https://hackaday.com/2018/11/19/diy-mini-helical-antennas-from-salvaged-co-ax-cable/
DIY Mini Helical Antennas From Salvaged Co-ax Cable | Hackaday
Nov 20, 2018 - [Mare] has a visual guide and simple instructions for making DIY mini helical 868 MHz antennas for LoRa applications. 868 MHz is a license-free band in Europe,...
helical antennasco axdiyminisalvaged