An ear-worn electronic device is configured to be worn by a wearer and comprises a wireless transceiver operably coupled to an antenna. The device is configured to transmit, from the transceiver to the antenna, signals at a plurality of different frequencies in accordance with a frequency hopping sequence. The device is configured collect two-dimensional (2-D) reflection coefficient data comprising a reflection coefficient of the antenna as a function of frequency and of time in response to transmission of the signals. The device is configured to detect a particular input gesture of a plurality of input gestures of the wearer using the 2-D reflection coefficient data, and implement a predetermined function of the ear-worn electronic device in response to detecting the particular input gesture.