High-frequency transmission line connection structure, circuit board, high-frequency module, and radar device

A high-frequency transmission line connection structure, for electrically connecting a high-frequency transmission line conductor and a laminated waveguide to each other, comprising:

• the laminated waveguide comprising a first laminated waveguide, a second laminated waveguide, and a common line part between the first laminated waveguide and the second laminated waveguide, wherein
• the first laminated waveguide comprises:
• a sub-line part, which is connected to the high-frequency transmission line conductor, comprising a dielectric layer, a pair of sub-line part main conductor layers that oppose each other in a thickness direction with the dielectric layer interposed therebetween, and an array of sidewall-forming via-hole conductors that electrically connects the pair of sub-line part main conductor layers in the thickness direction;
• a main-line part, which is connected to the sub-line part, comprising a dielectric layer thicker than the dielectric layer of the sub-line part, a pair of main-line part main conductor layers that oppose each other in the thickness direction with the dielectric layer interposed therebetween, and an array of sidewall-forming via-hole conductors that electrically connects the pair of main-line part main conductor layers in the thickness direction;
• and
• a conversion part composed of one layer of the pair of sub-line part main conductor layers and one layer of the pair of main-line part main conductor layers, both layers being formed as one, and the conversion part being electrically connected to the high-frequency transmission line conductor,
• the second laminated waveguide sharing at least one dielectric layer among the dielectric layers of the first laminated waveguide, comprises:
• a pair of main conductor layers that oppose each other in the thickness direction with a plurality of dielectric layers comprising the shared dielectric layer interposed therebetween;
• and
• an array of sidewall-forming via-hole conductors that electrically connects the pair of main conductor layers in the thickness direction,
• wherein one layer of the pair of main conductor layers is disposed closer to one side in the thickness direction than the conversion part, and the other layer of the pair of main conductor layers is disposed closer to one side in the thickness direction than the other layer of the pair of sub-line part main conductor layers, the common line part comprises:
• a pair of common line main conductor layers that oppose each other in the thickness direction with the dielectric layers of both the first laminated waveguide and the second laminated waveguide interposed therebetween;
• and
• an array of sidewall-forming via-hole conductors that electrically connects the pair of common line main conductor layers in the thickness direction, and
• wherein one layer of the pair of common line main conductor layers is electrically connected to the conversion part, and the other layer of the pair of common line main conductor layers is electrically connected to the other layer of the pair of main conductor layers.