Compact wireless antennas using an artificial dielectric lens

This paper presents a novel design for compact multifunction antennas for wireless applications. To reduce the physical size of the antenna, a high permittivity substrate or superstrate is utilized. In order to suppress the surface waves in the dielectric slab, a grading of the index profile is proposed in both axial and radial directions. Furthermore, the index grading can be done in the antenna feed area to achieve impedance matching. A low-cost and easy-to-manufacture way of achieving the graded index profile is proposed, whereby a set of air voids are created inside the dielectric material to realize an effective dielectric constant. Extensive simulation and experimental results are presented for a slot ring antenna with a high permittivity dielectric superstrate lens.