Hi,
Broadly speaking it is what would be called microwave radiation. Interesting point about wireless routers, I personally will not allow them in the house but my concern is one of security. The problem with a wireless router is the security against illicit access is not great hence if someone within range wishes to browse objectionable sites it is you that gets the 3 o'clock knock by the boys in blue not them.
Can I suggest to all K Bike riders if you must have them make sure they are locked down as tightly as they can be, get someone with the skills that Bert has to check your set-up on site at home. I don't mean bug Bert to check for you, find an IT guru locally who can check, it could avoid you having to answer very unpleasant lines of questioning along with the impounding of your computer/s for weeks for forensic examination.
Now back to the original question, as the power falls off as the inverse square of distance if your modem is right beside you and you spend all day beside it that would be a bad thing. If it is a way away then the signal level is low.
If anyone wants a surprise go in to your phone menu and look at the time spent on the phone it will be a scary number all of which is blasting your brain with microwave, don't know if it is bad but I do know it's not good!
One place often not considered for microwave exposure is beside shipping lanes and airports the focussed beam of ship radar is many kilowatts - not good. I know the main approach radar at King Fahd Airport is 2 megawatts others are probably similar. The pilot & co-pilot are facing right down the beam at times!
I recall a demonstration at a site which I cannot tell you where it is, the site engineer told me the beam killed birds and getting on his radio as a flight of birds passed in front of the antenna he said light her up and they all dropped out of the air like stones.
Regards,
K-BIKE