LeakyScatter: A Frequency-Agile Directional Backscatter Network Above 100 GHz

Wireless backscattering has been deemed suitable for various emerging energy-constrained applications given its low-power architectures. Although existing backscatter nodes often operate at sub-6 GHz frequency bands, moving to the sub-THz bands offers significant advantages in scaling low-power connectivity to dense user populations; as concurrent transmissions can be separated in both spectral and spatial domains given the large swath of available bandwidth and laser-shaped beam directionality in this frequency regime. However, the power consumption and complexity of wireless devices increase significantly with frequency. In this paper, we present LeakyScatter, the first backscatter system that enables directional, low-power, and frequency-agile wireless links above 100 GHz. LeakyScatter departs from conventional backscatter designs and introduces a novel architecture that relies on aperture reciprocity in leaky-wave devices. We have fabricated LeakyScatter and evaluated its performance through extensive simulations and over-the-air experiments. Our results demonstrate a scalable wireless link above 100 GHz that is retrodirective and operates at a large bandwidth (tens of GHz) and ultra-low-power (zero power consumed for directional steering and ≤1 mW for data modulation).