An electronic device (500; 1400) comprising: a housing including a front plate (501; 1401) and a rear plate (580; 1480) disposed opposite the front plate (501; 1401); a display (502; 1402) disposed in a space between the front plate (501; 1401) and the rear plate (580; 1480), and disposed at least partially along the front plate (501; 1401); a first antenna structure (540, 541, 542; 1440, 1441, 1442) disposed in the space and configured to transmit or receive a first signal in a first frequency band, wherein the first antenna structure (540, 541, 542; 1440, 1441, 1442) includes at least one first conductive pattern (540; 1440); a second antenna structure (550, 551, 552; 1500) disposed in the space without being overlapped with the first conductive pattern (540; 1440) when viewed from above the rear plate (580; 1480), and configured to transmit or receive a second signal in a second frequency band different from the first frequency band; and a conductive sheet (710; 1610) disposed in the space and directly on the rear plate (580; 1480), wherein the conductive sheet (710; 1610) is physically separated from the first conductive pattern (540; 1440) by no more than half a wavelength of the first signal, and at least partially overlapped with the first conductive pattern (540; 1440) when viewed from above the rear plate (580; 1480), the conductive sheet (710; 1610) is electromagnetically coupled with the at least one first conductive pattern (540; 1440), and characterized in that the conductive sheet (710; 1610) is disposed to be spaced apart from the second antenna structure (550, 551, 552; 1500) based on a wavelength of the second antenna structure (550, 551, 552; 1500) when viewed from above the rear plate (580; 1480) so as to be electromagnetically isolated from the second antenna structure (550, 551, 552; 1500). a housing including a front plate (501; 1401) and a rear plate (580; 1480) disposed opposite the front plate (501; 1401); a display (502; 1402) disposed in a space between the front plate (501; 1401) and the rear plate (580; 1480), and disposed at least partially along the front plate (501; 1401); a first antenna structure (540, 541, 542; 1440, 1441, 1442) disposed in the space and configured to transmit or receive a first signal in a first frequency band, wherein the first antenna structure (540, 541, 542; 1440, 1441, 1442) includes at least one first conductive pattern (540; 1440); a second antenna structure (550, 551, 552; 1500) disposed in the space without being overlapped with the first conductive pattern (540; 1440) when viewed from above the rear plate (580; 1480), and configured to transmit or receive a second signal in a second frequency band different from the first frequency band; and a conductive sheet (710; 1610) disposed in the space and directly on the rear plate (580; 1480), wherein the conductive sheet (710; 1610) is physically separated from the first conductive pattern (540; 1440) by no more than half a wavelength of the first signal, and at least partially overlapped with the first conductive pattern (540; 1440) when viewed from above the rear plate (580; 1480), the conductive sheet (710; 1610) is electromagnetically coupled with the at least one first conductive pattern (540; 1440), and characterized in that the conductive sheet (710; 1610) is disposed to be spaced apart from the second antenna structure (550, 551, 552; 1500) based on a wavelength of the second antenna structure (550, 551, 552; 1500) when viewed from above the rear plate (580; 1480) so as to be electromagnetically isolated from the second antenna structure (550, 551, 552; 1500).