This work introduces an optimal backscatter and energy harvesting solution for radio frequency identification (RFID) by using N antennas with N ports called a staggered patterned and retro-directive (SPAR) tag. By using multiple ports and a unitary scattering matrix on the SPAR tag, the structure is able to create multiple orthogonal radiation patterns to improve range of passive RFID tags. This is demonstrated on a 5.8 GHz RFID tag using a two-element patch antenna array fed by a 90˚ hybrid. In addition to canonical designs, new SPAR structures are hypothesized with optimized size, bandwidth, etc. A co-simulator is developed capable of searching a vast space of possible feed networks with N-by-N ports that meet the requirements of a unitary scattering matrix. A new structure that meets the 2-by-2 SPAR scattering matrix requirements is presented to demonstrate the capabilities of the software. The software can also be generalized to discover new physical structures of larger N−by−N SPAR tags or other microwave devices.
Archives for September 2018
WWB05: Power-Optimized Waveforms
This lecture in the Wireless Without Batteries Series discusses the fundamentals of Power Optimized Waveforms (POWs), which can be used to extend the range of wireless energy-harvesting links.
WWB05: Power-Optimized Waveforms
Paper: M.S. Trotter, J.D. Griffin, and G.D. Durgin. “Power-Optimized Waveforms for Improving the Range and Reliability of RFID Systems.”IEEE International Conference on RFID 09, Orlando, FL. April 2009. 8 pages.
Varner’s IEEE SPAWC 2018 Paper on Perfect Pulse Ambient Modulation
Michael Varner’s publication at IEEE SPAWC 2018 is now available for download in IEEExplore. Entitled “Reflection of Modulated Radio (ReMoRa): Link Analysis of Ambient Scatter Radio Using Perfect Pulses“, the work explores the spectral properties for perfect pulse modulation of ambient backscatter. The impact on this modulation scheme and the link budget is explored. The ideas in this paper will allow long-range communications by embedding information on existing RF sources and reflecting them to collection nodes. There are numerous applications in machine-to-machine, internet-of-things, and sensor networks.
Reminder of One of GT’s Great EM Professors
Prof. Pete Rodrigue received his B.S. and M.S. degrees in physics from Louisiana State University and his Ph.D. in applied physics from Harvard University. From 1958 to 1968, he worked for the Sperry Microwave Electronics Company in Clearwater, Florida, where he conducted research on properties and microwave applications of ferrites and developed parametric amplifiers and microwave acoustic devices. In 1968, Dr. Rodrigue joined the School of Electrical Engineering at Georgia Tech at the rank of professor and was promoted to Regents’ Professor in 1977. He introduced new microwave courses for undergraduate and graduate students, as well as in continuing education programs.
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