The dielectric lens for an ideal focusing effect requires a continuously varying dielectric constant. In this article, the varying dielectric constant is simulated by drilling holes in the lens. The gain improves significantly (˜3 dB) by placing holes in the lens when the lens diameter is much larger than the wavelength (>10 λ) but the hole size is small (<0.25 λ).
No takes yet. Share an insight, caveat, or question.
Lee et al. (1992) studied this question.
Synapse has enriched 5 related papers. Consider them for comparative context: