It isn't that easy to acquire and monitor Extremely Low Frequency electromagnetic radiation below, say, 30 Hz. The main problem is that it requires large antennae to capture the long wave, low power frequencies. This can be approached several ways. Physically large armatures (9 - 20 feet or more) can be wound with < 100 or small cores can be would with 100s to 1000s of turns.
Thinking about the issue, I decided to try a Cadillac door solenoid I had sitting in my junk box. It was small but had thousands of turns of fine coated wire. Not very rigorous from an engineering standpoint, but the signals would bear out the value of the approach.
This is the FFT results, The first peak at the far left is 12 Hz. There is a small peak at 8.74, the Schumann resonance. As expected, the main peaks were 60 Hz and harmonics. My next step is to create a half dozen calibrated sensors on the end of coax cables, and set them up to sample changes in a house for 24 hours. This should set a baseline for exposure to EMF in the house. I am working out the method of scanning and evaluating personal exposure in a fixed environment that goes (way) beyond walking through the living space with a hand-held TriField meter.
I use the TriField to calibrate in standard units of electromagnetic field strength, magnetic in milligauss and electrical in kilovolts per meter.
Posts
