Wi-Fi has become a cornerstone of modern connectivity, enabling wireless data transfer across homes, workplaces, and public spaces. It operates in the microwave range of the electromagnetic spectrum, typically at frequencies of 2.4 GHz or 5 GHz. While essential for internet access, these signals are invisible to the human eye because our vision is limited to the visible light spectrum, leaving other frequencies, such as microwaves, undetectable without specialised equipment.
The XJ9 radio telescope, by Justin Atkin from the Thought Emporium YouTube channel, is designed to bridge this gap by capturing and visualising Wi-Fi signals. Using a software-defined radio (SDR) and a movable antenna system, the XJ9 measures the intensity of Wi-Fi signals at various locations. In his setup, Justin used a HackRF for this purpose. These measurements are then processed into visual images, similar to heatmaps, which reveal the distribution and strength of Wi-Fi signals in an area. Constructed with geared stepper motors, a swappable antenna head, and precision components, the XJ9 offers a stable and scalable platform for analysing electromagnetic radiation in the Wi-Fi spectrum.
This project draws inspiration from radio astronomy, where large deep space radio telescopes map cosmic phenomena by detecting microwave frequencies. Similarly, the XJ9 applies these principles to visualise local Wi-Fi environments, highlighting its potential for spatial mapping and signal analysis. By offering a practical tool for understanding electromagnetic environments, the XJ9 demonstrates how techniques used in space exploration can be adapted for everyday technological applications. More details can be found on his YouTube video with all the open-source 3D files for the build available on the GitHub repository linked in the video description.
