An antenna apparatus and an electronic device are provided. The antenna apparatus includes an antenna module and an antenna radome. The antenna module is configured to receive and emit a radio frequency (RF) signal of a preset frequency band toward a preset direction range. The antenna radome is spaced apart from the antenna module, and located within the preset direction range. The antenna radome includes a substrate and a resonant structure carried on the substrate. The substrate is configured to allow a RF signal of a first preset frequency band to pass through, the resonant structure is configured to adjust a passband width of the substrate to the RF signal, to make the antenna radome allow a RF signal of a second frequency band to pass through. A bandwidth of the second frequency band is greater than that of the first frequency band.