hi,
an harmonic radar using zero bias diodes ad frequency doubler as in this article:
http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=1353476
shows a convertion efficiency quite low (0.8% at a 30 W/m2)
do you think replacing diodes with MMIC passive frequency doubler (as HMC-XDB112) can improve performance of tag of an harmonic radar? (note that input power can be very smaller respect datasheet specs)
br,
Maurice