A method of improving antenna performance and an electronic device configured to improve the antenna performance are provided. The electronic device include: a housing; an antenna located inside the housing or formed as part of the housing; a radio frequency (RF) interface configured to transmit/receive wireless signals via the antenna; a groove formed inside an opening in part of the housing; an electrical connector placed inside the groove; a ground member placed inside the housing; a processor electrically connected to the RF interface and the electrical connector; and a memory electrically connected to the processor. The memory stores instructions which enable the processor to detect an external electrical connector inserted into the electrical connector, and select at least one of a plurality of electrical paths between the RF interface and the ground member, in response to at least part of the inserted external electrical connector. Various embodiments are provided.