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Low-Observable Reflectors Using Perfect Pulses

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Low-Observable Reflectors Using Perfect Pulses
Mohammad Alhassoun, Michael A. Varner, Gregory D. Durgin
2018 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting
Year: 2018, Page s: 915 – 916

This paper presents a new technique for suppressing specular reflection using binary reflective surfaces (such as those easily fabricated on a printed circuit board)that maximally suppress mean currents on the reflector using the theory of perfect pulses. We simulate multiple versions (or orders)of these structures to characterize the nulling depth and manufacturing tolerance of the designs. In addition, we run another set of simulations to characterize the specular reflection as a function of the direction of incidence. The simulation reveals that the specular reflection from the proposed structures is at least 9.3 dB less than that from a flat metal plate of the same dimensions.

2011: R.E.S.T. Platform @ 5.8 GHz

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Chris Valenta designed the R.E.S.T. platform, a modular 5.8 GHz backscatter platform with a software radio reader that could be configured for a limitless combination of sensors, antennas, power sources, and modulation schemes.

The R.E.S.T. (RFID-Enabled Sensing Testbed) was published as a flexible development platform that allowed the group to experiment with all sorts of 5.8 GHz application platforms.  It was the quintessential low-power, microcontroller-based backscatter system.

Fun fact: although they did not exactly use the original R.E.S.T hardware, future group applications — the helmet shock sensor, the motion capture experiments, the ATM terminal protection system, and others — were based on the R.E.S.T.’s architecture.

WWB16: Balance Coding

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A lecture on the history, use, and backscatter applicability of balance codes.  Balance codes (also called recording codes, channel codes, line codes, or modulation codes) have been used in magnetic tape drives, swipe cards, optical disks, and many more places.  This lecture discusses and updates the concept with respect to backscatter channels.

WWB16:  Balance Coding

Paper:  G.D. Durgin. “Balanced Codes for More Throughput in RFID and Backscatter Links”.  IEEE RFID-TA 2015. Tokyo, Japan. 16-18 September 2015.

 

 

WWB15: Backscatter Demodulation

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This lecture discusses the receiver architecture of a backscatter reader, explaining the nature of coherent detection and direct down-conversion.  The nature of these receivers introduces interesting behavior in terms of noise, sensitivity, and dynamic range.  A discussion of the “orange noise” model for these receivers is included.

WWB15:  Backscatter Demodulation

Paper:  G.D. Durgin, C.R. Valenta, M.B. Akbar, M.M. Morys, B.R. Marshall, Y. Lu. “Modulation and Sensitivity Limits for Backscatter Receivers.” IEEE RFID Conference, Orlando, FL. May 2013.