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

A novel class of lightweight, single, and multirefractive 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 interdisk spacing. Several SDLs designed at 5 GHz using these guidelines, exhibiting stopband thresholds between 6.6 and 13 GHz, −3-dB 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 interdisk field propagation, diffraction, field focusing, and stopband 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 ultrawideband through-the-wall imaging and 92%–94% for ultrawideband (UWB) waveforms (for lenses having stopband thresholds near and above 10 GHz). An antenna prototype incorporating an 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.