Beamwidth Control for Directive Antennas using RF Lens

Broadband antennas such as horn and spirals are suitable for testing range references, direction-of- arrival estimation and other UWB applications. However, one problem with most broadband antennas is the frequency dependency of the antenna beamwidth as well as antenna gain. In this work, a beamwidth compensation measure is proposed by adding an RF lens in front of the broadband antenna. By adjusting the curvature profile, the RF lens can be made to reduce the antenna beamwidth. Simulation results show that the main beam becomes more compact after adding a spherical RF lens. Experiment results show that by adding an elongated bullet-shaped RF lens, the antenna patterns can be drastically reduced and hence improve the antenna directivity.