After studying existing solutions, I decided to use voltage multiplier topology, similar to WISP project (http://wisp.wikispaces.com/), which proved to be successful to lower RF frequencies (sub-1GHz).

The main difference is, that I should use other Schottky diodes, for higher frequencies.

After long search, I found one which made my day!  - HSMS-286x series diodes from Avago.  According to datasheet, these are "DC biased detector diodes, designed and optimized for use from 915MHz to 5.8GHz. They are ideal for RF/ID and RFTag applications as well as large signal detection, modulation, RF to DC conversion or voltage doubling" - Exactly what I need!!! :)

As result, Schematics now is ready for antenna and voltage doubler. I'll try to finish and order PCBs tomorrow or after tomorrow....