HI Dave1374,
I'm looking to do an outdoor project that needs to receive the signal from about 70 feet from the home router. Also, there are multiple walls (5?) between the router and the microcontroller.
Can it work with the Netduino 3 built in wifi or do I need to add an antena ?
The Netduino will be inside a shed.
With RF, for better or worse, results will depend on multiple factors include the signal strength of your access point. That said, 2.4GHz is a faster frequency so it will get blocked more by walls...and five walls and 70 feet may be stretching things a bit at that point. Add to that a possible outer-metal wall on the shed...
If the range is too much, you may consider adding a Wi-Fi repeater inside the outer wall of your home. Or using XBee with repeaters or another technology in conjunction with or as a replacement for Wi-Fi. Lots of options, some better for your application than others...
Chris