GoKawiilBoosting ESP32-C3 SuperMini WiFi: A Simple and Effective Antenna Mod
The ESP32-C3 SuperMini modules are incredibly affordable, costing around €2, and are equipped with a compact SMD antenna. However, this tiny antenna significantly limits the usable WiFi range due to its design. To address this issue with minimal effort, I implemented a simple antenna modification that drastically improved performance.
The Antenna Modification
This modification involves adding a 31 mm length of 1.0 mm silver-plated wire, configured as a quarter-wavelength (λ/4) antenna.
The bottom section of the wire is bent into a horizontal loop (approximately 16 mm of the wire length, forming a loop with a diameter of about 8 mm), while the remaining 15 mm section is angled vertically upwards.
I wrapped the circular loop around the shaft of a 5 mm drill and then widened the ends of the loop so that they touch the terminals of the SMD antenna. The SMD antenna effectively completes the wire loop—mechanically at a quarter of its circumference, but electrically as a λ/4 element in parallel with a λ/8 wire.
Solder the new antenna directly to both ends of the original SMD antenna on the ESP32 module. Specifically, solder to the 50 Ohm antenna pin (the left end of the original antenna) and to the other “hot” end of the original antenna. This effectively bypasses the original PCB antenna. Ensuring two good solder joints at both ends of the PCB antenna is crucial. Pay close attention to the position of the wire that goes up from the loop. The old aerial has been left in place as it becomes electrically ineffective in this configuration.
EDIT: Meanwhile, some adaptations of my antenna design have been published in blog posts and YouTube videos. However, some of these adaptations struggle with the TOTAL 31mm length of the antenna wire, leading to suggestions to elongate the vertical section to make the complete antenna a 5/8 lambda radiator. This isn’t very wise if you want the antenna to radiate omnidirectionally and preserve the acceptable mechanical dimensions.
Testing with the WiFi Logger Program
To evaluate the effectiveness of this modification, I used my custom WiFi logger program written for ANNEX32 BASIC. The program compares the signal strength (RSSI) of two ESP32 modules: one unmodified and one with the new antenna.
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