EFFICIENCY LIMIT OF RECTIFYING ANTENNA COLLECTION OF SOLAR ENERGY

摘要

Antennas with rectifiers, "rectennas", have attracted attention as potential solar energy collectors and converters, partly on the basis of demonstrated high efficiencies for collection of coherent, quasi-monochromatic radio communication transmissions. The fundamental differences of these two applications of antennas are outlined and it is confirmed theoretically that antennas receiving black body radiation may be modelled as a pair of resistors at the black body temperature, in the optimal case. Extraction of that power from a load as DC electricity by half wave rectification is shown to be limited to 48.8% for the sun modelled as a 6000K black body. The possible unavailability of a suitable antenna technology, meeting all the requirements of frequency independence, dual polarisation and narrow beamwidth, may restrict applications.