string output = string.Empty;

            ManagementClass mc = new ManagementClass("root\\WMI", "MSNdis_80211_BSSIList", null);

            //ManagementClass mc = new ManagementClass("root\\WMI", "MSNdis_80211_ReceivedSignalStrength", null);            
            ManagementObjectCollection moc = mc.GetInstances();
            foreach (ManagementObject mo in moc)
            {
                string wlanCard = (string)mo["InstanceName"];
                output = output + wlanCard;
                ManagementBaseObject[] bssiList = (ManagementBaseObject[])mo["Ndis80211BSSIList"];

                //ManagementBaseObject[] bssiList = (ManagementBaseObject[])mo["Ndis80211ReceivedSignalStrength"];
                foreach (ManagementBaseObject bssi in bssiList)
                {

                    byte[] macid = (byte[])bssi["Ndis80211MacAddress"];
                    string macidString = Encoding.ASCII.GetString(macid);

                    byte[] ssid = (byte[])bssi["Ndis80211SsId"];
                    string ssidString = Encoding.ASCII.GetString(ssid);
                    output = output + " " + ssidString;
                }

               output = output + "########################";
            }


            return output;