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.

An electronic device includes a circuit board and an electric element mounted on the circuit board. The electric element includes a multilayer body made of electrically insulating base materials, a transmission line portion, and connection portions. The transmission line portion and the connection portions are provided in the multilayer body. Each of the connection portions is continuous with a corresponding portion of the transmission line portion, and is connected to the circuit board by an electrically conductive bonding material. The transmission line portion other than the connection portions is not electrically connected to an electronic component on the circuit board. The electronic component not electrically connected to the electric element is disposed between the transmission line portion of the electric element and the circuit board.

A conductor non-formed portion where no conductor layer exists is provided in a first ground conductor layer. A multilayer body is provided with a void where no insulating resin exists. At least a portion of the conductor non-formed portion is provided in a first area positioned at a right of a first interlayer connection conductor with respect to a multilayer body left-right direction and at left of a second interlayer connection conductor with respect to the multilayer body left-right direction in a view in a multilayer body downward direction. At least a portion of a void overlaps with the conductor non-formed portion in the view in the multilayer body downward direction and is provided above a first signal conductor layer with respect to a multilayer body up-down direction and below the first ground conductor layer with respect to the multilayer body up-down direction.

A distributed amplifier includes a transmission line configured so as to transmit a signal, a variable capacitor having one end connected to the transmission line and the other end connected to the ground, and configured so that the capacitance is adjustable, and a variable capacitor having one end connected to the transmission line and the other end connected to the ground, and configured so that the capacitance is adjustable. The transmission line is configured in such a manner that the inductance is adjustable.

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.

A multi-layer waveguide including at least three physical layers assembled into a multi-layer waveguide. The layers are a top layer, one or more intermediate layer, and a bottom layer. The multi-layer waveguide further includes a waveguide channel being an elongated aperture in at least one intermediate layer. At least one layer has a metasurface on a first surface facing a first adjoining layer, wherein the metasurface surrounds the elongated aperture and comprise thick and thin sections.

This application provides a spoof surface plasmon polariton transmission line structure, a circuit board, and an electronic device, to reduce a size of the SSPP transmission line structure. The SSPP transmission line structure includes a first dielectric substrate, a first metal strip, and a second metal strip. The first metal strip and the second metal strip are respectively disposed on two opposite surfaces of the first dielectric substrate, the first metal strip and the second metal strip separately extend in a first direction, and a length of the first metal strip in the first direction is less than a length of the second metal strip in the first direction. In the first direction, a cross-sectional area of the first metal strip gradually decreases, and at least one side of the second metal strip has a plurality of protrusion parts spaced apart.

A transmission line has a first conductor layer extending in a first direction, a second conductor layer disposed on a side of a first surface of the first conductor layer via a first dielectric layer, the second conductor layer extending in the first direction, and a third conductor layer disposed on a side of a second surface of the first conductor layer opposite to the first surface, via a second dielectric layer, the third conductor layer extending in the first direction, wherein a width, in a second direction intersecting the first direction, of each of the second conductor layer and the third conductor layer is different at a plurality of locations in the first direction, and the first conductor layer, the second conductor layer, and the third conductor layer at least partially overlap each other in a plan view from a normal direction of the first surface.

In a transmission line, a thickness of a second section is smaller than that of a first section and of a third section. A center of the second section is above a center of the first section and a center of the third section in a laminated body up-down direction. A distance between a second signal conductor layer and a neutral plane of the second section is shorter than a distance between a first signal conductor layer and a neutral plane of the second section and a distance between a third signal conductor layer and a neutral plane of the second section in the laminated body up-down direction. A length of the second signal conductor layer between first and second interlayer connection conductors is equal to or less than about ½ of a wavelength of a high-frequency signal transmitted by the transmission line.

A transmission line includes connecting portion connected to the outside and a main body connected to the connecting portion. The connecting portion includes a terminal electrode connected to an external electrode, a signal conductor, and a ground conductor. The main body includes the signal conductor and the ground conductor. The connecting portion includes a first region including the terminal electrode, a second region adjacent to the first region along a signal transmission path, and a third region located between the second region and the main body. Impedance matching at the at least one of the connecting portions is achieved by the first region, the second region, and the third region.