In theory, sub-terahertz (sub-THz) communication offers the potential for near-field beam focusing, that can far surpass conventional far-field beam steering by directing energy to a specific point in space rather than a broad angular direction. In this paper, we introduce TeraFocus, the first adaptive beam focusing system for sub-THz wideband communication. Moreover, we present the first experimental demonstration of a wideband focusing link, in contrast to prior experiments with monochromatic sources. With TeraFocus, we demonstrate how metasurfaces with thousands of radiating elements (81 by 81 for a total of 6,561), can create the non-linear phase gradient required for precise beam focusing, achieving a 60 GHz 3-dB bandwidth. Moreover, TeraFocus maximizes link capacity by addressing the inherent spectral asymmetry in metasurface responses. Finally, for mobile clients, TeraFocus dynamically compensates for misalignment by leveraging the frequency-dependent focal length characteristic, allowing it to adapt to radial mobility without relying on traditional localization algorithms, which can be time-consuming, computationally expensive, and error-prone. Instead, TeraFocus re-localizes the client by analyzing the received spectral signature of a misaligned focusing beam, achieving a maximum error of less than 0.2 cm.

Wireless eavesdropping on phone conversations has become a major security concern as attackers repurpose advanced wireless capabilities in 5G and beyond featuring higher frequencies and higher sensing resolution. Recent studies have demonstrated that attackers can exploit off-the-shelf millimeter-wave radars to covertly detect even micron-scale vibrations of smartphones caused by the earpiece during the phone conversation, eavesdropping on audio information without the victim ever noticing. In our IEEE S&P'25 paper, we present a new architecture that not only thwarts such attacks but also injects false signatures to fool eavesdroppers into believing they have succeeded. Here, we demonstrate the eavesdropping countermeasure technique that enables the user to hide his private acoustic signals and simultaneously inject an alternative signal via a low-profile, reconfigurable metasurface. We present a metasurface-based audio encoding method that generates artificial audio-vibration signatures to send deceptive audio information to eavesdroppers. We showcase experimental audio samples from both the attack and the proposed countermeasure, which transforms defensive strategies from merely reactive to proactively deceptive.

The next generation of wireless networks will utilize highly directional beams to overcome the path loss at high frequencies, requiring angle inference during link establishment. Furthermore, the integration of location-based services into the wireless infrastructure is rapidly increasing, bringing in a significant demand for an integrated fast localization scheme. In this work, we present a first-of-its-kind one-shot angular localization method that is carried out with a re-configurable architecture that unlocks ISAC functionality. Specifically, we use an electrically tunable metasurface with broadband response to generate wavefronts that are randomized across the angular space with diverse wideband amplitude and phase observations, corresponding to a collection of angle-unique one-shot beacons. Our results show down to 0.26° mean absolute error at 20 dB SNR, an order of magnitude improvement over the recently proposed one-shot solutions based on leaky-wave antennas (LWAs), in addition to having wider area coverage and less stringent bandwidth requirements.