Patent ID: 7227428

Claim:
An RF module comprising: a first waveguide having a ground electrode, a dielectric substrate, and a line pattern of a conductor provided on the dielectric substrate, for propagating electromagnetic waves in a TEM mode; and a second waveguide connected to the first waveguide, for propagating electromagnetic waves in another mode different from the TEM mode, wherein the second waveguide has a region surrounded by at least two ground electrodes facing each other and conductors for bringing the at least two ground electrodes into conduction, wherein the electromagnetic waves in said another mode propagate in the region, the first waveguide extends in a direction orthogonal to a stacking direction of the ground electrodes of the second waveguide, an end of the line pattern of the conductor is directly connected so as to be conductive to one of the ground electrodes of the second waveguide from the direction orthogonal to the stacking direction, and magnetic fields of the first and second waveguides are coupled in an E plane of the second waveguide so that the direction of the magnetic field of the electromagnetic waves propagated in the first waveguide and the direction of the magnetic field of the electromagnetic waves in said another mode propagated in the second waveguide match with each other, wherein a plurality of penetrating conductors penetrating the dielectric substrate are provided around the line pattern so as to sandwich the line pattern between the plurality of penetrating conductors and an interval between the plurality of penetrating conductors sandwiching the line pattern in the width direction is equal to or less than a cut-off frequency of the electromagnetic waves propagating through the first waveguide.