Scanning Aperture Antennas with Spherical Shells

We report on a prototyping platform for antenna design at millimeter wave frequencies with a steerable beam. The antenna beam is formed by a designed aperture in a hollow metallic half-sphere (“shell”) on a circular ground plane which forms a cavity around the antenna feed. The aperture is rotatable around the fixed antenna feed which allows mechanical beam steering without the need for a millimeter wave rotary joint. The shell with the designed aperture is easily replaced by different designs to enable experiments with various beam shapes. Scanning is achieved by rotating the shell around a fixed monopole antenna feed at the center of the platform. Although our setup consists of several resonant parts, there are large enough regions of bandwidth with only a small variation in the antenna pattern.