Having read about frequency clashes around 5Ghz, the harmonization of said freqencies, 802.11h and whatnot didn't help much to clarify the issue for me. I've got the choice between Intels b/g WiFi card housed under the Centrino-brand and an american Atheros a+b/g card. I guess I won't be using the 5Ghz band much but the Atheros is said to consume less power. I assume one wouldn't be crashing planes with a low power card like this and there must be thousand of our american visitor walking all around Europe with 5Ghz WiFi cards in their laptops. But I'm still curious, is it technically legal to operate such a card in Europe?

Don't know for the rest of Europe (recall reading something regarding something about some common US item [very clear, ain't I ]
using some common US frequency and it causing problems in France...), but for Sweden it looks like some of the frequencys used
by 11a are OK. It'll try to summarize/translate the relevant part of this document

802.11a
Equipment operating according to 802.11a are considered equal to Hiperlan 1 equipments, which are excepted from
license requirements in Sweden in the band 5150 - 5250 MHz. Rules are that usage is limited to indoors with a maximal effect of 200mW eirp(?).
802.11a is not allowed to operate in the 5250-5250 MHz band since this type of equipment does not fulfill the requirements in the ERC-decision (99)23
primarily considering dynamic frequency choice, DFS, power limiting, TPC, and useage spread in sufficiently wide band.
If PTS (Post and Tele Board) were to excempt 802.11a equipment operating in the 5250-5250 MHz band the risk is high
for disturbances to for instance radar equipment. Since the equipment would the excempted from licensing would also mean that it would be hard to correct
disturbances since it would not be known who is causing the problem / where the equipment is located.


It looks like the base document for the Swedish rules regarding wireless LAN equipment are based on a European document,
ERC (99)23, which can be found here.

Thanks, right on the spot and from an official source, exactely what I was searching for. It looks like WLANs have quite an interesting history behind them. Hyperlan opened up 5.15-5.35 (indoor) and 5.470-5725 (outdoor) in Europe, while the 802.11a physical layer allocated the 5.15-5.35 (indoor) and 5.725-5.825 (outdoor). So they don't match up exactely. However the keywords in your pdf helped me google new sites I havn't found before and according to a finnish site Europe has already opened up 5.725-5.825 (although only at 100mw versus 800mw in the US) and under 802.11h the US will open up the 5.470-5.725 spectrum, effectively harmonizing the two.