Passive Radar System

A defense research organization required target detection capability that would not reveal the presence or location of the sensing system. Traditional active radar systems emit signals that can be detected, located, and exploited by adversaries—negating their tactical value in contested environments where emission control is paramount.

The core challenge was developing a passive sensing approach that could leverage existing RF infrastructure (cellular towers) as illumination sources, detecting targets through bistatic radar principles without generating any detectable emissions. This required solving signal processing challenges in separating target returns from direct-path interference at signal levels far below the noise floor.

Without passive sensing capability, operators would face an unacceptable choice between detection capability and operational security, limiting the scenarios where radar-based surveillance could be employed.

The engagement spanned the full system development lifecycle: algorithm design and simulation, antenna element development and characterization, receiver hardware integration, and field experimentation to validate detection performance against cooperative targets.

The engagement delivered a complete passive radar prototype: characterized antenna elements, integrated receiver hardware, real-time processing software, and documented performance data from field experimentation. The system demonstrated target detection using cellular illuminators without any active emissions.

Operators can now deploy covert surveillance capability in scenarios where active radar would compromise operational security. The approach leverages ubiquitous cellular infrastructure, enabling sensing in environments where dedicated illuminator deployment would be impractical or detectable.