Substitution of the numeric value for c followed by a unit conversion results in an easy way to calculate the radius of the first Fresnel zone F _ 1, knowing the distance between the two antennas D and the frequency of the transmitted signal f:
42.
If a signal is horizontally polarized and it deflects off a horizontal object such as a flat roof, and then bounces up to a receiving antenna, and if the roof is within the 1st region of the Fresnel zone, the resulting signal will be received favorably-as it will be in-phase.
43.
If a signal is vertically polarized and it deflects off a horizontal object such as a flat roof, and then bounces up to a receiving antenna, and if the roof is within the 1st region of the Fresnel zone, the resulting signal will be inverted relative to the original signal.
44.
Current hard X-ray microprobes based on Fresnel zone plate optics have demonstrated a spatial resolution of 150 nm at a photon energy of 8-10 keV . With advances in the fabrication of zone plate optics, coupled with an optimized beamline design, the performance goal is a spatial resolution of 30 nm.
