TransCore Amtech IT2200, Installation Maintenance And Service Manual

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Theory of Operation
2-5
Permanent programming (firmware) in the reader controls reader operation. The
firmware can accept commands from the user through the host computer system or a
local terminal; thus, the user can customize the reader’s operations to the user’s needs.
RF Module
The RF module is the RF source. It is mounted with the antennas. An RF module is a
radio transmitter/receiver that is controlled by a reader. Upon command from a reader,
the RF module generates an RF signal and delivers the signal to one of the antennas
for transmission. The RF module receives and demodulates the reflected tag signal
returned through the antenna(s). It then amplifies and conditions the signal before
sending it to the reader.
Antennas
The antenna is the transmitter and/or receiver for the RF. Each RFID system includes
at least one transmitting and receiving device, or antenna. In some systems, a single
antenna may be used to transmit the RF and receive the encoded RF signal from the
tag (monostatic); in others, one antenna transmits the RF and another receives the
signal returned by the tag (bistatic).
The sophistication of this device depends on the application and the type of tag used.
Antenna type is very important for the application; one type of antenna may transmit a
focused, strong field suitable for highly controlled, high-speed applications such as
rail. Another type may transmit a broad but relatively weak field suitable for relatively
open, slower-speed applications such as access control. Antennas may be stationary or
mobile, depending upon the application.
Transmission field size, shape, and polarization (directional sensitivity of energy
emitted from the antenna) are used to further define the reading range to desired
specifications.
Each type of antenna transmits RF energy generated by the RF module in a
characteristic pattern. The shape of the reading range generated by each antenna can
be related directly to the radiation pattern. In the AA3152 Universal Toll Antenna and
AA3153 Beacon Antenna, this pattern is balloon shaped (Figure 2-2 and Figure 2-3).
This type of antenna is ideal when the reading range must be relatively symmetrical.
When mounted with its elements oriented horizontally, the AA3152 and AA3153
Antennas are horizontally polarized.