domestic microwave sheilding

[lawrie]

I was testing a RFID tag in the office recently and wanted to loose the signal, I thought that by placing the little tag in a microwave oven 10 metres away I would loose the signal from the RFID reader. It suprised me that it still worked perfectly, why is this?
I assume that a microwave oven is a good Faraday cage and designed to stop RF emmisions at about 2.45GHz therefore the Tag which operates at 968MHz on something like 0.01mw should have been blocked, especially since it used a longer wavelength than the microwave.

Should I be running from the microwave when it is on?

The project I am looking into is to detect small inexpensive tags when placed inside a panelled delivery van when it passes a fixed reader, assuming worst case that the van is mostly metal sides, bottom, roof and doors with no windows what would be the best frequency to use if it was possible to receive a signal through minimal RF leakage ie through door seals, air vents etc etc?

All help would be gratefully received, thanks

 

[VEBill]

Interesting story about the microwave oven...

Are you using (or planning to use) RFID tags with internal batteries ? Or are you planning to use the RFID tags that extract miniscule amounts of electrical power from the signal emitted by the 'base station' antenna ? The difference is obviously the maximum range.

 

[lawrie]

I will be using the type with internal batteries.
thanks,
L.

 

[jbartos]

Suggestion: Visit

http://rapidttp.com/transponder/tadiran.html

for info on batteries