags—they quickly cycle, so one performs a read, then the next and then the next. The result is that you would be able to interrogate all the tags in the fields of all the antennas as though they were one large antenna.
If you want to tile the antennas and know which tag is in the field of which reader antenna, that is a little trickier. The challenge is to optimize the read fields so that antenna five, for example, is not reading a tag above adjacent antennas. Last year, Kathrein RFID introduced its Kathrein Reader Antenna Interface (KRAI) technology and Smart Shelf system that can link 32 antennas to a single KRAI reader without a multiplexer (see RFID News Roundup: Kathrein RFID Unveils UHF Reader System With Dynamically Adjustable Antenna Polarization). The product is designed to cover a shelf and let you know the specific area in which a particular tagged object is located.
Mark Roberti, Founder and Editor, RFID Journal
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