A Class of Stacked-Disk Dielectric Lenses for Lightweight Wideband Radiating Systems

A novel class of lightweight, single and multi-refractive dielectric stacked-disk lens (SDL) designs with excellent electromagnetic performances, exhibiting reduced cost and enhanced simplicity compared to their massive counterparts, is presented. Design guidelines, derived from an accurate frequency-dispersive uniaxial tensor model of periodic dual-layer planar stacks, allow optimization of the key lens parameters—disk number, permittivity, thickness, diameter, and inter-disk spacing. Several SDLs designed at 5 GHz using these guidelines, exhibiting stop-band thresholds between 6.6 GHz and 13 GHz, -3dB fractional gain lens-antenna bandwidths ranging from 46.6% to 81.1% and aperture efficiencies between 44.5% and 58.8%, are illustrated. Full-wave simulations, employing a locally-conformal finite-integration technique (FIT), show inter-disk field propagation, diffraction, field focusing and stop-band behaviors. A novel time-domain metric, the Proportional-Derivative Energy Fidelity Factor (PDEFF), is introduced to quantify received field waveform quality at the lens focus region, achieving 95–99% for ultra-wideband through-the-wall imaging and 92–94% for UWB waveforms (for lenses having stop-band thresholds near and above 10 GHz). An antenna prototype incorporating a SDL design approaches a peak gain of 17 dBi (approximately 10 dB attributable to the lens) and an 87% weight reduction relative to a conventional massive lens, confirming numerical simulation predictions.