An electronic device may be provided with wireless circuitry. The wireless circuitry may include antenna structures such as an antenna resonating element arm and an antenna ground. A split return path may be coupled between the antenna resonating element arm and the antenna ground. The antenna structures may form one or more inverted-F antennas when operated at non-near-field communications frequencies. The antenna structures may be coupled to near-field communications transceiver circuitry using a conductive path. When operated at near-field communications frequencies, near-field communications signals may be conveyed using the conductive path, the antenna resonating element arm, the return path, and the antenna ground. A capacitor may be coupled between the conductive path and an antenna ground. The capacitor may short non-near-field communications signals to the antenna ground and block near-field communications signals from passing from the conductive path to the antenna ground.