Abstract: A transmission line includes a first structure including a first flexible resin base material, and a first ground conductor thereon, a second structure including a second flexible resin base material, and a first signal line and an interlayer connection conductor in or on the second resin base material, a first spacer between the first and second structures, and a first metal joining material joining the first and second structures with the first spacer interposed therebetween. A first hollow portion is between the first and second structures with the first spacer interposed therebetween. The first signal line and the first ground conductor face each other in a joining direction with the first hollow portion interposed therebetween. The first resin base material and the second resin base material are not in contact with each other. The first metal joining material has a melting point lower than that of the interlayer connection conductor.

Abstract: A first conductive layer is in contact with a first inter-layer connection conductor and a second inter-layer connection conductor. The first conductive layer has a same composition as the first and second inter-layer connection conductors. At least one first metal foil layer is in contact with a third main surface of the first conductive layer. The at least one first metal foil layer overlaps the first and second inter-layer connection conductors when viewed in a first direction. At least one second metal foil layer overlaps the first and second inter-layer connection conductors when viewed in the first direction, and is electrically connected to the first and second inter-layer connection conductors. The at least one second metal foil layer has a composition different from that of the first conductive layer.

Abstract: An antenna element includes an insulative substrate including first and second main surfaces arranged in an up-down direction. At least one antenna conductor layer is provided on the first main surface of the insulative substrate. At least one insulative substrate non-forming region is provided between the insulative substrate and the antenna conductor layer in the up-down direction. An insulator layer does not exist in the at least one insulative substrate non-forming region. When seen in the up-down direction, all of an outer boundary of at least one antenna conductor overlaps the at least one insulative substrate non-forming region and is not in contact with the insulative substrate. At least one of the at least one insulative substrate non-forming region includes a void.

Abstract: A multilayer substrate includes a multilayer body including resin layers stacked in a Z-axis direction, a signal conductor layer, and one or more through conductors passing through a first resin layer in the Z-axis direction. A first main surface of the first resin layer includes one or more hollow portions not in contact with the signal conductor layer and overlapping the signal conductor layer when viewed in the Z-axis direction. Each of the one or more hollow portions and the one or more through conductors includes a tapered region in which each of a cross-sectional area of the one or more hollow portions orthogonal to the Z-axis direction and a cross-sectional area of the one or more through conductors orthogonal to the Z-axis direction increases toward the first main surface. The tapered region is in contact with the first main surface of the first resin layer.

Abstract: An antenna element includes a first opening including an annular outer boundary in an antenna conductor layer. A first insulative substrate non-forming region is provided between an insulative substrate and the antenna conductor layer in an up-down direction. The insulative substrate does not exist in the first insulative substrate non-forming region. The outer boundary of the first opening overlaps one or more first insulative substrate non-forming regions and is not in contact with the insulative substrate. The first insulative substrate non-forming region is a first void, and a low dielectric constant material having a lower dielectric constant than that of a material of the insulative substrate or a high dielectric constant material having a higher dielectric constant than that of the material of the insulative substrate is provided in the first insulative substrate non-forming region.

Abstract: A multilayer substrate includes a multilayer body including insulation layers stacked on top of one another in an up-and-down direction. The insulation layers include a porous insulation layer. The multilayer substrate includes a first region and a second region. A dimension of the porous insulation layer in the up-and-down direction is smaller in the first region than in the second region. An average void size of the porous insulation layer is smaller in the first region than in the second region, and/or the porous insulation layer is denser in the first region than in the second region.

Abstract: A transmission line includes an element body, a signal conductor layer, and a ground conductor layer. The element body includes an insulator layer. The signal conductor layer is below the insulator layer, and the ground conductor layer is above the insulator layer in an element body up-down direction. A hole is located at a surface of the insulator layer and penetrates the insulator layer in the element body up-down direction. At least a portion of the hole overlaps the signal conductor layer when viewed in the element body up-down direction. The hole extends between a left hole-defining surface and a right hole-defining surface. In a cross section orthogonal to the element body front-back direction, the left hole-defining surface includes a left upper end and a left lower end in the element body left-right direction, and the right hole-defining surface includes a right upper end and a right lower end in the element body left-right direction.

