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Chipless tags use different technologies, based on different physical principles, such as
printed or bonded inductors (capacitors or diodes), fibres, thin films, microwave reflec-
tors, remote magnetic, transistor or transistorless circuits.
Chip-containing tags cost more and do more with data.They can store larger amounts
of data, up to 10K, compared with chipless tags which generally hold 32 or 64 bits.
Chipless tags are much cheaper but currently cannot hold as much data without being
unacceptably large for their purpose.
Depending on the memory types embedded in RFID tags, the tags will typically fall
into one of following categories: read­only, read­write (R/W) and write once/read many
(WORM). Read-only tags contain a unique factory-programmed ID code, consisting of
bits or digits which cannot be altered later.They offer the lowest cost and lowest level of
data volatility.WORM tags are essentially read-only tags, except that the memory content
may be inserted ­ once only ­ after manufacture. Read-write tags can be programmed by
the user to revise and update data.Thus, a custom coding and numbering system can be
used and data can be easily integrated with other computerised systems.
Data collected from either type of tags can be sent directly to the host computer, or
stored in the reader until such times as it can be conveniently uploaded to a computer
for data processing.
Data types
RFID technology uses two extremes of data storage. Unique Signature tags do not store
any data, instead the reader's electronics simply sense something unique about the prod-
uct, and `point' to records held in a database. At the other extreme, Digitally Encoded tags
store digital information according to agreed rules, so that readers can retrieve informa-
tion directly from the tag without the need to refer back to a centralised database.This
latter feature should be carefully considered in the cultural heritage sector, and others, as
it influences all data processing procedures within the organisation.
Operating Frequencies
RFID devices can be divided into low-frequency and high-frequency tags. Low-fre-
quency tags typically provide slower data transfer and operate over shorter distances.
High-frequency devices, on the other hand, can work at greater distances and at higher
relative speeds.While RFID systems may vary by country or region, RFID tags will typi-
cally utilise the following frequency range:
- Low frequency: 30 to 300 KHz frequency range, primarily the 125 KHz band;
- High frequency: 13.56 MHz frequency range;
- Ultra high frequency: 300 MHz to 1 GHz frequency range;
- Microwave frequency: frequency range above 1 GHz, primarily the 2.45 GHz and
5.8 GHz bands.
Smart Labels
and Smart Tags