Diversity Measurements Aid Body-Worn Systems At 868 MHz

April 20, 2010
Mobile body-worn communications systems suffer from problems like near-field coupling, radiation-pattern fragmentation, and shifts in antenna impedance. Aside from degrading system efficiency, these issues can reduce signal reliability. To ...

Mobile body-worn communications systems suffer from problems like near-field coupling, radiation-pattern fragmentation, and shifts in antenna impedance. Aside from degrading system efficiency, these issues can reduce signal reliability. To mitigate these effects, Simon L. Cotton and William G. Scanlon from the Queen's University of Belfast have presented a systematic measurement campaign of diversity-measurement techniques for use in wearable multiple-antenna systems at 868 MHz.

The researchers performed experiments using six time-synchronized body-worn receivers. They considered mobile off-body communications in an anechoic chamber, open office area, and a hallway. The cross-correlation coefficient between the signal fading measured by the body-worn receivers was typically below 0.7. In an open office area, the 5.7-dB diversity gain obtained with a dual-branch, body-worn maximal-ratio diversity system was improved to 11.1 dB by using a six-branch system. See "Measurements, Modeling and Simulation of the Off-Body Radio Channel for the Implementation of Bodyworn Antenna Diversity at 868 MHz," IEEE Transactions On Antennas And Propagation, December 2009, p. 3951.

About the Author

Nancy Friedrich | RF Product Marketing Manager for Aerospace Defense, Keysight Technologies

Nancy Friedrich is RF Product Marketing Manager for Aerospace Defense at Keysight Technologies. Nancy Friedrich started a career in engineering media about two decades ago with a stint editing copy and writing news for Electronic Design. A few years later, she began writing full time as technology editor at Wireless Systems Design. In 2005, Nancy was named editor-in-chief of Microwaves & RF, a position she held (along with other positions as group content head) until 2018. Nancy then moved to a position at UBM, where she was editor-in-chief of Design News and content director for tradeshows including DesignCon, ESC, and the Smart Manufacturing shows.

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