Frequency as Aperture: Enabling Embeddable Near-Field Sensing for 6G Wireless Radios

Abstract: Integrated sensing and communication (ISAC) is expected to be natively supported by future 6G wireless radios, yet most mmWave sensing solutions still rely on dedicated radar hardware incompatible with cost and power constrained wireless nodes. This article introduces Frequency-as-Aperture (FaA), a wireless-first sensing paradigm that repurposes inherent frequency agility into a virtual sensing aperture, enabling near-field perception with minimal RF front end complexity. Using a single RF chain and a frequency-scanning leaky-wave antenna, FaA achieves two dimensional spatial sensing by reusing the local oscillator (LO) frequency sweep already employed for wideband communication. From a wireless-system perspective, this shifts spatial sampling from the antenna domain to the frequency domain, embedding radar-grade spatial fingerprints directly into the communication RF chain. A case study shows that FaA provides fine angular and range discrimination with low power consumption and unit cost, demonstrating significantly higher architectural efficiency than conventional multi-channel MIMO based sensing under identical physical and spectral constraints. These results indicate that near-field sensing can be seamlessly integrated into frequency-agile wireless radios, enabling hardware-efficient, embeddable, and privacy-preserving ISAC nodes for smart homes, wearables, and industrial edge deployments.