Abstract: The present invention proposes a coupling device, comprising a substrate (1), a conductive layer (2) covering a first surface of said substrate (1), at least two electromagnetically coupled lines (3a, 3b) being provided opposite to said first surface and at least one thereof being covered by at least one cover layer (4, 5) wherein at least one capacitor (C1, C2, C3, C4) is connected between a first end of at least one of said at least two lines (3a, 3b) and said conductive layer (2). The at least one capacitor is a buried capacitor grounded in order to equalize unequal phase velocities otherwise degrading the performance of e.g. broadside coupled structures in an inhomogeneous substrate structure such as for example microstrips in a multilayer LTCC. Therefore the present invention enables coupling devices having a high performance and offering in that way the best of all possible design scenarios in terms of wideband performance, size and cost.

Abstract: The present invention proposes a coupling device, comprising a substrate (1), a conductive layer (2) covering a first surface of said substrate (1), at least two electromagnetically coupled lines (3a, 3b) being provided opposite to said first surface and at least one thereof being covered by at least one cover layer (4, 5) wherein at least one capacitor (C1, C2, C3, C4) is connected between a first end of at least one of said at least two lines (3a, 3b) and said conductive layer (2). The at least one capacitor is a buried capacitor grounded in order to equalize unequal phase velocities otherwise degrading the performance of e.g. broadside coupled structures in an inhomogeneous substrate structure such as for example microstrips in a multilayer LTCC. Therefore the present invention enables coupling devices having a high performance and offering in that way the best of all possible design scenarios in terms of wideband performance, size and cost.