ESP32-S3-ZERO ANTENNA MOD

I have several Waveshare ESP32-S3-ZERO modules equipped with an Aircross C03 SMD chip antenna.
The modules were initially unstable and had a very unsatisfying WIFI performance.
Adding a low ESR 100nF capacitor to the 3V3 pin improved stability slightly.

However, after modifying the original antenna with my custom antenna, the module became reliably stable. The mod increased the gain by at least +10 dB and reduced power reflection, which likely helped stabilize the ESP32-S3 and at least doubled the WiFi operating range.

The antenna mod consists of a 32 mm, 1 mm silver-coated wire: 16 mm looped around the chip antenna (soldered to both ends), and 16 mm angled straight upwards.

Please obey the antenna’s foot point located at the chip antenna‘s solder pad with the white ring.

I’ve described more details at https://peterneufeld.wordpress.com/2025 ... ification/
A similar mod regards the ESP32-C3 SuperMini here at Elektor labs .

Above there  is a photo of my portable setup, showing a modified module next to an original one. This setup got moved around the WiFi-AP to log the quality of the connection.

Below is the RSSI of the Wi-Fi AP, logged simultaneously by both modules at nearly the same location. Green indicates the modified module.
The logger was  written with Annex32 a versatile script interpreter for ESP32-X https://cicciocb.com/links/

As expected and reported by many users of this board the unmodified board has a bad WIFI-performance. In my environment   it even often stopped transmitting after about one minute, although without rebooting.
I checked the temperature of the boards at that time and found a slight temperature difference. Overall, the board was more broadly heated and the internal protection circuit seems to limit the current at the TX circuit to acceptable  values.

The described mod enabled the modified antenna to radiate the WiFi power much better than the original antenna. There is less power reflected to the chip and no more trigger of the protection circuit. Additionally the better performance of the antenna results in better reception of low level signals as well.

BTW: All this also applies to the Bluetooth function!