Electronic device and method for controlling output power of antenna thereof

An electronic device comprising:

• a housing;
• an antenna disposed in the housing or formed in a part of the housing;
• a grip sensor configured to sense an external object that is in contact with or proximity to the electronic device;
• and
• a processor operatively connected to the antenna and the grip sensor,
• wherein the processor is configured to:
• when a first sensing value from the grip sensor is less than or equal to a first reference value, set a power level of a signal output via the antenna as a first power level;
• when a second sensing value from the grip sensor received after the first sensing value is between the first reference value and a second reference value higher than the first reference value, determine whether the electronic device is in a state of use based on whether a user input is received;
• and
• when the electronic device is not in the state of use, determine whether a difference between the first sensing value and a third sensing value of the grip sensor received after the second sensing value is greater than a third reference value;
• when the difference is less than or equal to the third reference value, maintain the power level of the signal output via the antenna as the first power level;
• and
• when the difference is greater than the third reference value, set the power level of the signal output via the antenna as a second power level lower than the first power level.