3D-printed GRIN Luneburg lenses
Field-ready RF optics for radars, SATCOM and drones
A GRIN (GRadient-INdex) lens is an optical or radio-frequency element whose refractive index is not constant, but varies continuously throughout the material.
Rather than relying on curved surfaces to bend waves, as a conventional lens does, a GRIN lens uses an index gradient to progressively steer the wavefront toward the intended focus.
The Luneburg lens is the best known and most useful case in this family: a permittivity profile that decreases from the center outward, reaching the value of air at the boundary.
That continuous gradient is what makes these lenses hard to build. Conventional methods approximate it with concentric dielectric shells, a stepped profile that reflects at every interface. 3D printing builds the gradient directly, varying local density basically voxel by voxel.
The result is a lens able to focus a wave arriving from any direction onto a single point on the opposite surface of the geometry, and, reciprocally to turn a point source placed on the surface into a collimated, highly directive beam.
(See the illustration alongside: how a spherical luneburg lens works).
Key advantages of Luneburg Lenses
The main benefits of this type of RF lens are:
- 360 Degrees coverage
- Beam steering: the beam direction is set by the feed position on the surface
- Multiple simultaneous beams from several feeds
- Performance independent of the angle of incidence
- Passive, lightweight element
Verne AM Additive Manufacturing technology
Verne AM prints GRIN/Luneburg lenses up to 28 cm in diameter, covering frequencies from the UHF band to the X/Ku band, using materials with a high dielectric constant and low loss.
This approach, combined with Verne’s laser sintering technology, offers complete geometric freedom, with continuous gradients that more closely match the theoretical profile, as well as reduced production times and costs.
Compared to FDM/FFF printing, laser sintering delivers significantly finer cell resolution, making it possible to operate at higher frequencies. At the same time, the greatly redurced layer-to-layer anisotropy yields a more accurate and repeatable dielectric gradient across the entire lens.
Customizing your lens
Proprietary in-house software allows us to design lenses with application-specific geometries and gradient profiles, tuning both the lattice topology and its local density to the target band. We work in close collaboration with your R&D team.
High-Performance Materials
Verne AM lenses are 3D printed with materials designed for high perfomances on the field.
High dielectric, low-loss
To maximize the aperture efficiency and minimize signal attenuation through the lens.
Not affected by UV rays
No deterioration in dielectric performance or mechanical properties due to prolonged exposure to sunlight.
Non-hygroscopic
Dielectric stability even under conditions of high humidity, without absorption of water (or other liquids
Suitable for field use
Designed for harsh outdoor and environmental operating conditions.
Expected RF performances
Achievable gain of 3D-Printed Luneburg Lenses
Based on a 65-mm-diameter lens, the estimated gain is around 16 dBi in the X-band.
As the diameter increases, the gain increases significantly: with a 28-cm-diameter lens, the theoretical gain in the X-band can reach approximately 29-30 dBi.
| Frequency | IEEE Band | Estimated Gain (typical efficiency ~55%) |
|---|---|---|
| 1–2 GHz | L | ≈ 9 dBi |
| 2–4 GHz | S | ≈ 15 dBi |
| 4–8 GHz | C | ≈ 21 dBi |
| 8–12 GHz | X | ≈ 27 dBi |
| 12 GHz | X / Ku | ≈ 29–30 dBi |
Liang, M., Ng, W.R., Chang, K., Gbele, K., Gehm, M.E., Xin, H., “A 3-D Luneburg Lens Antenna Fabricated by Polymer Jetting Rapid Prototyping,” IEEE Transactions on Antennas and Propagation, vol. 62, no. 4, 2014..
Radar Cross-Section (RCS) Amplification
Among the various possible applications of Luneburg lenses, the metallized-hemisphere configuration is particularly compelling.
Here the device acts as a radar retroreflector, returning incident energy back along the direction it came from. The incoming signal is focused onto the metallized surface and redirected toward the source, producing a substantial increase in radar cross section (RCS) compared to a target without a reflector.
Notable practical uses include drone decoy systems, as well as Radar Signature Augmentation Devices (RSAD) fitted to stealth aircraft during training, when a more visible radar signature is preferable.
Available sizes and reference ranges
Spherical lenses (6 diameters): 65mm / 85mm / 100 mm / 125mm / 200mm / 280mm
| Diameter | Approximate reference band | Application examples |
|---|---|---|
| 65–85 mm | C–X (~4–12 GHz) | Onboard radar for obstacle detection/anti-collision on drones; RF direction-finding and geolocation pods (SIGINT) in collaborative drone networks; compact drone-to-drone data links for swarms |
| 100–125 mm | S–X (~2–12 GHz) | Onboard SATCOM terminals for LEO and GEO uplink/downlink with satellite tracking; point-to-multipoint links for backhaul; compact multi-beam antennas for base stations |
| 200–280 mm | L–X (~1–12 GHz, with residual UHF margin in the high band) | Radar countermeasures/decoys (retro-reflector for anti-drone RCS amplification); multi-beam antennas for long-range base stations, maximum gain and isolation between sectors; high-capacity backhaul |
Cylindrical lenses: Maximum dimensions 280 mm
Alternative frequency bands: UHF and Ku/Ka bands are currently under study.
Areas of application
Telecommunications systems for the military, aerospace, and civilian sectors
- Randar antennas (surveillance, tracking)
- RCS reflectors for low-observable (stealth) aircraft training
- RF systems for mobile and vehicle-mounted platforms
- Tactical deployments in outdoor operating environments, where UV and moisture resistance is a critical requirement
- X-band satellite communications (SATCOM)
- Multi-beam scanning systems for high-capacity connectivity
Applications for UAV systems and drone technology
Radar decoy systems with RCS magnification
Systems that artificially amplify radar cross section (RCS), enlarging a target’s apparent radar size in order to deceive detection systems.
Unlike conventional radar reflectors such as corner reflectors, the Luneburg lens delivers 360° azimuthal reflection coverage, making the target credible from any radar viewing direction, not only from specific angles.
Direction finding and RF geolocation (SIGINT) in drone networks
Thanks to its 360° angular coverage and wide bandwidth, a 3D-printed Luneburg lens could enable a drone network to detect and locate adversarial RF emitters in contested environments, with an estimated improvement of at least 6× in bandwidth and field of view over baseline systems.
Full 360° coverage would allow signal sources to be triangulated, with each drone acting as a distributed passive sensor.
Drone-to-ground data links and counter UAS systems
As a passive, lightweight RF optic, the lens is well suited to drone-to-ground and drone-to-drone links (swarm coordination, video, telemetry), providing wide coverage without the need to physically steer a directive antenna.
A further application area lies in improving the performance of radar systems dedicated to drone detection.
Our technology, your parts
From functional prototypes and custom one-off parts to low and mid-volume production runs, our SLS expertise with specialty materials makes us the perfect partner for innovation-focused companies like yours.
Share your designs and requirements with us, and we’ll respond as quickly as possible.