Analysis of hemispherical Dielectric lens antennas for wireless applications

In this paper we present an accurate analytical formulation of an electrically small aperture radiating in the presence of a hemispherical dielectric lens based on spherical modal expansion (SME) and experimentally demonstrate an increase in directive gain due to lens collimation. The analysis treats the lens as a scatterer. It utilizes techniques for radial translation and coordinate rotation of the small aperture spherical modal coefficients to align them to the phase center of the lens. The SME coefficients of the scattered fields due to the lens are then obtained by application of boundary conditions. A sample computation using this approach shows a good match with experimental results. The analysis is flexible enough to accommodate different types of small radiating apertures with different shapes of dielectric lenses that are inherently broadband and double as an effective radome for environmental protection.