I was recently speaking with a woman who is working on a radio frequency identification deployment at her company’s retail stores. The way that she and her team determine a read field, she told me, is by holding up individual RFID tags and seeing if a reader picks them up. If it does, they step back and keep doing that until determining where the read field ends, and where the null spots are located.
Until recently, the alternative to this method was to purchase or rent a high-priced spectrum analyzer that can detect RF energy and provide visual indications of where the RF field is strongest and weakest. In May 2012, we reported on a new product called the Power Mapper, from ePix Ltd., a small British electronics firm (see Power Mapper Shows UHF Signal Strength, to Help Users Properly Install RFID Systems).
During our RFID Journal LIVE! Europe—UK conference and exhibition, held in London, England, on Oct. 30, I met Dave Mapleston, ePix’s founder. We shot a video of Mapleston demonstrating the Power Mapper, which has a meter that displays signal strength, and the Power Ranger, which has a diode that lights up upon receiving energy from the reader (view the video).
The video demonstrates how these inexpensive tools, which do not require batteries, can be valuable for any EPC Gen 2 ultrahigh-frequency (UHF) deployment. The meter clearly shows a null spot located approximately 10 feet in front of the reader antenna, even though tags can be easily read from up to 20 feet away. This makes it clear that you should not set up your reader antenna so that the items you want to interrogate are located within that null spot—they should be either closer or farther from the device.
RFID Journal‘s readers can purchase the Power Mapper and/or Power Ranger via RFID Connect (view product descriptions of the Power Mapper and the Power Ranger).
Mark Roberti is the founder and editor of RFID Journal. If you would like to comment on this article, click on the link below. To read more of Mark’s opinions, visit the RFID Journal Blog, the Editor’s Note archive or RFID Connect.