An ear-worn electronic device includes a housing comprising a first end and an opposing second end, a first side and an opposing second side, and the first and second sides extending between the first and second ends. The first side is configured to contact the wearer's head. A battery is disposed within the housing proximate the first end. An acoustic receiver or an acoustic receiver connector is disposed within the housing proximate the second end. Electronics including a near-field magnetic induction (NFMI) radio are disposed in the housing. A directional magnetic antenna is situated in or on the housing and coupled to the NFMI radio. The antenna comprises a core having a complex shape and a coil wound around a portion of the core. The core comprises a closed end oriented toward a source of magnetic noise and an open end oriented away from the source of magnetic noise.