I’m using a ESP32 with ESPHome connected to my heating system for climate control, as expained in a previous post.

The heating system is in a different builng than the router and I was experiencing some WiFi coverage issues (the WiFi signal needs to cross two metallic window blinds…).

To diagnose the WiFi coverage is very useful the wifi_signal sensor in ESPHome:

sensor:
  - platform: wifi_signal
    name: Wifi Signal
    update_interval: 60s

It was showing a WiFi signal of -95 dBm in the board: This is very low, and it was experiencing some disconnections.

Usually the ESP32 boards have an antenna integrated in the board, but the ESP32-WROOM-32U has an IPEX connector for an external antenna:

So, I spent less than 10 EUR in Aliexpress buying (affiliate links):

• ESP32-WROOM-32U module
• IPEX to SMA 2.5 dBi external antenna
• Expansion board that makes screwing the ESP32 to the wood mount much easier and simplifies the connections

And replaced the previous ESP32-WROOM-32 module with an ESP32-WROOM-32U, installing the external antenna. This is how it looks now:

The WiFi signal shown in ESPHome increased from -95 dBm to –75 dBm and it’s no longer experiencing any interruptions.