My mac book air suddely disconnects many times the wifi while using wifi

Question

my mac book air suddely disconnects many times the wifi while using wifi

Answer 1

Lots of things can impact wifi connections.  If you are at the marginal edge of the wifi range (which depends not only on distance, but what's between you and the transmitter) you may find the connection dropping in and out.  Sometimes a minor repositioning of the computer or transmitter can solve the issue.
As well, interference can also create problems.  For instance, microwave ovens are really good at disrupting 2.4Ghz signals, and that the frequency used most often in wifi routers--so if someone turns on the microwave and it's between you and the transmission point it won't be surprising if the connection drops.  As well, metal blocks the signal fairly effectively, so if (say) ductwork is between the CPU and the wireless router there can be problems.
Finally, I've run into some combos of devices and routers that just don't seem to like each other :-) .  That said, I've not hit that problem with either Air I'm running (an 11" and a 13"), though obviously I've not tried to connect them to every type of router out there.
Just this week I was at a hotel and in my room the hotel wifi was "interesting" with every device I tried (iPhone, Android phone, Kindle Fire, iPad and the two Airs) dropping connection regularly from the work desk.  Turned out if I moved the devices over to the nightstand on the other end of the room (not the best work environment) all of the problems went away, so it clearly was a signal issue and the exact layout of that room and the hotel's wifi.
If the machine has a problem when positioned close to a variety of routers, then I'd suspect a hardware issue with the wifi card in the Air and get that checked by Apple.  Similarly, if your problem is with your home router, I'd check to see if other devices also are getting dropped, since there could be a hardware issue on the router.