RFID
Antennas
RFID Antennas
connected to the RFID reader, can be of various size and structure,
depending on the communication distance required for a given
system’s performance. The antenna activates the RFID tag and
transfers data by emitting wireless pulses. RFID Antennas are
devices which use radio waves to read and write data to the
Tags/Labels/PCBs. Some systems use separate RFID Antennas and
Controllers, while other systems integrate the Antenna and
Controller into a single Reader or
Reader/Writer.
RFID Antennas
can be found in all shapes and sizes, including Antennas which can
fit into very tight spaces and larger Antennas for greater
read/write ranges. In addition, the Antennas provide unique solution
features. One such example is the submersible Antennas used for
media disc drive applications. The RFID Antennas are mounted under
deionized water to read/write data to the Tags while submerged.
Other examples include Antennas that offer portals around conveyors
or even dock doors. These portals (also called tunnels and gates)
read or write to Tags/Labels/PCBs as they pass
through.
RFID Antennas
emit radio waves that activate RFID tags as they pass through the
activation field. After a tag is activated, it can send information
to or receive information from the coupler. In a basic RFID system,
RFID Antennas and couplers are used to read the tags affixed to each
item in your collection. RFID Antennas are installed at entrance and
exit lanes that communicate by radio frequency with RFID tags that
are mounted in each vehicle. The system sends the tag number to a
computer database for verification. It takes only a few seconds to
verify access and open the gates. RFID Antennas can be placed on
walls, shelves and doorways. Not only can they read the RFID tags
that pass by, they can also electronically add brand new data to the
tag, such as shipping date, arrival date, and
condition.
New Ink for
Printed RFID Antennas: It may be a decade or more before conductive
inks replace silicon chips, but printed RFID Antennas are much
closer at hand. Today, most RFID Antennas are made from metals. Acid
is often used to etch away some material to improve conductivity.
That results in hazardous waste, an extra step in the process of
creating an RFID tag, and additional costs. A number of companies
are working on developing techniques for printing RFID Antennas
using conductive inks.
Advantages of a
printed RFID Antenna:
- Lower cost
- Environmentally friendly
- Greater
antenna flexibility
- In 900 MHz
products, the performance of a printed antenna is equal to
traditional copper-etched
antennas
In the venue
itself, which contains gallery and performance spaces, RFID Antennas
read tags in the participants’ tickets, linking their physical
presence to the database records. Because RFID Antennas can be
embedded into many objects, including plastic cards, and still be
detected, data is protected from the wear and tear of everyday use
and environmental elements. Depending on the power of the reader,
RFID Antennas can be read from direct contact up to 20
feet.
RFID Antennas
gather or add information to tags using radio wave transmission. For
this reason, RFID antennas are also known as "read/write heads." The
specifications of an antenna are dependent on space constraints,
read range, and data throughput
requirements.
An extension to
Electronic Access Control is Electronic Asset Tracking and
Protection Systems. These systems monitor the movement of an
identified asset within a facility. Identified assets are physically
tagged with a Radio Frequency Identification Device (RFID) device.
RFID Antennas that are placed at various locations throughout a
facility, typically at entrances, read these devices and record
their movement through the protected portals. The RFID Antennas
identify the RFID tag when it comes in close proximity to it. The
system then determines whether the asset is authorized to leave the
specified area based upon assigned parameters. Assets can also be
assigned to individual access control cardholders. The system can
then determine if a particular individual is authorized to remove an
asset from a secured area. Alarms can be generated and operators
notified of any unauthorized movement of an asset. Asset Tracking
Systems can also be used to determine the location of a selected
asset within a facility.
RFID-Antennas -
mainly loops - are very-very small compared to the wavelength (about
300m) resulting in a very-very poor efficiency in the far field
(long distance). RFID antennas are developed to generate a magnetic
near-field primarily. Unfortunately, the near field (which always
surrounds an antenna in the range up to wavelength / 16 => about
300m @ 125 kHz) decays with 60dB per decade - so ten times the
distance resulting in 1/1000000(!) of the received power. Reaching
the far-field (distance to antenna > 300m) the decay drops to
only 20dB per decade (ten times the distance resulting in 1/100 of
the received power).
