Thanks, Dave. I never thought of implementing a metamaterial in a PCB. On Wed, Aug 26, 2015 at 7:37 PM, David VanHorn wrote: > 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 anten= na > 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 fo= r > 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 t= o > 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 > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .