"One of our main questions was whether a high-frequency radio energy system would work in an environment like this, that has lots of radio energy floating around," Denari says. "2.45GHz is very discriminatory. A lot of the radio energy around any airport is low-frequency energy. So we decided to avoid that arena and go with high-frequency energy. I also think 2.45GHz provides a superior read rate, even in San Francisco's often humid and moist environment."
After the first field trials, Denari says his team redesigned both the RF tag itself and the way it was inserted in the paper IATA-standard baggage label. The RFID tag's antenna had originally been perpendicular to the paper label. But, because of the way the RFID tag behaved as it moved along the belt system, Denari's team discovered the read rate was below 95%. By redesigning the tag so that the antenna was parallel to the label, the read rate was improved [to more than 99%], and overall system performance was enhanced.
"Being parallel gives the tag just a split second longer to be read," Foster says. "It also makes a difference if the bag handle is metal. By re-positioning the tag, it made it less likely that a metal handle will interfere with the signal."
"With a project like this, you'll never know how airworthy it is until you get out there, get the engines going, take it around the pattern and touch down again," Denari says, calling on a metaphor from his days as a Navy reconnaissance pilot. "Even the greatest computer modeling in the world can't reveal things like this."
According to Denari, the technical challenges of implementing the system paled in comparison to the challenge of coordinating the needs of virtually hundreds of departments, contractors, consultants and vendors.
"I like to think of this project as a big quilt-and I was always tugging on the threads to make sure the quilt segments were pulled together closely," Denari says. "Anybody can throw technology in your lap, but you have got to stay on them and make sure all the components are refined and synthethized."
For example, the final design of the RFID tag has the bright orange part of the tag hanging outside the IATA label. This has nothing to do with the read rate, which would be the same if the tag were completely hidden in the label. However, various stakeholders decided it would be more advisable for the tags to be visible to baggage handlers, just in case a selectee bag missed its diversion to the CTX-9000 EDS.
