Transmission line and electronic device

A transmission line comprising:

• an element body including a first insulator layer and a main surface with a normal line extending in an element body up-down direction;
• a signal conductor layer below the first insulator layer in the element body in the element body up-down direction;
• and
• a first ground conductor layer above the first insulator layer in the element body in the element body up-down direction;
• wherein
• the first insulator layer includes a first hole penetrating the first insulator layer in the element body up-down direction;
• a direction in which the signal conductor layer extends is an element body front-back direction;
• a line width direction of the signal conductor layer is an element body left-right direction;
• at least a portion of the first hole overlaps the signal conductor layer when viewed in the element body up-down direction;
• the first hole extends between a first left hole-defining surface and a first right hole-defining surface;
• and
• in a cross section orthogonal to the element body front-back direction, the first left hole-defining surface includes a first left upper end and a first left lower end in the element body left-right direction, and the first right hole-defining surface includes a first right upper end and a first right lower end in the element body left-right direction.