Warning:  Possible black hole time sink for some people


I just had occasion to use metamaterials in a design project.
It's pretty cool stuff.

My problem was a PCB antenna for 2.4G that needs to tolerate being placed
on top of a DVD player or similar with a steel case.

The design came to me with a lot of conditions, including "no external
antenna" and "nothing sticking out of the case", and "as inexpensive as
possible"

I simulated a number of designs in Xfdtd and found a nice broadband antenna
that is better than 10dB return loss from about 1Ghz through 7+ Ghz.
Modeled in the plastics in free space, it's great.
Modeled on a wood shelf, it's great.  Modeled on the DVD player, it's a
total mess with horrible return loss.

As usual, the product owners could care less about the laws of physics,
they just don't want it to be ugly.  Plastic tooling has been finished for
a long time, so I couldn't do anything sensible like flip the PCB to the
top side of the case.

By chance, I hit on an article about metamaterials.  Without getting too
specific, I designed a PCB footprint to be a resonant metamaterial "atom"
and put an array of those in the PCB underneath the antenna.

Now when the horrible metal DVD player is present, the return loss goes to
hell everywhere except the 2.4-2.5 GHz band!  The metamaterial reflection
actually adds to the main signal and I get about 6.7 dBi gain on antenna
that would be normally 2-3dBi, and the radiation pattern is pretty decent
as well.  It's not isotropic, but it's "good enough".

Anyone else using metamaterials?

A nice overview:
https://www.nsa.gov/research/tnw/tnw203/articles/pdfs/TNW203_article4.pdf

One type of metamaterial
https://en.wikipedia.org/wiki/Split-ring_resonator

https://www.youtube.com/watch?v=3DKS3tX3O0EJQ
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