A triad of orthogonal Helmholtz coils that allow to create a uniform magnetic field, fixed or rotating, inside a sphere of 60 cm in diameter, or a cubic one of 35x35x35 cm3 (27U CubeSat). The Helmholtz Cage can be used both to cancel the Earth's magnetic field and generate an area with a magnetic field very close to zero, and to produce a magnetic field of intensity up to 4G (up to 5G for short periods), oriented at will in space, both fixed and slowly rotating (up to 1 revolution per second).