Researchers at Omron Electronics LLC say they've developed an antenna that could eliminate the problem of so-called "field holes" in Ultra-High Frequency (UHF) Radio Frequency Identification (RFID) systems.
Calling it a "first of a kind" antenna design, Omron engineers say the new technology could vastly improve reception of UHF-based RFID readers.
"It's going to help, especially in static applications, where the (RFID) tag is not moving," notes Toshiya Kitagawa, assistant manager for Omron's RFID Division Development Group. "Up until now, if a (static) tag existed in a field hole, you couldn't read it."
The concept of field holes (sometimes known as "field nulls"), which occur when reflecting radio frequency waves cancel one another, has long been known to users of UHF systems. The phenomenon is said to be especially problematic in static applications because there the tags can't move to areas of better reception.
Omron's researchers say they've licked the problem, however, by employing a "scan antenna" to control the reflected wave. In such applications, the scan antenna can set its own direction to compensate for the so-called "null direction" caused by the reflected wave. The resulting wave then suppresses the reflected wave, causing the RF signal to be more easily readable. In a case of multiple reflected waves in a single room, the new system uses a phased array to electrically move the radiation into the multiple directions of the field holes.
The company's researchers are currently testing the scan antenna in various applications ranging from dock door portals to item-level products, such as pharmaceutical bottles.
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 By sending out a signal to compensate for the “null direction” of the reflected wave, Omron engineers say the unreadable signal (left) can be changed to a readable signal (right).
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