Isotropic Magnetic Field Probe with ICNIRP 2020 Frequency Shaping in the Band up to 400 MHz

We present the design and validation of an isotropic field probe with geometry and frequency response shaped to correctly weight the aggregate contribution of the various frequency components of a broadband magnetic field in the band 100 kHz – 400 MHz according to the ICNIRP 2020 guidelines. The elementary sensor is a small strip loop printed on a thin dielectric substrate. The elementary sensor is initially analyzed via full-wave simulation from which a Thévenin equivalent model is extracted. Careful consideration of the frequency response of the loop and the power detector enabled the optimization of a canonical filtering topology to obtain the desired frequency response. Finally, the isotropic probe assembly consisting of a cubic arrangement of three elementary sensors is validated with respect to isotropy and isolation.