Patent attributes
An electronic device may be provided with a sidewall and an antenna module pressed against an interior surface of the sidewall. The module may include a phased antenna array. The sidewall may have apertures aligned with respective antenna in the array. The antennas may convey radio-frequency signals in first and second frequency bands greater than 10 GHz and with vertical and horizontal polarizations. Each aperture may include a corresponding cavity with non-linear cavity walls. The antennas may excite resonant cavity modes of the cavities that cause the cavities to radiate the radio-frequency signals as waveguide radiators. At the same time, the apertures may form a smooth impedance transition between the antennas and free space for the radio-frequency signals of both the horizontal and vertical polarizations.