Passive Radar
Emitter-free surveillance
What it is
Passive radar detects and tracks aircraft and drones by exploiting existing ambient signals (broadcast, communications and other transmitters of opportunity) instead of emitting its own. The result is a surveillance layer that cannot be located, targeted or easily jammed, because it transmits nothing.
How it is employed
Passive radar is deployed as a persistent, covert layer in the air-surveillance picture: watching borders, coastlines and critical sites without advertising sensor positions. It complements active radar rather than replacing it, filling the gaps active sensors create when they must stay silent to survive.
Why it matters now
Anti-radiation weapons and electronic attack have made every emitting sensor a target. At the same time, small drones fly below the coverage of classical air-defence radar. Emitter-free sensing addresses both problems at once, and does so without binding the buyer into a single-power sensor ecosystem.
Procurement & integration
Passive-radar coverage is site-dependent: performance is shaped by local transmitter geography and terrain. Procurement therefore starts with a coverage study, followed by staged deployment and integration into the existing air and coastal picture. Unstrat carries that chain from the first study to the sustained installation.
Capability
- Zero transmit power: no signature for anti-radiation missiles or ELINT receivers to home on
- Exploits illuminators already in the environment: LEO satellite downlinks, broadcast television, cellular base stations
- Persistent wide-area coverage over hundreds of square kilometres from a single receiver site
- No spectrum licence required to operate
- Counters targets that defeat traditional radar: small drones, low-RCS aircraft and slow-movers
- Suited to borders, coastlines, restricted zones and critical-asset protection
The Unstrat difference
01Independent, non-aligned origin, with no political exposure to any major-power ecosystem.
02One accountable team from first briefing through delivery and in-region sustainment.
03Detects without emitting: nothing for an adversary to locate.
Sourcing routes compared
| Consideration | Major-power prime | Independent principal via Unstrat |
|---|---|---|
| Survivability | Active sensors emit and can be located and targeted | Emits nothing, no signature for an adversary to find |
| Ecosystem lock-in | Tied into a major-power integrated air-defence architecture | Integrates into the buyer's existing picture-compilation chain |
| Political conditions | Disclosure rules, re-export restrictions and upgrade approvals held by a foreign government | Independent, non-aligned origin, accountable to the buyer's flag |
| Accountability | Multiple contractors and a foreign prime's release schedule | One accountable team from first briefing through delivery and in-region sustainment |
Comparison is qualitative. Detailed specifications are shared under briefing once the export-control position for your market is confirmed.
Related capabilities
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Passive Radar: questions
What is Passive Radar?
Passive Radar is Unstrat's Land (Land Domain) capability: Passive radar that exploits LEO satellite illumination to detect and track without emitting: zero transmit power, no spectrum licensing, persistent coverage over hundreds of square kilometres from a single receiver site. Integrated into the wider air and coastal picture-compilation chain.
How does Passive Radar work?
Passive Radar delivers its effect through zero transmit power: no signature for anti-radiation missiles or ELINT receivers to home on, Exploits illuminators already in the environment: LEO satellite downlinks, broadcast television, cellular base stations and Persistent wide-area coverage over hundreds of square kilometres from a single receiver site, capabilities matched to the requirement and confirmed under briefing rather than published.
Who makes Passive Radar?
Passive Radar is built by The Cybersecurity Group, whose focus is cyber & critical-infrastructure security. Unstrat represents The Cybersecurity Group to government and enterprise buyers worldwide as an independent, non-aligned prime vendor.
Who uses Passive Radar?
Government and enterprise buyers acquire Passive Radar to address border surveillance, drug smuggling, hostile drone attacks, port security, airport security, coastal surveillance and smuggling & customs evasion across the land domain, matched to the mission and accountable to them, not to a foreign vendor's government.
Why choose Passive Radar over a major-power alternative?
Passive Radar is sourced from an independent, non-aligned manufacturer, so it carries no major-power disclosure rules, upgrade-locks or political ramifications. Concretely: detects without emitting: nothing for an adversary to locate. The capability is accountable to you, not to a foreign vendor's government and its release schedule.
How is Passive Radar procured, and where can it be exported?
A surveillance layer that never emits, and never ties you to a single-power sensor ecosystem. Every engagement begins with a briefing, and export eligibility is confirmed per market under briefing rather than published. Where controlled capabilities are involved, the classification and end-user-certificate chain is confirmed first. Passive Radar is then sustained in-region by one accountable team from briefing through long-term operation.
Questions buyers ask
What is passive radar as an air-surveillance capability?
Passive radar detects and tracks aircraft and drones by exploiting ambient signals, broadcast, communications and other transmitters of opportunity, instead of emitting its own. The result is a surveillance layer that cannot be located, targeted or easily jammed, because it transmits nothing. It complements active radar rather than replacing it, filling the gaps active sensors create when they must stay silent to survive.
Why field emitter-free sensing now?
Anti-radiation weapons and electronic attack have made every emitting sensor a target, while small drones fly below the coverage of classical air-defence radar. Emitter-free sensing addresses both problems at once, and it does so without binding the buyer into a single-power sensor ecosystem. That combination is why buyers add a passive layer rather than more of the same active radar.
