An antenna module is provided for transmitting a wireless signal. The antenna module includes a reflective superstrate, an antenna substrate, a feed conductor, a ground layer and a reflective pattern. The reflective superstrate includes a third surface and a fourth surface, wherein the third surface is opposite to the fourth surface. The antenna substrate includes a first surface and a second surface, wherein the first surface is opposite to the second surface. A feed conductor is disposed on the first surface. The ground layer is disposed on the second surface. The reflective pattern is formed on the third surface and faces the feed conductor, wherein a reflection gap d is formed between the reflective pattern and the ground layer, and the wireless signal has a wavelength λ, and the reflection gap d is between λ/20 and λ/80.