iMac WiFi dropping signal

I bought my iMac about a month ago and just recently it has been dropping my WiFi signal all the time. I mean like every 5 min or so. And every time it goes to the screensaver or to sleep it will not reconnect unless I turn the WiFi off then on or even restart my computer. What could be causing this and is there anything I can do to fix it. I know it is my iMac bc my other computers and phones will stay connected all the time without dropping. Thanks for your help!!

I am sort of having the same issue with my mac mini, and this is what i know: my mini was dropping wireless randomly, but none of the other wireless devices in my house were. I took it to the apple store and they said it had a bad AirPort card and antenna, which they replaced under the Applecare warranty. That solved the signal problems, but i still have to restart my wireless router (a netgear) each time i reboot my mini, because it wont renew the DHCP lease for it. The other wireless computers in my house (pcs) dont have this issue.

I suspect your antenna is bad; go to apple, but as for the having to restart your wireless i have no idea how to fix it (i have talked to apple about it as well as netgear, and nobody seems to have an answer). If you get any leads, please let me know.

Thanks