The world of microwave RF design appears to the uninitiated to be full of unimaginably exotic devices, as engineers harness the laws of physics to tame radio signals to their will. Among the weapons in their arsenal are materials of known dielectric properties, from which can be made structures with the desired effects on RF that encounters them. This has traditionally been a difficult and expensive process, but it’s one now made much easier by the availability of 3D printer filaments with a range of known dielectric values.
It’s best to think of the structures which can be designed using these materials as analagous to Fresnel lenses we’re all used to in the light domain. The example piece given by Microwave Journal is a metasurface for use in a steerable antenna, something that would be a much more difficult piece of work by more traditional means.
Normally when we inform you of a new special filament we’d expect it to be more costly than standard PLA, but this filament is in a class of its own at 275 euros per kilogram. So the interest for most readers will probably be more in the technology than the expectation of use, but even then we can see that there will still be microwave experimenters in our range who might be tempted by its unique properties. We look forward to what is developed using it.
Via Microwave Journal. Thanks to [Eric Mockler] for the tip!
While I don’t have a direct use for this filament. It’s very useful to know it exists. It can greatly reduce cost for the RF prototypes I’ve build in the past. Even better, removing unknowns and reduce the guessing game, definitely worth the price in gold. If money is tight, then only print the necessary parts in the material, and switch to cheap filament for anything that’s not critical.
Even with solid infill there will likely be random volume of air bubbles in FDM printed part. Sounds like an issue if you need part with defined dielectric values…
Why do you consider that too expensive for hacker use. I wish all my project were that cheap. I guess the result is way cheaper this way.
So its a bit more than tenfold the price of regular PLA, very pricey, but probably still rather cheaper than any alternative non-3d-printing method of fabricating parts with the kind of known properties needed in very specific radio appplications. Now, the big question is going to be whether it could run from a perfectly normal printer, and how the naturally anisotropic nature of filament extruded parts, and the tiny gaps between adjacent extruded lines, would affect the properties.
Even better, read the datasheet on the ε=2.2 filament, and why it’s a different color.
And doesn’t permittivity depend on frequency? And doesn’t melting and cooling temperature and dwell time change crystalization?
I mean, cool for people who know about this, of which I am definitely not one, but I feel like this is just to sell titanium dioxide to people with more Francs than sense.
i know almost nothing about RF propagation and stuff but does this mean you could possibly use this as an RF shield by diverting the waves away from the critical components? also the tag of the article sais wicroave.
Well… possibly. But a bit like using clear glass to shade something. Much more easily shielded with something opaque to RF, like metal.
Tin foil hat would do better…
Im not sure what the design benefit of that metamaterial pic is. At first i thought I was looking at moire, but the pattern is actually printed to look that way.
Maybe im unimaginative, but wouldn’t you just want high impedance and low impedance? Either you want the highest quality signal to come from a certain direction, or otherwise you want to block it out. Why would you want variable impedance as provided by this range of filaments?
Impedance matching has always been a confusing concept. Since power is volts times amps, you get the highest power transferred not when impedance is 0 (no volts) or infinity (no amps), but when it’s just right. So instead of a 0 ohm generator feeding an infinity ohm load (0W transferred), you typically want about a 50 ohm generator feeding a 50 ohm load through a 50 ohm transmission line / cable. The 50 is just a convenient number used in rf and data. Video uses 75. That transmission line or cable is made using simple geometry and known permitivity. Being able to change the permitivity together with or instead of the dimensions is helpful, as sometimes things become just too big or too small to work well in the real world.