Get Wifi Signal in Windows CE 6.5

 foreach (var ni in NetworkInterface.GetAllNetworkInterfaces())
            {
                //var wzc = ni as WirelessZeroConfigNetworkInterface;
                //if (wzc != null)
                //{
                //    MessageBox.Show("WZC Signal: " + 
                      wzc.SignalStrength.Decibels+":"+wzc.Name);
                //    StrengthType st = wzc.SignalStrength.Strength;
                //    switch (st)
                //    {
                //        case StrengthType.NoSignal:
                //            break;
                //    }
                //    continue;
                //}

                var wni = ni as WirelessNetworkInterface;
                if(wni != null)
                {
                    StrengthType strength = wni.SignalStrength.Strength;
                    switch (strength)
                    {
                        case StrengthType.NoSignal: Program.batteryandtime.WifiUpdate(0);
                            label1.Text = "NoSignal";
                            wifi_strength = 0;
                            break;
                        case StrengthType.NotAWirelessAdapter:
                            Program.batteryandtime.WifiUpdate(0);
                            label1.Text = "NotAWirelessAdapter";
                            wifi_strength = 0;
                            break;
                        case StrengthType.Excellent:Program.batteryandtime.WifiUpdate(3);
                            label1.Text = "Excellent";
                            wifi_strength = 3;
                            break;
                        case StrengthType.VeryGood:Program.batteryandtime.WifiUpdate(3);
                            label1.Text = "VeryGood";
                            wifi_strength = 3;
                            break;
                        case StrengthType.Good:Program.batteryandtime.WifiUpdate(2);
                            label1.Text = "Good";
                            wifi_strength = 2;
                            break;
                        case StrengthType.Low: Program.batteryandtime.WifiUpdate(1);
                            label1.Text = "Low";
                            wifi_strength = 1;
                            break;
                        case StrengthType.VeryLow: Program.batteryandtime.WifiUpdate(1);
                            label1.Text = "VeryLow";
                            wifi_strength = 1;
                            break;
                    }
                   
                                    
                    continue;
                }

                MessageBox.Show("No signal info available");
            }              

Note : To use  OpenNetCF.Net.dll (2.3.12004.0)