3D Printed Feed
Understanding the 3D Printed Feed
If you look at a massive satellite dish (a Parabolic Reflector), the massive curved dish itself does not actually transmit or receive the radio wave. The dish is just a dumb mirror.
The actual radio is the small, conical trumpet sitting at the very center, hovering exactly at the focal point. This is the Feed Horn.
The Geometry of the Feed
To operate at maximum efficiency, the Feed Horn cannot be a simple smooth pipe. The inside of the trumpet must be carved with highly precise, circular grooves called Corrugations.
- These grooves prevent the radio wave from accidentally bleeding over the edges of the horn (reducing Sidelobe leakage).
- They ensure the radio wave expands outward in a perfectly uniform pattern, perfectly "illuminating" the entire surface area of the massive dish behind it.
The 3D Printing Advantage
Historically, to carve these deep, circular grooves inside a narrow trumpet, machinists had to use incredibly slow, expensive CNC lathing techniques. As frequencies push higher into the millimeter-wave bands (like the 40 GHz V-Band or the 80 GHz E-Band), the grooves become so microscopic that traditional drill bits simply snap.
3D Printing solves the manufacturing bottleneck.
By building the feed horn layer-by-layer from the ground up, engineers can easily generate these microscopic, mathematically perfect internal corrugations. Furthermore, they can seamlessly print complex Orthomode Transducers (OMTs) directly into the base of the feed horn. An OMT separates the Vertical and Horizontal polarization of the radio wave. By 3D printing the Feed and the OMT as one single, seamless, monolithic block of metal, the factory entirely eliminates the bolts, flanges, and microscopic air gaps that cause signal reflection and RF leakage.
Key Equations
Gain = 10log(4πAe/λ²) dBi
Ae = ηap×Aaperture
Surface loss penalty:
Δα = Rs,rough−Rs,smooth
Typ: 0.1–0.5 dB extra @Ka-band
Weight reduction:
30–70% lighter than machined (lattice fill)
Comparison
| Design | Frequency | Gain | Weight vs machined | Notes |
|---|---|---|---|---|
| Conical horn | Ku–Ka | 15–25 dBi | −40% | Simple geometry |
| Corrugated horn | Ka–W | 18–28 dBi | −50% | Complex but printable |
| OMT + horn | Ku–Ka | 15–22 dBi | −60% | Integrated feed |
| Multibeam feed | Ka | 12–18 dBi/beam | −50% | Array of horns |
| Spline horn | X–Ka | 15–25 dBi | −40% | Optimized profile |
Frequently Asked Questions
Why use metalized plastic for the feed?
Weight reduction. A massive satellite dish mounted to the roof of a news van must be precisely aimed by electric motors. If the Feed Horn assembly hanging off the front of the dish is made of solid CNC brass, it acts like a heavy pendulum, straining the motors and throwing the dish out of alignment in high winds. By 3D printing the Feed out of SLA plastic and coating it in a microscopic layer of copper, the assembly weighs virtually nothing, massively improving the mechanical stability of the dish.
Does a 3D Printed Feed handle high power?
It depends on the material. A pure metal feed (printed via DMLS titanium or aluminum) can easily handle massive, multi-kilowatt transmission power because the solid metal effortlessly dissipates the heat. A plastic metalized feed is strictly limited to low-power or receive-only applications; if you pump 1,000 Watts through a plastic horn, the microscopic copper skin will instantly overheat and the plastic structure will melt.
How precise is the 3D printing?
Astronomically precise. Modern SLA resin printers and DMLS metal printers can achieve layer heights of just 20 to 50 microns (thinner than a human hair). This is more than sufficient to perfectly replicate the mathematical geometries required for 40 GHz to 80 GHz millimeter-wave propagation.