Dark Matters [Microwave Bytes]

I´m not sure how and why all this started, but I seem to have taken a recent new interest in magnetics. Having spent most of my own technical career working in the GHz frequency range, I have really had little to do with ferrites and magnetic properties of materials in general. Other than occasionally thanking my lucky stars that such things as isolators exist (and even then feeling a sense of failure that I ended up needing to use one), dark matter, in the form of ferrite materials doesn´t really feature much in microwave circuits, certainly not to the extent they do at much lower frequencies. Indeed here is yet another cultural divide, one that I did touch upon in a recent column [S.C. Cripps, 2011], and maybe that was where the present interest was seeded.