Patent ID: 7612731

Claim:
An apparatus, comprising: a first conductive layer; a first dielectric layer proximate the first conductive layer; a second conductive layer substantially parallel to the first conductive layer and proximate the first dielectric layer so that the first and second conductive layers sandwich the first dielectric layer to create a resonant cavity for reducing radio frequency interference between a collocated first antenna and a second antenna operating in a first frequency band; a third conductive layer substantially parallel to the second conductive layer and proximate a second dielectric layer so that the second and third conductive layers sandwich the second dielectric layer to create a further resonant cavity, wherein the second conductive layer is larger than the first conductive layer to redirect energy due to diffraction at an edge of the first conductive layer, and the third conductive layer is larger than the second conductive layer to redirect energy due to diffraction at an edge of the second conductive layer, wherein the first and second conductive layers are spaced at a quarter wavelength for a first frequency in the first frequency band and the second and third conductive layers are spaced at a quarter wavelength for a second frequency in the first frequency band.