Abstract: In a transmission line, a multilayer body includes a hollow portion above a signal conductor layer and below a ground conductor layer and overlapping the ground conductor layer when viewed in an up-down direction, and a spacer facing the hollow portion. In a cross section orthogonal to a front-back direction, an overlapping region is a region in the hollow portion in which the hollow portion overlaps the spacer in the up-down direction. In a cross section orthogonal to the front-back direction, a non-overlapping region is a region in the hollow portion in which the hollow portion does not overlap the spacer in the up-down direction. A length of the hollow portion in the up-down direction in the overlapping region is shorter than a length of the hollow portion in the up-down direction in the non-overlapping region.

Abstract: A multilayer substrate includes layers stacked on each other in an up-down direction of a multilayer body. The layers include a first spacer, a first ground conductive layer above the first spacer, and a signal conductive layer that overlaps the first ground conductive layer and is located below the first spacer. First through-holes pass through the first spacer and are arranged along a first direction. A distance between centroids of first through-holes adjacent to each other in the first direction is uniform or substantially uniform. Sets of first through-holes are provided in the first spacer. Sets of first through-holes are arranged along a second direction. A distance between centroids of first through-holes adjacent to each other in the second direction is uniform or substantially uniform. At least one first through-hole is a first hollow through-hole overlapping the signal conductive layer.

Abstract: In a transmission line, a signal conductor layer extends in a front-back direction orthogonal to an up-down direction. A ground conductor layer is above the signal conductor layer. When viewed in a first orthogonal direction, first hollow portions are arranged in the front-back direction in a first direction of the signal conductor layer, and second hollow portions are arranged in the front-back direction in a second direction of the signal conductor layer. Each of regions between adjacent first hollow portions in the front-back direction is a first region. Each of regions between adjacent second hollow portions in the front-back direction is a second region. Each of the first hollow portions overlaps with a corresponding one of the second regions when viewed in a second orthogonal direction. Each of the second hollow portions overlaps with a corresponding one of the first regions when viewed in the second orthogonal direction.

Abstract: In a transmission line, a hollow portion overlaps a first ground conductor layer in an up-down direction. In a first orthogonal direction, the hollow portion includes a first portion extending in a second orthogonal direction of a signal conductor layer. In the first portion, a portion at which a width of the first portion in the second orthogonal direction has a first portion maximum width value is a first portion maximum width portion. A portion at which the width of the first portion in the second orthogonal direction has a first portion minimum width value is a first portion minimum width portion. A portion at which the width of the first portion in the second orthogonal direction has a first portion intermediate width value is a first portion intermediate width portion located between the first portion maximum width portion and the first portion minimum width portion in the front-back direction.

Abstract: A transmission line includes a laminated body, a first signal conductor layer in the laminated body and extending in a longitudinal direction, and a first ground conductor layer in the laminated body and provided above the first signal conductor layer to overlap the first signal conductor layer in a vertical direction. A first hollow portion is located above the first signal conductor layer and below or adjacent to the first ground conductor layer. The first hollow portion overlaps the first signal conductor layer and the first ground conductor layer in the vertical direction. An insulator layer in the laminated body is above the first hollow portion. A first upper cavity is provided in the first ground conductor layer. At least a portion of the first upper cavity overlaps the first hollow portion and the first signal conductor layer in the vertical direction.

Abstract: A signal transmission line includes a laminate, a signal conductor, a hollow portion, and a reinforcing conductor. The laminate includes a flexible laminate including resin layers each of which has flexibility. The signal conductor extends in a signal transmission direction of the laminate and is disposed in an intermediate position in a laminating direction of the resin layers. The hollow portion is in the laminate and defined by an opening provided at a portion of the plurality of resin layers. The reinforcing conductor is in the laminate. The hollow portion is disposed at a position overlapping with the signal conductor, in a plan view of the laminate from a surface perpendicular or substantially perpendicular to the laminating direction. The reinforcing conductor is disposed at a position different from the position of the hollow portion in a plan view.

