Printed wiring board

A printed wiring board comprising:

• a power supply layer and a ground layer,
• wherein a power supply layer pattern to be formed in the power supply layer includes a power supply layer electrode and a branch that is a direct-current power feeding path connecting adjacent electromagnetic band gap (EGB) unit cells,
• wherein a capacitive coupling element including a capacitive coupling element body is disposed to oppose the power supply layer electrode with an interlayer being provided between the capacitive coupling element and the power supply layer electrode,
• wherein the power supply layer pattern further includes a power supply layer wire that extends from the power supply layer electrode to surround at least a portion of a periphery of the power supply layer electrode, or the capacitive coupling element further includes a capacitive coupling element wire that extends from the capacitive coupling element body to surround at least a portion of a periphery of the capacitive coupling element body, or the power supply layer pattern further includes the power supply layer wire and the capacitive coupling element further includes the capacitive coupling element wire, and
• wherein the power supply layer pattern and the capacitive coupling element form an EBG structure in which the EBG unit cells are disposed at regular intervals, the EBG unit cells being disposed through a via connected to at least one of the power supply layer wire and the capacitive coupling element wire.