Are there wireless powering products for a distance of 50 cm? I want to design a sensor tag where it can be recharged wirelessly. Is that possible?

 

It is not practicable to transfer significant power across a 50cm air gap.
The nearest to this would be anti-theft tags. Read here: http://www.explainthatstuff.com/rfid.html

 

Agreed. There are examples of using a field to temporarily power a low-power transmitter. Chips that runners wear during a race sometimes use this principle, but the amount of power is tiny - just enough to chirp the transmitter.

 

I suppose you could use a bright light in a reflector and a solar panel. Whether that is a useful idea is up to you.

 

Thank you both for your response and suggestions. This is helpful.