PURPOSE: To reduce the adverse influence caused by permeation of radio wave from the outside by connecting in series a first and a second coils having specified inductance values, and making winding axis directions of the first and the second coils identical on a printed board.

CONSTITUTION: A first coil 1 and a second coil 2 have inductance values which are respectively one half of a specified inductance value. Said coils are connected in series and arranged on a printed board. The coils have the same winding axis directions. When the permeation of radio wave from the outside happens, an induction current I1 flows in the coil 1, and an induction current I2 flows in the coil 2. Since the winding axis directions of the coils 1 and 2 are identical with reference to the radio wave, the induction currents I1 and I2 flow in the opposite directions at a point (a). As the result, when the inductance values of the coils 1, 2 are equal, the amplitudes of induction currents I1, I2 become equal and cancel with each other. Thereby, the induction current caused by the permeation of radio wave from the outside is remarkably reduced, and the S/N deterioration of a signal can be prevented.