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Hi!
Anyone has any idea how far (diameter) can a 10mW powered AP project the RF signal? I'm looking for the standard specs and assumming that there's no obstruction - maybe a big exhibition hall.

Your radio transmits at 10 mW = 10 dBm. The guidelines that I use for quick math are that a typical 802.11 PCMCIA card needs -70 dBm for highest data rate, -80 dBm for medium data rate, and -90 dBm for lowest data rate (lots of cards deviate from these numbers, but I use them for rough estimates). I add in a 10 dB fade margin, to get a signal strength threshold of -60, -70, and -80 dbm for highest, medium, and lowest data rate. This means that we have a link budget of 70, 80, and 90 dBm respectively. Finally, I use free space path loss calculations to derive distances for these signal levels.

For -60 dBm, I get about 130 feet.
For -70 dBm, I get about 410 feet.
For -80 dBm, I get about 1200 feet.

This is using just FSPL predictions--in other words, assuming no obstructions whatsoever.

Thanks Joshua. That will do!