Abstract: An electronic apparatus includes a substrate and an electrical element mounted on the substrate. The electrical element includes a base material including a first principal surface and a second principal surface that are deformable and flat or substantially flat surfaces and a conductor pattern included on the base material. The electrical element further includes a first connection portion and a second connection portion that connect to a circuit included on the substrate and a transmission line portion located in a position different from positions of the first connection portion and the second connection portion that electrically connects the first connection portion and the second connection portion. The conductor pattern includes a conductor pattern of the first connection portion, a conductor pattern of the second connection portion, a conductor pattern of the transmission line portion, and an electrical-element-side bonding pattern arranged in the transmission line portion.

Abstract: An electronic device includes a first substrate and a second substrate. On or in the first substrate, a signal conductor extending in a transmission direction of a high-frequency signal and including a turn portion when viewed in plan is provided. On or in the second substrate, a base overlapping the signal conductor in plan view and including a turn portion while extending along the signal conductor is provided. The base is defined by, for example, a metal plate, has electrical conductivity, and serves as a ground conductor. A gap is provided between the signal conductor and the base having electrical conductivity.

Abstract: A signal transmission line includes first and second base materials, and conductive bonding materials. The first base material includes a signal conductor. The second base material includes a ground conductor. The conductive bonding materials bond the first base and second base material to provide a gap. The first base material includes a mounting conductor to which the conductive bonding materials are respectively bonded. The mounting conductor includes a portion extending in parallel or substantially in parallel with the signal conductor on a side of a first side surface, and a portion extending in parallel or substantially in parallel with the signal conductor on a side of a second side surface. A position of a portion of the mounting conductor on the side of the first side surface and a position of a portion of the mounting conductor on the side of the second side surface are different from each other in a signal transmission direction.

Abstract: A signal transmission line includes a signal region that includes a signal conductor layer and insulating base material layers, and a first ground region that includes a first ground conductor layer and insulating base material layers and is located above the signal region. The signal region is not fixed to the first ground region in a first section of a base. One or more first spacers are fixed to the signal region and in contact with the first ground region without being fixed thereto, or are in contact with the signal region without being fixed thereto and fixed to the first ground region. The one or more first spacers are in the first section.

Abstract: A resin multilayer substrate includes a multilayer body including resin base-material layers laminated in a thickness direction and a circuit conductor therein, an end-surface ground conductor provided directly on each end surface of the multilayer body in the thickness direction, an adhesion layer on a side surface of the multilayer body, and a side-surface ground conductor on the adhesion layer. The end-surface and side-surface ground conductors are made of a ground conductor material with a coefficient of thermal expansion whose difference from a coefficient of thermal expansion of the resin base-material layers in a plane direction is smaller than a difference from a coefficient of thermal expansion of the resin base-material layers in the thickness direction. The adhesion layer is made of a material with higher adhesiveness to the side surface of the multilayer body than adhesiveness of the ground conductor material.

Abstract: A transmission line includes a first structure including a first flexible resin base material, and a first ground conductor thereon, a second structure including a second flexible resin base material, and a first signal line and an interlayer connection conductor in or on the second resin base material, a first spacer between the first and second structures, and a first metal joining material joining the first and second structures with the first spacer interposed therebetween. A first hollow portion is between the first and second structures with the first spacer interposed therebetween. The first signal line and the first ground conductor face each other in a joining direction with the first hollow portion interposed therebetween. The first resin base material and the second resin base material are not in contact with each other. The first metal joining material has a melting point lower than that of the interlayer connection conductor.

Abstract: An RFID system includes an antenna of a reader/writer and an antenna of an RFID tag. Transmission and reception of a high-frequency signal of a UHF band is performed between the antenna of the reader/writer and the antenna of the RFID tag that are arranged so as to be adjacent to each other. A loop antenna including a loop conductor is used as the antenna of the reader/writer, and coil antennas including a plurality of laminated coil conductors are used as the antenna of an RFID tag. In addition, the conductor width of the loop conductor in the loop antenna is greater than the conductor widths of the coil conductors in the coil antennas.