7.4.3 Antenna Positioning
The positioning of RFID interrogation antennas depends primarily on the application.
Detailed operational considerations for the deployment of RFID system are presented in
Leong et al. (2006c). In this chapter, only one example will be given, which is the dock door
situation, as it will be used in the case study in the next section. A dock door is usually 2??“3m
in length and 3 m in height. The most effective way to create an RFID interrogation
zone is to position two antennas at the sides of the dock door, face-to-face, and with an
height elevation, h, as shown in Figure 7.5. The height elevation, h, mainly depends on the
average height of objects being shipped through the dock door. A normal choice of h is
between 0.5 and 1 m. In addition, antenna A and antenna B will be normally using
different channels for tag interrogation.
However, if antenna A and antenna B are operating at the same time, and a tag is located
in the middle of the dock door, the tag may be ??????confused??™??™ by the interrogation signals
Reader
LBT Sensor
Reader Reader ??? ??? ???
Antenna
FIGURE 7.4
Localized LBT system, where each reader has its own LBT sensor.
(From Leong, K.S., M.L. Ng, and P.H. Cole. 2006a. Synchronization of
RFID readers for dense RFID reader environments. International Symposium
on Applications and the Internet.
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