Passive Radar: use cases
A sensor that never emits is a sensor an adversary cannot locate. The Cybersecurity Group's passive radar detects and tracks by exploiting signals already in the environment, low-earth-orbit satellite downlinks, broadcast television and cellular base stations, instead of transmitting its own. Zero transmit power means no spectrum licence to arrange and nothing for an anti-radiation weapon or an electronic-intelligence receiver to home on. Anti-radiation weapons and electronic attack have made every emitting sensor a target, and at the same time small drones fly below the coverage of classical air-defence radar; emitter-free sensing addresses both problems at once. A single receiver site covers hundreds of square kilometres, and Unstrat integrates the feed into the wider air and coastal picture-compilation chain. The layer complements active radar rather than replacing it, and it does so without binding the buyer into a single-power sensor ecosystem.
Where it is used
Aircraft are detected and tracked off ambient illumination, so an air picture is built without radiating anything an adversary can find. The site that watches the sky is not itself lit up as a target. The same emitter-free property that hides the sensor also makes it hard to jam, because there is no transmission to interfere with and no fixed emission for a hostile force to characterise. It fills the gap that survivability forces open: the moment active radars have to fall silent to stay alive, the passive layer keeps the picture running because it was never on the target list.
One receiver site holds coverage across hundreds of square kilometres continuously, which suits long borders and coastal approaches where mounting active radars would be expensive and would announce exactly where the surveillance is. With no transmit power and no licensing to manage, sites can be added without a spectrum fight. Coverage is site-dependent, though, shaped by local transmitter geography and terrain, so the honest first step is a coverage study rather than a headline range. That study is not a formality: it decides where receivers go and what the layer can actually see, which is why every deployment begins with one.
A low-observable layer over contested land and coastal approaches feeds the compiled picture without giving away sensor positions, which matters where an adversary would otherwise map a force's coverage simply by listening for emissions. The layer is tuned to the targets that defeat traditional radar, small drones, low radar-cross-section aircraft and slow-movers, the kind of traffic that flies under a classical air-defence net. Watching a long border for small drones without revealing where the sensors sit is precisely the problem emitter-free sensing was built for, because it gives an adversary nothing to locate or target.
Passive sensing is one of three lanes in the spectrum fight this channel represents: it watches without emitting, electronic defeat severs hostile drone links, and software-defined radios keep friendly communications up under jamming. Scoped together they reinforce each other rather than competing for the same budget line, and the electronic-warfare capability maps passive radar, counter-UAS and software-defined radios as one portfolio. Alongside active drone-detection radar and the counter-UAS decision layer, passive radar is the covert element that keeps the whole air picture surviving when the emitting parts of it have to go quiet.
The path runs coverage study, staged deployment, integration into the existing air and coastal picture, then in-region sustainment, all through one accountable channel. Because coverage is site-dependent, the buyer is not stitching a study from one party to an installation from another. The independent route integrates into a buyer's existing picture-compilation chain rather than locking it into a single-power integrated air-defence architecture, so a survivable sensing layer is added under national control without inheriting a foreign system and its release schedule. Political conditions are the row where the two supply routes differ most, and every transfer still runs inside the governance applied before any capability is represented.
A surveillance layer that watches a nation's borders and coastlines is not a neutral tool; it is a record of what that nation can see and where it is looking. Referencing an independent, non-aligned system means a force is not committing to a foreign government's disclosure rules, re-export restrictions or upgrade approvals to hold its own air picture. A member-state licensing chain can be a single point of failure for a sensor programme, and the independent route is accountable to the buyer's flag instead, which is the concern the political-conditions comparison is built around.
