2007: Josh Griffin lead authors the immensely influential paper on the use of multiple antennas in a backscatter link for readers and tags. His work predicts big gains in both data rate and reliability.
Josh Griffin develops the theory of multi-antenna backscatter which forms the backbone of his PhD work. Highly original and highly cited, the work has led to a number of subsequent investigations into the potential for multi-antenna backscatter systems.
Fun Fact #1: Josh coined the term dyadic backscatter, since a dyad is literally “a pair” and one needs a pair of matrices to represent the channel effects of a multi-antenna backscatter system. There was precedent and intention in the use of this term. The term “dyadic” is often used by electromagnetics researchers to describe the Greens function relating current distributions to radiated fields. The authors felt this would be a familiar term for antenna engineers and “take the sting” out of introducing a very new and theoretical concept. This was obviously a strategy employed on a number of backscatter works from this group.
Fun Fact #2: The multi-antenna exchange theory outlined in Griffin’s work also anticipated the use of retrodirectivity, by allowing a multi-antenna tag that could “re-arrange” reflected power by representation with a matrix. If this aspect of backscatter is included, these links become extremely complicated to track information flow. Our group, on a lark, considered calling this Multiple Input, Multiple Absorption, Multiple Emission, Multiple Output (MIMEMAMO) links. Wiser heads prevailed and the term “dyadic backscatter” was used instead. Thankfully.