Active rfid tags - whitepaper by Savi

Active rfid tags - whitepaper by Savi - -1- Active RFID:...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
1 - 1 - Active RFID: Selecting the Optimal Frequency for Global Applications A White Paper by Savi Technology February, 2002
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Active RFID: Selecting the Optimal Frequency for Global Applications | February 2002 1 I. Introduction Selecting an optimal radio frequency for operation of an Active RFID system requires consideration of several factors, including technical performance, regulatory issues, and co-existence with other technologies. This paper assesses a broad range of radio frequencies against these parameters, and presents rationale for the selection of 433 megahertz (MHz) as the optimal frequency for global use of Active RFID. II. Technical Performance vs. Frequency Two key technical performance parameters of an Active RFID system are directly related to the frequency of operation: maximum communication range and propagation within crowded environments. i. Maximum communication range As a general rule, radio signals at lower frequencies will propagate farther than signals at higher frequencies, assuming similar transmitter power levels. The attenuation (or decrease) of a radio signal as it travels through a medium such as air is directly related to its wavelength. All signals experience the same decrease in signal strength per wavelength when traveling through the same medium. Because signals at lower frequencies have longer wavelengths , signal attenuation occurs at a slower rate. For example, if Signal A decreases by 10% over a distance of 10 feet, then a signal at half of the frequency of Signal A will decrease by 10% over a distance of 20 feet, thereby allowing the lower frequency signal to propagate farther. At frequencies less than 100 MHz, other factors have a greater impact on practical communication range. Systems at lower frequencies, such as 13.56 MHz, depend on inductive coupling as the primary mode of interaction. The range of an inductively coupled system drops sharply with distance, making communication beyond 10 to 20 feet impractical. Using longer- range electrical coupling at these frequencies is not recommended due to their high susceptibility to noise and interference from other devices. Selecting an optimal radio frequency for operation of an Active RFID system requires consideration of several factors, including technical performance, regulatory issues, and co- existence with other technologies.
Background image of page 2
2 ii. Propagation within crowded environments The ability for signals to propagate within crowded environments is also dependent on the signal wavelength, and hence frequency. Within warehouses, truck yards, and other facilities, the ability for an RFID system to operate in and around obstructions is critical. These obstructions are often
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/27/2010 for the course EE 600 taught by Professor Aodafkdlja during the Spring '10 term at Aarhus Universitet.

Page1 / 7

Active rfid tags - whitepaper by Savi - -1- Active RFID:...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online