The ISS

I would suggest contacting Professor Kai Chang at Texas A & M
http://ee.tamu.edu/people/bios/bchangka.html

his email is chang@... (remove the NOSPAM...)

He will likely know what is available in regards to your questions...

Tom M.
TomM@...

In vacuum, what is the highest conversion efficiency we can get
and at what frequencies for each of the following:

1) RF to DC
2) DC to RF
3) 1) in series with 2), i.e. DC -> RF -> DC

For each item above please provide as much of the following as
possible:
a) best conversion efficiency
b) frequency at which this efficiency is achieved
c) name of technology/device which does this
d) supplier(s)
e) references/datasheets

I find it difficult to believe conversion efficiencies greater than
50% for optical wavelengths.

I would expect the answer to this question to be somewhere in the
microwave region.

Thanks,

Charles F. Radley