Radar is not a competitor to RF detection — it is a complement. It becomes relevant when you must see non-cooperative drones that broadcast neither Remote ID nor a usable RF signature. Here is how it works and when it is justified.
Principle
A small-drone radar emits a wave and analyses the returned echo. Micro-Doppler radars exploit the frequency variations introduced by rotating blades, which allows discriminating a drone from a bird or a vehicle.
Modern radars typically operate in X, Ku or Ka bands. Useful range on a 25 cm drone goes from 1 to 5 km depending on power, sensitivity and environment.
Strengths and limits
Strengths: sees non-cooperative drones, all-weather, independent from RF signatures, good at long range.
Limits: requires transmit authorisation (ANFR, FCC), higher acquisition and installation cost than an RF detector, clutter sensitivity (buildings, trees, birds), higher weight and power requirements.
When to justify radar
- Site exposed to modified or home-made drones (defence, critical infrastructure).
- Large free-field perimeter (>1 km).
- 24/7 detection without dependency on an RF signature.
- Multi-sensor architecture with hypervision fusing radar and RF tracks.
RF + radar complementarity
Best practice on a sensitive site is to combine a passive RF detector (DECTYR RX-5) for the vast majority of consumer drones with a radar for non-cooperative ones. DECTYR Hub fuses the events and gives the operator a single view.
FAQ
Do I always need a radar?
No. For 80% of civilian sites, passive RF detection is enough. Radar makes sense on highly exposed sites or for large free-field coverage.
Does a small-drone radar pick up manned aircraft?
It may, but that is not its primary purpose. Manned traffic is mostly handled by other systems (ADS-B, transponders).
Which manufacturers in Europe?
Robin Radar (Netherlands), Aaronia (Germany), HENSOLDT, Thales, and several defence spin-offs. The market is consolidating.