How do I select the proper tag size, shape & package?
The tag type, RF modulation type, size, and material are all dictated by the item to be tracked, and then mainly on the read-write range required and any air-borne noise strength for the application at hand. Smaller tags have a small range. Amplitude Modulation (AM) is less robust than Frequency Modulation (FM) techniques. Full vs. half-duplex (FDX vs. HDX) affects the tag read performance, operation speed (duty cycle), data rates and noise immunity levels. Currently the smallest, fully packaged tag available is 1.5 mm square, which has an integrated silicon antenna and can provide a range of up to a quarter inch. They come in round and elliptical shapes as well or as long strips. The largest tag Sentinel has supplied to date is a 5 in x 5 in square x in thick, to give a range of up to 10-12 feet at 900 MHz. With dual, active antennas, one can achieve 20+ feet range at 4 watts RF power. The tag antenna has to have the correct impedence or capacitance/inductance so as to match it to the
