A 3-D-Printing Wideband Circumferentially Foldable Dual-Polarized Spherical Luneburg Lens Antenna

This communication proposes a novel 3D-printing wideband dual-polarized circumferentially foldable Luneburg lens antenna. The proposed Luneburg lens is stratified into three layers. Specifically, to balance foldability and radiation performance, the innermost layer consists of a dielectric sphere with a radially drilled air-filled conical hole, while the other two layers are composed of arc-shaped dielectric sheets that curved in sinusoidal regulation. The design of the foldable Luneburg lens is guided by effective medium theories. A wide-band ridged horn antenna is used to feed the lens. The foldable Luneburg lens antenna is fabricated by the 3D-printing technology. The measured results show that, in the unfolded state, the peak gain varies from 14.7dB to 19.8dB across the frequency band of 6GHz to 11.4GHz, and the aperture efficiency varies between 34.3% and 94.1%. The proposed foldable lens antenna can scan up to ±90° in all planes with the maximum scanning gain loss less than 1.7dB across the operating band. More importantly, the thickness of this lens in the folded state is only 34% of that in the unfolded state.