See: The threat case for passive sensingPassive radar in the catalogue
Does passive radar integrate with an existing air picture?
Yes. The independent route integrates into the buyer's existing picture-compilation chain rather than tying the force into a major-power integrated air-defence architecture. That keeps the surveillance layer under national control and avoids ecosystem lock-in. It sits alongside active sensors, not on top of a foreign architecture.
How does a passive-radar deployment start, given coverage depends on local transmitters?
Procurement starts with a coverage study, because performance is shaped by local transmitter geography and terrain. From there it moves to staged deployment and integration into the existing air and coastal picture. We carry that chain from the first study through to the sustained installation.
Where does passive radar fit in a layered counter-drone defence?
It is a persistent, covert sensing layer that watches borders, coastlines and critical sites without advertising sensor positions. In the counter-UAS fight it complements detection radar and electronic defeat rather than replacing them. We link it to counter-UAS and software-defined radios because those layers are usually specified together.
See: Counter-UAS as the layered air-threat answerDrone-detection radar
How is passive radar used under emission control?
It is the layer that keeps working when active air-defence radars must go silent to survive, because it emits nothing for an adversary to find. That makes it a survivable complement during emission control rather than a replacement for active sensing. Deployed as a covert layer, it does not reveal where the sensors are.
See: Survivability in the comparison tablePassive radar against Hensoldt Twinvis
Can passive radar be procured without a member-state licensing chain?
The independent route is non-aligned in origin and accountable to the buyer's flag, so a sensor programme is not gated by a foreign government's disclosure rules or re-export restrictions. Political conditions are the row where the two routes differ most. Every transfer still runs inside the governance we apply before representing any capability.
Who accounts for a passive-radar installation once the delivery contract closes?
One accountable team carries it from the first coverage study through the sustained installation, rather than the buyer stitching a study from one party to an installation from another. Sustainment stays in-region rather than tied to a supplier's home market. That single accountable relationship is the difference between a covert layer that keeps working and one that quietly degrades.
See: Accountability and sustainment in the tableHow we deliver and sustain
We want to watch a long land border for small drones without revealing where our sensors are. Is passive radar the right capability to reference?
It is, because the whole point of emitter-free sensing is coverage that gives an adversary nothing to locate or target. Performance depends on the local transmitter picture, so the honest first step is a coverage study against your terrain rather than a headline range. We then stage the deployment and fold it into your existing air and coastal picture, sustained in-region.
See: Employment and procurement for passive radarThe passive-radar catalogue entry
How does passive radar relate to electronic warfare and software-defined communications in a single spectrum programme?
Passive sensing is one of the three lanes in the spectrum fight we represent: it watches without emitting while 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. That is why the electronic-warfare capability page maps passive radar, counter-UAS and software-defined radios as one portfolio.
See: Electronic warfare across the three lanesSoftware-defined radios
Our air-defence radars are exposed to anti-radiation attack. What surveillance layer keeps the picture when we cannot afford to emit?
A passive layer, because it carries no signature for an adversary to find and so is not on the target list when active sensors have to fall silent. It does not replace active radar; it fills the gap survivability forces you to open. The design question is coverage against your transmitter geography, which is why every deployment begins with a study rather than a promise.
See: Why emitters became targetsPassive radar compared with the alternatives
What does the procurement path look like from a passive-radar coverage study to a sustained national installation?
It 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 study is not a formality; it decides where receivers go and what the layer can actually see. We carry the chain end to end so the buyer is not stitching together a study from one party and an installation from another.
See: The passive-radar procurement chainHow we deliver and sustain
Does referencing passive radar mean committing to a full major-power air-defence architecture?
No, and avoiding exactly that is part of the point. The independent route integrates into your existing picture-compilation chain instead of locking you into a single-power integrated air-defence system. You add a survivable sensing layer under national control without inheriting a foreign architecture and its release schedule. Where a comparison is useful, our side-by-side sets it against a named passive system.
See: Integration without ecosystem lock-inPassive radar against Hensoldt Twinvis
How does passive radar sit alongside drone-detection radar and counter-UAS in a single air-surveillance programme?
Passive radar is the covert sensing layer that gives an adversary nothing to locate, while drone-detection radar is active sensing tuned to small, slow, low targets, and counter-UAS turns those tracks into defeat decisions. Scoped together they form one air picture rather than three disconnected buys. We represent the sensing and defeat elements through one channel so they integrate into the buyer's existing picture rather than a foreign architecture.
We cannot rely on a member-state licensing chain for a sensor programme. How does the passive-radar reference address that?
The independent, non-aligned route is accountable to the buyer's flag, so a passive-radar programme is not gated by a foreign government's disclosure rules, re-export restrictions or upgrade approvals. Every transfer still runs inside the governance we apply before representing any capability. Political conditions are the row where the two supply routes differ most, which is exactly the concern behind the question.
See: Political conditions in the comparisonPassive radar against Hensoldt Twinvis