Directional coupler, high-frequency module, and communication device

A directional coupler comprising:

• a main line;
• a first sub line, a second sub line, and a third sub line;
• and
• a multilayer substrate comprising a plurality of dielectric layers,
• wherein the multilayer substrate has a first principal surface and a second principal surface opposed to each other,
• wherein the first sub line and the second sub line are connected to each other in series,
• wherein the second sub line and the third sub line are connected to each other in series,
• wherein each of the main line, the first sub line, the second sub line, and the third sub line comprises a portion having a loop shape in plan view from a thickness direction of the multilayer substrate,
• wherein the portions of the main line, the first sub line, the second sub line, and the third sub line are respectively in different ones of the plurality of dielectric layers,
• wherein in each of the first sub line, the second sub line, the third sub line, and the main line, a longest distance from an outer periphery to a center of gravity is a first distance,
• wherein the first distances of the first sub line, the second sub line, and the third sub are different from each other, and
• wherein the sub line having the longest first distance and the sub line having the shortest first distance are on a first principal surface side of the main line, and the sub line having an intermediate first distance is on a second principal surface side of the main line, the intermediate first distance being longer than the shortest first distance and shorter than the longest first distance.