Have you tried installing Portugese* as a language in your phone settings? Your current language obviously does not contain that character. If you download and install the Portugese* language pack for your phone, it should recognize that character in the Wi-Fi network name.
Alternately, you could try to manually add the Wi-Fi network to your phone using the network SSID. Simply type in the correct SSID (network name) with the special character instead of trying to auto-detect the network.
As a quick and dirty solution, you could also use an app like WiFi Connection Manager which claims to be able to handle special characters.
Also, according to this page (http://unix.stackexchange.com/questions/39352/unable-to-connect-to-a-wifi-network-with-a-special-ssid), it seems like the default Android encoding of SSID's is the source of your problem. The only fix I've seen is using an app or writing your own driver or script to connect to the network using the correct encoding for special characters.