Electronic device including high-frequency transmission circuit

A portable communication device, comprising:

• a housing;
• a first printed circuit board (PCB) accommodated in the housing;
• a wireless communication circuitry disposed on the first PCB;
• and
• a second PCB having a plurality of layers including:
• a first PCB portion;
• a second PCB portion continuously extended from the first PCB portion and more flexible than the first PCB portion;
• a third PCB portion continuously extended from the second PCB portion and less flexible than the second PCB portion;
• a fourth PCB portion continuously extended from the third PCB portion and more flexible than the third PCB portion;
• and
• a plurality of lines formed at a same layer of the plurality of layers as continuously extended from the second PCB portion through the third PCB portion to the fourth PCB portion, the plurality of lines including a first ground line and a second ground line spaced apart from each other, and a first signal line located between the first ground line and the second ground line.