A Spin-Filter Rectenna for Ambient Radio-Frequency Energy Harvesting

The design presented in this paper is a spin-filter rectenna intended for trickle-powering remote sensors near broadcast and wireless infrastructure. Its operating principle is that a patch antenna feeds a rectifying junction through a spin-filter layer that is modelled as suppressing reverse leakage, raising rectification efficiency at the very low input powers typical of ambient radio-frequency fields. The design is computed from stated assumptions throughout; it is simulated, not measured, and no prototype results are reported. The headline result is a DC output at the design ambient density of 110 µW, obtained with incident RF power on the aperture of 240 µW with a computed efficiency or performance coefficient of 46 per cent where that measure applies, for a unit of mass 0.05 kg whose characteristic scale is a effective aperture of 0.012 m^2. A parameter sweep reported in the Results section shows how the output moves when the principal variable is changed, and the density of the working material, 1.5e+03 kg per cubic metre, sits about 54.8 orders of magnitude below the neutron-carrier density bound of 9.72e+57 kg per cubic metre, so the bound enters this design as a sizing ceiling and a margin statement rather than as an operating condition. The limitations are stated plainly: ambient densities vary by orders of magnitude with location, so the design point describes a favourable site, not a typical room. Status: SIMULATED, NOT MEASURED.