Hi @laurent, one of the locations where I needed to fit a Wemos was outside, in a box that was going to be both strong and waterproof. I decided to use a diecast aluminium box, which meant that the Wemos was almost totally shielded. Using a Pro board and external antenna was an easy fix.
I also have another location where the the Wi-Fi signal is fairly weak and I’ve used used a similar solution there.
I’ve found that the antennas you buy on eBay vary enormously in terms of gain, and as I don’t have an antenna tester I used the ‘trial and error’ method, by monitoring RSSI values to find the most efficient type of antenna in a given location.
If you do use an external antenna with a Pro, you need to move the zero ohm resistor, otherwise the external antenna will make no difference.
I’ve not done any power consumption comparisons. Are you thinking of using deep sleep mode? If so, then you may want to consider an ESP8266 board that doesn’t have an onboard USB interface and 5v regulator - maybe one of the Sparkfun boards.
Pete.