Abstract: A signal coupling device comprises a low-frequency circuit including a magnetic ring having an opening and a high-frequency circuit including a rod-shaped magnet. A first-level circuit is formed around the magnetic ring and extends between a first-level circuit input and a first-level circuit output. A second-level circuit is formed around the magnetic ring and extends between a second-level circuit input and a second-level circuit output. The high-frequency circuit includes a third-level circuit formed around the rod-shaped magnet and extends between a third-level circuit input and a third-level circuit output. A fourth-level circuit is formed around the rod-shaped magnet and extends between a fourth-level circuit input and a fourth-level circuit output. The first-level circuit output is coupled to the third-level circuit input and the second-level circuit output is coupled to the fourth-level circuit input.