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 Wi-Fi range, due to its design. To address this issue with minimal effort, I implemented a simple antenna modification that drastically improved performance.

This modification involves adding a 1.0-mm silver-plated wire with a total length of 31 mm, 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 an oval loop with a diameter of about 8 mm), while the remaining section is angled vertically upwards (Figure 1).

Part of the wire is bent into a horizontal loop, while the remaining section is angled vertically upwards.
Figure 1: Part of the wire is bent into a horizontal loop,
while the remaining 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 (Fi...